Long life Ni-Cd

real_aurgathor

I normally use Mach3 blades for shaving, but if I let my beard grow too long, I usually trim it first using a Remington rechargeable shaver so it doesn’t jam up the blade assembly.

I wanted to use it a couple of days ago, and it was running way slower than usual. I kept it plugged in for a couple of days [which was lately required to make it useable] to no avail.

So I opened it up and I’m only measuring around 1.5V (no power) or _2V (with power, charging) indicating that one of the battery in the pack is shorted. Looks like the battery pack was made in 1979 (!!) and it was still working acceptably about 2 - 3 months ago.

I have some much newer Ni-Cds from Sanyo and Harbor Freight (early to late 2000s, I think) and some of those died (probably shorted out) in under 10 years.

Somewhat-Reticent

Looks like you got some good service from them.
( Some NiCDs get lazy if not fully discharged every bleeping time. )

Sometimes I cheat with LiPo.

codezer0

real_aurgathor Wowie.

We can’t even get a phone (or hp laptop) to last two years without a spicy pillow situation, but nickel cadmium is out here lasting like it was worth keeping around.

Somewhat-Reticent

Modern NiCD chargers avoid lazy-attitude by design.

Sparkchaser

If you can get to the “cell”, you can ZAP (1) the short. I’ve done it for years. Well, when NiCad was the thing. I still have a bunch of them I use to replace AA and AAA cells.

I use an old La Cross charger that seems to do the job.

(1) should only be attempted by an old engineer. 😄

real_aurgathor

Sparkchaser If you can get to the “cell”, you can ZAP (1) the short. I’ve done it for years. Well, when NiCad was the thing.

That’s actually my plan A, I just need to find a suitable cap.

I’m not sure if the built in charger circuitry (appears to be a capacitive dropper) is capable supplying a high enough voltage to charge a Li-ion, but that would be another option.

real_aurgathor

Somewhat-Reticent

Somewhat-Reticent Modern NiCD chargers avoid lazy-attitude by design.

That’s normally an option called “Conditioning” or somesuch

real_aurgathor

codezer0

Apparently, some of the older Ni-Cds are very robust and can handle rough service much better than newer, higher capacity chemistries. I’ve tried Ni-MH and Ni-Zn – both seem to be more failure prone, though for different reasons. Ni-Zn seem to get overdischarged since most gadgets are designed with 1.5V batteries in mind in while many Ni-MH chargers seem to overcharge and cook the batteries.

real_aurgathor

I instrumented the battery pack with a paper clip and confirmed that it’s truly the case of a shorted battery.

With no power I measured 0V and 1.245V, with power it was 0.08V and 1.263V, indicating that it’s probably not a “hard” short. I just need to find a suitable cap, and see if I can turn that short into an open.

Edit: forgot picture