Charging LiFePO4 batteries with OEM RV electrical system

[tallenhouston]

Rookie solar / 12VDC person here. So much good information is on this site, YouTube, etc., it can almost cause analysis paralysis. This is a question I did not consider before . . .
I just purchased (2) 100Ah LiFePO4 batteries for my 2019 GeoPro camper to replace the dead lead acid house batteries. From the factory, the electrical system has some form of autoswitch so if I'm plugged into 120V shore power, I get AC to my camper and it charges the 12VDC battery bank at the same time. Since I am switching to lithium batteries, do I need something in between the RV charging system and my 2 new batteries? I know a battery charger plugged into a wall outlet must have the specific capability to charge lithium batteries or they can be damaged.

Thanks in advance for the help!

(I am also putting my solar charging system together, but will ask question on that on a different thread).

 

[sunshine_eggo]

Depends. What AC-DC converter do you have? Please provide a link to the manual and/or datasheet.

 

[time2roll]

As long as there will be solar.... the existing converter (probably a WFCO) will be fine.
Do not spend money on a lithium converter. They are no better and some are worse.

 

[sunshine_eggo]

As long as there will be solar.... the existing converter (probably a WFCO) will be fine.
Do not spend money on a lithium converter. They are no better and some are worse.

I usually agree with this, but there are conditions.

 

[Bob B]

You will need to make sure your existing converter is NOT doing an equalization cycle.

 

[Pierre]

When I converted the caravan to Lithium I pulled out the original LA charging system and replaced it with a Victron charger capable of charging all chemistries and with the BT one can monitor on your phone.

 

[wme]

Why no equalize?? Is it a case of idiot proofing in case of BMS failure? Shouldn't the BMS over voltage cut off protect the battery. My equalize is set for 0 min, but just asking

 

[Bob B]

Why no equalize?? Is it a case of idiot proofing in case of BMS failure? Shouldn't the BMS over voltage cut off protect the battery. My equalize is set for 0 min, but just asking

Equalize is WAY too high a charge voltage for Life batteries .... it is only for FLA batteries .... not good for AGM either.

 

[OTRwSolar]

Equalize is WAY too high a charge voltage for Life batteries .... it is only for FLA batteries .... not good for AGM either.

Agree, the equalization mode on some FLA/lead-cell converters/chargers could damage a lifepo4.

However, not all equalization modes use excessively high voltages. For instance, quite a few Progressive Dynamic, 3-stage, FLA/lead-cell 13.2v/13.6v/14.4v converters (often used OEM in RV's) have a 14.4v equalization mode. All it does is go into 14.4v bulk mode for 15 min. after it's been in 13.2v float mode for 24 hours. Perfectly safe for a 12v lifepo4 battery.

We've been using one of these Progressive Dynamic 3-stage, FLA/lead-cell 13.2v/13.6v/14.4v converters to charge our lifepo4 200ah pack for over two years. Charges flawlessly.

On a somewhat related topic: A number of folks in the RV community, upgrading to lifepo4's, are removing their OEM Progressive Dynamic 3-stage FLA/lead-cell 13.2v/13.6v/14.4v converters and replacing them with Progressive Dynamic "lithium approved", single-stage 14.6v converters. Sad, because IMO, the Progressive Dynamic 3-stage FLA/lead-cell 13.2v/13.6v/14.4v converter is a much better, safer charging platform for lifepo4 than this single-stage 14.6v---especially if you're the set-it and forget-it type. I think most would agree subjecting a 12v lifepo4 to 14.6v, 24/7/365, is far from an ideal charge profile.

 

[Billy D.]

After spending $1000 on new batteries, spoil yourself by spending another $200 on an IP22.

RIght?

 

[OTRwSolar]

After spending $1000 on new batteries, spoil yourself by spending another $200 on an IP22.

RIght?

The IP22 is a nice unit. Good efficiency.

We kept our OEM FLA/lead-cell converter and spent $200 on a 2nd converter to bump up charge current to 100a. For us, speed over pampering.

 

[HRTKD]

Take the cheap route: Disable the existing converter.

Run your system for a while and see if the PV is enough. In my case, the PV system is enough and I don't need to use an AC source to charge my LiFePO4 battery bank.

If your RV's main distribution panel is setup just right, you may be able to disable the converter by flipping one of the breakers. The DC side will still be connected, but it draws a miniscule amount of power.

 

[tallenhouston]

Thanks for all of the great insight. I spoke with a tech at WFCO and confirmed all of the above. They do make a Lithium charging friendly unit, but I am going to shut off the breaker for the AC to DC charging circuit and use the Victron IP22 to charge when on 120V shore power.

 

[Liam M]

Depends. What AC-DC converter do you have? Please provide a link to the manual and/or datasheet.

I have this unit and wondering too if it will work for lifepo4:

WFCO WF-8735-P Black 30 Amp Power Center​

https://forestriverinc.com/files/Component-Manuals/Electrical/WFCO%20-%20Power%20Converter%20Model%20WF-8700%20Series%20Operator%20Manual.pdf

Any input appreciated!

 

[sunshine_eggo]

I have this unit and wondering too if it will work for lifepo4:

WFCO WF-8735-P Black 30 Amp Power Center​

https://forestriverinc.com/files/Component-Manuals/Electrical/WFCO%20-%20Power%20Converter%20Model%20WF-8700%20Series%20Operator%20Manual.pdf

Any input appreciated!

Chart on page 6.

up to 14.4V for up to 4 hours or drop to 5A
13.6V for 44 hours
13.2V after that

That's a pretty decent converter for use with LFP. It would even be decent with generator charging.

In an RV, there is always a notable voltage drop between converter and battery, so the converter will "see" 14.4V when the battery is at a lower voltage.

13.6V is a decent but slightly high float voltage, BUT even that level can get a battery fully charged over several hours.

Honestly, it's a better implementation than most of the Lithium specific versions I've seen, in other words, I would choose THIS unit for lead acid over a lithium specific converter.

 

[Liam M]

Chart on page 6.

up to 14.4V for up to 4 hours or drop to 5A
13.6V for 44 hours
13.2V after that

That's a pretty decent converter for use with LFP. It would even be decent with generator charging.

In an RV, there is always a notable voltage drop between converter and battery, so the converter will "see" 14.4V when the battery is at a lower voltage.

13.6V is a decent but slightly high float voltage, BUT even that level can get a battery fully charged over several hours.

Honestly, it's a better implementation than most of the Lithium specific versions I've seen, in other words, I would choose THIS unit for lead acid over a lithium specific converter.

Thanks, this was my thought as well in terms of voltage. But is there not a difference in the ‘type’ of charging for lead acid vs lifepo4?

 

[OTRwSolar]

I have this unit and wondering too if it will work for lifepo4:

WFCO WF-8735-P Black 30 Amp Power Center​

https://forestriverinc.com/files/Component-Manuals/Electrical/WFCO%20-%20Power%20Converter%20Model%20WF-8700%20Series%20Operator%20Manual.pdf

Any input appreciated!

We have the latest version of this WFCO 35a converter (and the same 30a power center) in our new teardrop trailer. Have also owned/used a number of other WFCO's through the years--replaced most of them with Progressive Dynamics.

WFCO's have a reputation for staying in 13.6v absorption mode--even when charging very depleted batteries. Charging at 13.6v, they only produce a fraction of their rated charge current. It takes a very large, low resistance load to bump these things into 14.4v bulk mode. When/if they go into bulk, they typically won't stay there long.

If your unit goes into (and stays in) bulk mode, you'll be one of the lucky ones. If it doesn't at least you know you're not alone.