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Originally Posted by 4Mrfisherman!
Unfortunately I haven't seen anything else.
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Let me give you a thumbnail sketch.
With lead acid batteries, for best long lasting life, draw them down only 50%. In other words, if it's a 100 amp hour battery, use only 50 amps and then recharge to full. Always keep them in a full state.
With lithium batteries you can use the full amount**. So if it's a 100Ah battery you can use all 100 amps and then recharge without damaging its life expectancy. **here's the caviat, quality lithium batteries have a BMS (battery management system) that will cut off the battery before you draw it so low that you will damage the cells. Therefore you can draw them down to dead without damaging them. But let's face it, you're doing something wrong if you do that with any regularity.
So in the same size battery footprint you get twice as many usable amp hours.
Lithium batteries charge much faster than lead acid. This usually comes into play when recharging with solar and there's only so many good hours of sunshine. But I suppose also with a generator. It should take less run time.
Your stock charger/converter (if it doesn't have a lithium setting (most don't)) will charge a lithium battery to only 80-90% full. So if that was your only source to recharge (no solar panels on the rooftop) the 100Ah lithium battery would only contain 80-90ish amp hours. Still, better than a 100ah lead acid with only 50 usable amps. The stock c/c won't damage the lithium batteries.
You can use the stock charger/converter and solar panels at the same time. In the summer time (more hours of sun) the solar will probably charge the lithium battery to 100% full. In the winter time, probably not because there's not enough good sun hours.
You don't have to to change out the stock converter/charger, but usually you do change to one that will charge lithium to 100%.
It's my personal opinion that switching to lithium will not "save you money." I switched because I had room for only two batteries, and I wanted 200 usable amp hours. It's an investment you don't have to lose. When we sold that RV, I kept both batteries, put the original charger/converter back into the RV, and kept my expensive solar charge controller and battery monitor (both Victron). I put in a cheap new lead acid battery for the buyer. I then installed all my lithium and gear into my next RV.
I think it's step one to have a battery monitor. You need to know how many amps you consume between charging, regardless if the charge comes from shore power, generator, or solar panels. Look at the the Victron Smart Shunt ($130 Amazon). Bluetooth to your phone. Once you know how many amps you use, and from that how many more amps you wish you had before recharging, then you can analyze what kind of battery bank you want. 2x 12v lead acid, 2x 6v golf cart lead acid, or lithium. And maybe in that process you'll decide how best to recharge the batteries.
By the way, if you boondock and recharge by generator, the battery monitor will also show you how many amps you put back into your batteries. You can calculate how many hours you need to run it etc.
Using a battery voltage chart to judge battery state of charge, to judge how many amp hours you used, is just to imprecise.
Let me know if you have any questions.
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