LiTime 12V 400Ah Plus LiFePO4 Lithium Battery w/ 250A BMS, 5120Wh Energy, 3200W Max, 4000-15000 Cycles & 10-Year Lifetime, Load Power Group 8D Battery Perfect for RV Home Solar System Fishing

Information is power and FINALLY a smarter battery (Bluetooth) to know what is going on (what I am doing wrong?) as shunts, solar controllers and inverters are only part of the information game.The CON is if you are going to break the "Never let your wife or RV get cold" rule, This one is (finally) smarter than the bunch of other LiTime I have prior BUT it is not heated (at least it knows what to not do in the cold)STOP NOW, GO DIRECTLY TO LiTime BlueTooth+HEATEDI have an entire archive of photos of how I bought silicone heat pads, insulation, high temp adhesive, temp controllers etc $$$ all wrapped in bubble foil to make it "heated" ... but by the time I did (spent $) on all this to upgrade ... LiTime came out with the Bluetooth PLUS heated version (and I bought yet 2 more to go with the even dumber 3 I had prior)Down side: It's hard to keep up with technology changes. Up side: Technology changes to choices you do or don't needIf you DON'T need heated then save some cash. If you have earlier dumb LiTime (or equal amp rated/not smart Bluetooth) then wire them in parallel with this affordable smart one and it will tell you state of charge (for one and for all in the bank) at least.(ok disclaimer: trusting a bank based on one battery stats is a leap of faith, but bringing it to 100% SOC or it not achieving 100% charge will at least give you some insight vs a dumb bank of batteries and a shunt alone. In fairness my shunt is generally way off over time and it takes a smart battery to know the truth anyway)Just warning, with features can come problems. It's smart but if you "turn it off" you will have to "wake it up" (and you will have to wake it up on delivery anyway from sleep). It is no kiss, it needs a smack by a good LiFePo4 charger sufficiently high voltage to wake out of slumber. (same as heated versions)I just happened to already have an SLA LiFePo combo jump charger that put out enough to do the trick. You might need a 2fer in your cart to avoid a "not DOA but not ON back to Amazon shopping daze" delay. Probably wise to charge the bank up individually with said charger occasionally to be sure the bank is fine anywayMAYBE most CRITICAL is non heated (this one) and heated all work in the LiTime API BUT if you are doing a true "bank" you WILL NEED MATCHING HEATED or NON HEATED batteries (they don't mix at least for ex: 2S and 2P in the API grouping ... assuming that matters). I did get away with buying a second heated 6 months later. Your mileage may vary on that (their disclaimer) and the software versions are slightly different on screen but not within families...yet. Also go in the API, out and in again to get newest SOC (even if it is the current battery showing connected). BUT that is an API issue.

I replaced two 6 volt lead acid batteries with four of these batteries, wired together in parallel to power the 12-volt system in my 13-foot trailer, including a new 60 watt fridge in. We enjoy remote camping for a week at a time, and need to be able to keep the fridge running while still being free to unhook and go exploring with our 4WD vehicle, without leave all our equipment out, unlocked charging (you know, solar panels, etc.) while we are gone. I have tested these batteries and find that they will last about 6 days before they are discharged to the point that they turn themselves off. (They have internal protection so they won't overcharge or overdischarge and get damaged.)The company has representatives who respond to questions within 1-2 days via email and I have been very happy with their service. When wiring four batteries, it is important that they stay in balance. To do that, I wired all the positives to a positive busbar, and all the negative wires to a negative busbar, using identical length wires (instead of to each other.) (see photo) This keeps them in balance with each other during charging and discharging. (You can also wire them in series in order to increase the voltage, of course, but I needed to stay with my 12-volt system and just increase the battery capacity, so I wired them in parallel.)My only issue is that LiTime's wiring diagram for wiring in parallel does not seem to be correct. They show wiring with a busbar and ALSO wires between each battery which is definitely not necessary and probably also defeats the purpose of using the busbars. When I asked them about it, they stood by their diagram, but their reason made no sense to me. They said the batteries also have to be connected to each other. But they ARE connected to each other via the busbars! I checked with an electrician who said he couldn't see why the extra wires would be needed, but didn't want to contradict the company's instructions. I can't even imagine how crowded the wires would have been if I had used twice the number of wires, LOL! The system is working beautifully by wiring just to busbars.The batteries fit in a standard group 31 battery box and weigh half the amount of a lead acid battery, so I can handle them easily by myself (69 y/o 100 pound female). (I could never begin to lift a lead acid battery by myself.)Changing from lead acid to LiFePO4 batteries is a steep learning curve! We tried to get the help of an autoelectric business, but they said they didn't have any experience with Lithium batteries. You'll have better luck at an RV service place, or study youtube instructional videos. But there are numerous advantages! The LiFePO4 batteries charge much faster, last a lot longer with each discharge cycle, have a much longer life overall, and are half the weight of lead acid batteries!Here is the learning curve part: If you discharge Lead acid batteries past 50 percent of their capacity, you damage them; whereas you can discharge the LiFePO4 batteries down to 20 percent and still maintain their long life. The trick is figuring out when they are getting close to 20-25 percent of their capacity. LiFePO4 batteries have a very flat charge/discharge curve. They stay at 13 volts from 100% (at rest not charging) down to 25% capacity, then drop precipitously. If the voltage reads 12.8, they are almost dead and need to be charged immediately! You need a multimeter to check the capacity, which is read in 10ths and 100ths of a volt, because the change is very tiny until the end. (see page from LiTime manual.) It's important to know to check the voltage with loads removed (i.e. fridge and lights turned off in my case). Also, the voltage drops on the way to the load (i.e. the fridge wiring), so the fridge reads a lower voltage than that measured at the battery. You will have to get used to what your fridge (or other device) says the voltage is, versus what the actual voltage is at the batteries by using some kind of voltage meter. I have been able to develop a feel for the actual voltage vs the fridge reading by checking and rechecking over time. As I say, it is a learning curve.While running, by the way, the fridge says the battery is at 12.4 or 12.8 volts usually. That is normal. The battery capacity is measured at rest. So I just turn off the fridge for a moment to see what it is measuring at rest. Then I compare that reading with what the voltage is at the battery itself. When the fridge says 13.0, for example, the multimeter at the battery says 13.26. If the fridge gives me 12.8 volts at rest, I know it's time to recharge! You'll need to do the testing to know the parameters for your own system to be sure.