Overview
Model: Back-UPS ES 750
Battery Details
| Specification | Detail |
|---|---|
| Image |
|
| Part | AJC-D7S |
| Voltage | 12v |
| Capacity | 7Ah |
| Type | Sealed Lead Acid (AGM) |
| Terminals | F2 |
| Length | 5.94 in / 150.9 mm |
| Width | 2.56 in / 65 mm |
| Height | 3.7 in / 94 mm |
| Weight | 4.5 lbs |
Lithium Iron Phosphate Battery Replacement
I ordered this LiFePO4 battery off amazon which is the exact same size as the original.
Cost: $63 CA plus Taxes.
NASTIMA 12V 8Ah Rechargeable Lithium Iron Phosphate Battery,Built-in BMS, 4000+ Cycles LiFePO4 Battery Pack, 10A Max Output.
https://www.amazon.ca/dp/B0B5WBHDDN?smid=A32QMQUDJWY3FO&ref_=chk_typ_imgToDp&th=1
Tested this battery's capacity pulling 2A. Capacity came up as 8.8Ah.
Note: Battery voltage stays at 0v once discharged until voltage is applied. Does not bounce back on it's own.
I performed a capacity test on the old lead acid battery. The battery had a 3 Ah capacity when drained to 10.5v at 2A.
Shutdown Problem
I ended up having some quick shutdowns after replacing the battery.
On this UPS I have the following items connected:
| Item | Estimated Power Consumption |
|---|---|
| QNAP TS251 Network Attached Storage | ~20W (spec: 18.09 W) |
| HP Compaq Elite 8300 SFF | ~100W |
| Dell PowerEdge T150 | ~100W |
| Raspberry Pi 1 | ~5W |
| Asus RT-AC56U Router | ~5W |
| Smart/RG DSL Modem | ~5W |
| Asus Hub | ~5W |
Total Power | 240W (~ 2A@120V) |
Battery Amperage | 20A@12V |
Ok, so battery has a 10A max output, which is 1A at 120V.
Lets figure out what are real power usage is....
| Item | Actual Power | Amperage |
|---|---|---|
| QNAP TS251 Network Attached Storage | 20W | 0.16A |
| HP Compaq Elite 8300 SFF | 76W | 0.63A |
| Dell PowerEdge T150 | - | - |
| Raspberry Pi 1 | 24W | 0.2A |
| Asus RT-AC56U Router | ||
| Smart/RG DSL Modem | ||
| Asus Hub | ||
Total | 120W | 1.0A |
Battery Amperage | 10A | 10A |
It looks like this will work if we don't have the Dell PowerEdge on the UPS.
So, 10A is beyond the 1C, so ideally we should aim for a max of 8A discharge.
Based on this information, this battery is insufficient for our load.
Testing the battery with a 10A load, the battery quickly dropped to 11.6V which the UPS would consider to be 0% left!
References
| Reference | URL |
|---|---|
| Manual | |
| Specifications | |
| DIY Replacement Battery 12V 18650 Li-ion For APC Back-UPS 650 | https://www.yousun.org/archives/101 |
| Replace battery | https://www.youtube.com/watch?v=_dydlRHFjrc |
| Details | https://www.yousun.org/archives/660 |