I've gotten three years, so far, out of two $99 Walmart Marine/Deep cycle FLA.
Each Battieborn 100AH costs $994, I would need to get thirty years from a Battleborn.

I have said this before...

The less you want to be knowledgeable about lithium the more it will cost.

Battleborn is for those who just want to drop in and ignore everything about them....hence, they cost a lot!

If you are building your own system, the cost is a great deal cheaper, but the knowledge required goes up a lot. Also, it is hard to know who to listen to. First lesson I learned...ignore anyone who isn’t actually using them in their rig (RV or sailboat).

My entire system (batteries, monitors, balances, relays) cost me $2300. For 400ah LiFePo4
And, that cost could have been a few hundred lower...but I learned a few lessons the hard way...namely, I bought hardware I didn’t need.

So, when you consider that I do not need a generator or the gas for it, and I get approx 10-15 years of life from it....it is cheaper than lead acid technology. In the SW desert I get more than enough sun to recharge them every day. I often turn off the panels for a day or two to avoid keeping the batteries fully charged all the time.

A quick additional note...I purchased by batteries 3 years ago (before the China tariffs) ... so the price is probably a lot higher now.

This is a perfect example of why the technology is not so widespread. It's simple a question of do they like to be kept at full charge or is this damaging. The reaction I've seen on so many forms. No straight answer to the question and then: "my old Mac computer doesn't get viruses."

Wait Apple computers have nothing to do with lithium batteries.

Yes you're correct.

Lead acid batteries have nothing to do with lithium.

But they both run my wheatgrass smoothie maker.

Correct and I still edit videos on my 10-year-old Mac. This process kind of looks like a St. Bernard humping football.

The point is the different technology. Yes they both store energy and that's where it stops. Same as my 10-year-old MAC they both edit videos but my iPad Pro is faster in every way and different in more ways than it is similar.

The math question of which is cheaper has been proven by smarter people than me and lithium wins. Providing they're charged discharged and taken care of properly. At issue is most people can't afford to buy into a proper system at one time. So they try to do it in stages and that is the niche that battle born falls into. Retrofitting an RV to a different electrical system is not easy; it looks easy at the start but then you start throwing things around: charging from multiple sources, charging multiple battery chemistries and the nightmares begin. I've done this merry-go-round numerous times and when you solve one problem you create another problem. This is coming from the boat owners perspective and not an RV perspective but doing it an RV just makes it more difficult.

Past the silly it will do 300 cycles it'll do 3000 cycles it'll do 5000 cycles comparisons what makes this chemistry ideal is it will take a charge at an extraordinarily high rate. Lead acid chemistry are basically heat sinks the internal resistance creates issues when you charge or discharge. Lithium batteries also can discharge or give their energy to an inverter at an extremely high rate. So that surge that your induction heating element on your stove or your air conditioner needs is not such a problem. I'm just using general examples here are not getting in depth as that's not the topic of this post. If you're living down by the river And you just need to use a lightbulb and a refrigerator then discussion of this topic it is not for you. Unless of course this is purely cerebral and you're just trying to learn more. Nothing wrong with that.
But if your rig is hovering around the max gross vehicle weight and you need power then you really don't have any other choice.
Early adopters of this technology actually cooked duel alternator set ups as the batteries could except the max amperage both alternators are putting out.
The standard separating relay regardless of type and brand didn't really address the problem of different chemistries. Lead acid for the starting battery and lithium for the house.
I'm not trying to sell anyone on any particular set up. If you want to use Trojan or lifeline flooded or absorbed glass mat, then do so. It's easier, much simpler. Sternwake has written pages of how to do that simpler and easier system correctly and yet many people still cook their batteries. Doing this with lithium is far more complicated, far harder, and probably why he doesn't chime in on too many of these lithium discussions. For me I have worked with my ship engineer who specializes in electrical systems for large boats for years. We have looked at alternative lead acid technology batteries to keep the chemistry the same. But for me being on the edge of my Weight allowance I need the lighter batteries.
While I can't answer the original posters question I hope we have pointed her in the right direction to find the answer. In doing some research to try and help I located and answered one of my own questions. How to charge lithium in the house from the alternators without Changing the engine batteries while simultaneously charging the house batteries with solar. One person on a sailboat uses a separate inverter hooked up to the 12 V engine power that only runs when the engine is running and from the 12 V power through the inverter he has a special 120 V lithium charging system on his house batteries. Agreed it is not the most efficient way of doing it but it protects the alternators and it protects the batteries and gives you some redundancy as you have a second Pure sine wave inverter if your primary inverter goes down.

