Help needed with La Crosse Technology BC-700 and Kodak Rechargeable batteries AA

[TKhanson]

Folks:

I own the BC-700 and many Eneloop AA and AAA. All works well. However, when visiting my friend, I noticed an older AM/FM radio he leaves running in his office. He said he uses rechargeable batteries to power this older radio. I noticed he had Kodak 1.2V Ni-MH with a dumb charger. I asked him if I could borrow a set of batteries as I wanted to see if my La Crosse could increase the capacity of the batteries, since they weren't being charged with a smart charger.

I put two in; one under "Test" and one under 'refresh". I thought I could use both settings to see if the refresh could breath more life into these batteries by comparing the Test results to the Refresh. I assumed refresh would cycle until the battery couldn't hold more.

After 2 days both finished. I got 1451 and 1478 mAh out of both and both at 1.38v. Here is where it goes strange. I wanted to run a few more refresh cycles on both to see if the mAh increases. Each time I run them in Test or Refresh, the charger chargest them to about 1.42v (which is an increase) and then goes to the FULL stage or stop. La Crosse device doesn't discharge and recharge, over and over. Just charges and stops. I don't know why.

I thought my device might have gone bad so I put a AAA and AA eneloop in under refresh and it charged them both and is now discharging them. So its working fine there.

I suppose my question is does this type of thing happen if I have a bad or failing battery? Could it be these Kodak batteries are too old of a Ni-MH battery for the La Crosse to properly refresh?

Thanks!

TKH

 

[ChrisGarrett]

They probably have high internal resistance and are ready for the recycle bin.

Buy him a new set of Eneloops, or Duracell Ion Core AAs and move on.

I'm about to recycle 8 Sanyo 2700s that only charge up on a dumb charger and hardly have any punch to them.

I got about 4 years out of them, but now they're more trouble than they're worth.

Chris

 

[TKhanson]

They probably have high internal resistance and are ready for the recycle bin.

Buy him a new set of Eneloops, or Duracell Ion Core AAs and move on.

I'm about to recycle 8 Sanyo 2700s that only charge up on a dumb charger and hardly have any punch to them.

I got about 4 years out of them, but now they're more trouble than they're worth.

Chris

So is that what happens when a battery is on its way out? It can't be refreshed or it won't reach the max voltage? I've not yet had batteries get that old yet.

 

[ChrisGarrett]

So is that what happens when a battery is on its way out? It can't be refreshed or it won't reach the max voltage? I've not yet had batteries get that old yet.

We wish, lol.

Battery makers would be out of business if we could bring them back from the dead.

Electrolytes dry up, internal resistance goes up, chargers have to reject them because it's too hard to charge them and capacity just goes south.

And the cycle of life repeats.

They're consumables and the cruddier ones don't last all that long.

Chris

 

[MidnightDistortions]

The charger is designed so it will continue refreshing as each cycle increases the batteries capacity. However, if the capacity is not increasing or is lower than what you got on the previous results the charger will end the cycle process when the capacity is lower than the first cycle.

More than likely those cells have an internal resistance of 80% or higher. Using a dumb charger will increase the IR more quickly when the cells are being subjected to overcharge or undercharge (over discharging the weaker cells in a device) on the regular basis. Any cells older than 3 years being primarily charged in a dumb charger will most likely be no good. The older they are the worse the cells will be. As Chris has mentioned, just get some Eneloops or Duracells and you'll be set. I also recommend getting a Maha C9000 so you can see when the cells are on their way out as that charger will do an internal resistance test, otherwise you would have to do the math to make sure the cells hold 80% or more capacity, i have found a few though that are under 80% but the IR test still shows that the cells are only 40-60% internal resistant. 80% resistant (that would be 1.9 to 2.0v, IR test on the C9000) is generally what i go by when the cell becomes too weak for high to mid drain devices and demote the cell to low drain stuff such as clocks or remotes.

 

[n3eg]

...After 2 days both finished. I got 1451 and 1478 mAh out of both and both at 1.38v.

That is below 75% rated capacity, and they are considered bad at below 80%. Time for new ones.