THISS 12V 30Ah LiFePO4 Deep Cycle Lithium Battery with BMS - 4000+ Rechargeable Cycles - Perfect for Home Backup Power, RV, Solar System & Trolling Motor Applications

I bought two of these to replace the heavy and low capacity AGM batteries in my mother's mobility scooter. The first one tested over 15Ahrs as rated with 20A output for 15+ minutes no problem and 30A output for 5 minutes. Got a scary 40A out for over 30sec (didn't want to risk more than 30s) that was not cut off by the BMS. The second battery tested at an unacceptable 10.3Ahrs. I contacted THISS via Amazon messaging and they promptly sent me a new battery. The third battery tested at a disappointing, but usable 14.3Ahrs. I did test the voltage on all three to make sure they were not too low to be useful.Now the fun part (don't do this kids).... I disassembled the second battery to see how it is made and if the low capacity could be repaired. The batteries are 4 cyclindrical cells with test stickers of about 1500+/- Ahrs dated July 2021. The copper appearance cell busses are welded to the cell contacts substantially. The four cells are in plastic holders wrapped in heavy duty PVC shrink wrap. The battery pack was glued into place with a silicon type glue which also holds the top on it. The 30A BMS is taped with fiber reinforced tape to the top of the cells separated by a fiberglass sheet. There is a temperature switch for overtemp shutdown. The balancing leads are soldered to the busses securely. Two iffy things I noticed the silicone insulated leads were soldered to the underside of the F2 tabs. That's OK, but could be a failure point. The shrink wrapped cell pack is glued firmly into the ABS (barely ABS) casing not touching the top or long sides. My thermal imager showed minimal heat transfer at 20A load at the bottom and smaller sides, which fits the assembly method. I manually balanced the cells on pack two; one of which was about 50% charged after full charge cutoff. The cells were badly unbalanced which indicates a cell with high self discharge and a substantially lower total battery life. Or, badly mismatched internal resistance. Or both. After top balancing the cells battery two tested at 15.5Ahrs twice. I tried charging the third battery slowly at 1.5A, but that improved the capacity to 14.4Ahrs.My thermal imager did confirm the balancing resistors were hot and working on battery two.Overall, I need two for the scooter and they worked within normal (generously speaking) parameters. I would use this for a radio easily, but not for anything needing 30A continuous discharge for more than a few minutes. I am not too confident THISS will last past this first batch of batteries, we'll see....I bought this battery to install into an aging Hensel Porty 1200 AS battery cartridge. This battery is literally the only one I found that can handle the peak amp draw the Hensel pack puts onto a battery without the BMS cutting power.The Hensel Porty 1200 originally ran on 12v 15ah SLA batteries and as such was designed around the performance of those batteries. At full power output on the Hensel an SLA battery can provide the 30A peak amp but most LiFePo batteries will turn off because they think they're being shorted. You can get around the issue by putting the Porty pack into slow mode but it's kinda a kludge.This battery on the other hand works flawlessly with the pack at full power and speed! It's literally a third of the price I paid for some older LiFePo batteries I had bought several years ago and are actually better!Buying more to replace the last few SLA batteries I had been using!So far, I couldn't have asked for a better product for the price I paid.Be sure to read the bottom to see how I rate products.I am very impressed with this battery (15Ah) and was pleasantly surprised of its weight. I knew this was lithium ion but because of its size I expected it to weigh more. Yes, I know I could see the weight on the detail page but there is a difference between reading it and feeling it.I am using this for a homemade lightbox that I use to get my squid jigs to glow and have led light strips in it. I realize that these light strips do not draw a lot of power and for me the use is anywhere between two and five hours. After six hours I turned the lights off so it more than past my test.The next big test will be lifespan of the battery and over time I will come back to amend this review to say "after x amount of months battery is still working".The terminal prongs are well made, thick and not at all flimsy. I fully expect them to last as long as the battery as I remove the connecting wires.I am very happy with this battery, would purchase it again and would recommend it to a friend.When I give a rating to a product said product automatically starts with four or five stars as I rarely will purchase anything below four stars. I then subtract stars based on certain criteria as listed below.1. If an item is exactly what I expected and nothing more it will receive a four- or five-star rating. The difference between the two is a bit subjective but is also based on the information on the Detail Page, customer service (if necessary), good instruction manual, etc.2. If an item surpasses my expectations, it will definitely receive five-stars and an extra callout3. If an item goes slightly below my expectations, it will lose a star (3 Stars)4. If the instructions for the product (if needed) are poorly written (hard to understand due to language issues or grammar) or just too hard to follow it will lose a star no matter if the product meets or exceed my expectations. I hate poorly written instructions5. If a product is significantly below my expectations, I will deduct two stars6. It will be rare that I would give a product one star since I buy mostly items that have a 4+ rating but in rare instances there may be a good reason that even a four-star product receives a one star rating from me. It could be because of customer service issues from the company but whatever the case is I will clearly explain my reason for giving a product only one starAdditionally, if a product fails over a short time period I will come back and update my review but will also take into consideration how the company’s customer service handles the repair or replacement. I understand that issues sometime arise, even with the best of products and a rating update may not be necessary.