Emergency: Charging Lifepo4 batteries with agm/leadacid charger

[Surfsolar]

On my first trip in my Camper van and suddenly realizing that I there’s not enough sun to keep my batteries charged. I have two valence Lifepo4 batteries 400w solar.

I’ve had the system set up for two years in Florida and have never drained past 50% so I never thought to put a external charger other than the solar panels.

I plan on buying a Victron smart battery charger but it won’t come in for a few weeks is there anyway to charge these batteries with a normal charger from Walmart or harbor freight?

 

[cass3825]

Definitely not recommended due to the much lower internal resistance of your bank versus lead acid tech. If there’s a radio control hobby store nearby, they will likely have a LFP compatible charger (that hobby calls it LiFe) that will get you by.

Hope this helps…

 

[Rednecktek]

My understanding was that if the charger has an AGM mode it'll get you Almost full.

 

[Roswell Bob]

I would stick the charger on it if I knew it would not overcharge the LiFePO4. Do you trust your BMS?

 

[JAS]

I guess it depends on what Valence recommends... I know my older Renogy(EPEver Rebrand) MPPT SCC does not have a LFP mode and I asked Battleborn if I could use the AGM mode. They looked at the specs of the Renogy and said the AGM mode would be OK and would not hurt the battery...

I would probably use it to charge up most of the way (do you have a battery shunt/monitor?). But, not leave it connected for an extended period after that.

 

[noenegdod]

is there anyway to charge these batteries with a normal charger from Walmart or harbor freight?

Yes. Regardless of the charger( paying attention to the voltage of course), it will never "hurt" anything if you are bulk charging. If you know what your SOC is and what the output of the charger is, you know exactly how long you can plug it in for to get up to say 60, 70 80% SOC, then unplug and let the solar take over for the balance of the day. Just do a little math and check it periodically for the first few charges and you will be fine.

 

[fratermus]

is there anyway to charge these batteries with a normal charger from Walmart or harbor freight?

My take: as long as

1. the charging current does not exceed the battery mfg recmmendations
2. you babysit it to watch voltage / state of charge

I see no issue. In theory the BMS should catch egregious overvoltage at the cell or pack level, but it will not prevent long periods holding 100% SoC.

 

[Surfsolar]

I do not have a bms as a regular Lifepo4 battery has, I use my bmv 712 as the temp/LV/HV warning and I always monitor it. Then I have the valence software (acts as the bms) on my computer that once a month to balance and check the status. I know kinda an ordeal, in hindsight I would have probably just gotten battleborns.

Ok I’ll get a agm charger and won’t just leave it. And I won’t fully charge it either.

I don’t know much about chargers, but this one from HF looks pretty legit and seems to have the modern specs for better charging right? Should I get the bigger one or I’m thinking with the 4 amp I could probably be more casual with monitoring it and just ket it trickle charge overnight? 4 amps might not be enough juice to make a timely difference though.

https://www.harborfreight.com/2815-...ocessor-controlled-battery-charger-56796.html


https://www.harborfreight.com/4-amp...ntrolled-battery-chargermaintainer-63350.html

 

[noenegdod]

I do not have a bms as a regular Lifepo4 battery has, I use my bmv 712 as the temp/LV/HV warning and I always monitor it. Then I have the valence software (acts as the bms) on my computer that once a month to balance and check the status. I know kinda an ordeal, in hindsight I would have probably just gotten battleborns.

Ok I’ll get a agm charger and won’t just leave it. And I won’t fully charge it either.

I don’t know much about chargers, but this one from HF looks pretty legit and seems to have the modern specs for better charging right? Should I get the bigger one or I’m thinking with the 4 amp I could probably be more casual with monitoring it and just ket it trickle charge overnight? 4 amps might not be enough juice to make a timely difference though.

https://www.harborfreight.com/2815-...ocessor-controlled-battery-charger-56796.html


https://www.harborfreight.com/4-amp...ntrolled-battery-chargermaintainer-63350.html

Charging current options are good. Id go with the first one if space is not an issue. On the other hand, if space a concern and 4 amps is actually enough for how often you have access to shore power, save the $30 and get started!

 

[Surfsolar]

Charging current options are good. Id go with the first one if space is not an issue. On the other hand, if space a concern and 4 amps is actually enough for how often you have access to shore power, save the $30 and get started!

This is janky but, If I get the 4 amp one could I use a cigarette lighter inverter to charge while I’m driving? HF has a 120watt continuous/240 watt peak one.

Also just to add this is all to get out of a pinch once back home I’ll either hook up alternator charging or a actual shore power connect or both.

 

[noenegdod]

This is janky but, If I get the 4 amp one could I use a cigarette lighter inverter to charge while I’m driving? HF has a 120watt continuous/240 watt peak one.

Also just to add this is all to get out of a pinch once back home I’ll either hook up alternator charging or a actual shore power connect or both.

Its a work around and not very efficient but who cares. It would certainly work and especially if it is a short term stop gap measure. Id do it.

Puts on flame suite.

I am not recommending this or suggesting you try it.

For nothing more than a stop gap measure, I would wire in a switch straight off the vehicle battery to the lifepo4 bank and charge for 30 seconds every 10 minutes while I was driving down the highway. Its not a good idea but I know my gear would "tolerate" it short term. I have no idea if yours would so the safest "bush league" work around is as you suggest above.

 

[jjchvl]

On my first trip in my Camper van and suddenly realizing that I there’s not enough sun to keep my batteries charged. I have two valence Lifepo4 batteries 400w solar.

I’ve had the system set up for two years in Florida and have never drained past 50% so I never thought to put a external charger other than the solar panels.

I plan on buying a Victron smart battery charger but it won’t come in for a few weeks is there anyway to charge these batteries with a normal charger from Walmart or harbor freight?

Guess Im a bit late to the party but here goes anyway; I ordered my first Lifepo's and an volt/amp adjustable lithium charger at the same time. Batteries arrived quickly but charger delivery got delayed by a week. Impatient to charge up and install my new batteries, I searched the net to learn charging lithiums using a "regular" charger is usually not a problem-depending upon the output of the charger. So I have a "regular" charger that I normally use on my AGMs. The amp output can be user adjusted to up to 40amps. It charges to a voltage of 14.3. Well, the manufacturer of my lifepos recommend charging them between 14.2v and 14.6v therefore 14.3v is perfectly fine. I connected the charger to my Lifepo's, set it to charge at 15amps max and waited. The charger actually did a very good job charging up my new lifepo's to full. At the end of charging, the voltage of each Lifepo was above 14v. Over the next hour or so, the voltage of each Lifepo slowly dropped to that partucular battery's base voltage(one battery settled out at 13.58v, another 13.63, and so on). The only potential "issue" I noted was that the charger wanted to go into float mode after each battery reached full charge. This really isnt an issue though since your lithiums would basically ignore the float charge. From what Ive read, a float charge wouldnt help your lithiims but wont hurt em either.

So yes. You can charge your lifepo's with a charger made for LA batteries. My LA battery charger did the job very nicely.