Thursday, January 20, 2022


Ask Dave: Can I just replace my house battery with lithium?

Dave Solberg is a leading expert in the RV industry and author of the “RV Handbook” as well as the Managing Editor of the RV Repair Club. Today he discusses lithium batteries.

Dear Dave,
I am considering changing to a lithium battery for my house battery. No solar, just the factory setup. I will change out the charger for lithium. Will my truck have any problems with that? —Chuck

Dear Chuck,
Got your question and it falls in line with another question I got recently from staff at Go Power sent them a new lithium battery to “demo” in their Winnebago class A. They wanted help with information on how to set the inverter and wondered if the charger was compatible.

Fortunately, Winnebago has all their construction schematics available online so we were able to get not only wiring diagrams, but exploded view schematics showing where the charger is and the part number.

I was able to find the specific floor plan and locate the charger and the inverter part numbers. The inverter is a Xantrex ProXM 1000 and only runs to a few outlets located in the kitchen and living room. It is not large enough to be a charger, so it does not need to be “set” for lithium as it only receives 12 volts and “inverts” to 120 volts.

Go Power only offers one model of Lithium 100 ah battery, the Sun Cycle GP-LIFE40P-100.

I talked with a technician at Go Power!, and he indicated the battery had a maximum charging capacity of 14.6 volts, as shown on the upper left of this battery. So the charger must not have a “boost” or bulk initial stage charge that would exceed that.

I found the charger in this unit was a Magnatek 7455BT that is owned by Parallax. I contacted their technical department and found this was a special charger formatted for Winnebago that produces a 13.6 volt charge for 8 hours. This means it will not harm the lithium battery; however, it also means it will not charge it to maximum capacity.

If in doubt, contact electrical expert Mike Sokol

This prompted me to contact my “go to” electrical guru, Mike Sokol, as he has conducted exhaustive research on various lithium batteries and charging options.

What I did learn was this type charger will only charge the battery to about 70%, so they would not get the full benefit of the expensive lithium battery. However, it would provide much more power than their current situation of two 12-volt batteries that originally started out as 100 amp-hr to provide 200 amp-hr, but can only be used to 50%, AND… are sulfated beyond useful operation. Lithium batteries can be drawn down to almost 0%.

The options are to get an inverter/charger that matches the voltage for the lithium battery or get a solar system with the proper charge controller. Go Power is a good option for both.

So in your situation, Chuck, I would suggest checking your charger to see what the output is and make a decision on either staying with what you have or upgrading the charger. In that case, I would suggest either Parallax or Progressive Dynamics, and make sure it matches the voltage.

Another question is how much are you going to boondock? In the previous case, they will not be dry camping for much more than an overnight stop at a rest area, so the expensive lithium is a waste of money, in my opinion.

You should not have any issue with your truck. But keep in mind your system should have a charging feature as you drive down the road – from the truck charging system to your house battery.

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Tommy Molnar
1 month ago

My solar charger charges my Lithium Ion batts at the suggested voltage, then drops to a maintenance charge. But, I have shut down the solar charger because it’s in the 20’s at night here in northern NV (and our trailer is parked next to the house). So, I put my converter on a timer so it only charges after 10am when it’s well over 32° outside, and shuts down at 4pm. I also finally put an old ‘trouble light’ in the forward storage area (where my batteries are located) to keep the temperature well above the 32° mark. So far, so good. In fact, I may just eliminate the timer in this situation. It’s 27° outside right now, and the storage area is 40°.

1 month ago

Why put a lithium battery there? It is harmful to charge below the mid-30s. it is costly. its longer “power curve” serves no purpose when all you’re doing is starting the engine.

James Starling
1 month ago
Reply to  bill

This article is about the “house” batteries and not the vehicle battery.

Bill T
1 month ago

Hi Dave. In your example of the Winnebego Class A I didn’t see anything about how the engines alternator/charging system would handle the 14.6 volts max charging requirement. Would the stock alternator handle any additional current draws required or would you need to add a DC/DC converter in your “drop in” coach battery swap example?

1 month ago

!00 amp hour lithium batteries are showing up on Amazon in the 350-400 dollar range. Internet battery guru Will Prowse has videos on YouTube ripping many of these open and have found some to be quite good, although not necessarily with all the bells and whistles (especially service) of ones costing twice as much. He finds many of them quite acceptable for RV use as long as generally not exposed directly to the elements. Some of the more expensive ones are “assembled” in the US, but all the cells come from China anyway. Your automatic adjective of “expensive” associated with lithium may not be true any longer when compared to an equivalent capacity of AGM. To me, any RV manufacturer who does not start of with lithium in their system is living in the past, perhaps hoping to sell an “upgrade” at a wildly inflated price.

Bob p
1 month ago
Reply to  Richard

IMHO it’s probably like any other type of mfg, as the supply of stored parts run out they start with the newer technology. i.e. GM discontinuing the 4.3L V6, as the supply chain dwindled it’s been replaced by the 2.7L Turbo 4 cyl. As the supply of 6 spd automatic transmission dwindled now the 8 spd and 10 spd are becoming standard.