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Author Topic: resurrecting batteries  (Read 1163 times)

Neil

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resurrecting batteries
« on: March 15, 2018, 07:27:04 PM »


I have two nihm, battery packs that I bought some time ago to power a 36" ST200 sea plane tender, but never really got to grips with the boat or the batteries which I felt were not giving maximum power or run time......and I had linked them in parallel, to give twice the ampage,...they were both 4200mh.........and I neglected them.


I had them on charge for25 hours even though the battery charger delivers 500mh.......


however when I linked the two batteries to a motor about the size of a 700 the motor ran slowly about 1500 - 2000 revs for just under an hour and then the motor stopped.........these batteries cost me 50 quid around 6 years ago, and I admit I have neglected them, but is there any way of getting them back to a peak performance, even though they never had peak in the first place.


cheers. neil.
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Stavros

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Re: resurrecting batteries
« Reply #1 on: March 15, 2018, 07:57:08 PM »

Sorry Neil but they are furbarred ....got 4 12v ones which are around 4 years old and the same has happened I Neglected them.....get some more when you get the speed contoller M8




Dave
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sparkey

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Re: resurrecting batteries
« Reply #2 on: March 15, 2018, 08:13:23 PM »

Use them or lose em. {:-{ {:-{ {:-{ {:-{
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roycv

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Re: resurrecting batteries
« Reply #3 on: March 15, 2018, 11:14:57 PM »

Hi all, not quite in agreement here.  As they look due for the bin it is no harm to strip them down and see what you have.  First check that the plug connection to the end cells is good, not a corroded joint usually found on the negative pole.
Get them down to the almost bare cell level and then put each battery on charge and use a volt meter to measure the voltage across each cell.  If it is zero discard the cell, if it is over  2 volts discard the cell. You are looking for cells that have a reading of 1.4 -1.65 volts on charge, they should be OK.

If you have sufficient good cells and there is no reason why not, as these were originally good quality cells, you can make up a new pack.
I brought back to life a 12 volt pack by replacing 2 shorted cells some years ago (same brand).  Also consider 4 and 5 cell packs, not every function needs a 6 cell pack.

If just one cell has failed then buy a new cell to replace the failed one.  Keep to the same amp hour capacity and also if you replace the Tamiya connector make sure it is correctly wired.  I solder with wire to connect cells together using a 70 watt iron.  Clean cell surface as it will have been welded use a solder flux to tin the cell and solder the wire on quickly, I have wet tissue on hand to cool it down asap.  Take some care with charged cells as they can discharge high currents and may cause heating or even a small fire.

If you strip the outer plastic coverings carefully you can re-use the casing with some adhesive tape.  I have in use lots of batteries over 10 years old, the capacity slowly reduces over time and I have found using a watt meter that some very old batteries are down about 10 - 20 % on capacity, but I use relatively low powered motors and this is not a problem.
Hope this helps,
regards Roy
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Neil

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Re: resurrecting batteries
« Reply #4 on: March 16, 2018, 12:00:37 AM »


thanks guys, and thank you roy for your very comprehensive instructions..........there's definitely no harm in trying.


cheers, neil.
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Neil

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Re: resurrecting batteries
« Reply #5 on: March 17, 2018, 11:59:54 AM »


following Roys  advice about separating the batteries and breaking them down.......I first just separated the two battery packs which had been wired in parallel to give 8.4 amps, and put both on different battery chargers to the one I had used the other day.


bareing in mind I don't as yet have a gizmo for testing amp/volts/battery drain, I have to use simple methods first in testing!! {-) {-)

I left them both for the full day, about 16 hours and then this morning connected one pack to the same motor that I had the other day.........the motor is spinning round at top speed at the moment, under no load and has been for just under 90 minutes without any sense of slowing down..........I'll wait till this has died and then recharge the battery pack whilst connecting the other pack to the motor to see what is what, but if it is what I think it is, and the second pack is kaput, then to me being a simple person, it would seem that the duff set was draining the life out of the good battery as it was being charged.........would I be correct in thinking that.


neil.
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roycv

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Re: resurrecting batteries
« Reply #6 on: March 17, 2018, 12:07:14 PM »

Hello Neil I did not know you had the packs in parallel.  You could be right one pack permanently draining the other, you would only need one cell duff to do this.  Slowly slowly is best policy check it all out and if the other pack is dodgy then try the stripping down, you may gain some good cells, I have never had a whole pack go u/s on me.  Do check the voltage on load of the good pack as that sounds alright.
regards Roy
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Neil

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Re: resurrecting batteries
« Reply #7 on: March 17, 2018, 02:54:27 PM »


