Recharging "Non-rechargable" Alkaline Batteries

[TromboneAl]

I came across this product

Battery Xtender

which claims to recharge disposable alkaline batteries (info and review) up to about 10 times.

Since 2005, California has required recycling of alkaline batteries, so I've been putting my used batteries in a box. When I read about the charger, I thought I'd see how many I had for recharging. Turns out that even though I already use NiMH rechargeables for most things, I still had about 80 alkalines waiting to be recycled.

The main problem with the NiMH batteries is that they self-discharge. That is, if you leave it in a box, or use it for a remote control, it will go from 1.4V to 1.0 V in a month or so. So for very low drain applications, or for something that sits a long time between use (emergency flashlight), alkaline is better. Also, my NiMH charger doesn't work with C or D sized batteries.

I've been going through the box of used batteries, and am able to recharge most of them. Here is an example of some pre and post-charge voltages:

Pre Post
.185 can't charge (dead)
1.484 1.486
1.263 1.484
1.282 1.485
1.539 1.570
1.368 1.521
1.443 1.445
1.058 1.304
0.370 1.347
1.469 1.556
1.094 1.480

 

[REWahoo]

Do the recharged alkaline have a similar shelf life to new ones or do they lose charge over a relatively short time like the NiMH? Also, how long does it take to recharge an alkaline, several hours? How much electricity are you using?

 

[REWahoo]

One more question: Were any beavers harmed in the manufacture or testing of the recharger?

 

[TromboneAl]

I don't know about the shelf life yet, I'm testing that and will tell you in a month or two. I'm expecting a similar shelf life to new alkalines.

The charger uses two watts, less when the charging is done. Some batteries finish charging in 10-20 minutes, others take 16 hours or so. I charged a new battery and it was done in 20 seconds. Went from 1.604 to 1.612 volts. There are status lights for the individual batteries, which is good.

Which kind of beavers were you referring to?

 

[REWahoo]

Which kind of beavers were you referring to?

OH!!! OH!! I get it!!

 

[HFWR]

It's pretty good once you get past the used...

 

[REWahoo]

It's pretty good once you get past the used...

Al's working on recharging the used ones to get more out of them.

 

[mathjak107]

I came across this product

Battery Xtender

which claims to recharge disposable alkaline batteries (info and review) up to about 10 times.

Since 2005, California has required recycling of alkaline batteries, so I've been putting my used batteries in a box. When I read about the charger, I thought I'd see how many I had for recharging. Turns out that even though I already use NiMH rechargeables for most things, I still had about 80 alkalines waiting to be recycled.

The main problem with the NiMH batteries is that they self-discharge. That is, if you leave it in a box, or use it for a remote control, it will go from 1.4V to 1.0 V in a month or so. So for very low drain applications, or for something that sits a long time between use (emergency flashlight), alkaline is better. Also, my NiMH charger doesn't work with C or D sized batteries.

I've been going through the box of used batteries, and am able to recharge most of them. Here is an example of some pre and post-charge voltages:

Pre Post
.185 can't charge (dead)
1.484 1.486
1.263 1.484
1.282 1.485
1.539 1.570
1.368 1.521
1.443 1.445
1.058 1.304
0.370 1.347
1.469 1.556
1.094 1.480

try the sanyo eneloop nmh batteries. they are really good. they still hold a minimum of 85% of their charge a year later. they require no charging taking them out of the package the first time either.

i use them in my camera flash and for spares.

SANYO eneloop | Ready to use Rechargeable Battery - The only battery you will ever need: Home

 

[TromboneAl]

Yes, those look good. Price is high now, but it will probably come down.

 

[mathjak107]

Yes, those look good. Price is high now, but it will probably come down.

they are perfect for things like cameras,flashes and spares. no more guessing as to whether your spares are good or leaky alkalines.

recycling time on my nikon sb-800 flash is extremely quick

 

[cute fuzzy bunny]

I had one of those rechargers years ago. Perhaps the newer models are better, but the old alkaline recharger was good to give me about a quarter life on the first charge and perhaps a short bit of life on the second recharge. Then the batteries started to ooze.

I decided that costco batteries were pretty cheap and worried that the dang things would explode or catch fire or something equally bad.

 

[greg]

Al's working on recharging the used ones to get more out of them.

So youse guys are using electricity. I've always used wine.

 

[TromboneAl]

Do the recharged alkaline have a similar shelf life to new ones or do they lose charge over a relatively short time like the NiMH?

Based on the first 2.5 months, it looks like they have a similar shelf life (see attachment that shows changes in voltage for some charged AA batteries over time).

But, I also had some leakage, so I'm not sure I recommend this charger.

 

[TromboneAl]

The owner of the company just called me. He says that alkaline batteries simply leak now and then, and that it's not caused by the charger.

Maybe, maybe not.

 

[Nords]

The owner of the company just called me. He says that alkaline batteries simply leak now and then, and that it's not caused by the charger.

