48V 100AH Lithium LiFePO4 Battery, Built-in 100A BMS, with Touchable Smart Display & Mobile APP, Max. 4800W Power Output, 5000+ Cycles, Perfect for Solar System &Off-Grid Applications

This review is for "48V 100AH Lithium LiFePO4 Battery, Built-in 100A BMS, with Touchable Smart Display & Mobile APP, Max. 4800W Power Output, 5000+ Cycles, Perfect for Solar System &Off-Grid Applications", Vatrer Item model number 51.2V 100Ah (ASIN B0C9HPYKNG). Title and ASIN are included in the review because sometimes reviews get re-sorted and are no longer associated with the correct product.The Vatrer 51.2v 100Ah LiFePO4 battery shipped quickly and was packaged particularly well a double-walled cardboard box via UPS Ground. Within the double-walled shipping box was a second double-walled cardboard box which held the battery. The was battery was boxed in an inner double-walled box, and within this box the battery was covered in a plastic bag and cradled in 2in foam on all six sides. Very impressive, and probably sufficient to escape damage even with a shipper's rough handling. Along with the battery came a sheet of stickers and box containing a manual, rack mount wings, and two battery cables.I plan to use the Vatrer 51.2v 100Ah LiFePO4 battery with a 2200VA 48v UPS unit which should draw a maximum of about 65A under a worst-case scenario, so the battery's 100A BMS should have no trouble. Furthermore, I rarely load this UPS unit above 50%.SUMMARYTesting shows that the Vatrer 51.2v 100Ah LiFePO4 battery delivers over 100Ah of capacity.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. Vatrer claims the battery to be 51.2v and 100Ah. In addition to the 100Ah claim Vatrer claims that the battery is 5120wh which is consistent with the voltage and amp-hour claim (51.2v)(100Ah) = 5120Wh. I typically test batteries by fulling cycling them until two consecutive capacity tests indicate the same result 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., 40v for a 16-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. For this battery that would be 95Ah-98Ah or 4864Wh-5018Wh.Why do I perform this sort of testing? It has been widely reported that sellers exaggerate the capacity of the batteries that they sell. I've personally encountered these many times. For an example, see an 18v Li-Ion battery which was marketed here on Amazon as compatible with Ryobi 18v tools (see https://www.amazon.com/dp/B08TR82J1D). The compatible 18v battery claimed to be 3,000mAh capacity, but extensive testing revealed that the battery actually delivered less than half of that and the battery had other problems as well.Unfortunately, my computerized battery analyzer (or "CBA", a device designed to accurately measure the capacity of a battery pack) is rated for a maximum load of 100W and a max voltage of 55v. The Vatrer battery will be at 58.4v when fully charged, and this means that the maximum discharge rate I can configure the CBA for would be (100W)/(58.4v) = 1.7A. For a battery rated 100Ah, that's a rate of 0.017C. I strive to complete a discharge test on smaller batteries in about one hour, but for such a large battery this test would take about 59 hours -- longer than two days! For testing, I connected a 1500VA online UPS through my datalogger's shunt. I also connected an AC power meter to the output (https://www.amazon.com/dp/B07JB9B2QL).When I first powered on the Vatrer battery it indicated that it was charged to 55%, so I began by charging the Vatrer battery with a 10A LiFePO4 charger. Charging to 100% took about 4.5 hours. I then disconnected the charger and connected the Vatrer to my 1500VA Online UPS (powered down, AC input not connected, no load). I plugged the UPS into an AC outlet and with no load plugged the UPS into a utility outlet. I powered on the UPS and waited for it to go through it's power on checks and indicate that it was online. I then plugged a ceramic space heater into the UPS, set it to LOW, turned it on and waited for the power meter to stabilize, which took several minutes and the power draw settled in at around 620W.I reset the counts on the datalogger (DC input) and AC energy meter (AC output), then unplugged the UPS from utility power. The meter on the face of the Vatrer indicated that at this rate the battery would be depleted in 7.5 hours. Boy I like being able to see at a glance how much run time remains! I walked away, but popped by several times to observe. At about 6 hours in I observed 51.26v and 13.9A (713W) from the battery as per my datalogger, 51.33v and 13.8A (708W) as per the Vatrer panel, and 120v/5.144A/615W on the AC meter. Therefore, the UPS is about (615W)/(713W) = 86% efficient. I further observed on the Vatrer panel that the cell voltages ranged from 3205mV to 3212mV, indicating well balanced cells in a tight range of only 7mV! The battery eventually gave out and I was not present when that happened.I reviewed the data and created a graph of the discharge curve. I uploaded graphs showing the entire discharge, the first two minutes, and the final five minutes. The full curve shows that the current draw was 13.5A-14A for most of the time, and that the Vatrer battery maintained 51v-52v during that time. The beginning of the curve shows that the voltage and current took about two minutes to settle in around 53v and 13.5A. The end of the curve shows that UPS disconnected the load when the low voltage threshold was reached at 7:23:54 (41.27v and 17.1A). The Amps drawn immediately dropped to 0.3A, though that also happens to be the lower limit for the datalogger so it may actually have been a bit less. At this point the UPS is supposed to draw just enough current to keep powering the display panel and the internal cooling fans for an additional four minutes. During these four minutes we see the Vatrer battery's voltage start to recover thanks to the significantly decreased load. The UPS then shuts down at 7:27:54. The capacity of the Vatrer is measured at 101.7493Ah. This exceeds the 100Ah rating. Nice!I plugged the UPS back in and it started charging the Vatrer at it's fixed rate of 800mAh. At this rate it'll take 125 hours to fully recharge the battery! I forgot to record the status of the cell balance, but I do remember checking it and being impressed with the small span. I connected my 10A LiFePO4 charger and walked away. The Vatrer has two sets of terminal posts, so it was easy to connect the 10A charger without having to disconnect the UPS first. I returned after about 7 hours (shortly before retiring for the evening) and the Vatrer indicated that it was charged to 78% and the cell voltages were in a range of 3377mV to 3382mV, a span of 5mV. I disconnected the charger because I knew that if the battery is charged beyond about 55v the UPS will start beeping and indicate an overvoltage fault which cannot be cleared without power cycling the UPS. The next morning I used the 10A charger for another 90 minutes then allowed the UPS to top off the Vatrer. At some time later the UPS discontinued charging the battery. I'm not sure when this happened, I left it and came back the next day. On the following day the Bluetooth app indicated 100.8Ah/100.0Ah, 54.8v, current 0.0A, power 0.0W, a maximum voltage difference in the cells of 0.009V, an average cell voltage of 3.427v. and number of cycles 2.I screwed the rackmount wings onto the Vatrer and then mounted it in my 19in rack where I have two 2200VA Online UPS units. The battery is tall and requires a 4U space. The two UPS units in the rack are each currently powered 48v 50Ah LiFePO4 batteries which I purchased at the same time six months ago. I connected the Vatrer to UPS #1, and I reconfigured the two 50Ah batteries into a parallel configuration then connected them to UPS #2. We were expecting 4-8 inches of snow later that week so I was confident that we'd lose power at some point, yet we never did.A couple of trouble-free weeks passed, and I used the Bluetooth app regularly to check the status of the battery. I downloaded Overkill Solar's app, which readily connected to the Vatrer. The Overkill app provides far more information about the Vatrer battery, including BMS manufacturer (ZJDY), firmware version, device name and manufacture date, plus access to numerous configurable BMS parameters.The Vatrer 48v 100Ah rack mount battery is really a nice battery! Testing shows that its capacity exceeds its rating, the rackmount design is what I was looking for, dual terminal posts make it easy to parallel multiple batteries or connect an extra device (such as an external charger) and the display gives all much of the information I'd like to see at a glance, as does the Bluetooth app. Third party apps provide the ability to access and change BMS settings.