I did not want to take this off topic, and I don't think I did. But I also thought it was important that people understand it's not just weight amp hours and cost. One of the primary builders of overland expedition vehicles in Canada has just switched to using battle born batteries from a significantly more expensive German brand because Battle born has newer and better technology and cheaper prices than who he had been dealing with in the past. While one of the best builders of these rigs he had no idea about the battle born product because discussions about lithium on the web are exactly what the original poster was concerned about.

Thank you Scott for bringing this back to that question.

Apparently there is no straight forward mathematical equation to use in order to figure out how often and for how long I should keep my panels turned off and drain the batteries.

This much I know...if I just let the system be...the panels will bring the batteries back to full everyday. Even when I run the electric heat for an hour or so in the morning, if the sun is shining brightly the batteries are full by the end of the day.

What I do not know...is it the same degree of bad for the batteries to bring them full everyday as opposed to having them full that entire time? What would be a good amount of time to have them stay unfull?

Too bad there isn’t a quick guide to this.

Just when you finally think you know all about life-po-4 they'll go and make some new formulation that everybody has to figure out..........(they used to do this stuff before selling something) Carbon Foam anyone ?

I went to Carbon Foam route. The weight savings wouldn't be enough as they still have the 50% discharge ratio. Initial tests by "" experts" said you could go lower but in reality this was not the case. Still a great battery if you have that weight allowance.

Here is a boatload of information on LiFePo4 batteries:

https://www.solacity.com/how-to-keep-lif...ies-happy/

Good article TX. I think the op will find the answer she was looking for.

That was a great article...one thing I take exception to...

The article claims that at 13.1 the battery has 40% capacity remaining. This is totally not true.

My batteries drop rapidly to 13.1....but will sit there for days without a charge.

At 400ah....dropping below 13.1 (which the manufacturer says is the point it will hold steady at between 80% and 30%) would require me to discharge 280ah. Except for the time I tried to change an electric car from my lithium batteries, have never seen that happen.

(03-22-2019, 05:46 AM)RoamingKat Wrote: That was a great article...one thing I take exception to...

The article claims that at 13.1 the battery has 40% capacity remaining.    This is totally not true.

My batteries drop rapidly to 13.1....but will sit there for days without a charge.

Something to keep in mind is that digital meters (either stand-alone or in a solar controller) are not always 100% accurate. I can put 4 different meters, all good quality, on the same battery and they might vary by up to 1 or 2 tenths of a volt. So which one is correct? And just exactly how much do the test leads affect the accuracy? Many digital meters in the consumer market have a listed accuracy of plus or minus around 2-5% of full scale, or maybe .1 volts or some similar number.

A digital readout with 2 digits to the right of the decimal place is one, one-hundredth, resolution, but that is not the same as being calibrated to one one-hundredth of a volt accuracy. If you own and use a lab quality, certified accurate digital meter, and you get it certified every year, then we can assume it is close to 100% correct. Otherwise, no. 

Probably, the voltages obtained by your lithium batteries under differing conditions can be used as the reference voltage to calibrate your meter, if it can be calibrated. Does your solar controller have a remote battery voltage sensor? If not, that might account for the variation you see. Or it could just be that your batteries have a slightly different charge and discharge profile.

Also, the charts provide seperate voltages for both resting and loaded voltages at .25C....which number in which chart do you disagree with? And if you do have differing numbers, isn't it possible your measuring equipment is possibly slightly incorrect?

I know that happens. I've seen it. But if you only have one meter or display, you might assume it is 100% accurate and calibrated to lab measurement standards, but it very likely is not. QC at the chinese factory often means: hey, its close, box it up and ship it. It could easily be off by a tenth of a volt. Ambient temperature fluctuations also affect the accuracy of almost any digital meter...but some lab quality instruments have temperature compensation built in.

Hey, even $50,000 cars will have slightly inaccurate digital speedometers.

What you are really looking for are 'trends': be familiar with your system, and the way it behaves, and take the voltage readings with a little 'grain of salt'.