another dreaded alternator charge lithium thread

[coachgeo]

. I have a 24v " NOT very SMART" alt. with plenty available power amps. Likely 115amp / 24v available when driving AFTER start/truck batts are charged in daytime (it's a 150amp alt). Since the trucks lighting system is 12v (there is another 50 amp 12v alternator source built in) then even at night much of the 24v alternator's amps is still available. (not very smart= it has some temperature compensation built in... but was not designed with lithium charging in mind)

. have four 12v lead acid making up start/truck batts.
. will have 24v house batts of chemistry type I have not decided.... hence the question in this thread. Weight no so much an issue in using lead acid for this project due to capacity of the truck-camper
. have 500 amp battery isolator to cause start/truck batts to be charged first.... then house batts... but it is NOT SMART except it can jump start truck from house batts.
. will have around 1000 watts of solar.

>>> wanting to charge house batts while driving as quick as possible so can 1) reduce drag on alternator; thus improving mpg on this big CAT engine. 2) use solar to run a hho to improve mpg on this big CAT engine. HHO is worthless in improving mpg when run from alternator.... different story when it is from solar.

ok.... yeah dc to dc..... b2b charger is the common suggestion here if went some other chemistry beside lead acid for "house" batts.... orrrrrrrrrr??? asking "or" cause when you get to 24v and higher everything triples in price. Have you priced dc/dc 24v b2b chargers? and it is STUPID to have 24v/115 available amps for charging but only get to use 20 to 60 of it .... but that seems to be an issue across the board no matter how you try to charge house batts with alternator. Heck I can get a 570amp alternator for my truck... (its military)

anyway could you in an "or" situation; instead of using dc/dc b2b charger... somehow pipe the from the battery isolator the house's charge portion to an inverter charger to top up the house's NOT lead acid batts; such as the one in the link below. Gotta buy an inverter anyway and maybeeee (its close) the inverter charger is less costly when you add it all up, than purchasing an inverter and a dc/dc b2b charger separately

3000W DC 24V Pure Sine Wave Inverter With Charger

Sungoldpower 3000W DC 24V Pure Sine Wave Inverter With Charger. Hightlight: This LFP Series Pure Sine Wave Inverter is a combination of an power inverter 3000w, battery charger and AC auto-transfer switch. GFCI socket, low frequency, low Idle Current, BTS cable, remote control. Adjustable...

sungoldpower.com

 

[eXodus]

So many of the "Fears" are coming from that one video where a Lithium is burning up a alternator.
I haven't found a single source aside form the sellers of DC2DC charge controllers that verify that need for a DC/DC when the voltages are necessary.

There is a lot wrong about that video:
- first - you usually have a lithium battery in parallel with lead battery while hanging on the alternator. The lead battery smoothest out a lot.
- second the lithium battery negative is usually connected through the vehicle frame - which is a poor conductor. Thus limiting the charge naturally. The truck frame is a giant resistor and heat sink. Mount the lithium all the way on the back and hook the negative with as much frame as possible in between. This is one of the situation where you don't want to have a efficient charge
- last - most people never charge from full empty.

What Voltage is your not smart alternator running at? Just choose a lithium chemistry which optimal charge point is above.

For instance - if your alternator puts out 28V - choose a lithium which is a maximum charge is slighly above. So you will never get the battery full charged from the alternator - but up to 80-90%. Which is better for longevity anyhow.

So you need only a Relay.

 

[coachgeo]

....

What Voltage is your not smart alternator running at? Just choose a lithium chemistry which optimal charge point is above.

For instance - if your alternator puts out 28V - choose a lithium which is a maximum charge is slighly above. So you will never get the battery full charged from the alternator - but up to 80-90%. Which is better for longevity anyhow.

So you need only a Relay.

little confused by this..... yes mine puts out up to 28v.... so your saying use 36v lithium batts as house bank or is lithium 12v batts not really 12v.... but some are actually more... such as 15 or 16v?

what relay are you speaking off? a battery isolator style? (in my case I have one)

PS- good input on that video being potentially tweaked by manufacture of the b2b products to sell their products

 

[Boondock Saint]

1) pick a non SLA voltage already
2) pick a proper DC-DC step up converter
3) install and wire correctly
4) drive your military vehicle

If you have it more complicated than that, well . . .


