A Few Auxiliary Battery Questions

[craig333]

I purchased one of the used lithiums Will tested and I've been very pleased with its performance. I love that I don't have to treat it gently like I did my AGM's. I got eight years out of my AGM's but I had to do a lot of research to find out how to charge them. Kept a close eye on them all the time making sure the S.O.C. never dipped to far. Instead of changing a dozen settings on my charge controller the lithium only required changing two and I don't have to keep a close eye on it to keep it happy.

 

[VanWaLife]

I'm not sure how the Victron works, but my system (admittedly an unusual Australian Pirhana system) wasn't fully charging my aux bat because my start bat was old. After I swapped that out the aux bat gets charged nicely.

 

[Nailhead]

It looks like I was barking up the wrong tree: the water pump and furnace were still powered by the original undersized Alaskan wiring which takes a roundabout route from the battery to these devices, and grounds through the outer aluminum skin. I finally did what I should have originally and ran upsized power and ground wiring to my Blue Sea fuse block and ground terminal strip to these.

The furnace runs like it should, and there’s no more “disco lighting” effect when I run the water pump with the house lights on.

I checked into lithiums again and was close to pulling the trigger on a couple less breathtakingly priced ones, but for two aspects that queered the deal: 1. There is no lithium battery charge setting on my inverter/charger. 2. I would have to completely reconfigure my battery cables because I could not find any lithium batteries with a dual-post configuration.

This thread got me thinking, though; lithium batteries are clearly the better choice over AGM if your vehicle is configured to support them.


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[Nailhead]

I don’t know if you’ve looked at the price of AGMs lately but I don’t think they’re as cheap as they used to be.

Nothing is.


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[DiploStrat]

Bravo! I feel your pain. I have been chasing a gremlin in my alternator to camper battery charge for over six years. Used two different products - nothing worked. Turned out that the camper builder never grounded the camper batteries. There were negative cables everywhere, but none connected to the frame/stater battery. Fixed that and, boom!, everything works as it should. (Anyone want some B2B? Turns out they are fine.)

As to the other. If you fixed your wiring, try a recovery charge on your AGM and keep on trucking. Don't spend money you don't have to.

As to lihium iron batteries, I am always nervous of off brands, less for the battery, more for the BMS. The nice thing about lithium iron is that almost any voltage source capable of about 14v will work, especially if you are talking about charging from the engine, where you are going to be time limited to about six hours a day.

Doesn't mean you should not get lithium specific, but, as long as you limit the load on your alternator, the voltage is not as critical as AGM

 

[Nailhead]

While they may contain devices in their construction.
To split hairs, a waterpump and furnace are not electrical devices.

To split a couple more, your fist sentence isn’t; it’s a clause with a period where a comma should be.


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[DaveInDenver]

I wouldn't presume to tell @Nailhead he should or should not do anything. The AGM solution worked for 6 years at what was probably non-ideal handling (almost certainly left routinely undercharged) so that is nothing to scoff at.

I don’t know if you’ve looked at the price of AGMs lately but I don’t think they’re as cheap as they used to be.

There's truth in that point. I just had to buy a new group 27 AGM for a vehicle starting battery and that hurt more than I expected for "old" technology.

So I would only point out here to do an honest assessment on a per cycle or per year basis. If a pair of replacement AGM cost $600 and last 6 years again in his use he's at $100/year.

Battleborn say are $2000 so will have to last 20 years to hit the same value, which they probably won't. Lithium age, too. Although being left in a partially charged state between uses isn't as damaging to them as it would be lead-acid so chances are they'd last longer regardless of cycle count.

There may be benefits such as less weight and more useable capacity but acknowledge those as valuable in their own right and budget appropriately. Don't overlook ancillaries such as chargers that may need to addressed. Those are one time expenses but expenses just the same. Even if it's just as simple as needing to buy a programming cable to adjust parameters.

And, sure, it is possible to save money with non-premium brands or doing it yourself (which I did). But even those may not actually be cheaper than a Battleborn when you value your time or the benefit of support and warranty.

None of this is any different with AGM. A couple of X2 AGM is more than a store brand and say they go 9 years for $800 or getting just 4 years from generic AGM that cost $300 would skew the calculation as well.

None of this is to say I wouldn't do the switch to lithium for my house battery again. It was worth every penny. But it wasn't a 1:1 money question, in particular the capacity-per-weight benefit. But my situation was facing a $400 AGM replacement so spending $500 instead didn't hurt enough to not justify it. Especially since by building it myself everything except the bulk cells is one-time money spent. So even if these cells don't last any longer than the AGM did the next time refreshing the battery will be cheap(er).