Purchased a Ryobi 36V 6Ah battery pack maybe just over a year ago.
Battery pack had been used on about 3 or 4 occasions for powering a cordless lawnmower. I was wanting to use this battery pack again recently, but on checking the battery charge state via the battery pack test button, there was no LED indication at all of charge state which suggested the pack was fully discharged.
I found this to be odd as I usually fully recharge battery packs shortly after use. So either the pack developed some sort of fault which completely discharged the pack cells (after recharging), or I might have forgotten to recharge the pack after last use?
I measured the voltage at the battery pack terminals, 0V!!
On putting the pack into the Ryobi charger, the pack didn't charge and charger displayed alternating green and red LED colors which (according to the charger) suggest pack is faulty.
These battery packs are supposed to have a 3 year warranty, but the problem is I no longer have the sales receipt for the pack. So I can't prove that I purchased it and therefore can't exchange this pack for a new one.
On searching the internet and watching some YouTube videos, I decided to open the pack up and see if I could get this pack to function again.
After removing battery pack bottom cover I measured voltage again, but this time with the negative test lead measuring off the negative solder pad on the pack circuit board, and the positive test lead measuring off the pack positive terminal. This time I measured about 1.7V! So the cells still had a bit of charge still left on them.
I connected a negative power lead to the negative solder pad on the pack circuit board and a positive power lead to the pack positive terminal from a bench power supply set at 36V and current limited to 0.5A.
After an hour plus of "recharging" the pack cells via the bench power supply, the pack cell voltage did rise and reached about 34.5V before I stopped recharging. I again measured pack voltage via pack negative solder pad and pack positive terminal, voltage was about 34.5V. So that looked promising as it suggested the cells were accepting charge OK.
But I then measured pack voltage via the battery pack main terminals, and the voltage was initially around 20V but then started to drop off rapidly!?
I tried testing the pack charge status again by pressing a small test button on the pack circuit board, but no LED's lit up!??
I tried to "reset" the BMS (Battery Management System) by using a jumper from the "RESET" hole on the pack circuit board to the "GND" hole on the pack circuit board, but nothing seemed to have happened with the same voltages as before. Jumper 'trick' was as per suggestions on internet.
Tried to recharge the pack in the Ryobi charger, but once again the pack didn't charge, and again got alternating red and green light LED's flashing suggesting faulty pack.
As the pack cells seem to accept charge, it seems unlikely they are faulty. So maybe there is a fault on the battery pack circuit board?
Maybe I haven't charged the cells enough for the charge status LED's to indicate and also for the Ryobi charger to start recharging this pack?
Maybe I didn't "reset" the pack properly by shorting/grounding the wrong holes on the pack circuit board?
Here are a couple of photos of the battery pack circuit board with annotations.
Any ideas on what is wrong and/or what to try next?
Thank you!
Battery pack had been used on about 3 or 4 occasions for powering a cordless lawnmower. I was wanting to use this battery pack again recently, but on checking the battery charge state via the battery pack test button, there was no LED indication at all of charge state which suggested the pack was fully discharged.
I found this to be odd as I usually fully recharge battery packs shortly after use. So either the pack developed some sort of fault which completely discharged the pack cells (after recharging), or I might have forgotten to recharge the pack after last use?
I measured the voltage at the battery pack terminals, 0V!!
On putting the pack into the Ryobi charger, the pack didn't charge and charger displayed alternating green and red LED colors which (according to the charger) suggest pack is faulty.
These battery packs are supposed to have a 3 year warranty, but the problem is I no longer have the sales receipt for the pack. So I can't prove that I purchased it and therefore can't exchange this pack for a new one.
On searching the internet and watching some YouTube videos, I decided to open the pack up and see if I could get this pack to function again.
After removing battery pack bottom cover I measured voltage again, but this time with the negative test lead measuring off the negative solder pad on the pack circuit board, and the positive test lead measuring off the pack positive terminal. This time I measured about 1.7V! So the cells still had a bit of charge still left on them.
I connected a negative power lead to the negative solder pad on the pack circuit board and a positive power lead to the pack positive terminal from a bench power supply set at 36V and current limited to 0.5A.
After an hour plus of "recharging" the pack cells via the bench power supply, the pack cell voltage did rise and reached about 34.5V before I stopped recharging. I again measured pack voltage via pack negative solder pad and pack positive terminal, voltage was about 34.5V. So that looked promising as it suggested the cells were accepting charge OK.
But I then measured pack voltage via the battery pack main terminals, and the voltage was initially around 20V but then started to drop off rapidly!?
I tried testing the pack charge status again by pressing a small test button on the pack circuit board, but no LED's lit up!??
I tried to "reset" the BMS (Battery Management System) by using a jumper from the "RESET" hole on the pack circuit board to the "GND" hole on the pack circuit board, but nothing seemed to have happened with the same voltages as before. Jumper 'trick' was as per suggestions on internet.
Tried to recharge the pack in the Ryobi charger, but once again the pack didn't charge, and again got alternating red and green light LED's flashing suggesting faulty pack.
As the pack cells seem to accept charge, it seems unlikely they are faulty. So maybe there is a fault on the battery pack circuit board?
Maybe I haven't charged the cells enough for the charge status LED's to indicate and also for the Ryobi charger to start recharging this pack?
Maybe I didn't "reset" the pack properly by shorting/grounding the wrong holes on the pack circuit board?
Here are a couple of photos of the battery pack circuit board with annotations.
Any ideas on what is wrong and/or what to try next?
Thank you!
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