I have NO affirmation with this site whatsoever, besides a phone call with Garret Towne > https://amsolar.com/rv-solar-panel-kit/alternator-charging

.

 

[coachgeo]

1) pick a non SLA voltage already
2) pick a proper DC-DC step up converter
3) install and wire correctly
4) drive your military vehicle

If you have it more complicated than that, well . . .


I have NO affirmation with this site whatsoever, besides a phone call with Garret Towne > https://amsolar.com/rv-solar-panel-kit/alternator-charging

.

No clue what number one is.... SLA? sealed lead acid? already stated Im 24v truck and 24v house.... just not purchased house batts yet.
No. clue what number two is unless that is another term for the 24v to 110v inverter

3 and 4 is self evident

Reply

 

[coachgeo]

delete.. double post

 

[eXodus]

little confused by this..... yes mine puts out up to 28v.... so your saying use 36v lithium batts as house bank or is lithium 12v batts not really 12v.... but some are actually more... such as 15 or 16v?

what relay are you speaking off? a battery isolator style? (in my case I have one)

PS- good input on that video being potentially tweaked by manufacture of the b2b products to sell their products

correct a isolator relay.

So your alternator puts out 28V - get a 24V nominal Lithium battery with a maximum charge voltage of like 28.8 to 29.3V

Different lithium batteries have different voltages - so you do not want to pick one which is fully charged at 27.8V - because your alternator would overcharge that one. (and charge to fast)



That pretty much sums it up. As soon as the engine runs - the relay closes - the lithium charges - you turn it off - relay open and no charge anymore.

Put a fuse in between to limit current ( I got a 150A breaker on my 180A alternator and it never tripped)

 

[eXodus]

what relay are you speaking off? a battery isolator style? (in my case I have one)

PS- good input on that video being potentially tweaked by manufacture of the b2b products to sell their products

Get a clamp on amp meter and a infrared temperature probe when you put that together.
Use a fully charged lithium battery the first time and observe how much current it draws from the alternator.

Further point the infrared meter on your alternator.

The drain it a little - try again

and so forth - the lower the battery gets the more current it should draw from the alternator - If it ever gets into crazy territory (100A+ then you can just shut it down.

 

[NPhil]

I suggest listening to the boat guy. I have, and, while my minivan is still a testbed, it does seem to be working, with the 12V batteries (I have a mix of 12V and 24V at the moment, charging between them is another subject), which are LiFePO4, in direct parallel with the (lead acid) starter battery. The problem I'm sure of is, if were to only have LiFePO4 on an alternator, and the battery management system opened the connection to protect it, while the engine was running, there would suddenly be zero load on the alternator, which has been known to cause voltage spikes which blow the diodes, and maybe other things, like the engine computer. With the original lead acid in parallel, that doesn't happen. There is still the question of not draining the starter battery by accident, but you have a switch for that (my plan is to get fancy with relays and cheap Chinese low voltage battery protect modules, combined with an ignition switch connection required to enable charging from the starter to the house batteries). He didn't do this, and I didn't test it, but I can't think of a reason why you can't just double the voltage, by doubling the number of cells in series (8 instead of 4), with the same battery chemistry and get similar results with a (nominal) 24V system.

 

[coachgeo]

I suggest listening to the boat guy. I have, and, while my minivan is still a testbed, it does seem to be working, with the 12V batteries (I have a mix of 12V and 24V at the moment, charging between them is another subject), which are LiFePO4, in direct parallel with the (lead acid) starter battery. The problem I'm sure of is, if were to only have LiFePO4 on an alternator, and the battery management system opened the connection to protect it, while the engine was running, there would suddenly be zero load on the alternator, which has been known to cause voltage spikes which blow the diodes, and maybe other things, like the engine computer. With the original lead acid in parallel, that doesn't happen. There is still the question of not draining the starter battery by accident, but you have a switch for that (my plan is to get fancy with relays and cheap Chinese low voltage battery protect modules, combined with an ignition switch connection required to enable charging from the starter to the house batteries). He didn't do this, and I didn't test it, but I can't think of a reason why you can't just double the voltage, by doubling the number of cells in series (8 instead of 4), with the same battery chemistry and get similar results with a (nominal) 24V system.

interesting stuff..... not sure if this interesting mix of chemistries helps with alternator charging or not? Not addressed in that vid.

