I discharged the “good” battery awhile, then I put it into the original charger and the “Fully charged” green light came on immediately.
I think that we can conclude that that charger is “toast”!!
On the other hand, I have the “bad” battery on my Accucel charging. I put it at 0.8A and it’s been charging for awhile now and is at over 300 mAh already.
Maybe it’s rescuscitated?
Not necessarily. At a very low rate the dV/dT may not kick in and it will just keep charging……forever. A “bad battery” may show this characteristic. The (sorta) good cells take charge, and dump it as heat. The bad cell gets nothing.
I have some really crappy AA cells that will never terminate in my best chargers. I keep them around for those solar yard light where they are good enough.
But, to be optimistic, maybe it’ll work. You got nothing to lose. Experiment!
Ok, it stopped at 24.35V and 299 mAh (sorry the “300” I said earlier was wrong), but here’s the thing: I put it in the drill and ran it for awhile and it seems to be holding.
300mAh is pathetic, half the capacity of a decent AAA.
Did you simply run it or did you stress it? Big difference.
BTW- trying to charge up my 2x 15-cell NiMh weed whacker batteries. One is fine. After only 2 weeks the other one is down to 10v :SICK:
Trying to charge it with my AC-6 and like yours the voltage readings are jumping all over the place. I’d say I have a questionable/bad pack.
I had to jump this one a few weeks ago to get it going again. It worked, but like I said, it’s not really a fix, just a patch.
Sawmaster (et al),
Your charger arrived today, and it looks like it’s charging the batteries (the red “charging” light is now lit).
I ran both batteries for a little while then am now charging one of them (the “good” one, although that didn’t seem to have held much power).
I’ll post back in a bit.
Thanks,
Jim
EDIT: Charger seems to be charging both batteries, but I noticed that when the battery comes off of the charger, the area around the “neck” of the charger, where the contacts are, is quite warm/hot. Does anyone know if that is “normal”?
That area has a cell in it and little path to dispel heat from use or charging. Plus it’s at the end of the series string, so every bit of current passes through it where a cell in the middle of the string doesn’t see as much current passing through. Should be OK and I’m glad the charger is doing somebody some good.
Phil
(adding: the other cells are isolated from the plastic thermally by cardboard; that cell has only it’s cardboard wrapper.)
I’ve taken the batteries through several charge cycles now with the charger that SawMaster generously provided, and they seem to be working.;
So, in summary it looks like:
- The original charger was bad (always showed “Fully charged”) and
Thanks!
Jim
EDIT: BTW, I did open up the original charger, and I didn’t see anything obviously bad (no burnt chip, etc.).
Is there any voltage difference between the 2 batteries when fully charged?
I seem to have 1 OK battery, and a dud. The OK batt. shows 20.3v right off the AC-6 charger. The dud-18.6.
I ran the dud in the whacker until it got ‘tired’ (not dead), and the resting voltage was ~13v. Should have been 15+ (15-cell).
I opened it up and tested each cell. Most were 1.2v, 3 cells were 0v.
I zapped those and regained voltage, put it on the stock 210mA charger overnight and just checked > 18.6v.
Checked the marked ‘bad’ cells and found 1 still zero. Zapped that one and am now charging it individually with the AC-6.
I’m pretty sure I can get back to 20+v on this pack. I’m also pretty sure that when I put it to work those ‘lame’ cells are going to be sucked dry and die again.
I think I’m going to Li-on it.
Addendum - After sitting a week voltage was down to 13v. Charged it up on the AC-6 and it would not get past the 18.6v ‘barrier’ again. I have a cell that seems to insist on being dead.
Hi,
I agree re. your addendum, probably that one battery is “weak” or not able to hold charge?
Question 1: What did you mean by “going to Li-on”? Are you thinking of replacing the Nimh batteries with Li-ion batteries, but use the same battery housing? What about a charger for that then?
Question 2: Did you still need the voltages of the 2 batteries I have?
I would re-use the housing and populate it with (in this case) 6s 18650’s. I found someone that did the same thing with this weed whacker and got good results. Surprisingly he used the stock charger (210mA) to charge it and just watched the voltage. 2 years later he opened it up , checked individual voltages and the system was balanced.
I may try that but use my AC-6 charger. I don’t have a suitable tap right now but I’ll probably order one, or 2 since I don’t trust the other battery.
I’m curious about your voltages. I’ve been sharing my experience to expand the knowledge base for both of us.
Do the batteries take a full charge……and work OK?
Hi,
Sorry I haven’t been watching this thread lately.
FYI, I ended up buying a corded Ridgid drill today.
The batteries do charge, but it seems like they drain very quickly… the drill will run for a short time but then will start slowing down after a short while.
I will take the voltages and let you know.
BTW, I tried to open one of them today, but it was kind of strange. I think it uses Torx screws and I was able to unscrew one screw, but when I tried with the same screwdriver on the other screws, it didn’t fit (too large, I think). So I wasn’t able open it up.
Did that person just put the 6 18650s in series? And he removed all the other circuitry inside the battery enclosure?
Sounds like you have tired, or at least a lame cell or 2. My experience is that once a pack does this it’s a goner, unless you want to go through the grief of sorting out the dead ones and replacing them. Even then the remaining cells are likely right behind.
Yes, the guy simply wired them in series. Of course he kept the proprietary connector. Some of them have thermal sensors but those aren’t of any use since they are for the charger.
I don’t kinow if you know, but was he able to remove the screws to open the pack using a “regular” Torx driver, and where the screws all one size (driver)?
Jim
They’re tamper-resistant Torx, looks like a T-10 but can’t confirm size till tomorrow (those bits are out in the work van). I seem to recall having come across a box of new Tenergy cells for replacing these when I cleaned up the shop but I don’t know how many I have or quite where they’re at- I’ll look for them tomorrow as well.
Phil
I found a video and yes, it’s apparently T10 security Torx bit. I’ll see when I can get one.
I just measured one of the batteries just off of the charger (thanks, Sawmaster!) and got 21.95 V.
Also, BTW, I measured the battery pack, and it’s approx. 2.5” x 5” and a little over 2” height. How did your friend fit 6 x 18650 into that?
I was hoping to put the 18650s in holders, like these http://www.amazon.com/Black-Plastic-Battery-Holder-18650/dp/B00I8JJKD8.
Those have dimensions:
It seems like two of those, stacked on top of each other would just barely fit into the battery pack?
Jim
IIRC these are what used to be known as “sub-C” cells. I think they call them “2/3 C” now. Going to dig in the shop shortly and I’ll do some measuring when I find everything.
Phil
Yes, I think “Sub-C” was mentioned re. the original Nicd batteries. In any even I’m not planning to just replace the Nicd batteries, but want to “go Lithium”. 6S1P sounds abour right to try?
Jim
yes they would be sub c.95% of nicad tool packs use them.
there are 4/5 sub c but i have never seen a 2/3sc.
if one has gone the others are right behind it.replace all.
get good ones like panasonic or sanyo.
everything else is hit or miss leaning heavily towards miss quality wise.
If you’re interested I found the 16 cells these packs take. Brand new by Tenergy but have been sitting here I don’t know how long; at least 8 years. Being NiMh and never used I think they’re OK (someone chime in if they aren’t please!) Should equal the factory cells based on them being what I’ve built packs with before. They even have tabs to make the build easier.
Yours if you want them, same price as the charger but may take me a few days to ship. Let me know.
Phil