Titan battery expansion port experience?

[ed6269]

Hello everyone
I recently purchased a Titan and have questions about the external battery port , I have tried to get some answers from Point Zero and found their answers short and not vary helpful, after alot of back and forth I know I can charge my 4 Lion energy safari batteries via the expansion port provided all batteries are the same 24 volts and within 0.5 volts of each other even if they are different chemistry than the Titan battery.
They also informed me that with the Lion energy batteries hooked up in conjunction with the Titan battery I can use the full 3000 watt output of the inverter (they require at least 2 batteries to get the 3000 watt output without damaging a single battery which I would prefer not buying)
What worries me now is that the Titan battery when topped off is 29.2 volts and I don't think the Lion energy batteries will charge that high in 24 volt configuration, and Point Zero said they ALL need to be within 0.5 volts, am I wrong, any suggestions?
Also I am wondering if I can just use the Lion energy batteries without the Titan battery hooked up because the chemistry lasts so much longer?
Any other pointers or experiences with the battery expansion port would be appreciated .
Thanks so much
Eddie

 

[bdbugbee]

Hello everyone
I recently purchased a Titan and have questions about the external battery port , I have tried to get some answers from Point Zero and found their answers short and not vary helpful, after alot of back and forth I know I can charge my 4 Lion energy safari batteries via the expansion port provided all batteries are the same 24 volts and within 0.5 volts of each other even if they are different chemistry than the Titan battery.
They also informed me that with the Lion energy batteries hooked up in conjunction with the Titan battery I can use the full 3000 watt output of the inverter (they require at least 2 batteries to get the 3000 watt output without damaging a single battery which I would prefer not buying)
What worries me now is that the Titan battery when topped off is 29.2 volts and I don't think the Lion energy batteries will charge that high in 24 volt configuration, and Point Zero said they ALL need to be within 0.5 volts, am I wrong, any suggestions?
Also I am wondering if I can just use the Lion energy batteries without the Titan battery hooked up because the chemistry lasts so much longer?
Any other pointers or experiences with the battery expansion port would be appreciated .
Thanks so much
Eddie

I installed a Titan in my camper under the bed with 2x2 kWh stackable batteries which are NMC chemistry, but I wanted more battery capacity in limited space without paying the steep price for more Titan batteries. I built a relatively inexpensive ($850) 24V 8S 176Ah external LiFePo4 battery pack w/ its own BMS to supplement the Titan batteries with an additional 4.4 kWh of capacity. I did not want to directly connect batteries with different chemistries because even though they are somewhat similar, a 7S NMC battery has a different voltage/capacity curve than an 8S LiFePo4 battery. I also did not want to charge my external LiFePo4 battery to 29.2V. So I decided to connect the batteries thru an ISDT Q8 DC-DC charger/converter to connect the output of my LiFePo4 battery to the 50A Anderson wall charging port on the Titan and use it as a 24V "battery charger" for the Titan. I also found that you can flow 24V DC power out from the wall charger port of the Titan with no problems and bi-directional net power flow shows up correctly on the Titan's display as well. So I wired up the DC-DC converter through a 4 pole switch so that I can quickly set up directional flow to "charge" my LiFePo4 battery from the Titan as well. The ISDT Q8 DC-DC converter is capable of up to 20 Amps of charging current in either direction and I don't have to worry about keeping the battery voltages matched or overcharging either battery.

Note: I connected my external battery pack to the Titan's wall charger port and not the external battery port, since I used a DC-DC converter between them and use the external battery as a "charger" or "load". I do not consider the external battery as part of my main Titan battery and thus I did not update the AH capacity on the Titan in this use case. I track the external battery's SOC thru its own Bluetooth BMS. I can also charge the external battery from my truck's alternator thru a separate Victron Orion 12/24-15 DC-DC converter. My external battery is in the plywood box below the ISDT/4-pole switch and the Victron DC-DC converter. Also shown in the photo is my AC transfer switch (Titan AC or shore power) and shore power input breaker box and receptacle for powering the Titan's AC wall chargers. Since this photo was taken I have also installed multiple cabinet cooling fans which are powered from one of the Titan's AC receptacles.



If you decide to directly connect an LiFePo4 external battery without a DC-DC converter, you should only connect it to the Titan's external battery port (not the wall charging port) when the batteries are at the same voltage because they will be paralleled and then considered one big battery bank. You can't control or monitor the power flow between them. In this case you would have to update the total bank AH capability of the Titan's display to reflect the total bank capacity and SOC. You would also have to make sure that you keep your total bank voltage within the range of the most limiting battery chemistry.