 

[eXodus]

interesting stuff..... not sure if this interesting mix of chemistries helps with alternator charging or not? Not addressed in that vid.

Oh yeah mixing helps a lot with alternator charging.

The output of the alternator is a pulsating DC and the slow lead battery is actually the part of the system which makes a pure DC out of it. Further the lead supplies charge to the lithium battery and the other way around depending on level of charge. So a safety measure.

Never connected a lithium battery to a lead alternator alone

 

[coachgeo]

Oh yeah mixing helps a lot with alternator charging.

The output of the alternator is a pulsating DC and the slow lead battery is actually the part of the system which makes a pure DC out of it. Further the lead supplies charge to the lithium battery and the other way around depending on level of charge. So a safety measure.

Never connected a lithium battery to a lead alternator alone

yeah that was part of my thinking in how going thru first a lead batt bank large enough might could buffer things some before they connect to a lithium.

 

[eXodus]

Further a lead battery is also a large resistance. While lithium depending on charge are much lower

 

[Jasgeer]

I generally agree with the above comments but there is another side to consider. The higher impedance of the lead acid battery (whether Maintenance Free, AGM or deep cycle) means that a significant amount of ripple still remains on the power line. How large of a wet cell battery must be connected in parallel to accomplish the desired results? I think there is an error in the schematic as shown as the alternator's regulator will discharge the battery directly connected to it unless there is a mechanism to disconnect current to the field winding.

I am unfamiliar with any evidence that an alternator directly charging any form of Lithium battery will damage it. Even the output of a DC to DC converter/charger is delivering current to the Lithium battery in buckets as it is a step up/down switching device. I acknowledge that the pulse frequency is higher with the DC-DC than with an alternator.

The biggest problem I see is that the lead acid battery that is being used supposedly to filter the full wave output from the alternator has a specific voltage range which may not coincide with the voltage needed to fully charge the Lithium battery. Different lead acid batteries have different voltage parameters. For example, Maintenace Free batteries cannot be charged over ~14V without outgasing which is why most cars/trucks charge to the mid-13 Volt range. A deep cycle or AGM battery needs >14V. The temperature characteristics of the lead acid and Lithium batteries are also different, not to mention that the alternator is sensing the temperature under the hood and not at the Lithium battery.

In this attached video by Victron you will see that the potential problem of charging a Lithium battery from an alternator is damage to the alternator, not damage to the battery.

Here is a second Victron video. The relevant section starts at 10 minutes.

Another article from our boating friends: https://livsailing.com/2019/11/04/protecting-your-alternator-when-switching-to-lithium/


Here is an article on the dangers due to "load dump" when a load is disconnected from an alternator and how to prevent it. It states that once activated that most alternators cannot be easily turned off. http://www.aeroelectric.com/articles/Alternator_Failures.pdf


What are your thoughts?

 

[NPhil]

interesting stuff..... not sure if this interesting mix of chemistries helps with alternator charging or not? Not addressed in that vid.

The video makes a good case that you can parallel the correct Lithium Ion chemistry with a lead acid battery, without shortening battery lifetime, and maybe significantly extending it. My argument is that if you can do that, you can connect the alternator to the lead acid battery, and, if the voltage is right (in my van, it's 14.4) safely charge the paralleled (4S, in my case) LiFePO4 battery, too.

The question of LiFePO4 damage is a question of lifetime, I guess. Some prefer not to charge them so close to full voltage, to extend lifetime.

 

[NPhil]

I generally agree with the above comments but there is another side to consider. The higher impedance of the lead acid battery (whether Maintenance Free, AGM or deep cycle) means that a significant amount of ripple still remains on the power line. How large of a wet cell battery must be connected in parallel to accomplish the desired results? I think there is an error in the schematic as shown as the alternator's regulator will discharge the battery directly connected to it unless there is a mechanism to disconnect current to the field winding.

