Switching my RVs house battery to a LifePO4

[Photobug]

My Born Free 22 has a two bank house battery that are needing replacement. I am tempted to replace them with the same large Walmart batteries for $300. Given the price of LifePO4 batteries are getting much lower, I am considering going LifePO.

What are the stumbling blocks of adding LifePO4 to my house power system? What do I need to do to get the LifePO to work with my current charging system? RIght now it gets charged when I plug the RV in at home or when I drive the vehicle. Would I need to add two separate charging systems to power from both the AC and DC source?

The batteries are stored in an outside accessed cabinet and at outside temps. I camp a lot in the cold will the lithium batteries be limited by cold temps? Is this just in charging or in use as well?

 

[crazysccrmd]

Do you know what model your power converter is? Depending on that it may be as simple as flipping a switch to change to a lithium charge profile. If it isn’t compatible it is easy and fairly cheap to swap to a converter that is. Do you have solar? Same concept there - does your current charge controller have the ability to charge lithium?

You can buy self heating lithium batteries that use a portion of the incoming charge to warm up so they can be charged in cold weather. I use Renogy self heating batteries and have had no issues charging well below freezing and discharging down to -25°F.

 

[Gravelette]

Even if your converter does not have an Li setting, you can still charge to 90+% w/o hurting anything. You can buy an inexpensive stand alone Li charger to use at home before a trip if you want to squeeze in that last bit of charge. In other words, the conversion could be as simple as swapping the batteries for Li. For the same size in batteries, you'll gain nearly double the usable Ah with Li.

 

[rruff]

The batteries are stored in an outside accessed cabinet and at outside temps. I camp a lot in the cold will the lithium batteries be limited by cold temps? Is this just in charging or in use as well?

Yep, don't charge if it's below freezing! You can ruin them. Discharging is ok. Some LiFePO4 batteries have a auto shutoff if they are cold, and some have auto heating like crazysccrmd mentioned; you want the ones that use the input energy to heat the battery up first, before charging it.

Since I only use a portable panel to charge, I'd just keep the charging off in the morning if the batteries got too cold. It hasn't happened yet, with outside temps in the teens and no heat.

 

[Red90]

Even if your converter does not have an Li setting, you can still charge to 90+% w/o hurting anything. You can buy an inexpensive stand alone Li charger to use at home before a trip if you want to squeeze in that last bit of charge. In other words, the conversion could be as simple as swapping the batteries for Li. For the same size in batteries, you'll gain nearly double the usable Ah with Li.

That is not true. Many lead acid chargers will charge to a voltage that will cause the lithium battery BMS to trip out on high voltage.

 

[Gravelette]

"Many"? AFAIK no RV converter/charger sold in USA will damage a Li battery. If you have seen actual reports to the contrary I'm happy to learn of them.

 

[Peter_n_Margaret]

In my limited experience, provided a charger has no "equalising" mode, or if it does it can be switched off, it is probably OK for LiFePO4.
I can also charge my 325Ah CALB directly from the 85A alternator.
Cheers,
Peter

 

[Buddha.]

Look in the fuse box area for the converter model number. Google if it’s lithium compatible.

 

[jonyjoe101]

max charge for a lifepo4 is 14.6 volts, most alternators put out 14.4 volts. Many of the lead battery chargers also charge to 14.4 volts. As long as the battery charger doesnt have a equalizing feature (which charges past 14.4 volts to refresh the lead acid battery) it should be good.
You don't want the lifepo4 BMS to activate due to overcharge or undercharge, then you would have to re-activate the battery.
Make sure you get a coulombcounter, thats the only way to know the lifepo4 SOC. If there is any voltage drop between the charger and the battery, undercharging the battery might be a problem. Lifepo4 can be kept undercharged with no problem, but if you have a 100ah battery, you want to always keep as close to fully charge as possible to get the max use out of it.

 

[DirtWhiskey]

Depending on your converter Progressive Dynamics makes drop in lithium conversions for your box. Took me 30 minutes:

lithium-converter-replacement-units - Progressive Dynamics

The Mighty Mini Compact All-In-One System offers an AC/DC Power Distribution Panel and Inteli-Power Converter with Charge Wizard battery charging technology.

www.progressivedyn.com

Don't be intimidated, it's easy and you'll kick yourself for not doing it sooner. I've been really happy with my SOK self heated units. Don't bother with no self heating.

 

[CappyJax]

If you are handy and take the time to research how to build a back, you can get them much cheaper than a pre-made battery. https://www.18650batterystore.com/

 

[rruff]

^ Doesn't pencil out. $575 for 4,000 Whr shipped. Then you need a BMS, cables, case, packing, etc.... At least $700 just for materials. 5.71 Whr per $.

Last battery I bought was $160 shipped for 1280 Whr. 8.00 Whr per $. Plug and play.

 

[Photobug]

^ Doesn't pencil out. $575 for 4,000 Whr shipped. Then you need a BMS, cables, case, packing, etc.... At least $700 just for materials. 5.71 Whr per $.

Last battery I bought was $160 shipped for 1280 Whr. 8.00 Whr per $. Plug and play.

I bought my first LifePo for $10/ah. At that time I considered rolling my own, now, not worth it.

 

[Photobug]

Depending on your converter Progressive Dynamics makes drop in lithium conversions for your box. Took me 30 minutes:

lithium-converter-replacement-units - Progressive Dynamics

The Mighty Mini Compact All-In-One System offers an AC/DC Power Distribution Panel and Inteli-Power Converter with Charge Wizard battery charging technology.

www.progressivedyn.com

Don't be intimidated, it's easy and you'll kick yourself for not doing it sooner. I've been really happy with my SOK self heated units. Don't bother with no self heating.

Im pretty good at wiring stuff, so plan on doing this. It turns out my batteries which have been drained to beyond flat are still useable at least for now. I am about to start working so much there is no chance to spend more than two day in the RV which I just tested my current batteries are good for two days.

I will once work starts and money starts flowing replace that converter portion of my system to a lithium compatible one, looks to be under $200.

 

[Photobug]

One more clarification if you guys would?

Does a charger or converter only provide a specific voltage and the BMS provides the charging functions? So if I were to upgrade to the proper converter in my RV it would put out 14.6 volts when the RV is plugged in but on the road my alternator will only be putting out 14.4 Volts and I will only get about 90% charged?

I ask because I almost never am at a place where I can plug in and even then never do figuring the next days drive will top off the batteries. Also I have two NOCO chargers I use to repair, top off my batteries at home and to maintain batteries in the off season. I could use the NOCO to charge my new LifePo battery at home. Maybe my money would be better spent buying a DC-DC charger to ensure the battery is properly charged while driving?