 

[ed6269]

I installed a Titan in my camper under the bed with 2x2 kWh stackable batteries which are NMC chemistry, but I wanted more battery capacity in limited space without paying the steep price for more Titan batteries. I built a relatively inexpensive ($850) 24V 8S 176Ah external LiFePo4 battery pack w/ its own BMS to supplement the Titan batteries with an additional 4.4 kWh of capacity. I did not want to directly connect batteries with different chemistries because even though they are somewhat similar, a 7S NMC battery has a different voltage/capacity curve than an 8S LiFePo4 battery. I also did not want to charge my external LiFePo4 battery to 29.2V. So I decided to connect the batteries thru an ISDT Q8 DC-DC charger/converter to connect the output of my LiFePo4 battery to the 50A Anderson wall charging port on the Titan and use it as a 24V "battery charger" for the Titan. I also found that you can flow 24V DC power out from the wall charger port of the Titan with no problems and bi-directional net power flow shows up correctly on the Titan's display as well. So I wired up the DC-DC converter through a 4 pole switch so that I can quickly set up directional flow to "charge" my LiFePo4 battery from the Titan as well. The ISDT Q8 DC-DC converter is capable of up to 20 Amps of charging current in either direction and I don't have to worry about keeping the battery voltages matched or overcharging either battery.

Note: I connected my external battery pack to the Titan's wall charger port and not the external battery port, since I used a DC-DC converter between them and use the external battery as a "charger" or "load". I do not consider the external battery as part of my main Titan battery and thus I did not update the AH capacity on the Titan in this use case. I track the external battery's SOC thru its own Bluetooth BMS. I can also charge the external battery from my truck's alternator thru a separate Victron Orion 12/24-15 DC-DC converter. My external battery is in the plywood box below the ISDT/4-pole switch and the Victron DC-DC converter. Also shown in the photo is my AC transfer switch (Titan AC or shore power) and shore power input breaker box and receptacle for powering the Titan's AC wall chargers. Since this photo was taken I have also installed multiple cabinet cooling fans which are powered from one of the Titan's AC receptacles.

View attachment 52558

If you decide to directly connect an LiFePo4 external battery without a DC-DC converter, you should only connect it to the Titan's external battery port (not the wall charging port) when the batteries are at the same voltage because they will be paralleled and then considered one big battery bank. You can't control or monitor the power flow between them. In this case you would have to update the total bank AH capability of the Titan's display to reflect the total bank capacity and SOC. You would also have to make sure that you keep your total bank voltage within the range of the most limiting battery chemistry.

WOW that's a lot of great information and options , Thanks
Just on a side note , The people that I was seeking information from on this subject was not Point Zero as stated in the OP but a distributor for the Titan , I have since been in contact with Point Zero and they have been extremely responsive and helpful.
Here is the information that I received today as follows.


Yes you can connect the LiFePo4 batteries to the external battery expansion port without the Titan Battery, and it should charge fine. The Charge voltage of a 24V LiFePo4 battery is 29.2V, which is what our Titan charges to. So that should be fine.

The only issue you could run into is that the SB50 port can only handle 1500 watts. So if you plan on running anything more than 1500 watts without the Titan battery, you would need to connect your batteries to the two battery ports on the bottom of the Titan in order to be able to handle the power load.

If you want to run the LiFePo4 batteries with the Titan battery, you just need to make sure the voltage of the two batteries are within 0.5V before connecting. Then set the meter to the correct total amp hours, and fully charge the system to calibrate the meter.

 

[bdbugbee]

WOW that's a lot of great information and options , Thanks
Just on a side note , The people that I was seeking information from on this subject was not Point Zero as stated in the OP but a distributor for the Titan , I have since been in contact with Point Zero and they have been extremely responsive and helpful.
Here is the information that I received today as follows.


Yes you can connect the LiFePo4 batteries to the external battery expansion port without the Titan Battery, and it should charge fine. The Charge voltage of a 24V LiFePo4 battery is 29.2V, which is what our Titan charges to. So that should be fine.

The only issue you could run into is that the SB50 port can only handle 1500 watts. So if you plan on running anything more than 1500 watts without the Titan battery, you would need to connect your batteries to the two battery ports on the bottom of the Titan in order to be able to handle the power load.

If you want to run the LiFePo4 batteries with the Titan battery, you just need to make sure the voltage of the two batteries are within 0.5V before connecting. Then set the meter to the correct total amp hours, and fully charge the system to calibrate the meter.

