diy solar

diy solar

LiFePo Charger question

blacksheep6

New Member
Joined
May 10, 2021
Messages
5
Sorry to ask another question about charging, but I am getting information overload and need some simple knuckle dragging instructions/advice:

I have a Travel Trailer and I am currently waiting on the delivery of 2x 100Ah SOK LiFePo batteries that I am going to replace the current Lead Acid batteries with. We boondock most of the time. My current power control center is a WFCO 8955 (rates are Absorption 13.6v, bulk 14.4v and float 13.2 v). I attempted to buy the drop in lithium controller/MBA for this, but it is unavailable. From my understanding this current setup will only bring up the batteries to approx 80%.

My current plan is to utilize our 1600 watt generator connecting to the camper with the 30A shore cable and use a 120v charger plugged into one of the AC outlets in the camper and connect to the batteries, which will be wired in parallel. I am eventually going to add solar to the camper, but I will still need the generator option, because most of the time we are camping under tree canopy. We do not use a lot of power and at most will need to replace less than 50 Ah per day. From some of the threads I have read I believe that one of the best options for me is Victron Blue Smart Charger IP65 or the IP67 .

So here are my questions:

1) Not sure which Victron to get, leaning toward IP67 - 25amps will this work for what I a trying to accomplish?

2) Will the Victron charger work as I have described to charge both batteries in parallel, once installed? I plan on leaving the cable connected to the battery terminals and just disconnect from the charger. Do I connect the charger leads to positive terminal battery #1 and negative terminal battery #2?

3) When I wire the new batteries into the current power center, will I need to disconnect the batteries from the WFCO charger in order to use the Victron when on the generator?

Thanks
 
The wfco 8955 can charge your batteries to >95% full.
I wouldn't buy an ac charger until you have tested the wfco.

Page 6 of the manual says the absorption phase is 44 hours at 13.6 volts.

If you are planning on using an inverter then you need to ensure that a power loop is not possible but that is another story.
I can also help you design a test for the wfco if you are interested.
 
Use the existing WFCO. If you see voltage climbing to 14+ you are fully charged. Going all the way to 14.4/14.6 is overrated.
And the 55 amp WFCO will charge faster than a 25 amp Victron.
 
Thanks again, When I receive the batteries, do I need to make sure they are both at the same state of charge before wiring them in parallel? If I need to, I should be able to do this, just by connecting each battery individually to the WFCO, charge it up and switch out, then wire parallel. I only have a standard lead acid battery charger ( 4A).
 
The wfco 8955 can charge your batteries to >95% full.
I wouldn't buy an ac charger until you have tested the wfco.

Page 6 of the manual says the absorption phase is 44 hours at 13.6 volts.

If you are planning on using an inverter then you need to ensure that a power loop is not possible but that is another story.
I can also help you design a test for the wfco if you are interested.
Any input on a test setup would be awesome!
 
Thanks again, When I receive the batteries, do I need to make sure they are both at the same state of charge before wiring them in parallel? If I need to, I should be able to do this, just by connecting each battery individually to the WFCO, charge it up and switch out, then wire parallel. I only have a standard lead acid battery charger ( 4A).
Start with just measuring the voltage. If within 100 mV I would just connect and go. Otherwise connect the low battery and start charging. Have the second battery ready to connect as voltage comes up to match.
 
by my understanding the convertor will charge fine... but won't charge till they run quite low (because float is 13.2 before it starts bulk charging again) but a power cycle will reactivate bulk charging.
 
I don't have an inverter, just the WFCO power center/converter
You should have a shunt based battery monitor to measure the current flow in and out of the batteries.

1Before you discharge the batteries make sure the converter will actually charge the batteries.
All you need to do is verify that there is current flow into the batteries when the converter is on and current flow out of the batteries when the converter is off and a load is present.

2 Discharge the batteries to ~12volts(90% depth of discharge).
Now turn on the converter.
The current flow should be ~55amps as measured by the shunt based battery monitor.
You should put ~180amps back in to the battery bank in ~3.3 hours.
If that doesn't happen then we can fix the potential bottlenecks in your system.

