Any particular reason? (there's both founded and unfounded reasons for maintaining an arbitrary state of charge)
That article was super helpful. Thank you! Making me rethink everything....
I was thinking maintain 50% so as not to damage the batteries. I keep reading that everywhere and I'm pretty sure that's what screwed up my current batteries. Left it at an rv shop for renovation and he let it sit for 10 months unplugged saying he would get to it.... (He never got to it...)
You need to understand that with any battery, the voltage changes depending upon the battery's state of charge. Looking at lead-acid batteries such as most RVs come with, a fully charged battery that has had time to rest (no remaining surface charge) will typically read about 12.6V if ambient temperatures are in the 60° to 90°F range. As the battery is discharged that voltage will fall to about 12V at 50% charge level and 11.7V at 25%. Those numbers will be less as the battery ages and they also mean that the electrolyte is at proper level and has been maintained there. In the real world, most batteries experience a varying electrolyte level and frequently are allowed to fall below the optimum level and that is hard on your batteries. Very heavy charging is also and higher charge rates will evaporate the water out of the electrolyte much more rapidly. Discharging lead-acid batteries below 50% charge will increase a chemical reaction called suffocation and damage the battery. Because of this, the battery really should never put out more than half of its rated capacity, or life will be reduced.
It's not damage, it's wear. There's a difference. Damage is an impact that reduces performance or life in some way. Depth of discharge does not appreciably affect service life - energy stored and delivered - what they're designed to do and what you're paying for. RV'ers always cite cycle life but cycles don't run things, amp hours do. Few RV'ers ever come close to cycling out a battery much less wearing one out, so the 50% Rule has no real significance.
That's a system problem, not a battery problem. Can't speak to all RV's but in my itasca, everything is spec'd for and I've tested to operate at 10.5V. Even my generator will start from my discharged house batteries (something I wanted to find out before I needed to). One can accommodate a narrower range spec through state of charge and that works if the capacity is still sufficient to run what you need. If not you're either buying more battery (to throw away later) or come up with a different device. Just depends on what ends up being more practical.
I would; it's a superior battery for RV use in terms of weight and performance, and none of the shortcomings of lithium are of importance to me, e.g. charging in sub-freezing weather. It's fairly easy to justify the battery cost alone based on cost/year of use. However, the potential cost of retrofitting a system designed for lead-acid batteries to lithium use raises the question of "how much better" vs the extra cost. That's where the upgrade question can get difficult.
Whether you call it damage or premature wear seems academic; the batteries can no longer function and need to be replaced. The probably cause is leaving the batteries discharged for a lengthy period, a condition that lead-acid batteries seldom recover from. That's a somewhat different ill than merely discharging below 50% once or twice.
You don't need battery capacity for that. In fact, it's an ideal use of the onboard generator. You probably don't have enough inverter capability to run two a/c units from an inverter while driving anyway, but if you do the size of your battery bank would need to double or triple even with the engine alternator helping.
In simple terms, if it ain't broke there is no need to fix it.
Yea, mine is broke, so just trying to fix it right!In simple terms, if it ain't broke there is no need to fix it.
Nothing williamrver has said so far indicates he needs more or different battery capacity than his OEM system provided.
Lead acid batteries have a certain set of traits, and Lithium Ion, in this case most likely LiFePo4 batteries have a different set of traits. A number of the traits LiFePo4 Lithium have are very nice for typical RV use, they can last for 5,000+ charge / discharge cycles, think a full charge discharge cycle every day for nearly 14 years, they are happy to being stored for prolonged periods of time at partial state of charge, in fact they will last longer doing so unlike lead acid that needs to be topped up and float charged to maximize life. The downside of Lithium is that they like to operate in the same general temperature ranges that people like (35-85F), and can't be charged at below freezing temperatures. This is why when I switched to LiFePo4 I relocated my battery bank to a cabinet inside the RV from its exposed to the weather located under the entry steps. In addition to this you can treat LiFePo4 much more like a bucket you pour electricity into and out of as they have far less charge and discharge losses, ie they are both buckets that leak, but LiFePo4 leaks much much less. On an economics point Lithium is looking more and more favorable every year.
In Florida, we spend a lot of time north of 90 degrees. The battery bay is in the rear left of the rv, near the diesel engine. I was concerned about charging when we were traveling in cold climates, but is high temp also going to be an issue?
I was referring to the system design and component selection as "ain't broke", not the worn out component. The worn out batteries could be replaced with an identical component and be fully functional again, and it appears it would meet your needs.
Gotcha! I might be overthinking this. I'm prone to do so.
If you've got a lot of vertical room you can go with a pair of L-16 batteries and get close to 400aH out of the pair. Of course they're about double the price of the GC-2's.