The answer that Point Zero gave you is consistent with my experience. However I would still be leery of directly paralleling the LiFePo4 with the NMC chemistry for the reasons I mentioned above. It is true that an 8S LiFePo4 battery can be charged to 29.2V but that assumes the cells are perfectly top balanced. Mine are close but not perfect and a 29.2V total bank voltage would drive at least one of my LifEpo4 cells past 3.65V. In order to stay in my comfort zone I really don't like charging my LiFePo4 bank above 28.4V. I find that I have to de-rate the Titan battery about 10% if I only charge it to 28.4V. I also have had a few times when my Titan solar charge controllers didn't stop charging the Titan batteries at 29.2V. It sometimes goes to 29.4V and once I observed it as high as 29.7V which is definitely too high for LiFePo4 (and the Titan NMC) batteries. Point Zero has offered to check and fix it if necessary under warranty, but at this point I'm still debating whether or not I want to ship my Titan back across country and not have it during camping season. If you parallel an external LiFePo4 battery keep a close eye on the charge voltage from the built-in solar controllers and the AC wall chargers. If you have already purchased a Titan battery I would continue to use that as your primary battery and connect an external LiFePo4 battery thru a DC-DC converter/charger. In addition to the $59 Q8 (500W max), ISDT also sells the P20 dual channel (~$129) that would allow you move up to 35A (800W) between batteries, so you could run your inverter at 1500 watts + 800 watts = 2300 watts, without damaging your Titan battery. ISDT also sells the P30 dual channel with 1500W max transfer capability and Bluetooth monitoring, but that was a little too expensive (~$189) for my needs. The P30 would however allow you to run the inverter at the full 3000W with one Titan battery plus the external LiFePo4 battery. Let me know if you have any other questions regarding the external battery connection.

 

[ed6269]

The answer that Point Zero gave you is consistent with my experience. However I would still be leery of directly paralleling the LiFePo4 with the NMC chemistry for the reasons I mentioned above. It is true that an 8S LiFePo4 battery can be charged to 29.2V but that assumes the cells are perfectly top balanced. Mine are close but not perfect and a 29.2V total bank voltage would drive at least one of my LifEpo4 cells past 3.65V. In order to stay in my comfort zone I really don't like charging my LiFePo4 bank above 28.4V. I find that I have to de-rate the Titan battery about 10% if I only charge it to 28.4V. I also have had a few times when my Titan solar charge controllers didn't stop charging the Titan batteries at 29.2V. It sometimes goes to 29.4V and once I observed it as high as 29.7V which is definitely too high for LiFePo4 (and the Titan NMC) batteries. Point Zero has offered to check and fix it if necessary under warranty, but at this point I'm still debating whether or not I want to ship my Titan back across country and not have it during camping season. If you parallel an external LiFePo4 battery keep a close eye on the charge voltage from the built-in solar controllers and the AC wall chargers. If you have already purchased a Titan battery I would continue to use that as your primary battery and connect an external LiFePo4 battery thru a DC-DC converter/charger. In addition to the $59 Q8 (500W max), ISDT also sells the P20 dual channel (~$129) that would allow you move up to 35A (800W) between batteries, so you could run your inverter at 1500 watts + 800 watts = 2300 watts, without damaging your Titan battery. ISDT also sells the P30 dual channel with 1500W max transfer capability and Bluetooth monitoring, but that was a little too expensive (~$189) for my needs. The P30 would however allow you to run the inverter at the full 3000W with one Titan battery plus the external LiFePo4 battery. Let me know if you have any other questions regarding the external battery connection.

Yes I agree I am definitely not comfortable charging LiFePO4 to 29.2 and 28.4 sounds much better. Are you saying you were able to lower the SCC by 10%?
I was playing in the screen menu and saw it was set at 29.0 volts but it charges up to 29.2. Did you adjust this down successfully?
I certainly appreciate all your advice on the DC to DC converter but I am not really understanding how all this works as far as charging the external battery pack thru the AC charging port, maybe if you gave me some links to where to buy these units I would be able to read up on them, I would be most interested in the 189.00 one so I could get the full 3000 watts from the inverter but I would read up on all of them , if I can derate the titan battery to 28.4 or less I think that would make life easier on the Titan battery and definitely prolong the life of the Lion energy battery pack. If you drop the voltage of the SCC do you also drop the AH from 74 and if so how much for a voltage of 28.2.
Thanks
Eddie

 

[bdbugbee]

