Resurrect NiCd pack

[1911Colt]

That was the trick, shock the cell with 12v to try and break up crystallisation. Zapping the cell with reverse polarity also seems to ring a bell.

Do you zap each individual cell with 12V, or zap the pack?

I have a couple of packs that improved quite a bit with charge/discharge cycling, but they are still fairly weak. Would you recommend zapping, continuing to cycle, or something else?

[RC10th]

Zap each individual cell but be careful, just quick touches are all you need. I've never had a cell explode personally but beware that they can, I think an old weak cell would take a lot of abuse.

Your battery pack is only as good as your weakest cell.

[Lizardking]

What is that?
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I believe it was a fix done by the previous owner to replace the Voltage regulator of the BEC. I posted this same ESC when I got it in this condition a couple of years ago.

Seemed like a good fit for this particular truck. First Tekin ESC, first Losi Stadium Truck (converted from a buggy). Both were raced hard and have battle damage. Both were cleaned up and given a second life.

[Lizardking]

It's a 40 year old battery, using 50+ year old technology. Let it RIP. It is a very nice looking pack, and would go great in a shelfer. For a runner, maybe upgrade to 30+ year old NiMH technology.

I’ll try to bring it to life as much as possible. I did the freezer thing. Trickle charging it now then I’ll try zapping them. Bring them up to as good condition as can be. Just enjoying the process.

Like you say, it just looks really good. I love vintage battery packs. I associate them with running RCs back in the day.

For actually running the truck I’m eyeing a small lipo cell pack that came with a henglong tank I have. It has the same tamiya connector, and its much lighter (96g vs 230g) and smaller than this race pack. Plus its 1800mah vs 1400mah (more like 850mah). Will be interesting running a super light modern battery on this truck.

[Frankentruck]

If you're using that Tekin, be sure to use a lipo low voltage alarm so you don't run the battery down too low. I have one of these that I use with a Novak:

1000014016.png (748.43 KiB) Viewed 921 times

1000014016.png (748.43 KiB) Viewed 921 times

[RC10th]

Do they give you a C rating on that small lipo?

[Lizardking]

NiCd's generally aren't affected by being stored for long periods in a discharged state. Old race packs used to be stored with battery bugs attached to keep them fully discharged. The NiCd is far better than the NiMh for devices that rarely get used.

NiMh on the other hand would be ruined by sitting discharged for long periods. Also keep in mind that the high capacity NiMh cells also started getting physically larger so be careful if you do chose NiMh cells.

I would charge and discharge the pack a few times, it will likely false peak quite a few times, so if your charger has a peak detection lock out feature set it so the pack gets a decent charge, or temporarily lower the peak sensitivity. Keep an eye on cell temps while charging this way. Also warming the pack will help reduce false peaks and help the pack take a charge. After discharging put the battery on a equalizing tray to bring all the cells down to the same voltage before charging. You'll know the pack is taking a charge when it gets warm, if one cell is getting really hot and the others are cold/luke warm then you may have a problem.

Do this a few times and you should notice the pack performance increase.


From memory some of the fancy chargers from back in the day had a buzz mode which was hard on cells but was designed to break up crystallization within the cell and remove their memory. The theory of the 12v zap method from a car battery was to "blow" the crystals off the electrodes inside the battery. Many batteries can be saved but some cells cannot, they won't be as good as brand new but make good practice packs. If you have multiple packs you can swap dead cells out.

Yep, one thing i like about NiCd is you can beat the snot out of them and they still perform, plus the metal melting amps they output. NiMh and flat lipos, you have to baby those or they’ll inflate or stop working. I’m warming up to round cell lipos though.

[Lizardking]

[quote=RC10th post_id=571330 time=1724246188 user_id=8506]
Do they give you a C rating on that small lipo?
[/quote]

I don’t see a C rating anywhere on the label. These are inexpensive 18650 style cells (18mm diameter, 65mm length). My wild guess is .5c or maybe 1c max? I’ll check the temp when I run them on the truck.

[Lizardking]

Drove around with the lithium ion li-ion battery (round cell) for about 10minutes and they still had charge left. They got pretty warm but nothing extreme. Will experiment some more. The lightness really brought the truck to life, it felt super agile and sprightly. I may even replace the old Cirrus servo with a new servo with faster response, higher torque and lighter weight. The jrxt was much more peppy than with a regular working nicd.

The red cell battery is pretty much dead, only taking ~200mah. Freezing and zapping didnt help. Even when left overnight with a trickle charge they didnt take a charge. It will end up as a shelf demo. On the other hand, a yellow cell saddle pack that came with a rc12L is pretty much taking the full charge (1200mah). Might try that next for a better comparison between old battery tech vs new.

[1911Colt]

Zap each individual cell but be careful, just quick touches are all you need.

Worked perfectly! My original Top Cat thanks you. More correctly, the 12x2 brushed motor thanks you. Now it won't get cooked by a LiPo when I get carried away and run it for half hour straight.

The process also revealed which cell was bad on another pack I have. I used a car battery charger for the 12v source. When I tapped each cell, the amp gauge pegged. On the bad cell, it barely moved. It doesn't matter to me as I just won't use that pack. But I would know which cell to replace if I were inclined to do so.

[Lizardking]

Now that you mention it one of the cells did not spark when I zapped it. I have two more red cell packs, maybe i can make a good pack or two.