Bests & Worsts Reviews from Amazon

=== BUYER BEWARE === UNSCRUPULOUS SELLER === DANGEROUS PRODUCT === 1. There is NO WARRANTY on these batteries at all!! Seller will require you to return the battery which you will not be able to do because shipping LFP batteries is considered dangerous cargo. They can ship to you but you cannot return them effectively negating any warranty. 2. They are built with used cells - performance will easily be 10-15% less than advertised. 3. Internal electrical construction is unsafe using soldered copper to aluminum cell terminals that rapidly fail. Undersized copper strips for cell interconnections. My batteries experienced internal failure after just 3 months - in STORAGE!! 4. Amazon A-Z warranty for these batteries was denied without any explanation even after an appeal. Seller is listing the same product under different listings to avoid bad reviews like mine. Here are the details: On December 18, 2019 I purchased two 400Ah batteries from this seller. I had been researching LFP batteries for marine use for the last 2 years. In the course of my research I had come to discover that many LFP batteries were poorly constructed internally and so after reviewing this seller's product it appeared to be superior to the majority of Chinese built batteries. In addition I figured that purchasing from AMazon would provide some more protection against being ripped off. Sadly I have found out that I am wrong on both counts. One of the attractive features of this seller's LFP battery is the stainless steel case which I felt would provide better protection against the possibility of a catastrophic battery failure and this was important for use in a boat. In addition the seller was willing to customize the BMS to my specifications. I had the two batteries fitted with a bluetooth enabled BMS that was capable of delivering 120A and 100A charge. In addition I would be able to monitor the battery's health. The transaction with the seller went fine and the batteries were delivered within 3 weeks of my order. Visually the batteries looked good. The stainless steel cases are good quality, non-magnetic grade stainless steel - better than most stainless steel BBQs. Unfortunately all of the hardware is nickel plated steel so the hardware will rust quite quickly in a marine environment. I subjected both batteries to a series of 0.2C discharge and charge cycles. This is where I discovered that they would only deliver about 350Ah, well below the 400Ah that they should have been at. This is likely due to the fact that the internal LFP cells are used and at the end of their useful life in spite of the seller claiming that they use new cells. This was the first major issue I had with the batteries. The seller offered to compensate me with a partial refund of about 10% of the purchase price to offset the roughly 10% less performance and I accepted it as I was willing to take a chance on the remaining cell life and overall capacity to be suitable for my purposes. The batteries were scheduled to be installed on my boat in late February and then the Corona virus pandemic hit and stopped everything. The batteries had been charged to about 90% and left in storage and not connected to a charger. In late March I checked their condition and discovered that one of them had a severe cell voltage imbalance internally. Cell #3 had dropped to 2.8V and #4 had risen to 3.862V - quite an odd situation given that all cells were balance to within 0.01V when the batteries were placed in storage in February. I reported the problem to the seller and was offered a cell charger and told that in spite of one cell being at the upper limit, that "when you charge the low voltage cell separately, the other high voltage cell will go down, no problem." This was a highly suspect answer. After about 2 weeks I received an individual cell charger. At this point I had to remove the cover from the battery to figure out which cell had to be charged. I measured each cell with a meter and they were all within 0.01V of each other. So the voltage reported by the BMS was incorrect. I started checking the sense wire connections and quickly discovered the problem. They were crudely soldered onto the aluminum cell terminals and had come loose. I found the same issue with ALL of the cell sense wires. The cell interconnects for similarly soldered copper strips (not even buss bars) to the aluminum cell terminals. Everything was slathered with white RTV and the solder joints were abysmal for all of the cell interconnections. While they still worked it was unlikely that they would last over time. There are no screw terminals on the cells and their terminals are pre-connected in cell pairs. It is not possible to solder onto the terminals without running the risk of overheating the cells and there is no way to tap a screw into the cells without puncturing the call case. I reported my dis-satisfaction to the seller and they turned cold. The seller quickly informed me that if I wanted my money back I would have to ship them back to China and to be aware that it wasn't possible for me to ship an LFP battery as they were considered dangerous cargo. In effect - sorry - no warranty since you cannot return them. I reported the issue to Amazon under the A-Z warranty and while the customer service reps were quite nice at taking the information I was summarily denied any warranty coverage - even after an appeal. So buyer beware - you are purchasing a product that is made of used LFP cells, using abysmal internal quality that could easily result in the catastrophic failure of the battery due to a high resistance internal cell connection. In my case I suffered an internal failure after just 3 months and found that their 3 year warranty is a cruel joke and that Amazon will not provide any A-Z coverage at all.