Giant EnergyPak 36V battery charges fine with aftermarket charger, but battery % never updates – any workaround?

[goranimo]

Giant EnergyPak 36V battery charges fine with aftermarket charger, but SOC/% never updates – any workaround?


Innlegg:


Hi,


I have an older Giant Aspiro e-bike with a Giant EnergyPak 36V 10Ah (360Wh) rear rack battery.


The original Giant charger (DPS-83CB A, 41.5V 2A) failed, so I replaced it with a generic 42V 2A Li-ion charger and reused the original 5-pin Giant charging cable, using only the VO + and VO -


The battery now charges perfectly:

• Battery voltage reaches about 41.9V
• The bike works normally
• Range seems reasonable
• The charger correctly switches to "fully charged"

However, the battery percentage appears to be completely wrong.


Example:

• Bike/display shows 75% (and LED bar on the battery)
• Battery voltage is 39.5V
• I charge the battery to 41.9V
• After reinstalling the battery, both the bike display and the battery LEDs still show 75%

Seems like the original Giant charger will signal to the battery that when fully charged it will show 100% in the display, and this function is lost with an aftermarket charger, using only VO+ and VO-?

Any workaround?

 

[offroad]

Great to see your Aspiro still going strong and well done with charger re-wire. Generally the battery BMS controls everything and the firmware will simply measure the battery voltage and adjust the LED display, which is the case with recent models.

If the LED display is showing 75% three quarters full and battery is same (3/4 LED's) the measurement could be correct. Batteries will lose full capacity over time and never achieve 100%.

Try leaving the charger on longer and see if the stage 3 trickle charge tops the battery further. Heading back to old charger, did it always reach and report 100% previously ? Charging with an inline ammeter / watt meter can provide good feedback. Handy diagnostic tool.

https://www.ebay.com.au/itm/326230643095

 

[offroad]

I slept on this. Your 42V generic charger may not be calibrated correctly and is falling short in the stage 1 constant current or stage 2 constant voltage phases and the BMS is reacting strangely and turning off the tap when it thinks it's full.

You could test this roughly by depleting the battery and timing the recharge. 10.4A battery / 2A charger = 5 hours or so. 75% fill is around 4 hours ?

 

[goranimo]

I slept on this. Your 42V generic charger may not be calibrated correctly and is falling short in the stage 1 constant current or stage 2 constant voltage phases and the BMS is reacting strangely and turning off the tap when it thinks it's full.

You could test this roughly by depleting the battery and timing the recharge. 10.4A battery / 2A charger = 5 hours or so. 75% fill is around 4 hours ?

@offroad Thanks for your reply. I didn't get notification that anyone had replied on this thread.

I tried depleting battery to 9% (which seems to be the lowest percentage the display will show). I fully charged it again with the new charger. When it was fully charged I measured 42V which shows it was indeed fully charged. When I turned on the display it still showed 9% battery and the bars on the battery (when pushing mode button) also showed empty battery, but the bike worked well. So I assume that the charger is charging battery full, but the BMW did not update the battery status.

I borrowed an original Giant charger from a friend and then the battery status was updated after charging.

I bought a 0-100V battery indicator I planned to mount to check battery status, but I hoped to find a solution for the BMS to update the battery status so that i could see it in the display