Yesterday I went to use this one, which I hadn't used for a good 6 months, and pressing the button for power showed me that only on dot was blinking, so before grabbing another one, I put it on the charger only to get the red and green flashing - alerting me to a failure to charge.
I wondered what the problem could be so I took it apart. Having never done one of these (but have rebuilt a few older Ryobi NiMH battery packs) I started by undoing the screws here:
which uses a #10 Torx driver.
The bottom stays attached and has some lugs (inside) that keep the base snapped on even without the screws (don't count on that) and I needed to prise it off starting at the front (pulling apart with my hands at first then fitting in a wide flat blade screwdriver working around left to right.
When the base comes off beware of the spring that us under the battery relase button and the small bit of plastic that is underneath what you press when you check the voltage.
Now I didn't know what to expect, but when I pulled it apart I found it was all pretty clean, no tabs broken off, corroded or anything obvious so I decided to then just measure the batteries.
A quick measurement with my meter showed that one cell was down (out of 5) and while the other 4 were perfect (4.13V) that one was 3.9 ... now I know that it has a Battery Management System (BMS) and I know that the role of a BMS is to charge the pack in a balanced manner, but I also know that some BMS do not cope if one cell (or group in parallel arrangements) is down too far below the others. Some only cope with 0.2V. (Note you can see the spring I mentioned above at the back there).
So I hooked up my iMAX charger and charged that cell up
which took some time actually, so either its been getting slowly out of balance for a while or the BMS has a fault ... I'll find out eventually. Worth observing here is that all those spot welds are impeccable, among the best I've seen anywhere.
Either way I was able to put it onto the charger (as it was) and confirmed it was then charging fine, put it back together and tested it last night with the blower (yes I'm evil).
Hopefully Win Win.
So if you have some Bunnings Ozito packs which may not have been used for a while, and won't charge, its worth having a go at this yourself. You'll need:
- a lithium battery charger (worth having if you have a number of things with lithium cells, scooter, skateboard, laptop ...
- a multi-meter (even a $20 one)
- some basic tools
Hope that helps
23 comments:
Cheers, mine had the exact some issue and the same steps solved it. Thank God for me hoarding a Lipo charger.
I've got the same issue.
I'll do as you suggested and see if I'm as fortunate.
Thanks!!
Same issue. All except one cell were around the 4v mark. One was down to 2.9. I was able to charge it up to 3.55 and this was enough for the Ozito charger to accept the whole pack again. Great instructions.
I had the same issue, one of my cells was reading 2.7 whilst the others were sitting around 3.3
I didn't have a lithium charger but I did have a battery charger for 18650 cells which I use for my torch. I was able to connect this to the low reading cell using croc clips and topped it up enough for the Ozito charger to pick it up again.
Thanks so much for the guide!
Just jump start the faulty pack with another fully charged pack for about 30 secs, then put in charger and you will be good to go.
How do you do it, please show me.cheers.
Gary, if after reading that and looking at the pictures you can't work out how to do it then I think its safe to say you can't do it.
I definitely do not have the skills of equipment to repair the two Ozito batteries I have that have failed. Is there anyone near Canberra who can do this for me?
Thanks,
Glyn
Sorry mate, I'm a banana bender
Glyn, I'm in Goulburn and happy to help if you can get the batteries to me.
Just found this guide on Good Friday 2022. Works great. Had an old pack that wasn't charging. No lipo charger so I stripped back an old USB cable, 10 minutes charging the two low voltage 18650s and the charger is happy to accept the pack again. Great to have an additional battery that's been sitting idle for 2 years back in action.
Hey, for anyone reading this in the future, I had 2x 3 amphr batteries, 1 being faulty from no use.
I fashioned a makeshift jumper out of an old USB cable and connected the positive and negative terminals of the faulty battery to the operational one. There is a chance of a zap here, so just always grab from the insulation to be safe. Left it for 30 seconds (battery lights won't come on). Then connected both batteries to the charger and all was good.
Hey Terry, that's also an interesting plan, and you are temporarially putting one cell in parallel with the other. Should be ok as long as you first measure the faulty cell and its not far into dead (anything over 2V should be ok)
I top the low volt cell with 12v battery about 5 seconds and the pack is charge again,good,thanks.
Did you connect the charger (12-18 volts across) the dud cell? I was thinking of putting 4-5 volts from my bench top current limited power supply across the dud cell?
No Marty, I used the LiPO charger as described, properly set to charge a single cell across that cell. Each cell is 3.8V ...
I have a 3ah pack that isn't charging. 0v between positive and negative terminals but battery is fully charged per the indicator.
20v between NTC and either positive or negative terminals.
Each cell is sitting at 4v roughly.
Pack won't charge or power the tool.
Trying to jump start the pack by connecting another pack in parallel didn't fix it.
Any ideas?
Haven't used the pack in awhile
Hi
sounds like the actual circuit board has gone south. I'm willing to bet that you can scavenge one from another battery which is dead and attach by soldering. It would be the only way I can think of.
Thanks all. Not having a seperate charger I did what another poster suggested - connect it to another ozito battery, + to +, - to -, to force in some charge . Leave for 2 minutes then retry. Works!
Hey, I love the zero dollar solutions of forcing two cells into parallel
(+ve to +ve and -ve to -ve). Just make sure you get that right ;-)
Thanks for your fix. It has saved me $60 and a trip to Bunnings.
thanks for the info. is that a T10 tamper bit? I just got some 4.0AH Ozito batteries (3 for $99 at Bunnings on 20/2/2024). Looks like a tamper proof security bit required.
Mine wasn't, things could change. Tamper prevention tools are much less on eBay
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