Minor edit after 4 more months of constant use: No issues at all with the Vatrer batts, i just upped the bulk charge a little from 55.2v to 56.0v and bulk charge time to 1 hour+ to help the onesie slowpoke cell in each pack with a bit more internal resistance than the others (found in every 16-cell rack battery made on planet Earth) catch up with its fellows to full-charge and to better reset the BMSs to more even 100% state-of-charge readouts. Still working flawlessly all around ------- I really like these Vatrer batteries, got two of them and they've been operating flawlessly for about a month now, powering a 3000W transfer-circuit bank through an off-grid EG4-3000 inverter/charger and solar panels in the totally spotty sunshine/clouds/storms of the rural Southeastern USA. No comm cables between the Vatrer batts and inverter/chargers but manually input bulk/absorption time/float charges on the EG4 are seamlessly accepted by these paralleled Vatrer BMSs (I use 55.2v, 15 minutes, and 53.6v respectively based on expert online opinions). These values differ from the Vatrer manual, but the only issue I had since operating them was once early on at maximum charge voltage from the manual which drove one of the cells in one of the batteries to over-voltage state causing the BMS to shut that battery down until the internal passive balancer leveled the cell voltages out and reduced the over-voltage cell to normal resting max charge state. This phenomenon is totally normal across the whole LiFePO4 battery universe and not a Vatrer problem (check online forums for more info). Since downtuning the charging values a little off of maximum from the inverter/charger, these batteries have performed flawlessly with no BMS overrides or shutdowns, and I see only a few millivolts of unbalance across all 16 cells each if allowed to rest and passive-balance from time to time, which is exceptionally good for any LFP battery out there. The BMS also seems to seamlessly cross back-and-forth between charging and discharging with no hiccups in the lousy on/off solar power conditions we have here in the SE swamps, and run all the connected appliances with no issues ever: microwaves, internet/computer devices, portable air conditioners, etc, all run well with no problems from the Vatrer BMSs switching back and forth between charge and discharge constantly all day long. Very happy with these batteries, and I intend to get one or two more in the near future.

Been using this battery for over 6 months. Excellent quality product. Bright touchscreen display. Solid battery terminals that fit 5/16" cable lugs. Lugs fit tight, but they do fit. Using it in parallel with an EG4 LL battery for communications back to the inverters. Lighter weight than the EG4 battery and the handles are in a better position. Wish the Vatrer battery had a communications port that would interface with EG4 inverters. Also wish it had WiFi communcation for checking the status while away from home. It does has bluetooth, but that is only good for a short distance (about 20 ft). Would have bought a second one of these instead of the EG4 if it had inverter communications capability. Connected to the DC bus bars, both batteries charge and discharge simultaneously without any problems. The BMS in each battery ensures that compatibility.