Usually the 7 Ah LA in the gate motor lasted 2 years max, with all the load shedding we had the last year, I doubt a LA would have lasted this single year.
One day a few months ago I remember as things went my gate opened and closed at least 10 times the morning during load shedding and the early evening we had load shedding again, and again it got opened a few times. That day alone would have permanently damaged a LA.
I paid around R900 for the 8 Ah Blue Nova think January this year, but I see they are now going for around R750.
If it lasts 4, 5 years Iâll be happy, but Iâm sure it will last longer.
Well 7 months in, I can report my 8Ah Blue Nova is still kicking strong.
Even after a little incident earlier this year, the AC charger cable of my gate motor vibrated loose and the battery was left to discharge until the gate could no longer open, I just reconnected the charger and it charged back up and still works perfectly. If that was a LA battery it would have been toast already.
I emailed BlueNova a while back just to confirm, and they said yes, first put the batteries in parallel get them fully charged, then you can put them in series.
No, but it is 4 LFP cells in series, so you would expect it to be between 12.8V (3.2V) and 14.5V (3.65V). Ideally these batteries should be kept under 14.2V of course.
A typical smart lead acid battery charger has a voltage ramp that attempts to charge the battery voltage up to a float voltage but as soon as it reaches this voltage it drops the voltage down to the regular 13.8V (for a 12V battery)
This then repeats so that it doesnât maintain a high battery voltage. On the charger I have I measured 14.45V as a peak voltage (attached)
This would exceed the LiFePO4 charge voltage⌠PA-120-spec.pdf (180.3 KB)
Curios if these things donât just maybe have a little built in buck convertor or voltage limiter circuit or something that just blocks/limits/alters things when lead acid chargers feed them too much. (Like a really primitive BMS of sorts?)
Would not be 100% optimal or perfect/ideal or whatever but would be âgood enoughâ I imagine?
Something like that might explain how they can confidently call it a lead acid drop in replacement.
It charges it up to an absorption voltage, which is typically 14.5V, and then it drops back to a float voltage, which is 13.5 to 13.8V. That is IF it has a proper three-stage charger. Many many alarms and gate motors and things like that donât have a three-stage charger and instead just always charges to around 13.5V. Which, ironically, is better for these LFP replacements.
The issue with a 14.5V absorption voltage is that if the battery is at all imbalanced, itâs going to spike some of those cells quite high. Even with a perfectly balanced battery it already needs to go to 3.65V per cell.
I havenât seen a Li-Ion battery pack without a BMS. This will at least disconnect the battery when one cell goes out of limits. But this isnât a complaint I have read about with these.
Current limit is howeverâŚ
What happens to these cells when you overcook them? Has anyone done this and can share their experience
A systematic approach was taken to investigate the effects of overcharge with different SOCs
on the cycle performance of A123 18650 cells. Using a normal cycle, where a cell is charged to
100% SOC, the cycle life for the A123 18650 LiFePO4cell reached over 1950 cycles with 80%
capacity (typical criteria for EV application) and 2600 cycles with 60% capacity; however, the
overcharge process had a signiďŹcant impact on cycle performance. When the cells were charged
to 105%, 110%, 115%, and 120% SOC, the cells failed after 100 cycles, 11 cycles, 5 cycles, and
3 cycles, respectively.
