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Forum Index : Solar : old sanyo 4AH nimhs
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| isochronic Guru  Joined: 21/01/2012 Location: AustraliaPosts: 689 |
A long time ago when nimh cells were the mainstream I saw a batch of Panasonic batteries being sold as the old video recorders that used them had been replaced, they were brand new but obsolete and the shop was moving etc. So I grabbed them very cheaply. On opening one up, they had Sanyo 4 AH NiMhs in 4.8/6 v config...nice... They then sat on a shelf for many years (10 ?). To my amazement, there is still 2.5 ~ 3 volts still showing - and I never even charged them. Pretty impressed Mr Sanyo !! I got the datasheet, it looks like a charge of 16 hrs x 400 mA should be the go if they wil take it. I am thinking of a 11 x 3 config which should give a 12 v pack with 12 amp hours. Do these batteries fall over after a few years or are they likely to be ok I wonder ? Any advice ? |
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Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904 |
In my experience, these NiMh batteries do "fall over" with time - badly. A couple of years ago I bought a cheap 18V battery drill which had a NiMh battery pack. It worked fine for a while. Then the time between requiring charges became shorter & shorter, ditto the run time. Now it won't hold any charge for longer than overnight. So it has been replaced by another cheap battery drill with a lithium battery pack. What a difference! As drill #1 is still mechanically sound its waiting until I find a source of lithium cells to replace the NiMh ones with. Of course, I might have to modify the charger? Klaus |
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yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
No they dont deteriorate with time, they do damage with use and they suffer from "memory" when they are short cycled. There are specific discharge/ charge cycles to recondition them to their full potential. I only know about the 2000-2006 Honda insight Nimh packs. I have seen Peter Parker post here, he might be able to point you in the right direction. If I remember correctly he was involved in developing DIY conditioners from LED drivers over on insight central. I'm confused, no wait... maybe I'm not... |
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| yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
 I meant perkins! retepsnikrepthe other guy is spiderman, he has no clue about batteries Duh! I'm confused, no wait... maybe I'm not... |
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| Phil23 Guru Joined: 27/03/2016 Location: AustraliaPosts: 1664 |
Being that they are Sanyo, they are probably Low Self Discharging, much like Sanyo's Eneloop batteries. Sanyo developed a new technology & apparently protected it so their competitors needed to licence it. Competitors just fought back with greater capacities which moved more easily off the shelves. Who's gonna by 2000mAh over the pack that says 2650..... As a photographer, I have about 8 sets of 4 AA's all approaching 10 years old & very little failure, the only sus ones being a couple of AAA's. Brilliant shelf life & a well known name in the photography world. Cheers. |
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| isochronic Guru Joined: 21/01/2012 Location: AustraliaPosts: 689 |
I tried charging one cell with an improvised charger as an experiment, it seems fine. Pushing about 300 - 330 mA through, the voltage was a bit high but no drama, the temperature stayed cool for about 18 hours then increased to slightly warm to touch when I stopped it. After a month the voltage is now ~1.289, I should measure the stored amp hours I guess but there seems plenty stored OK. So - does it make much difference how multiple cells are connected ? For 33 cells, would 3 x 11 cell strings in parallel be best, or 11 sets of three parallel cells in one string ? |
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Revlac Guru Joined: 31/12/2016 Location: AustraliaPosts: 1024 |
Well I have these Panasonic cells that were thrown out, apparently they get replaced after a certain time even when they are still good. I have read many times that, many cells arranged in parallel will be less than the rated total amp hours compared with a single large cell or series arrangement. But that really doesn't matter as we will work with the cells we have just don't expect the full amp hour rating. (I hope that makes sense)  The one on the left is 24v 20 X 1.2v cell's The one on the right is 12v I made up with 5 banks of 10 cells, total of 50 cell's they are a bit tired by now and will get used to run the electric fence soon.  I think it would be worth finding out how much amp hours is still available. Cheers Aaron Off The Grid |
