New 24V 25Ah Max LiFePO4 Battery, 2C High Discharge Rate, 50A BMS 640Wh Lithium Battery, 1280W Continuous Load Power for Electric Lawnmower, Mobility Scooter Electric Wheelchair,Farm Equipment

This review is for "24V 25Ah LiFePO4 Battery, 2C High Discharge Rate Built-in 50A BMS 640Wh Lithium Battery, 1280W Continuous Load Power for Electric Lawnmower, Mobility Scooter Electric Wheelchair,Farm Equipment", Timeusb Model ‎24V25Ah (ASIN B0CYH54LDS). Title and ASIN are included in the review because sometimes reviews get re-sorted and are no longer associated with the correct product.The Timeusb 24v 25Ah LiFePO4 battery shipped quickly and was packaged well. The listing indicated that delivery would require 11-14 calendar days, but I purchased on 29-Mar-2024 and it was delivered on 05-Apr-2024 (exactly 5 business days/7 calendar days including the Easter weekend). Not bad at all for a FedEx ground delivery from coast-to-coast. The Timeusb battery arrived in a fitted, double-walled cardboard box. Inside the box, the battery was cradled in foam on the bottom and around all four corners, and also on the top and around all four corners. the battery was wrapped in an oversized cellophane bag and the accessories (M8 bolts, washers, red and black caps) were wrapped in a small bubble bag. The well-written 16-page Product Manual, quick start, 8.5"x11" illustrated Operation Guide, and a full sheet of Timeusb stickers were packaged in a slide-to-close watertight bag. All very impressive and give an initial impression that the seller and/or company really care about their product and reputation.After crimping/soldering a new cable (10AWG pure copper wire, 5/16" copper lugs to 45A Anderson PowerPole) I connected the Timeusb battery to a battery charger. I selected an HTRC automatic charger which is designed to charge Lithium, LiFePO4, and various lead acid batteries at 12v (10A max) or 24v (5A max). See https://www.amazon.com/dp/B0CWLCH93W. The charger quickly determined that this was a 24v battery and began charging at a rate of about 3.7A. If we assume that the battery arrived at 50% SoC and is genuinely a 25Ah battery, then at this rate the full charge will be reached after (25Ah)(0.5 SoC)/(3.7A)= 3.4 hours. Sure enough, the charger cut off and indicated "FUL" about 3.5 hours later. My datalogger indicated that the HTRC had delivered 12,100mAh and that the battery had reached a maximum voltage of 29.24v. When I reviewed the data later I found that the battery had reached that maximum voltage for only 1/4th of second at the very end of the CC stage and at the same moment that the HTRC charger dropped its charge rate from 3.3A to 0.0A. The voltage immediately before was 28.38v and immediately after the battery measured 29.29v. At that point the charger waited about 7 seconds then started the CV charging stage. The CV stage lasted only about 52 seconds before the trickle stage at 600mA began. I disconnected the charger after about three minutes of trickle charging.SUMMARYCareful capacity testing shows that the Timeusb battery's claim of 25Ah is absolutely true. The battery actually tested at 27Ah!The Long NarrativeBefore using any rechargeable battery I perform a series of capacity tests using my computerized battery analyzer (CBA). I like to confirm that a battery has the advertised capacity as claimed. Timeusb claims that the battery is 25.6v and 25Ah. I typically test batteries by fully cycling them until two consecutive capacity tests indicate the same capacity to within 3%. I choose a discharge rate of 1C (or a max rate which does not exceed my tester's limit of 100W) and I configure the test to stop on LiFePO4 batteries when the cells have been discharged down to 2.5v (i.e., 20v for an 8-cell battery pack). I have performed capacity tests on literally thousands of batteries (NiCD, NiMH, Li-Ion, LiFePO4, SLA) and my expectation is that a new LiFePO4 battery should be able to deliver 95%-98% of its rated capacity.Why do I perform this sort of testing? It has been widely reported that non-OEM battery manufacturers exaggerate the capacity of the batteries that they sell. I've personally encountered this several times, most recently with an 14.4v NiMH battery which was marketed here on Amazon as compatible with Roomba vacuums (see https://www.amazon.com/dp/B07Q4TWVHR). The compatible battery claimed to be 4,500mAh capacity, but extensive testing revealed that the battery actually delivered less than half of that.I am unable to test the Timeusb 24v25Ah battery a 1C rate as this would exceed my computerized battery analyzer's limit of 100W. I chose a rate of 3.5A (0.14C) instead, which should keep the power draw under 100W (around 90W for most of the test).I started the test on the Timeusb battery at a 3.5A/0.14C discharge rate and after an hour I could see that the battery voltage was holding steady at 26.3v. I left and returned seven hours after the test had started to find that the test was still ongoing and despite having drawn 24.7Ah the battery was still above 25v! I decided to stay and wait out the rest of the test. Amazingly, the voltage dipped to 25.00v at the same moment that the measured capacity struck 25.000Ah. The first test result clocked in at 26.732Ah. That's 690.624Wh or about 106.9% of the rated 25h capacity. I'm very impressed!I recharged the Timeusb battery with the same charger as before. After starting the charge I observed 21.1v and a 4.6A charge rate, then I left the setup to charge overnight. When I returned in the morning the charger indicated "FUL" and my datalogger indicated that 26,994mAh had been delivered.I started up test #2 on the Timeusb battery at the same 3.5A/0.14C discharge rate I'd used before. This time the result was 27.08Ah/697.691Wh or 108.1% of the rated 25Ah capacity. Wow! That's two results within 3% of one another so we're done with capacity testing. See the photo.I should note that both tests were ended by the CBA when the voltage dipped to 20v. It was NOT the Timeusb battery, which means that either the battery's low-voltage cutoff is below 20v or it doesn't work. To test this, I started an additional test after the second test completed and before charging, with the low voltage cutoff set to 19v. This additional test ran for two minutes, drew an extra 0.116Ah, and the Timeusb battery's BMS disconnected the load at 19.539v. That seems set a little low to me, but it does work! After engaging the low cutoff I did have to apply 24V in order to reset the battery before the charger would operate. See the photo.Finally, on to testing the Timeusb in the manner I intend to use it, in my Tripp Lite SU750XL Smart Online Tower UPS (See https://www.amazon.com/Tripp-Lite-SU750XL-Online-Outlets/dp/B000HVRQL8). This is an "online" or "double conversion" UPS, meaning that the inverter is designed to be used 100% of the time, not just when there is a power interruption. The runtime of this sort of UPS can be extended as much as one likes by adding additional battery capacity, and the unit has 75A Anderson PowerPole connectors on the back to connect with an external battery pack. The UPS runs on 24V and ships with a couple of internal 12v SLA batteries. I'm not certain what capacity SLA batteries originally shipped with the unit, but when I last replaced them I installed 9Ah SLA batteries (see https://www.amazon.com/gp/product/B0761KNJNK). This means that the UPS had (12v)(9Ah)(2 batteries) = 216Wh of energy available, though SLA batteries don't like to be discharged beyond 50% so really only 108Wh of USABLE energy. A LiFePO4 battery can easily handle a 100% DoD, so with the Timeusb battery the UPS' usable energy capacity will increase by about 6X, 108Wh to 640Wh!I removed the two internal SLA batteries from the UPS and connected the Timeusb 24v25Ah battery. The UPS did not complain. I attached a "personal" space heater to the UPS then disconnected power. My datalogger measured about 11A drawn from the Timeusb battery. I let it run this way until 1,823mAh had been drawn from the battery, then reconnected power. The UPS soon stopped drawing from the Timeusb battery and switched to charging at 800mAh. About 2.5 hours later, the had UPS stopped charging (see the photo). 1,895mAh had been delivered, the battery was resting at 27.6v, and a maximum of 27.65v had been reached. I typically use this UPS loaded 250W-300W, but even when fully loaded it should not draw more current than the Timeusb battery is rated for. If we assume 85% efficiency with a 600W load then our highest/worst case current draw would occur right before the BMS disconnects the battery at it's lowest voltage, so: (600W)/(.85 efficiency)/(19.539v) = 36.1A. That's comfortably below the battery's 50A continuous rating. Besides, it's far more likely that the battery will remain over 24v for most of the discharge, which would mean most of the time it would be drawing under 30A. Perfect!Based on all of the above testing I'm convinced that the Timeusb 24v25A LiFePO4 battery is the best possible choice to replace two 12v SLA batteries in a 750VA online UPS. The cost is currently 2.2x more than SLA, but the LiFePO4 battery should outlast the SLA by way more than 2.2x. I also own Tripp Lite 1500VA and 2200VA Online UPS units which are based on 48v, and I'll likely replace the SLA batteries in each of those units with two Timeusb 24v25A batteries in series. If the Timeusb battery BMS was rated for THREE in series I'd likely use them to replace the SLA batteries in my Tripp Lite 3000VA online UPS (based on 72v).

