Large Scale Central

Dead NI-Cad Batteries

Electronics Power and Sound
#1

I’m stumped at the moment about some dead Ni-Cad batteries.

  1. I ran my locomotive on Friday using said Ni-Cad battery. For the past month or so I’ve been regularly charging and discharging the battery as I’ve been playing around with it.

On Sunday, I charged the battery like normal, expecting to have the locomotive charged and ready to go. Yesterday after I got home late from work (battery charged for 24’), I clicked the switch on and nothing happened… I can get a small less than 1 volt reading.

So did I kill the battery by either accidentally leaving it ‘on’ over the weekend, slowly draining the battery down to 0, and the latest charge hasn’t held? I put it back on the charger last night and checked this morning before I went to work real quick and still no voltage. Should I try the 12 volt zap method? I keep it charging when I left for work.

Unrelated, but related…

  1. I have three other sets of Ni-Cad and/or NiMh (can’t remember the moment) installed in other locomotives (and extra battery car) that I haven’t used in probably 5-6 years. I tried charging them a while back to see if they would hold a charge, but I never got a decent charge.

Here’s my question(s).

  1. Is there anything I can do to revive the NiCad/NiMh batteries that I have before plunking down $ for new ones?

  2. Is it time to switch to LiOn?

The irony of the whole thing is one of my caboose batteries just keeps on taking a beating…

It can sit for years with no charge, and it works great. But then again it is only powering a few LED’s…

#2

One of the failure modes in NiCads is the growth of “dendrites” between the plates (your cell is 2 plates rolled up into a cylinder)

These dendrites are crystalline in nature and conductive, thus they become a local short or low resistance spot where charging current goes through this short and does not “fill up” the electrolyte.

Similarly, you have analogous issues discharging.

If you “zap” a cell, most of the current goes through these “shorts” and usually vaporizes them. Yes, often after zapping you can get the batteries to charge, but realize that it’s most likely that there are other weak points in the cell, besides the “damaged” area, so at best you have a weakened battery, that’s likely to have this problem again.

Also realize that is normally the charging routine/method that made this happen. You cannot leave nicads in a discharged state, and not charge them for years.

So the answers are:

  1. you can zap them and they might come back to life in a degraded condition, but likely to happen again.

  2. yes it is time!

Greg

#3

Greg,

I get that the under used ones would be long ‘dead’ and need replacing, but why would a good battery all the sudden go dead over the course of the weekend?

Craig

#4

Well, it normally takes some time to build up the internal short, but it can happen. No offense, but clearly it DID happen.

Remember that it may have been growing all along, and usually it’s not just one “dendrite” but several (shorts)… since the charging method and electrolyte condition is across the entire cell, it more likely several small shorts…

Greg

#5

No offense taken Greg. I think these batteries are somewhere in the 15-20 year age range, so I think I got my money’s worth.

I guess no harm from trying to give one of the batteries a jump and see what happens before I order some new ones.

#6

15-20 years. Manny times a rechargeable battery has a set number of cycles that it can be reliably charged and discharged. After that, its on borrowed time. And yes, rechargeables usually don’t like to be completely discharged, but NiCads also don’t like to be “topped off” after a partial discharge neither.

After 17 years of service, I am finding that my NiMh sound board batteries don’t hold a charge for long anymore. I think it may be time for me to replace them. But, with them just running a sound board, I can live with them discharging between runs.

#7

Humm beginning to think that I have a loose connection somewhere. Battery shows fully charged and it runs a motor block on its own under load. I have a sneaky feeling that it is the DPDT switch. I’ve already had to replace one…

#8

Craig Townsend said:

Greg,

I get that the under used ones would be long ‘dead’ and need replacing, but why would a good battery all the sudden go dead over the course of the weekend?

Craig

Massive solar flares ?

Seems my Iphone 7 did exactly the same thing twice !

#9

Craig Townsend said:

Humm beginning to think that I have a loose connection somewhere. Battery shows fully charged and it runs a motor block on its own under load. I have a sneaky feeling that it is the DPDT switch. I’ve already had to replace one…

Bypass it for a test, it’s only for reversing right?