Nicad Battery Charger with NiMH Batteries.............

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Janitor Tzap
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Nicad Battery Charger with NiMH Batteries.............

Post by Janitor Tzap » Tue May 15, 2018 9:16 pm

I have an old ARCHER 23-133A Nicad Battery Charger.
Image
It will Trickle Charge 4 or 2 AA Nicad Batteries at 2.9V 50ma for 14 to 16 hours.

The old Nicad Batteries I currently have are just about completely spent, and are no longer taking much of a charge.
Image
{They're 20+ years old now.} :lol:

Any way, the Nicad Charger is still functional, but I'm wondering if I could use it with AA NiMH Batteries?

I found some 4 packs of AA NiMH 400mAH for $3.50.
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It would be nice if I could use the old Nicad Charger with them, without having to modify it first.


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dyarker
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Re: Nicad Battery Charger with NiMH Batteries.............

Post by dyarker » Wed May 16, 2018 5:28 am

What is the mAH rating of the cells? (AKA "C")

spec sheets for two manufacturers and Wikipedia say Trickle charge (no delta temp or delta V) at 0.1 times mAH, or less, is safe. (0.1 x C)

If your charger really is limited to 50mA max, it should be okay.

Cheers,
Dale Y

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Re: Nicad Battery Charger with NiMH Batteries.............

Post by Janitor Tzap » Wed May 16, 2018 1:42 pm

dyarker wrote:What is the mAH rating of the cells? (AKA "C")
Sorry, I forgot the H in the NiMH battery rating, so it should read 400 mAH.
dyarker wrote:spec sheets for two manufacturers and Wikipedia say Trickle charge (no delta temp or delta V) at 0.1 times mAH, or less, is safe. (0.1 x C)

If your charger really is limited to 50mA max, it should be okay.

Cheers,
Yeah, the 50mA max is right.
Okay then, I'll give these NiMH Batteries a try.

I've got an old Polaroid Digital Camera that just eats AA batteries like a pig.
Image
Even though the camera isn't technically turned on, it seems to be drawing about 1-to-5 ma.
Thus, when I'm not using it, I take out the batteries.
Because if I don't, the next time I need to use the camera.
I'll find the batteries are completely dead.

Thanks dyarker.


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Re: Nicad Battery Charger with NiMH Batteries.............

Post by dyarker » Wed May 16, 2018 2:25 pm

At 400mAH, 50mA trickle would be 10mA over.

The AA size NiMH cells I saw at Digikey were 2300mAH and 1900mAH (2.3AH and 1.9 AH). I thought the 400mA in your first post was the max discharge current, not the Amp Hours rating.
Dale Y

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Re: Nicad Battery Charger with NiMH Batteries.............

Post by evahle » Tue Aug 14, 2018 7:54 pm

Janitor Tzap, the BTY batteries I bought on Ebay are complete junk. They tested about 1/5 of the advertised capacity.
The best AA NimH batteries I've tested are the Rayovac 2400mAh. They tested at about 2300mAh, also the Energizers were good at 2300mAh. Both run about $2-$2.50 each at my local store.
I don't know if you have a Harbor Freight or Menards in your area, but their North Tech and Thunderbolt brands worked out to about 1900mAh for around $1.50 each.
I've been testing batteries since I started working with Solar Lights.
If you test yours, let me know what capacity you got.

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Re: Nicad Battery Charger with NiMH Batteries.............

Post by MrAl » Wed Aug 15, 2018 11:09 am

Hello there,

Because the charger only puts out 50ma and only charges for 16 hours it should be ok. However, it will not charge the cells to full capacity if these are modern AA NiMH cells. That's because these cells will be around 2000mAHr or better, and 50ma for 16 hours would only charge them to about 800mAHr which is LESS than half of 2000mAHr. That means it would take two chargings in a row to get to 1600mAHr, and three to fully charge.
That means 32 to 48 hours to fully charge the modern AA cells.
If you dont care about full charge then it doesnt matter of course.

Also, the best NiMH cells these days are the Eneloop brand AA NiMH cells. They have 2000mAHr capacity and also have low self discharge so two month later they still have a lot of charge left.
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Re: Nicad Battery Charger with NiMH Batteries.............