I am unfamiliar with any evidence that an alternator directly charging any form of Lithium battery will damage it. Even the output of a DC to DC converter/charger is delivering current to the Lithium battery in buckets as it is a step up/down switching device. I acknowledge that the pulse frequency is higher with the DC-DC than with an alternator.

The biggest problem I see is that the lead acid battery that is being used supposedly to filter the full wave output from the alternator has a specific voltage range which may not coincide with the voltage needed to fully charge the Lithium battery. Different lead acid batteries have different voltage parameters. For example, Maintenace Free batteries cannot be charged over ~14V without outgasing which is why most cars/trucks charge to the mid-13 Volt range. A deep cycle or AGM battery needs >14V. The temperature characteristics of the lead acid and Lithium batteries are also different, not to mention that the alternator is sensing the temperature under the hood and not at the Lithium battery.

In this attached video by Victron you will see that the potential problem of charging a Lithium battery from an alternator is damage to the alternator, not damage to the battery.

Here is a second Victron video. The relevant section starts at 10 minutes.

Another article from our boating friends: https://livsailing.com/2019/11/04/protecting-your-alternator-when-switching-to-lithium/


What are your thoughts?

My van testbed has two 10P4S batteries of K2 26650 3800mah LiFePO4 cells, currently in parallel, connected to the group 65 starter battery in front through a 12 gauge SAE plug cable (so, there is no way it's going over 20A or so for long, even if it didn't have fuses which are smaller than that). That's not going to overheat my 95A alternator. One of my batteries does not have a BMS yet, the other has a BMS, with a separate charge connection. I just checked, its maximum charge current is 10A. Adding all that together, everything is fine, here.

I guess obviously, I'm taking a more experimental approach than many would, but, for those less experimentally inclined, I suggest that if you're connecting a lead-acid starter battery in the front, with LiFePO4 house batteries in the back, the voltage drop on the cable, if you don't go nuts buying many lbs. of (expensive) copper, and inline fuses, will save you from smoking alternators.

I just remembered. Someone said, somewhere, that smoking alternators happen when you charge heavily at idle, because of insufficient airflow. And, thanks for the video explaining that!

 

[Jasgeer]

Just to point out that 12awg copper wire has only .016 Ohms in 10 ft. For an example if you took a 3V voltage drop the current would be 187A! Even assuming only a 1V differential the current is 62.5A. I would conclude that 12awg wire is not sufficient by itself to reduce the current to a safe value.

 

[NPhil]

Just to point out that 12awg copper wire has only .016 Ohms in 10 ft. For an example if you took a 3V voltage drop the current would be 187A! Even assuming only a 1V differential the current is 62.5A. I would conclude that 12awg wire is not sufficient by itself to reduce the current to a safe value.

Not _my_ 12AWG (it's Chinese)! Actually it might be 14AWG, and it's stranded, and there are connectors...
BTW, 1V can be a lot. The BMS I'm using recommends 15V on the charge port, but it never sees that. And, it never reaches 10A charging.

 

[eXodus]

In this attached video by Victron you will see that the potential problem of charging a Lithium battery from an alternator is damage to the alternator, not damage to the battery.

There is a lot wrong about that video:
- first - you usually have a lithium battery in parallel with lead battery while hanging on the alternator. The lead battery smoothest out a lot.
- second the lithium battery negative is usually connected through the vehicle frame - which is a poor conductor. Thus limiting the charge naturally. The truck frame is a giant resistor and heat sink. Mount the lithium all the way on the back and hook the negative with as much frame as possible in between. This is one of the situation where you don't want to have a efficient charge
- last - most people never charge from completely empty battery, charge slows down when you hit 80%.


I mean put a smart shunt or a clamp on meter in the middle when you try it and watch the amps.

 

[eXodus]

may not coincide with the voltage needed to fully charge the Lithium battery

This is the primary disadvantage from direct (relay )alternator charging, you are not charging at optimal parameter.

The difference is - so you put in a 20A DC2CD charge controller - you are limited to 20A.

If you put in a relay - you maybe charging at 60A (what mine is doing) for about an hour and then it starts dropping until the battery is at the voltage the alternator is putting out - this is not the optimal charging voltage - but it will still charge with a few amps.