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| Phil23 Guru Joined: 27/03/2016 Location: AustraliaPosts: 1664 |
One of these is not bad for measuring capacity.  This one is a bit primitive, current is set with fine & coarse Pots. Minimum voltage can be set etc, not perfect, but works. It's well worth knowing though that there are others about that are more sophisticated, but most are fake copies of what was a very good unit. I've got two of them also; their firmware is dangerously flawed. After they disconnect, they will reconnect again when the surface voltage rises, But, they reconnect at full load, 10A or more, whatever it can draw & then doesn't disconnect at all. They will then stay connected indefinitely after that. Managed to melt some hook-up leads here with one; testing a 9 Cell Li-Ion laptop battery I planned on robbing. Vaguely recall I was pulling a bit over an amp from them & had the cut off set to 8.9V. It was in my office & I watched it periodically, & heard the finish alarm, checked & wandered off. Came back a couple of minutes later to burning & dripping insulation & just lightly burnt my palm ripping the wires off. Anyway, one above, while a bit primitive, has none of the flaws of the fakes, which are well discussed in many places. Cheers Phil. |
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| Phil23 Guru Joined: 27/03/2016 Location: AustraliaPosts: 1664 |
Should add, this is what the fake/faulty ones look like,  And, when I just search eBay for that image with, "Constant Current Electronic Load", I noticed that there's a few more variations available now; maybe some of them will behave Ok. |
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| yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
http://projekt.com/locouki/Website/insight/grid-charger-discharger.html there is some info here about battery pack rejuvenation, it is specific to the 170 volt insight pack but the principals can be adapted. I'm confused, no wait... maybe I'm not... |
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| Revlac Guru Joined: 31/12/2016 Location: AustraliaPosts: 1024 |
Hi Phil That battery tester looks pretty fancy, I never thought of doing it that way. These Ni-MH batteries are 4amp rated but this 24v pack only run a little computer fan for half an hour. As for note book batteries, (dealt with many of them 2.2Ah) I never did a load test on them, probably should have but they have been running well for years now.  All i did was charge them and leave them sit for 3 days to a week if the voltage did not drop much, they were good enough for me. Actually perhaps 1 load test, I was wiring up a set of notebook batteries to 20v on the bench outside and left them for about 2 minutes. I came back to see a little bit of smoke above the batteries. Turns out THIS LITTLE GREEN FART Thought he would try and be a sparky.  Just burnt the tab off the end of the cell, no other damage done, must have taken 30amp to burn that off. Anyway the 12v pack of Ni-MH batteries is on a solar charger and will see if they improve overtime. Thank's to yahoo for providing that link, good info towards the end of that page. Cheers Aaron Off The Grid |
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| yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
If I can find a link to Peter Perkins simple cycler i will include that as well, he used a 100w 300 ohm or 400ohm resistor for the honda hybrid car packs enabling them to use time to calculate the capacity. and not have the resistance change and draw the battery down too fast. it is most important the pack is grid charged for a long time first to get the cells topped up and as even as possible. they used to do 3 cycles to progressively lower voltage but then experimented with one discharge over 36 hours to as low as they could get it. I'm confused, no wait... maybe I'm not... |
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| isochronic Guru Joined: 21/01/2012 Location: AustraliaPosts: 689 |
well..after a delay.. I got around to actual actioning :) I charged 11 in a series pack and it is excellent.. and another 11 pack looks good as well. The first charge was 4 blocks of 0.4 amps, the cells were luke-warm at the end but no drama. The instigation was to test a car HID headlight kit - the spec says it can draw 15 amps at startup and then 3 thereafter, preferably at 13 ish volts. I wa going to use 3 packs in parallel but got impatient and tried it on one; the cells are rated for 8 amps so I though it may be a goer. The 11 cell pack started and ran it after a first start. The cells got a bit warmish, but a good interim result until I get the 3 set up. Nice bright arc !! |
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