Yes I agree I am definitely not comfortable charging LiFePO4 to 29.2 and 28.4 sounds much better. Are you saying you were able to lower the SCC by 10%?
I was playing in the screen menu and saw it was set at 29.0 volts but it charges up to 29.2. Did you adjust this down successfully?
I certainly appreciate all your advice on the DC to DC converter but I am not really understanding how all this works as far as charging the external battery pack thru the AC charging port, maybe if you gave me some links to where to buy these units I would be able to read up on them, I would be most interested in the 189.00 one so I could get the full 3000 watts from the inverter but I would read up on all of them , if I can derate the titan battery to 28.4 or less I think that would make life easier on the Titan battery and definitely prolong the life of the Lion energy battery pack. If you drop the voltage of the SCC do you also drop the AH from 74 and if so how much for a voltage of 28.2.
Thanks
Eddie

Unfortunately the customer can't adjust the charging voltage parameters of the Titan's solar charge controllers (or the AC wall chargers for that matter). The screen menu has no bearing on the settings of the charge controllers. They are preset to charge up to around 29.2V, but if my unit is any indicator, they can go higher if you don't manually stop the charging. When I referred to derating the Titan I was simply saying that my particular Titan unit only reaches a SOC of about 90% if I manually stop charging it when the voltage reaches 28.4V, which is what I would have to do if I directly connected a LiFePo4 battery to the Titan NMC battery. It's a manual process, unfortunately.

The AC wall charging ports are wired directly to the Titan's 24V battery bus and appear to be capable of 50a for each port (but I'm not sure if each is rated 50a or both in total are 50a - I haven't pushed it that far). Remember that the AC wall charger that comes with the Titan converts 120V AC power to 24V DC and plugs into one of the wall charging ports on the Titan and puts out about 500 watts. In addition to the wall charger, I have made an Anderson connector lead which plugs into the other wall charger port from the output/input of the ISDT DC-DC charger as another way to charge/load the Titan's 24V battery from/to the LiFePo4 battery depending on the 4 pole 3 position switch. Here is an Amazon link to the high power version of the ISDT charger (P30):

Amazon.com

Here are the link's to the 4 pole, 3 position switch and enclosure that I used to be able to switch the direction of the power flow between my batteries:

VictorsHome Changeover Switch LW28-63 3 Positions 16 Terminals Universal Rotary Cam Selector Latching Switches 690V 63A: Amazon.com: Industrial & Scientific

VictorsHome Changeover Switch LW28-63 3 Positions 16 Terminals Universal Rotary Cam Selector Latching Switches 690V 63A: Amazon.com: Industrial & Scientific

www.amazon.com

Amazon.com

Here is a link to the BMS that I used for my LiFePo4 battery pack. It is a quality BMS and I highly recommend it:

8s BMS 100a LifePo4 with M6 Threaded Terminals – Overkill Solar

overkillsolar.com

If you are looking at using the ISDT P30 you have to combine both output channels to get the full 1500 watts of capability of the P30. You also have to make sure your wiring and connectors are rated to handle the maximum available amps flowing between the batteries.

I did not change nor do I recommend that you change the 74AH rating of the Titan battery unless you directly connect your external battery to the Titan 24V bus through the external battery port without a DC-DC converter. Just know that if you manually stop charging the Titan at 28.4V, the max SOC of the Titan battery will be closer to 90% or 67AH and the LiFePo4 SOC will be at 100%. Your experience with your unit may vary from my experience with my unit. If you have a DC-DC converter between the batteries you can comfortably charge the Titan's battery up to 29.0V and won't have to worry about the LiFePo4 battery being overcharged. In that case the Titan battery will reach 100% SOC.

There is one other thing to note on the ISDT DC-DC chargers/converters. I do not use the balancing ports on the output of the ISDT unit. I only use the main output ports to charge the battery pack as a whole. I rely on my BMS to protect and balance individual cells of my LiFePo4 battery pack. I also have set my ISDT charger to stop charging when the battery pack output voltage reaches 28.35V (7S x 4.05V in the Li-ion setting) for either direction.

By the way I have no affiliation with any of the companies whose products I have mentioned. I purchased these with my own money and use these products based on my own research and needs. Your needs may be different and you will have to draw your own conclusions as to whether or not these would work for your use case.

 

[ed6269]

Unfortunately the customer can't adjust the charging voltage parameters of the Titan's solar charge controllers (or the AC wall chargers for that matter). The screen menu has no bearing on the settings of the charge controllers. They are preset to charge up to around 29.2V, but if my unit is any indicator, they can go higher if you don't manually stop the charging. When I referred to derating the Titan I was simply saying that my particular Titan unit only reaches a SOC of about 90% if I manually stop charging it when the voltage reaches 28.4V, which is what I would have to do if I directly connected a LiFePo4 battery to the Titan NMC battery. It's a manual process, unfortunately.

