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Old 01-02-2013, 01:39 AM   #1
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Default Reviving older NiMh Batteries

Hi guys, hoping someone can help me out. I was cleaning out my hobby room/closet and found some of my older NiMh batteries, which turned out well because I've just overhauled my old HPI Pro 2 and was hoping to run these packs in it, just for fun in the street and during free practice at my local track. I can't remember when I used them last, and when I try to charge them they start, and then after a few minutes they cut-off. I know that the most likely answer is going to be bin them, and I'm quite prepared to do so, just wondering if anyone has any old school tips for reviving them... trickle charge for hours then try to cycle them???

Thanks in advance for any help
Daniel

ps - I'm using a Duratrax Ice Charger
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Old 01-02-2013, 01:57 AM   #2
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Hi guys, hoping someone can help me out. I was cleaning out my hobby room/closet and found some of my older NiMh batteries, which turned out well because I've just overhauled my old HPI Pro 2 and was hoping to run these packs in it, just for fun in the street and during free practice at my local track. I can't remember when I used them last, and when I try to charge them they start, and then after a few minutes they cut-off. I know that the most likely answer is going to be bin them, and I'm quite prepared to do so, just wondering if anyone has any old school tips for reviving them... trickle charge for hours then try to cycle them???

Thanks in advance for any help
Daniel

ps - I'm using a Duratrax Ice Charger
I'd forget about it and bin then, I tried just about every trick I could find on some myself, cold/heat, high and low charge, they come up briefly then die again just as fast, not worth the effort when you can buy a few perfectly good LiPo pack from Hobbyking for around $30 a pack these days.
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Old 01-02-2013, 03:09 AM   #3
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Yeah that's what I'm thinking, only thing is fitting the LiPo into this car will be tight, even with saddle packs, and I'd also have to get a new LiPo compatible ESC... Might have to shelve this plan
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Old 01-02-2013, 04:06 AM   #4
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Yeah that's what I'm thinking, only thing is fitting the LiPo into this car will be tight, even with saddle packs, and I'd also have to get a new LiPo compatible ESC... Might have to shelve this plan
You don't *have* to get a Lipo compatible ESC. Only thing to worry about is the LIPO cutoff. A cheap way to still run on old ESC is to use a Low Voltage Buzzer Alarm Indicator you can by them on ebay for $2US.

I use it in my RC tank
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Old 01-02-2013, 04:13 AM   #5
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Yeah that's what I'm thinking, only thing is fitting the LiPo into this car will be tight, even with saddle packs, and I'd also have to get a new LiPo compatible ESC... Might have to shelve this plan
Mate chin up, hobby king turnigy saddle lipos should fit into you pro2. If your not sure take it to a track and see if you can test fit a pack before you make a purchase.
Lipo chargers like the B6 are cheap and balance, you can get one for about $30. If you need a lipo cutoff for your ESC to stop over discharging the battery when running, either the buzzer, or an inline cutoff is available. Around $15.

A cheap brushless motor combo will only set you back a little over $100.
Longer runtime, let maintenance, and generally faster.

Last edited by OldSkool; 01-02-2013 at 04:18 AM. Reason: Covered most in above post
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Old 01-02-2013, 06:23 AM   #6
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I can't remember when I used them last, and when I try to charge them they start, and then after a few minutes they cut-off. I know that the most likely answer is going to be bin them, and I'm quite prepared to do so, just wondering if anyone has any old school tips for reviving them... trickle charge for hours then try to cycle them???
it depends on the nimh, some makes can be brought back to life, some struggled to last a whole seasons racing before having to be binned. I regularly use old nimhs for bashing every year and after being left over winter they usually need a few cycles to come back to life. If they can be brought back a long trickle charge will stabilise the voltage so your charger can then monitor the cells when being charged as the battery voltage is too low for your charger. If they do recover they will need a few cycles before you can see how much power they have.

If the cells are dead, you still don't have to spend on lipos and all the equipment to go with them. Nimhs are still around, still the most popular battery packs amongst non racers. Because racers don't use them any more decent nimhs are available for $20-30 a pack. It can be hard to find saddle pack nimhs, but www.cheapbatterypacks.com will happily build them for you.
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Old 01-02-2013, 08:56 AM   #7
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NiMh did have memory like NiCd. Completely discharged, charge half the capacity. Let them cool down a couple hours the discharge. Then cycle them to 75% then 100%. remember to let them cool down while cycling. Then discharge them by running the car.

If you charge the cold!! You'll probably see or hear one of the cells burst.

Then you can consider Lipo's, that everyone recommends. Answering the original question.
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Old 01-02-2013, 10:40 AM   #8
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I'm not recommending this, but I used to 'flash' them with a 12V battery.

A very quick flick of some wires connected to a 12V and then to the individual cell, so the 12V source is connected fora fraction of a second. It's not to charge them in any way, but to 'wake them up' Leave alone for an hour or so then try charging them.

But in all honesty, get some cheap lipo's or saddle lipo's as others have mentioned.

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Old 01-02-2013, 10:45 AM   #9
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Old NiMh cells internally have crystalization that forms between the positive and negative plates. In order to revive the cell you have to shock the battery and break the short that the crystalization creates. There used to be some chargers that had a dead cell revival mode if you can find one. Other wise you can use a big capacitor and charge it up and zap the battery a couple of times to get rid of the short. From there the pack can be charged the same as normal. All the cycleing and trickle charging in the world won't get them back to working order as long as the internal short exists.
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Old 01-02-2013, 02:48 PM   #10
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Thanks for the help guys. Might try to duck into the LHS when the wife goes to the shops today.
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Old 01-02-2013, 03:23 PM   #11
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Don't forget that the HPI PRO 2 can be configured to use stick pack batteries as well. If you are just bashing, this might be the easiest option. In case you don't have the manual, here is the information directly from HPI (http://www.hpiracing.com/graphics/instr/p2/pro2-17.jpg)

Companies like Orion sell inexpensive "stick pack" lipos that should fit in the car just fine.

Hopefully you will be able to revive your Nihm batteries though...good luck.
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Old 01-02-2013, 03:36 PM   #12
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You should be able to find some cheap NiMh sport packs that you could break up into saddles if you want. Alternatively I have an old Tekin 112 AC/DC charger that has a cold start mode and different types of charge to help bring the cells back if your interested...but new batts are probably your best bet.
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Old 01-02-2013, 04:30 PM   #13
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You should be able to find some cheap NiMh sport packs that you could break up into saddles if you want. Alternatively I have an old Tekin 112 AC/DC charger that has a cold start mode and different types of charge to help bring the cells back if your interested...but new batts are probably your best bet.
exellant charger for NiMh's for cold mode or any mode. Wont sell it also.
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Old 01-02-2013, 04:36 PM   #14
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Well I have 2 chargers for LiPo now that will also do any Ni cell as well so I don't really need it any more. Was thinking on putting that and my discharge trays up on ebay but haven't gotten around to it yet.
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Old 01-02-2013, 04:55 PM   #15
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Nah mate I don't need to buy a new charger yet, even if I go down the Lipo road my Duratrax ICE wil do LiPo charging. Will be taking my car to the LHS with me, if I can get some Lipo saddle packs to fit I might buy some of those, or else I'm sure they'll have some NiMh packs/cells that I will be able to use.

Thanks for all the help guys
Daniel
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