LiTime 12V 100Ah LiFePO4 Battery BCI Group 31 Lithium Battery Built-in 100A BMS, Up to 15000 Deep Cycles, Perfect for RV, Marine, Home Energy Storage

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.

I bought two of these batteries (12V 100ah). First ordered one to test, satisfied I ordered a second. Both Received On-Time, Good Packaging. Extra terminal bolts provided each. Documentation is good, clear values for User programmed chargers.These are setup in series now to form a 24V 100ah battery pack. I opted to pay more by having two batteries rather than one 24V battery for a few reasons. As stated above, I was concerned with the quality and wanted to test one battery before doubling down for twice the expense. Second, these batteries have a battery management system which is internal to the battery. If it goes bad, chances are the battery will be useless. Having two go bad is unlikely. So I can always reconfigure my system to run from the good 12V battery. Finally, I have a lot of 12V stuff and having a pair of very good 12V batteries gives me more options.These batteries are well built, case seems generic but sturdy. Especially happy with the Terminals, they seem very firmly mounted to the case and hold connections tight.I've run several capacity checks on this, but the only full capacity test I made would be characterized as a .1C test. That is a constant discharge of 100watts, but in my case it was a refrigerator with defrost so when it did run it was about 110watts and about 330watts during the defrost cycle.I was expecting it to run about 39hours but it only made 32 hours. However, then I worked in the inverter efficiency (90%) and the vampire power used by the inverter even when it is not generating wattage. I did several different discharge tests and always got above 95% of the rated watt/hours. That is excellent considering the price point on these batteries in comparison to other similar batteries.I DO NOT recommend any PWM charger with these. I tried charging the battery with a Renogy Voyager and the pulses exceeded the max voltage causing the Battery's Management System to disconnect. Even though this Renogy charger has a LifePO4 setting. I contacted Renogy they were no help, I also contacted AmperTime and the good news is they actually responded. But I knew what the problem was and it simply was not a battery or Battery Management System issue. Needless to say I bought an MPPT charger, EPEVER Triron and it works great. But that is for another review.Couple more notes. I am shocked at how lightweight this battery is, they weigh about a third of what a typical flooded battery would. Every time I pick them up I am surprised by their lightweight. I am sure RV people will appreciate this.The max voltage I got on these batteries is 13.5V after it settles, I was expecting 14.4V. Without making this longer, don't worry about it. It is a weird charge curve and 13.5V is basically 99% charge. My discharge test confirm these batteries will perform to there approximate 100ah rating.In Summary, very happy, highly recommended and I did buy two, perhaps get more in the future.