The AC wall charging ports are wired directly to the Titan's 24V battery bus and appear to be capable of 50a for each port (but I'm not sure if each is rated 50a or both in total are 50a - I haven't pushed it that far). Remember that the AC wall charger that comes with the Titan converts 120V AC power to 24V DC and plugs into one of the wall charging ports on the Titan and puts out about 500 watts. In addition to the wall charger, I have made an Anderson connector lead which plugs into the other wall charger port from the output/input of the ISDT DC-DC charger as another way to charge/load the Titan's 24V battery from/to the LiFePo4 battery depending on the 4 pole 3 position switch. Here is an Amazon link to the high power version of the ISDT charger (P30):

Amazon.com

Here are the link's to the 4 pole, 3 position switch and enclosure that I used to be able to switch the direction of the power flow between my batteries:

VictorsHome Changeover Switch LW28-63 3 Positions 16 Terminals Universal Rotary Cam Selector Latching Switches 690V 63A: Amazon.com: Industrial & Scientific

VictorsHome Changeover Switch LW28-63 3 Positions 16 Terminals Universal Rotary Cam Selector Latching Switches 690V 63A: Amazon.com: Industrial & Scientific

www.amazon.com

Amazon.com

Here is a link to the BMS that I used for my LiFePo4 battery pack. It is a quality BMS and I highly recommend it:

8s BMS 100a LifePo4 with M6 Threaded Terminals – Overkill Solar

overkillsolar.com

If you are looking at using the ISDT P30 you have to combine both output channels to get the full 1500 watts of capability of the P30. You also have to make sure your wiring and connectors are rated to handle the maximum available amps flowing between the batteries.

I did not change nor do I recommend that you change the 74AH rating of the Titan battery unless you directly connect your external battery to the Titan 24V bus through the external battery port without a DC-DC converter. Just know that if you manually stop charging the Titan at 28.4V, the max SOC of the Titan battery will be closer to 90% or 67AH and the LiFePo4 SOC will be at 100%. Your experience with your unit may vary from my experience with my unit. If you have a DC-DC converter between the batteries you can comfortably charge the Titan's battery up to 29.0V and won't have to worry about the LiFePo4 battery being overcharged. In that case the Titan battery will reach 100% SOC.

There is one other thing to note on the ISDT DC-DC chargers/converters. I do not use the balancing ports on the output of the ISDT unit. I only use the main output ports to charge the battery pack as a whole. I rely on my BMS to protect and balance individual cells of my LiFePo4 battery pack. I also have set my ISDT charger to stop charging when the battery pack output voltage reaches 28.35V (7S x 4.05V in the Li-ion setting) for either direction.

By the way I have no affiliation with any of the companies whose products I have mentioned. I purchased these with my own money and use these products based on my own research and needs. Your needs may be different and you will have to draw your own conclusions as to whether or not these would work for your use case.

So after looking at the products you sent link's to I just don't understand how these items can transfer power to the Titan and keep the external battery pack at the proper voltage, it all seems over my head.
If I charge my Lion energy batteries to 28.7 which is within the 0.5 voltage tolerance that point zero recommended , I wonder if the Titan would just charge the NMC battery to 29.2V and stop charging the external battery pack at 28.7 which is not ideal but better than 29.2 , or if it would just bring all the batteries to 29.2 volts.
They should have just made the SCC adjustable and that would have solved everything or make it so you could hook up a external battery pack and not charge it thru the Titan , just add a separate SCC for the external battery pack .
As it is in my opinion the external battery port is basically useless if it charges above 28.7 volts.

 

[bdbugbee]

So after looking at the products you sent link's to I just don't understand how these items can transfer power to the Titan and keep the external battery pack at the proper voltage, it all seems over my head.
If I charge my Lion energy batteries to 28.7 which is within the 0.5 voltage tolerance that point zero recommended , I wonder if the Titan would just charge the NMC battery to 29.2V and stop charging the external battery pack at 28.7 which is not ideal but better than 29.2 , or if it would just bring all the batteries to 29.2 volts.
They should have just made the SCC adjustable and that would have solved everything or make it so you could hook up a external battery pack and not charge it thru the Titan , just add a separate SCC for the external battery pack .
As it is in my opinion the external battery port is basically useless if it charges above 28.7 volts.

