comments:
As with any aftermarket (non-RBC) battery options, you need to move the wiring harness and mounting bracket(s) over from the old pack to assemble a new one. The really tricky ones are assembling the 36V packages, but all are a simple series. Follow the wires and take photos if necessary. If the old label tape doesn’t stick pack on, use clear packing tape over the old label tape. Do not use electrical tape of duct tape as it adds thickness to the pack dimensions and may cause clearance issues. Lead acid chemistry has incredibly high discharge capability. That’s why they still use them in vehicles as their cranking amps are extraordinary. However, they cannot be totally discharged without causing damage to the lead plates. Hence the middle ground: deep cycle trades some cranking amps and discharge current capability for durability. Without getting into the chemical differences between typical lead acid cells and deep cycle cells, the later is what SLA cells used in UPS products are most closely related to. All that said, your concerns are not without merit. Deep cycle, SLA and AGM cells usually have higher discharge current than what these LiFePO4 battery equivalents offer, but it has more to do with the BMS than the chemistry. Lithium batteries of all types can be made to have high discharge current…my RC car uses 8000mah 11.1v (3S - 3 cells) battery packs with a discharge rating of 50C. That means they can discharge at 50x their capacity: 400 amps. That’s required for the surge demand of the brushless motor and speed controller. They get hot as hell and are wrapped in Nomex for fire suppression and reinforced with Kevlar for shock and impact resistance. In the end, the BMS in the GoldenMate battery likely limits the discharge rate to 1-2C for thermal stability, safety and voltage consistency. A higher discharge may cause a voltage drop causing the UPS transformer to overheat, so if the discharge rate is exceeded, the BMS will actually terminate/cut power flow momentarily, causing the UPS to shut down. The simplest way to determine the actual discharge rate is to load up the UPS and see at what point the unit shuts down. If you have a 900w unit and the battery pack can’t provide the desired discharge current without the BMS cutting in at 900w, it may work fine at 800w. But I’ve never had this issue with GoldenMate batteries. Quite the contrary, as I’ve had peak draw over 1000w (such as starting a motor) on a 1500VA/900w UPS and the BMS didn’t interfere, but who knows maybe prolong 900w draw will cause the BMS to eventually cut in. Either way it would be nonsense to draw 900w constant from a UPS even with LiPo batteries because the runtime will still only be a few minutes. OEM runtime on a 24V RBC48, RBC124 etc in a 1500VA unit is usually rated at 4.5 minutes. A LiPo will double or even quadruple that as they have substantially higher watt-hour rating but you are still looking at best case scenario 20 minutes of 900w continuous draw before the BMS low-voltage cut-off triggers, assuming the transformer doesn’t overheat in the UPS (though many higher end units are active cooled and could likely sustain prolonged voltage conversion at a low ambient temperature) If you want prolonged 120v power output from a battery, the best method is to make your own UPS. Get a large deep cycle lead acid battery (or two, run in parallel) at Menards, a 1000w+ inverter commonly used in automotive applications, and a 120v trickle charger like a battery tender to keep it topped off until needed. If you are running sensitive equipment it’s important to get something that is pure sine wave with PFC, otherwise your PC power supply has to work harder to compensate for the simulated nature of the AC curve; you will notice AC motors have resonant noise when running on a simulated AC circuit but pure sine wave will at least guarantee the motor operates. https://a.co/d/0cTAOjhz