Most common are...
1 batteries to far away from converter.
2 wire too small between batteries and converter.
 
Sorry to ask another question about charging, but I am getting information overload and need some simple knuckle dragging instructions/advice:

I have a Travel Trailer and I am currently waiting on the delivery of 2x 100Ah SOK LiFePo batteries that I am going to replace the current Lead Acid batteries with. We boondock most of the time. My current power control center is a WFCO 8955 (rates are Absorption 13.6v, bulk 14.4v and float 13.2 v). I attempted to buy the drop in lithium controller/MBA for this, but it is unavailable. From my understanding this current setup will only bring up the batteries to approx 80%.

My current plan is to utilize our 1600 watt generator connecting to the camper with the 30A shore cable and use a 120v charger plugged into one of the AC outlets in the camper and connect to the batteries, which will be wired in parallel. I am eventually going to add solar to the camper, but I will still need the generator option, because most of the time we are camping under tree canopy. We do not use a lot of power and at most will need to replace less than 50 Ah per day. From some of the threads I have read I believe that one of the best options for me is Victron Blue Smart Charger IP65 or the IP67 .

So here are my questions:

1) Not sure which Victron to get, leaning toward IP67 - 25amps will this work for what I a trying to accomplish?

2) Will the Victron charger work as I have described to charge both batteries in parallel, once installed? I plan on leaving the cable connected to the battery terminals and just disconnect from the charger. Do I connect the charger leads to positive terminal battery #1 and negative terminal battery #2?

3) When I wire the new batteries into the current power center, will I need to disconnect the batteries from the WFCO charger in order to use the Victron when on the generator?

Thanks
You may want to take a look at his thread where a similar discussion is taking place. Your current charge controller may be what you want when hook to shore or gen: https://diysolarforum.com/threads/stopping-inverter-at-90.23388/
 
You should have a shunt based battery monitor to measure the current flow in and out of the batteries.

1Before you discharge the batteries make sure the converter will actually charge the batteries.
All you need to do is verify that there is current flow into the batteries when the converter is on and current flow out of the batteries when the converter is off and a load is present.

2 Discharge the batteries to ~12volts(90% depth of discharge).
Now turn on the converter.
The current flow should be ~55amps as measured by the shunt based battery monitor.
You should put ~180amps back in to the battery bank in ~3.3 hours.
If that doesn't happen then we can fix the potential bottlenecks in your system.

Most common are...
1 batteries to far away from converter.
2 wire too small between batteries and converter.
My original plan is to move the batteries from the tongue and run new wires from the batteries to the converter. I am not planning on using the 7 pin Tow vehicle to trickle charge when we are driving. The batteries will be a little bit away from the converter, the wire length will be approx 20' I was planning on using 8 awg, but looking at the wire gauge it looks like I should use 4 awg for both the pos and neg. I might be able to move the batteries closer, but it will be a tight fit and tough to wire. I have a 350 amp shunted battery monitor. I am hoping that SOK will be shipping the batteries on June 10th? Once I get them I will follow the steps you have outlined and update this thread. Thanks again for your assistance with this.
 
My original plan is to move the batteries from the tongue and run new wires from the batteries to the converter. I am not planning on using the 7 pin Tow vehicle to trickle charge when we are driving. The batteries will be a little bit away from the converter, the wire length will be approx 20' I was planning on using 8 awg, but looking at the wire gauge it looks like I should use 4 awg for both the pos and neg. I might be able to move the batteries closer, but it will be a tight fit and tough to wire. I have a 350 amp shunted battery monitor. I am hoping that SOK will be shipping the batteries on June 10th? Once I get them I will follow the steps you have outlined and update this thread. Thanks again for your assistance with this.
Have a look at this voltage drop calculator.
40 feet round trip
55 amps
12.8 volts
indicates 2 awg for <3% voltage drop.
Probably the max awg the wfco panel will accept is 6 awg.
Suggest you try to move the batteries closer to the panel.
 
Back
Top