I think anytime a bunch of electrons are jammed through something, its substance will experience heating effects-- including swelling and maybe even leaking.

Now if you run the charger in the freezer... hmmm...

 

[ERD50]

Seems like $40 may be a steep price for the potential payback.

Technically, alkaline are not really 're-charged', the chemical process is not reversible as in true re-chargeable batteries. So the 'XTender' name is actually fairly accurate.

I've done some of this, seems like over time one of those leakers will destroy something (the charger most likely) and you just are not ahead of the game.

Someone asked about electricity usage - miniscule. Even at 2 watts max (it will be much less on average) That would take 500 hours to get to 1KWHour - about 10 cents for me.

Even at 16 hours per battery, that would be 30 cycles of batteries 'extended' for 10 cents worth of electricity. That 2 watts is probably for four batteries, so 4 batteries times 30 cycles is 120 batteries 'extended' for 10 cents of electricity.

Wow, batteries sure are an expensive way to buy electricity!

-ERD50

 

[TromboneAl]

Technically, alkaline are not really 're-charged', the chemical process is not reversible as in true re-chargeable batteries. So the 'XTender' name is actually fairly accurate.

So, what is happening, electrochemically, that changes the voltage from, for example, 1.094 to 1.480?

In the manual, it says the best use of the charger is to continually "top up" the batteries. That is, use a new battery just a little, then top it up with the xTender.

 

[TromboneAl]

P.S. The batteries do not get at all warm during charging.

 

[ERD50]

So, what is happening, electrochemically, that changes the voltage from, for example, 1.094 to 1.480?

In the manual, it says the best use of the charger is to continually "top up" the batteries. That is, use a new battery just a little, then top it up with the xTender.

Well, this is more in the field of chemistry than electronics, but I'll give it a shot:

Alkaline batteries are 'primary cells', the electro-chemical reaction is not reversible, like it is in a lead-acid for example.

I think what happens is, as an alkaline cell is used, chemical layers build up and interfere with any more current being produced. So the power is still in there, it just can't get out. Running some reverse current through it removes that chemical layer, and allows more current to be released. Until the layer builds up again. So you are not really adding any energy back in, you are just helping to get the original energy out.

I think that is why they recc frequent 'Xtending' - the layer is easier to remove if it is still a thin layer.

Maybe someone with a better understanding of chemistry can say if that is on the right track, but I think that is the basic mechanism.

-ERD50

 

[TromboneAl]

Interesting. That's clear to me, thanks.

 

[TromboneAl]

I've now had about seven more batteries leak.

So, this product is NOT RECOMMENDED.

 

[ERD50]

I've now had about seven more batteries leak.

So, this product is NOT RECOMMENDED.

T-Al, there was a line of Alkaline batteries that were designed to be re-energized. I'm pretty sure they took them off the market, though.

I don't know if they had leak problems, or just not enough consumer interest. It's kind of a hard sell, each re-energize gives a bit less power out each time, but it could still be a good thing to get a bit more life out of each.

I had one, and IIRC, the charger got ruined from leaks from the regular alkaline I put in there. By then, they were off the market already.

-ERD50

 

[TromboneAl]

I just bought some Hybrio batteries -- same idea as the Eneloops, but head-to-head tests give a slight edge to the Hybrios.

 

[REWahoo]

I've now had about seven more batteries leak.

So, this product is NOT RECOMMENDED.

My BIL is a retired engineer who spent his career working for the company with the pink bunny. He says attempting to recharge alkaline batteries is a bad idea, as you have confirmed.

But heck, I enjoyed hearing about your experiment. Yep, got a real charge out of it.

 

[mb]

Ray-o-vac produced a line of rechargeable alkaline cells. The cycle life wasn't very good. I think they would lose about 50% of the original capacity in the first couple of cycles.

RE-Wahoo is correct, I do not recommend recharging alkaline cells. You might save a bit of money. But I just don't think it is worth it.

Alkaline cells have a zinc negative electrode and manganese postive electrode. Both electrodes have cycling problems.

The zinc electrode problems include

- During charge the zinc tends to replate as zinc metal in different locations from where it was discharged. This makes it harder to discharge on the next cycle.
- It can grow dendrites to the positive electrode during charge and that short circuits the cell.
- Part of the charge current can go to produce hydrogen gas rather than to recharge the electrode. This may be one cause of leakage.

Don't know as as much about the manganese electrode but IRRC there are two discharge products MnO2 (the favored product) and Mn3O4. The Mn3O4 is difficult to recharge and forms non-conductive "barriers" that may also inhibit recharge of the MnO2.

By the way electric vehicles with re-chargeable zinc electrode batteries were supposed to be one of the technologies that would "solve the energy crisis" in the 1970s but the cycle life issues were never satisfactorily resolved and the energy crisis went into hibernation in the 80s and 90s. Since then nickel metal hydride and lithium-ion batteries have been developed and they are the favored technologies.

MB (who once did research on the Zn electrode)