Thanks Ron, appreciate your time in explaining to me, as I really am a technophobe when it comes to electricity and electronics........but i connected the first battery pack I got hold of to a motor bigger than a 545 and with no load on it, it has now been running at full speed for the 7.2 volts for 4.25 hours with no sign of going any slower, and even after the 4 hours plus i still cannot stall the motor with my fingers........so that pack looks as though it is a decent set..........the other pack that was attached had been on the same charge time of 14 hours but showed no signs of life when I touched terminals together......but is now back on charge so will see if there is any life in it in a few hours...........at least it looks as though I have one decent pack to put into the little rib I'm reconstructing.....again, thanks for your time...........without people like yourself and others helping thick sods like me I'd have dumped both pack thinking they were both gonners.


cheers. neil.
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Neil

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Re: resurrecting batteries
« Reply #8 on: March 17, 2018, 06:19:38 PM »


Ron, just to keep you up to date on the battery situation......the first set i connected the motor to ran the motor at full 7.2volts and speedy enough for 6 hours 22 minutes before it "dropped of the cliff" and the motor slowed down to around 400rpm...........which i reckon would give me probably with a small brushless around 20 - 30 minutes........by which time i'd be bored so much i'd be asleep.


i connected the second pack for around 2 hours to the same charger that i used for the first pack, and connected the motor  after disconnecting the charger, and it i still running the motor at the same revs and has done 1 hour 25 up to now.


i can't understand that linked together they wouldn't power a 6v lightbulb for more than a few minutes, but apart, they seem to be working...........i'll see how the suspect pack is coping and running the motor, and let you know the outcome.


neil.
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JimG

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Re: resurrecting batteries
« Reply #9 on: March 17, 2018, 06:34:33 PM »

NiMh often need to be cycled a few times after being left unused for a while. Does your charger have a cycling function? This will charge then discharge the pack to a set voltage, do this 2 or 3 times and it will help recover the cells. Reading your posts it seems that you have a slow charger set for overnight charging, it might be an idea to get a more up to date charger which allows for a faster charge (1 hour) and will also tell you how much charge has been put into the cells.
Jim
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Neil

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Re: resurrecting batteries
« Reply #10 on: March 17, 2018, 07:16:52 PM »


Thanks Jim.......no, my chargers don't have such a function and all charge at 500mah, except one which is a 6/12v charger and charges at 1000mah which I'm using at the mo.


Mind you the second pack is still running strong after 2.5 hours so I'm beginning to think that in my spaghetti of wiring the two up in parallel, I might have cocked it up somewhere, because both packs are giving off power that I never had in all their life, because as soon as I bought them I wired them up to fit into my flying Christine, and they never worked.....got about 8 minutes max out of them...........obviously they weren't somehow receiving any charge, or very little
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roycv

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Re: resurrecting batteries
« Reply #11 on: March 17, 2018, 11:16:40 PM »

Hello Neil, glad you are back with some useful batteries now, I agree a fast charger is a good idea.  Just for the record I am Roy, never been a Ron before!
regards Roy
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chas

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Re: resurrecting batteries
« Reply #12 on: March 18, 2018, 12:12:03 AM »

Just a thought, in the wireing loom, was the wire thick enough to carry the amps ? It might explain the lack of performance with batteries that seem OK.
Chas

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roycv

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Re: resurrecting batteries
« Reply #13 on: March 18, 2018, 12:30:29 AM »

Hi Chas in my experience wires that are too thin usually identify themselves with smoke!
Roy
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Neil

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Re: resurrecting batteries
« Reply #14 on: March 18, 2018, 01:21:45 AM »


Hello Neil, glad you are back with some useful batteries now, I agree a fast charger is a good idea.  Just for the record I am Roy, never been a Ron before!
regards Roy


sorry Roy.........why the h*** did i call you ron.........senior moment.......sorry.


age is no excuse, lol........
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Neil

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Re: resurrecting batteries
« Reply #15 on: March 18, 2018, 01:27:24 AM »


Just a thought, in the wireing loom, was the wire thick enough to carry the amps ? It might explain the lack of performance with batteries that seem OK.
Chas


hi, Chas.........I would presume so as it was what was supplied attached to the battery, but then again, the "loom" I made up with wire from an electrical appliance......think a radio might not have been, as it was only thin stuff with multiple spade connecters.
but the two packs separately are now performing well
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roycv

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Re: resurrecting batteries
« Reply #16 on: March 18, 2018, 01:46:42 AM »

Hi Neil, no offence, glad that the batteries did not get binned and now back to life again.
kind regards Roy
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chas

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Re: resurrecting batteries
« Reply #17 on: March 18, 2018, 08:10:45 AM »

I was thinking of any additional wireing between the batteries / ESC and the motor. If I remember correctly resistance in copper wire rises with temperature. It needn't get hot enough to burn out to cause a problem.
  I'm probably barking up the wrong tree, but I thought it was worth checking.
Chas



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