I agree that it would be better if the Titan SCC was adjustable or only charged up to 28.4V. I would be more comfortable hooking up a LiFePo4 battery to the external port. But then the Titan would lose about 10% of its NMC battery capacity. The whole point of having the DC-DC converter in the circuit between the batteries is so that you can set the voltage you want the external battery to charge at independent of the voltage on the Titan 24V bus. If you don't use a DC-DC converter, both batteries charge and discharge to the same voltage. Thus if you have different battery chemistries with different voltage/capacity profiles, you can't optimize or maximize the capacity of both banks. The converter that I previously linked to has an input port that you connect to the source battery and an output port that you connect to the receiving battery. The DC-DC converter has a menu system which allows you to specify the voltage you want the output port to charge to. Thus if you use the Titan as the source battery and connect it to the input port of the converter, and set the charge voltage on the output port to 28.35V, you can connect a LiFePo4 external battery to the output of the DC-DC converter and reach full capacity at 28.35V, even though the Titan's bus voltage is different.

The switch that I linked to, allows me to wire up both batteries, such that when the switch is in position 1, the Titan is the source battery and the LiFePo4 is the battery being charged. When the switch is off, both batteries are disconnected from each other. When the switch is in position 2, the LiFePo4 battery is the source battery and the Titan is being charged. The switch and DC-DC converter controls which direction the power flows between the batteries and the charging voltage that I want the battery to charge to.

Granted my solution is a manual process in that I have to set the switch and DC-DC converter settings depending on which battery I want to charge/discharge, but for my use case in a camper boondocking situation, it works great. During the day when the Titan is being charged from my solar panels and I have excess solar, I set the switch to charge from the Titan to my LiFePo4 battery. During the evening and overnight, I set the switch to charge from the LiFePo4 battery to the Titan.

 

[ed6269]

I agree that it would be better if the Titan SCC was adjustable or only charged up to 28.4V. I would be more comfortable hooking up a LiFePo4 battery to the external port. But then the Titan would lose about 10% of its NMC battery capacity. The whole point of having the DC-DC converter in the circuit between the batteries is so that you can set the voltage you want the external battery to charge at independent of the voltage on the Titan 24V bus. If you don't use a DC-DC converter, both batteries charge and discharge to the same voltage. Thus if you have different battery chemistries with different voltage/capacity profiles, you can't optimize or maximize the capacity of both banks. The converter that I previously linked to has an input port that you connect to the source battery and an output port that you connect to the receiving battery. The DC-DC converter has a menu system which allows you to specify the voltage you want the output port to charge to. Thus if you use the Titan as the source battery and connect it to the input port of the converter, and set the charge voltage on the output port to 28.35V, you can connect a LiFePo4 external battery to the output of the DC-DC converter and reach full capacity at 28.35V, even though the Titan's bus voltage is different.

The switch that I linked to, allows me to wire up both batteries, such that when the switch is in position 1, the Titan is the source battery and the LiFePo4 is the battery being charged. When the switch is off, both batteries are disconnected from each other. When the switch is in position 2, the LiFePo4 battery is the source battery and the Titan is being charged. The switch and DC-DC converter controls which direction the power flows between the batteries and the charging voltage that I want the battery to charge to.

Granted my solution is a manual process in that I have to set the switch and DC-DC converter settings depending on which battery I want to charge/discharge, but for my use case in a camper boondocking situation, it works great. During the day when the Titan is being charged from my solar panels and I have excess solar, I set the switch to charge from the Titan to my LiFePo4 battery. During the evening and overnight, I set the switch to charge from the LiFePo4 battery to the Titan.

First off let me thank you for your patience in trying to convey how you pull this off.
After reading your last post I am almost able to picture what you have going on and I wouldn't mind the manual aspect of your setup at all,can you give me a link to your DC to DC converter. I will want to use that ISDS P30 , it looks like some sort of charge controller to me , but reads every cell voltage , not sure about what you mean when wiring it to combine both outputs channels to get full 1500 watt output (this is where I get lost) maybe if you could send me a wiring diagram or even better yet a utube video then maybe I could pull this off . I am not vary smart when it comes to written instructions, I am so much better with a picture or a video. The picture that you sent on your first response helps but I can't see how its wired, a diagram might clear it up for me.
On another note I contacted Lion energy to see if they thought it would be ok to charge my batteries to 29.2 and the said to only charge to 27.8 which seems low to me , I see that Battle Born batteries recomend to charge to 14.6 or 29.2V in series, I don't know why they would have such a large difference.
But it looks to me like you're way is my only option. I know this is a pain to walk me thru this and I hate asking , but the ability to utilize these Lion energy batteries was one of the main reasons for buying the Titan. I hate proprietary equipment and this voltage issue didn't seem like a problem until I finally got it , I only wanted 1 Titan battery and if I can't make this work I will be stuck in proprietary hell.
Thanks again and if you want to be done with me I understand.
Eddie

 

[bdbugbee]

I included a link to the P30 in one of my previous posts.

