Miady 12V 100Ah LiFePO4 Lithium Battery - 2000+ Deep Cycles, Built-in BMS - Perfect for Solar Power Systems, RV, Marine & Electric Vehicles - Ideal for Off-Grid Living, Camping & Backup Power Solutions

So I previously trashed this product in a similar way to the other 1 star review due to my lack of knowledge on how these batteries work. These batteries have internal battery management systems (BMS) which cutoff the current at 10V and cause the batteries to read 0V. I was under the impression this was either a "recommended cutoff" on the datasheet or the BMS would cut the current and then restart a moment later like many other BMS's do. When looking online, many people stated the drop to 0V was part of the protection circuit and was permanent: This isn't true!These batteries are designed to go into a sleep mode when they reach 10V and will wake up when voltage is applied from a charger. This is actually an incredibly useful feature for my application of using these as a portable power bank for heated motorcycle gear. I no longer need to worry about over discharge. I can just let the internal cutoff activate if the cells get too low (obviously this isn't preferred, but will work in a pinch if I run the batteries longer than normal).Now here's the issue: The charger I'm using, which is a smart charger for sealed lead acid (SLA) and Li Ion batteries used in cars, needs to detect the voltage coming from the battery to turn on charging. As a result, it does not send out any voltage of its own and will not wake up a sleeping battery. To turn the batteries back on, I VERY quickly tapped a 9v battery across the terminals of the battery (another 12v battery would have been better), positive to positive and negative to negative. This supplied the needed voltage to wake up the BMS and allow the 11.2 or so volts remaining to be present on the terminals once again. Now my smart charger could detect the battery and charge it like normal.Yes, the battery had 11.2V when the cutoff is 10V. This is not a defect in the BMS, rather, the voltage will sag under load to 10V, the cutoff will activate, and when the battery is woken up it will once again read the non-sagging "open circuit" voltage as there is no load any more.Overall I'm very happy with the 3 batteries I bought which arrived with identical voltages, perfect for parallel configurations. They have more power than I was expecting and should easily run my heated gear for 2+ hours on max heat. Being able the use a standard SLA charger and having an automatic low voltage cutoff makes these a versatile power source for many projects. Just make sure you have a way to "wake up" a battery that has reached the low voltage cutoff; either another battery or a non-smart charger.Here's the result of my discharge test for those who are curious about how much power these have. I'm using 3 batteries in parallel for roughly 18Ah of capacity (Series configurations are not recommended without a BMS, and even then, these batteries have internal BMS's so most people wouldn't recommend series configurations at all. I'll leave you to decide if you want to run series or not). I was powering a heated vest which consumes 5 amps at max heat and has 5 power settings. You can very roughly estimate that each power setting draws 1 amp (setting 1 is 1 amp, setting 2 is 2 amps, etc.), but the actual current draw is likely higher based on my testing. Here's the results:Heat 1 for 1.5 hoursHeat 2 for 3 hoursHeat 4 for 2 hoursAt this point the low voltage cutoff activated around 6.5 hours after I started running the heater! Obviously this isn't even remotely scientific as I used different settings and the only power setting that I can check the current draw accurately on is setting 5 which draws 5 amps (other settings use PWM so my cheap multi-meter is pretty useless). I'm pretty happy with these results and this pack should power my gear for a few hours with medium heat settings.*****Old Review: I used these batteries to build a large battery pack (wired three in parallel). They charged up just fine, but near the end of their first discharge (powering a heated motorcycle vest on medium heat, about 3 amps) all three cells dropped to 0.1 volts and ceased functioning. At my last voltage check (about 15 minutes before failure) the cells read 12.1 volts, well above the 10 volt discharge cutoff. Because the load was spread over the batteries, I had roughly 1 amp on each battery, which is within the 1.2 amp standard discharge rating on the datasheet. These batteries are rated for a continuous discharge of 6 amps each which I never hit in my testing. Really disappointed in these batteries.Three years ago I purchased the 6AH version for my home alarm panel. Had a two day power failure among many smaller power outages over the years and my alarm panel never went dead. Replacing the larger SLA battery with this smaller battery left room in the panel for the SMS transmitter.From factory, it came with full charged instead of 1/3rd charged. As top terminals are very small, I think; this battery is mostly made for replacement lead acid battery in emergency LED lights in the dark factory as power failure. At 14.0 volt BMS will cut off instead of 14.4 to 14.6 volt cut off. I think the reason for, formor lead acid battery auto charger cut off up to 14.2 volt. I have notice of, during light duty use at around 2 amp drawing, the voltage will sagged to 13.0 volt from 12.25 volt. As it said on the battery, it 12.8 volt. You can use this battery for CB radio for very long battery life per charge. Even this very cheaply built battery is still the far better than lead acid battery. Reason of flimsy handle is very easily pull out from battery slot, it not made for carry the battery along, as handle will break. And by the way; I had watched another guy on YouTube, he had ran cotton candy maker from battery with inverter. It has drawn around 450 watts until he has made whole cotton candy. I bet you battery terminals and BMS has gotten very hot, as it wasn't mention.I bought this 20 AH LiFePO4 for diy solar generator. It works very well for solar charge and discharge at 10 A. I used a battery load tester to measure and got 19.8 AH capacity. Really good capacity as 99% of rated value.It’s exactly what it’s rated to be. It’s advertised as 20ah, and from my daily use from the past 2 months, I measured that it consistently gets to 19.7ah. Close enough. I have never tested its maximum instantaneous output, so it maybe worse or better than other brands, I don’t know. But from its construction to capacity alone, I would say that you are getting a lot for the cost. Highly recommendedTested twice. Once at 10 Amps discharge and once at 5 Amps. Nearly identical results ~18.6Ah - See attached. I’m charging it with a custom Lifepo4 charger ~(14.6-14.7v) so I know I'm starting with full. Overall still good value.[06JUL2022]At this point, the seller has gone above and beyond to help me get this squared away. Ultimately, the needed up replacing my original battery with a new one under their warranty and refunding the second per my request. I was pleasantly surprised with how hickory they got this resolved. It is worth noting, that they did NOT want the original/defective battery packs back. So, with one functional battery, two defective packs, and a curious nature; I dissected the defective ones to understand how they work.The pack I have opened has 72 x 18730 lithium cells (3.2v, 6.4Wh, 2Ah each). Model number appears to be, “GZNF18730HP-2000”.These 72 cells are arranged in 4 groups (18 cells each) that are connected in series. Within each of the four groups, the respective 18 cells are connected in parallel.2Ah each x 18 cells = 36Ah total3.2v each x 4 = 12.8v totalIn both cases, my original pack and the pack that was dead on arrival; both appeared to have a defective BMS. The individual cells appear to be in working order. I may attempt to repair these packs as a learning opportunity *if and when* I have some free time. If I do, I will do my best to update this comment with my results.[07May2022]I have purchased 2 of the 36ah battery. The first was purchased Sep2021 and failed APR2022. I have reached out to the seller via Amazon but no response to date.The second was purchased to replace the first battery. It arrived today 07MAY2022 and was dead on arrival.Pictures are from the second battery. I will attempt to return the second one. I will give the seller a chance, but so far I am not impressed.Two out of four I received are loose inside. The two defective ones were from different sellers, so it's not a seller related problem. The packaging was different on the two defective ones vs the two good ones. The barcode labels on the bad ones were metallic silver plastic, while the good ones had a white paper label, and also contained bubble wrap. I've attached a picture to identify them.works great powering my fish finder