Battery for a "Pure One Classic" radio.

[march.brown]

Hi George. I never intended to run any of these packs down past where I could see that a bad/under performing cell did in fact exist. The one time that I did see a second cell crap out, it happened almost immediately after the first, and again, this was accidentally. I did not want to damage the packs anymore than necessary, just far enough to determine if indeed there was a bad cell.



I can't answer that question. Tom (SilverFox) suggested I monitor individual cells in the pack while discharging on the CBA II. The problem was that these packs are shrink wrapped and I would have had to puncture through and measure each cell with a needle, or something to take measurements. Since these packs are welded cells, I really could not replace the bad cells anyway, and as they still worked and ran about $60-$70 a pack, I didn't bother potentialy damaging the wrap, to find out. I have no doubt that at least sometimes, the weak cells were reverse charged. It would be almost impossible, considering the 10A+ load put on these diminutive cells.



These packs still work, just not nearly as long as a new pack. The 14.4 Volt pack should run the M@g for about 9 minutes, and the 15.6 Volt pack for about 7 minutes. The 14.4V pack will only go for about 2 minutes or less, last I checked. The 15.6V pack fares a bit better and will go for about 5 minutes. Actually these are cumulative runtimes. At 140-170 Watts, the "2D" M@g gets way too hot after about one minute and needs a "rest".

Anyway, both packs have bad cells in them, but still work. No one makes packs for them anymore, either. This light isn't really all that useful anyway, although it is quite capable of illuminating a large pasture etc. and has been used for such. I have a FiveMega "2D" 12 x 2/3A cell holder (the light body is "tri bored"), that I've never used. When these packs finally die, I'll just use it, albeit it will only give me the lower 14.4 Volt output. Good 10A+ capable cells are hard to find also, adding to the problem.

Dave

Hi again Dave

If you were able to push needles into the shrink wrap you would be able to check each cell individually ... When you located the poorer cells , you could charge individual cells via the same needles that were used for measurement ... I realise that the needles would only be a "point-contact" , but you should be able to give some sort of equalising charge to the low cells ... You could even discharge (using resistors) individual good cells to bring them down to more closely match the poorer cells ... I'm assuming that all the cells are charged in series with no balancing leads ... Would a long trickle-charge help to bring up the poor cells ?

Perhaps when the battery packs get down too low for further use (or die) , you could try this ... After the needle testing , is there enough room to add another layer of shrink wrap for security without making the pack too large to fit the torch ?

Regards

George
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[45/70]

I'll take your ideas under consideration, George. The needle idea would work as you suggest. These packs are now so old that I usually charge them either with the "forming charge" option on my iCharger, or simply charge them with a bench supply at a 0.1C rate for 14 hrs. This, especially the later, should balance the cells out, and the packs seem to work about the same, either way I charge them. Also, the individual cells do not get too hot, just warm, so I think I'll just ride it out this way to the end.

Thanks for your tips, and I may still try that. If for no other reason, it would be interesting to see just how bad the cells are and which ones, at this point. They are the only NiMh cells (actually "batteries") that are ever stored in the Fridge. Mostly because they are no longer available. Hopefully they'll last a little while longer. Technically, they're past "done" now, but......

Dave

 

[march.brown]

I'll take your ideas under consideration, George. The needle idea would work as you suggest. These packs are now so old that I usually charge them either with the "forming charge" option on my iCharger, or simply charge them with a bench supply at a 0.1C rate for 14 hrs. This, especially the later, should balance the cells out, and the packs seem to work about the same, either way I charge them. Also, the individual cells do not get too hot, just warm, so I think I'll just ride it out this way to the end.

Thanks for your tips, and I may still try that. If for no other reason, it would be interesting to see just how bad the cells are and which ones, at this point. They are the only NiMh cells (actually "batteries") that are ever stored in the Fridge. Mostly because they are no longer available. Hopefully they'll last a little while longer. Technically, they're past "done" now, but......

Dave

I've just received my Fameart AA to C converters in the post and am now using them with six freshly topped-up Eneloop AA's in the "Pure One Radio" ... I will keep an eye on their performance ... I topped up the six Eneloops with no problem but I then charged up eight AA Hybrios (two sets of four) ... One of the Hybrios wouldn't reach full charge according to the LCD display on the charger ... It got quite warm though ... I tried it in a different slot but it still didn't get the full four bars on the display ... That cell is now being discharged by the charger which will then recharge it ... If that doesn't work , then it's time to scrap it ... It is only (I think) the second Hybrio cell that has failed in the last three years ... So far I have not yet had an Eneloop fail ... Perhaps it's not worth trying to revive the Hybrio AA and maybe it's a hint for me to buy more AA Eneloops ... I decided to standardise on Eneloops as and when the Hybrios die , maybe now is the time.
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[march.brown]

One of the Hybrios wouldn't reach full charge according to the LCD display on the charger ... It got quite warm though ... I tried it in a different slot but it still didn't get the full four bars on the display ... That cell is now being discharged by the charger which will then recharge it ... If that doesn't work , then it's time to scrap it ... It is only (I think) the second Hybrio cell that has failed in the last three years ... So far I have not yet had an Eneloop fail ... Perhaps it's not worth trying to revive the Hybrio AA and maybe it's a hint for me to buy more AA Eneloops ... I decided to standardise on Eneloops as and when the Hybrios die , maybe now is the time.
.

Well , after the discharge , the Hybrio has charged OK according to the LCD display on the charger and it wasn't as warm ... I have labelled (felt tip pen) the cell with a question mark and will not use it in multi-cell devices and will get a few more Eneloops now ... Just in case the other Hybrios go the same way ... Sort of preparing for the future in a way !
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