Here are a few photos of my external battery build including the switch. I'll try to explain what's going on.

The 3 position rotary switch has 16 terminals which are connected as per the following manufacturers diagram.


I used the above chart to map out the internal switch wiring to give me the following switching logic:

Switch Position 1: Titan battery -> Input port of DC-DC converter, Output port of DC-DC converter -> Lifepo4 battery
Switch Position 0: everything disconnected
Switch Position 2: Lifepo4 battery -> Input port of DC-DC converter, Output port of DC-DC converter -> Titan battery

I mounted an ISDT Q8 DC-DC converter (which I subsequently upgraded to a P20) on top of the switch box. On the left side of the picture, the top set of wires is the Input port of the DC-DC converter. The lower left set of wires goes to the Titan battery charging port. On the right side, the top set of wires is the output port of the DC-DC converter. The lower right set of wires goes to the Lifepo4 battery terminals.



The picture below shows the back side of my Lifepo4 battery box with the switch box and DC-DC converter mounted on the top right side. The other components shown are the Victron DC-DC converter for the truck charging circuit on the top left. The BMS, balance leads and battery fuse are on the back side of the battery box.



The picture below is a top view of the backside of the Lifepo4 battery box.



Here is a top view of the battery box installed in the compartment below my camper bed to the right of the Titan. The wires running along the upper portion of the picture are my solar panel wires coming from the roof to the Titan. Since this picture was taken I have installed a DC breaker panel as a means of turning off the panels if the Titan is fully charged.



The nice part about this setup is that it is modular. When I put my camper in storage for the winter, I can easily disconnect the wiring at the Anderson connectors and remove the Titan and my external battery box from the camper.

Hopefully this helps you visualize the way I set up my external battery connection to the Titan. I've been using it for the last month in my camper on two week long trips and so far it's working like a charm.

 

[bdbugbee]

FYI, here's a look inside of my external Lifepo4 battery box with the top removed, with negative terminal on the left, positive terminal on the right. I put 8 176ah cells together in series of 2-4 cell groups for ease of future remove if necessary. I placed a plastic insulator between cells. I did not use solid bus bars because this pack is used in a mobile setup with high vibration so the cell orientation is a little different than a standard 8S configuration. I used #2 AWG copper between the cells. The battery pack is fused with a 30 amp fuse since my max load is only 20 amps. I also fused the balance leads with 3a in-line fuses and then covered any exposed terminals with kapton tape.

 

[bdbugbee]

Here's one more switching logic diagram showing the wiring of my switch terminals to the batteries. Caution: Use these diagrams at your own risk. If you do something like this, make sure that you test the switch logic wiring for your particular setup before connecting it to the batteries. Use a connectivity meter to make sure the switch is wired properly and the polarities are correct in each switch position. I'm just showing you my thought process for how I went about wiring up my switch. Your wiring requirements may be different. I also recommend fusing the leads to each battery terminal in case there is an internal problem with the switch. Since my battery connection never exceeds 20 amps of current flow I used #10 flexible wire with silicon insulation and 30 amp fuses for the switch and battery leads. Your use case may require larger wire and fuses. The switch manufacturer claims the switch is good to 63 amps. I did find that #10 wire was a tight fit inside the switch enclosure, so going to #8 might not be doable. #6 would definitely not be doable.

Note this diagram applies for my use of the ISDT Q8. The P30 has two output ports which need to be combined before entering the switch. The menu settings on the P30 would have to be set to combine the output channels in parallel.

Good luck!

 

[studioMiguel]

WOW that's a lot of great information and options , Thanks
Just on a side note , The people that I was seeking information from on this subject was not Point Zero as stated in the OP but a distributor for the Titan , I have since been in contact with Point Zero and they have been extremely responsive and helpful.
Here is the information that I received today as follows.


Yes you can connect the LiFePo4 batteries to the external battery expansion port without the Titan Battery, and it should charge fine. The Charge voltage of a 24V LiFePo4 battery is 29.2V, which is what our Titan charges to. So that should be fine.

The only issue you could run into is that the SB50 port can only handle 1500 watts. So if you plan on running anything more than 1500 watts without the Titan battery, you would need to connect your batteries to the two battery ports on the bottom of the Titan in order to be able to handle the power load.