Post by Janitor Tzap » Wed Aug 15, 2018 6:43 pm

Yeah, I know the BTY batteries are {(N)ew (O)ld (S)tock}, and the 3000 label on them has nothing too do with it's actual 400Mah rating. :roll:

Originally, I was going to get the rechargeable batteries for use with the Polariod Digital Camera.
But the camera is taking blurry photos, and no matter what I try to correct the problem, the problem persists.
I can only think that the optics have somehow been knocked out of alignment.
Or that it being only a 5.1 mega pixel camera, it has trouble with fine detail.
When you try taking pic's close up, {12" - 8"} away from an object. :(


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Re: Nicad Battery Charger with NiMH Batteries.............

Post by evahle » Thu Aug 16, 2018 9:14 am

dyarker, I noticed that too. The 3000 on the cell IS the advertised mAh rating being claimed by the BTY company. Here's a link to just one of the bad reviews at Amazon:
https://www.amazon.com/Rechargeable-Bat ... merReviews

I was wondering where he came up with the 400 mAh capacity rating? I don't see that anywhere. Maybe I'm missing something.

Anyway, here's one of the Youtube videos reviewing these batteries:
https://www.youtube.com/watch?v=558-GSrNn7o

I've done several tests using various batteries and made a spreadsheet with what I came up with. I wish there was a way to upload that here without going through a host.

I wish I knew myself whether we could use a nicad charger to charge NiMH batteries. I read some about that some time ago but can't remember where.

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Re: Nicad Battery Charger with NiMH Batteries.............

Post by Janitor Tzap » Thu Aug 16, 2018 5:20 pm

evahle wrote:
Thu Aug 16, 2018 9:14 am
I was wondering where he came up with the 400 mAh capacity rating? I don't see that anywhere. Maybe I'm missing something.
I got it from Electronic Goldmine.

They tested the batteries, and found that they only had a 400Mah rating.
Here's the catalog page: http://www.goldmine-elec-products.com/p ... ber=G22993


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Re: Nicad Battery Charger with NiMH Batteries.............

Post by evahle » Thu Aug 16, 2018 7:34 pm

Thanks! I was just wondering.

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Re: Nicad Battery Charger with NiMH Batteries.............

Post by MrAl » Fri Aug 17, 2018 8:37 am

Hi,

Wow, 400mAHr cells? Wow, where can i get 1000 of them :smile:

Seriously that is way low, with most these days around 2000mAHr.
Nice of EG to be honest about the 400 rating though, that shows integrity in sales.

So the 400mAHr rating at 50mA means about a 4 to 5 hours charge. That means 16 hours is way too long.

I have to be honest too though, i think the cells are a complete waste of time unless you have some seriously low current stuff.
Some quick run time calculations:
0.4 amp, 1 hour
0.8 amp, 30 minutes
1.6 amp, 15 minutes (actually less)

and now a modern 2000mAHr cell:
0.4 amp, 5 hours
0.8 amp, 2 hours 30 minutes
1.6 amp, 1 hour, 15 minutes (actually less)

Price difference:
400mAHr cells: 3.50 for 4
2000mAHr low self discharge cells: 8.00 for 4 (maybe less)

So the 400mAHr cells are about half the price with 1/5 the rating.

The more important question though is what is the number of the charge cycles. How many charge cycles for the 400mAHr cells.
The 2000mAHr cells boast about 1000 recharge cycles. We dont know how many cycles the 400mAHr cells have (yet).
For long term use, it could turn out that the higher priced better cells are actually cheaper.

What i found out in the past is if the cells are obtained from unusual sources, the number charge cycles is very low. We wont know for sure though until someone tests some of these cells.
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Re: Nicad Battery Charger with NiMH Batteries.............

Post by evahle » Fri Aug 17, 2018 10:11 am

If anyone wants to run a few of the cycles' tests, please let us know the results. Let's see; 1000 cycles at maybe 2 hrs charge time = 2000 hrs per cell. We may get pretty old while we're waiting. Lol!
I can't help but wonder how the manufacturer came up with 1000 cycles. I know that some guys test the mAh capacity on their Opus BT-C3100 testers. They'll run it through 5 cycles to see if the capacity drops. Maybe there's a way to calculate the maximum cycles from the results?
I bought one of those testers for $35 from Walmart just because it will charge and test 4 cells at once. It works great so far.
It tests many types of batteries including the 18650 Li-Ion. Speaking of those batteries, they put out 3 times the power as the AA NiMH batteries at the same price! I just starting working with these for future projects.

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