I picked up the Timeusb 24V 25Ah Max LiFePO4 battery for running a well pump at my off grid cabin, and I’ve been really impressed with how it performs. It’s lightweight, compact, and easy to install—perfect for someone like me who just needs something reliable without spending a fortune.The built-in 50A BMS is a big plus. It gives me peace of mind knowing it's protected from overcharging, short circuits, and other common issues.No, it doesn’t have Bluetooth or fancy monitoring features, but honestly, for the price, I didn’t expect it to. If you just need a dependable battery that gets the job done and lasts a long time, this is a great choice. Definitely recommend.

So far so good. It works as designed. It includes above average documentation. I prefer more detailed datasheets, but the docs are easy to read, included sufficient details, and probably more accessible to the typical customer. The inclusion of the wire gauge chart was a nice touch. (I'm not sure what's standard for batteries.) Great customer service. There was an issue with UPS and it looked like the package had been lost. They promptly filed a claim with UPS and it eventually made it to my home.

I ordered 2 of these batteries and they arrived on time and are working well for me. I wanted to get more of them but when I when back to order more they had increased to 150% of the price they were when I ordered a week prior. Also I need them in pairs and they only show 1 in stock. I have been waiting a month and still only 1 in stock and a price that is too high. Too bad they must be lost on a big ship that got stuck on an iceberg South of South America. Hopefully some day they get back in stock at a reasonable price soon. Or maybe some other manufacturer will produce a battery in this size and spec.

Great battery and an amazing value when first offered. With 2 discounts it was $ 90. Then greed set it and the pricing went from 90 to 129 to 149 to 159 and the last battery is now $ 180. This is predatory is it not?

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