If you want to run the LiFePo4 batteries with the Titan battery, you just need to make sure the voltage of the two batteries are within 0.5V before connecting. Then set the meter to the correct total amp hours, and fully charge the system to calibrate the meter.

Similar experience with reseller vs Point Zero direct. PZ seems very responsive.

 

[rarquile]

I see that Battle Born batteries recomend to charge to 14.6 or 29.2V in series

So are Battle Born batteries the solution to using the Battery Expansion Port in conjunction with 2 Titan batteries?

 

[ed6269]

So are Battle Born batteries the solution to using the Battery Expansion Port in conjunction with 2 Titan batteries?

That or SOK says it's OK to charge to 29.2 , but I still don't like having different chemistrys I would prefer NMC to match the Titan's chemistry but nobody uses NMC any more and LiFePO4 29.2 is at the top of its max charge capacity and I have seen my Titan go as high as 29.4 rarely but it happens.
Also I was told my Lion energy batteries are good to go to 29.2 by the manufacturer even though the manual says only 27.6 in series, I was getting them ready and charging them up 1 at a time to 14.6 and after doing so and after letting them rest the voltage would drop to 13.3, and before I took them to 14.6 they used to rest at 13.7 but now they only rest at 13.3 so be warned it might take some life out of the battleborn or SOKs if you take them that high, although they say it's OK in the manual and Lion energy does not.
I don't think I could use the Lion energy batteries in the expansion port of the Titan because you need to be within .5 of a volt of the NMC battery according to the manual and when the Lion energy batteries rest they would fall out of that requirement.
I still haven't found a work around that I am comfortable with.
Big battery has a listing for a 24 volt NMC battery for 900.00 that would be perfect but
it's always out of stock and I don't think they are interested in making any more after talking to them .
If you have good results with any other setup let me know.

 

[rarquile]

@ed6269 - Thanks for the reply. I feel the same about mixing chemistry especially being a newbie and not fully understanding everything that is involved. I just confirmed with Big Battery that they, "don't foresee those units making a comeback anytime soon." Makes me wonder if at some point our only option for expanding with NMC batteries will be via the Titan battery or perhaps we're already there?

 

[ed6269]

Yes it sucks that big battery won't make that NMC battery, it would have been perfect with larger capacity and a cheaper price.
I only have 1 battery for my Titan so I can't use the full 3000 watt output without diminishing the cycles and I hate proprietary batteries (if the Titan craps out on me would be stuck with all these proprietary batteries and not be able to use them anything in the future) I don't need the full 3000 watts that much anyway, but it would be nice to know it's there.
If you just need more watt hours capacity you can input batteries hooked up in series and input the voltage into one of the solar inputs as long as the voltage is within the Titan's range of 35-145 volts it will then act like solar panels are hooked to 1 of the 2 solar inputs and if you only have 1 Titan battery you can only input 1000 watts solar anyway.
Point Zero told me also that when you have solar input while running the Titan it increases the max AC output by what ever the solar input is(the Titan's max output with 1 battery is 1500 watts and if you add 800 watts of solar input you can output 2300 watts safely without losing battery cycles)
This is not a perfect workaround from buying a Titan battery but it might be a little cheaper.
The only advantages Big Batteries NMC would have over this scenario is you would be able to input 2000 watts of solar into the Titan while also charging the external battery pack simultaneously and have the full 3000 watt output instead of only 2500 watts. And also charging the workaround battery pack would be something else to deal with.
Other than that all you can do is buy another Titan battery, or do what bdbugbe was explaining farther back in the post , but I couldn't really figure out where he was going with all that.

 

[fdwlaw]

Great thread. I haven’t read through all the comments but am working on it, and sure to have many questions.

 

[Lysergeon]

Hi all, I realize this threat ended ages ago, but.. back looking at the same thing.. I am wanting to add a lifep04 100ah 24v (power queen) battery to expand my titan (I have 3 nmc's on it now) so I would charge the 100ah battery to max (likely 27.6v or something) and then drain the titan to match. Then set my AH on screen to 322ah and connect it right? well... I am wondering, to protect the lifepo4 battery, if I just set the titan to like say.. 310ah (for instance, maybe there is a better number) will this stop them from over charging to like 29 etc as some of you have witnessed? I realize I would be giving up a bit of top end power.. but if it is going to save the batteries in the long run, seems worth it.. or maybe that is not how this works at all.. in which case.. dang.. guess I gotta just unplug my solar at like 95% all the time to protect it? Thanks all!

 

[Lysergeon]

ok after speaking to point zero, changing the on screen items doesn't actually effect charge etc so nm that..