NERMAK 12V 20Ah Lithium LiFePO4 Deep Cycle Battery, 2000+ Cycles Lithium Iron Phosphate Rechargeable Battery for Solar Power, Lighting, Outdoor camping, Power Wheels, Fish Finder, Built-in 20A BMS

I picked up this NERMAK 12V 20Ah LiFePO4 Deep Cycle Battery to build out a custom, mobile 12V auxiliary power pack for my outdoor shop tools and high-flow pressure washer supply pumps. To handle outdoor overspray and demanding start-up currents safely, I paired this battery directly with the 12 AWG marine-grade waterproof fuse holders I reviewed previously. This setup has operated flawlessly, proving to be a highly efficient, lightweight power source that works just fine under continuous workshop load. Why this LiFePO4 battery is an exceptional energy upgrade: Shockingly Lightweight Footprint: If you are used to lugging around old-school 12V sealed lead-acid (SLA) batteries, switching to lithium iron phosphate is a total revelation. This 20Ah pack delivers twice the usable energy capacity of a comparable SLA battery at a tiny fraction of the physical weight, making it incredibly easy to integrate into a mobile tool carriage or camping rig. Dependable 20A Built-In BMS Protection: The integrated Battery Management System (BMS) is excellently calibrated. It monitors cell balance and protects against short circuits, over-charging, and deep over-discharging. It handles the continuous high-amperage current draw of my auxiliary water pumps with zero voltage sag, clicking off instantly only during genuine over-current thresholds to protect the internal cells. Flat Voltage Discharge Curve: Unlike lead-acid cells that suffer from constant voltage drops as they deplete, this LiFePO4 battery maintains a rock-solid, steady 12.8V output through nearly 90% of its discharge capacity, keeping connected pumps running at maximum efficiency right until the pack is empty. Workshop Wiring & Charging Tips: Always Pair with Circuit Safety: Because lithium batteries can discharge energy incredibly fast during a dead short, do not wire them raw. Follow my previous build steps and splice a dedicated in-line fuse holder (equipped with a 20A fuse to match the BMS ceiling) directly onto the positive lead wire right at the terminal. Utilize a Dedicated LiFePO4 Charger: Do not attempt to charge this with a legacy automotive lead-acid battery tender. Lithium chemistry requires a specific multi-stage charging algorithm (typically pushing a bulk charge up to 14.4V–14.6V) to properly balance the internal cells and hit that advertised 2000+ cycle lifespan. The big takeaway: NERMAK has delivered a premier, ruggedly housed power cell that offers an unbeatable combination of capacity density and safety features for a very reasonable price. The screw-down terminal posts are clean and provide a rock-solid mechanical connection point, the internal protection circuits are highly responsive, and the weight savings are massive. It is an exceptional value purchase that modernizes any custom low-voltage electrical build.

I needed replacement battery for my Tzora electric scooter, and the 25 AH lead acid battery pack. This barely fit into the enclosure of the lead acid battery, I had to modify it somewhat, so I could not recommend it for that use. In other scooters, it should fit great. If you are handy with tools, then it might work great for you as well. It seems to offer a higher voltage than the 25 AH lead acid battery, the voltage always reads top of the range in the volt meter. It does not sag as much when going up a incline. It feels more powerful than the 25 AH battery it replaced. But it also has the problem of shutting off when the voltage is low, not just slowing to a crawl when the voltage is low like a lead acid battery. It is a safety feature of all lithium battery packs to shut themselves off at a low voltage cut out. Just be sure to recharge it more often. I would expect a longer range than the 25 AH lead acid battery, and many more recharges than lead acid style battery.

Battery arrived dead. Bought a charger just for this battery. Charger indicated it was charged. I'm taking time it camping and tested it as I'm about to leave. It's dead and will not charge at all. I wasted money on a bad battery and a charger I no longer need.

I ordered this battery to replace the lead cell battery in the Stanley Fatmax 450A starter unit. The battery is accessed by removing about 8-10 Phillips screws on the bottom of the unit. Disconnect the battery and replace with the Nermak 12V 20ah battery. Pretty good fit. I did go up in amperage to provide a little more power and hopefully usefulness for the unit. I did have to reroute the negative cable slightly to get the battery in. Goodness what a difference in weight. The battery was partially charged upon arrival and ran the light and air compressor right away. I don't know yet about reliability and longevity but if it's anything like the battery I installed on my solar power gate operator a year ago. It should be trouble free. UPDATE: On 09/14/2023- As it turns out on the following morning my wife's car wouldn't start. I used the FatMax and it jump started up the car on the first turn! One thing I didn't mention on the install. The original battery had lug posts for the positive and negative connections. This battery has surface mounted connections with included bolts. I just used pliers to straighten the lug wire terminals and bolted each set of wires to the corresponding connections. Red wires to red positive connection and black wires to negative connection on the new battery. GL!

Worked great while it lasted. Had it hooked up to a chicken coop door and 30W solar panel. After about 4 months (just outside support window) it stopped taking a charge from either the solar panel or a battery charger after I hooked it up. Eventually just degraded down to 1V. Maybe I got a dud... *** Seller contacted me and offered a full refund which is generous since product is outside return and support window. I’d already replaced the battery but I’d give it another shot especially since they backup their product. I upped to 4 stars based on product support.

Update 1/20/2026 I am raising my product review to 5 Stars because of excellent Customer Service. The seller reached out to me and offered a replacement or full refund. I purchased an Eco-Worthy battery right before I returned this one, except a 30Ah instead of a 20Ah. I assembled a whole Brand New system around it and the Eco-worthy lasted exactly Three Days and did the exact same thing. These batteries are leaving the factory with unbalanced cells, the lowest voltage cell is going to pull the others down and instant BMS chip failure. Now I have to return the Eco-Worthy battery. All my old SLA batteries are old and need replacing so this is about the only way to go. You NEVER want to buy used or Bin store or reseller batteries ever, This is a great seller and I am going to continue to order from this seller simply because of the excellent customer service. Which for these batteries is something you are going to need or find out the Hard Way. My other NERMAK 20Ah battery is hanging in so far, fingers crossed! Great seller, Highly recommend. I bought one and my wife ordered one on her account. They charged up just fine, I put one in my solar power system with a 150 watt inverter, high end charge controller and 200 watts of solar panels. It ran fine for a few days and we went to the store, came back and the inverter was beeping and the charge controller said zero volts. There was NO reason that battery should have died like that, under full sunlight. I returned it with no issues and I got a full refund very quickly and ordered a different brand of battery. Have not received it yet. I did attempt to recharge the battery on my smart LiFePO4 charger but the charger would not even turn on. This battery definitely has a faulty BMS chip or something. The 2nd battery did the same thing the other day, but I was able to make it come back to life and is holding in there, but now I always turn the inverter off when I leave. If it lasts 6 months I will come back and update this review and give it the proper star rating. But great seller, fast ship, and no problems with the return. Very happy and confident buying off Amazon.

Their customer service is amazing. I had a problem with a previous item I purchased and they got back to me the same day and quickly resolved it. I am very impressed with their dedication to provide a quality product and provide excellence service to customers. I will definitely purchase again.

I opened the box and the battery was sealed in plastic wrap. I removed the wrap and grabbed my Fluke multimeter to check the voltage. 0.16 volts. I unboxed my NOCO charger and connected it and the charger didn't sense the anything was connected to it so I tried a regular charger, same result even though I left it connected several minutes. I also tried a solar charger. I returned the battery and will buy a different brand. I would not recommend this battery.