Any problem with mixing old and new batteries?

Newbie here, I have a batch of 8 AA Zinc Carbon cells that came with a RC toy transmitter. These cells lasted only a short while before tx stop functioning. I checked on DMM and found they still have 1.2v in them but unable to use on tx. Thinking that it may be wasteful to throw them away, I took one of these 1.2v cell and mixed with 7 new Duracell Alkaline batteries that were tested in the 1.6v range and tx's LED was flashing full bar. On the next time when tx was flashing low on LED, I re-tested all batteries and found Duracells at 1.4v and the Zn Carbon at 0.001v, I did not notice any problem with leakage or anything when I ran the Zn carbon batt to almost zero v, I'm wondering if what I did really save me some dollars on new cells or is it dangerous practice?

Len

I'm pretty sure I've seen the warning a number of times not to mix battery types or used with new batteries for fear of leakage. I assume it puts more of a strain on the batteries since they're not all pulling their weight.

Phredd

Yeah time after time I also hear DONT mix new and used batteries, or different brands...As far as alkalines go I have done it before myself and never had a problem, but I do not want to push my luck, and now after reading up on flashlights and batteries in general I do NOT mix old and new or different brands...

the battery might have read 1.2v , but its capacity was likly depleated.
there is that "recovery" thing, where if you were drawing off it harder than it can take it, it will droop down, yet still have some capacity.

when you put that cell with the newer alkalines , you probably got a little blip of power out of it , but you also set it up for a reverse charge, which could cause it to leak (more likely) so your kinda encouraging a mostly dead battery to leak on you.

if you "load" tested the battery, it would probably have shown that it was basically dead, even though it shows 1.2v without a load.
there are battery checkers that have NO load, and provide little info about the state of the battery, and checkers that put a load on the battery, and are better at determining its remaining capacity. without a load, the 1.2v only means it has a bit left.

its not really a "dangerous" situation, unless you figure that caustic junk leaking into your high priced toys is dangerous but you will gain nothing from it.

so, just for discussion sake, lets keep going.
now that your done with that cell, you have to put a NEW alkaline in series with a set of alkalines that are partly depeleated. so now you still have a set of batteries that will end at completly different times, now wasting them, and encouraging them to leak.

or a person could just say, dont mix batterys Age, capacity, different chemistry, and different discharge rates, because your going to encourage something to leak.

And when you move on from alkalines to using lithium batteries (whether you are using disposable cells or Lithium-Ion rechargeables) NEVER mix up cells of different type, capacity, age, brand or state of charge/discharge. If you do, there will be a high risk of an explosion.

In addition to what DM51 has stated, when using any type of rechargeable it is best to match cells of like capacity. Reason being, if you have one cell that drains faster than the other(s), it will pull the performance of all to a lower level. Not only that, you run the risk of cell voltage reversal if the device has no voltage monitoring circuitry. This is the reason for balancers in Lithium chargers and also the reason for matched cells in higher end R/C applications.

I put an energizer and a duracell in a plastic brinkmann led light. In no time flat, about three weeks. the energizer startead sweating out goo. Way faster than normal for an energizer to blow up. Till then I thought using different brands was an urban myth.

No problem mixing old and new unless you consider leakage to be a problem.

Battery Question

Here it goes...

Say you have a 6 cell flashlight (MagLite in my case); if you had 5 new batteries and one used battery somewhat to pretty depleted....would it be better to put the depleted battery first into the tube or last into the tube by the tailcap? Or would it not matter (much)? Would it just end up draining all the other batteries? Alkalines if it makes a difference.

Re: Battery Question

I am not going to try to address your question, perhaps others here will know the actually mechanics of whether it would matter. I will only comment that if this 6 cell light is going to be relied upon for any emergency or important situation I would personally toss that low cell in the trash or use it up elsewhere and replace it with a good cell. Perhaps it really makes no difference and others can comment. I only am telling you what I would do in that case. I know you didnt ask for opinions like this but I was bored. LOL:thumbsup:

Re: Battery Question

You run the risk of leakage.
Similar question answered here

Re: Battery Question

Always replace all batteries at the same time. Mixing old and new batteries or mixing types (such as alkaline with zinc carbon) could cause leakage.

Norm

Re: Battery Question

Thanks all. And thanks for pointing to this thread Norm. I guess I need to find the time to read Battery University.

Re: Battery Question

EscapeVelocity said:

Here it goes...

Say you have a 6 cell flashlight (MagLite in my case); if you had 5 new batteries and one used battery somewhat to pretty depleted....would it be better to put the depleted battery first into the tube or last into the tube by the tailcap? Or would it not matter (much)? Would it just end up draining all the other batteries? Alkalines if it makes a difference.

Click to expand...

It would not make any difference at all where the depleted cell was located in the stack. As this is a series circuit, the same current flows through each and every cell. The depleted cell will be reverse charged through the load with the voltage at the base being higher than the voltage at the top button. This will exacerbate the nasty tendancy of alkaline cells to leak. In the case of lithium ion cells, this condition can cause the depleted cell to vent with flame.

Okay to use used battery with new one

I have two Orbtronic 18650 cells that I have been alternating in a single-cell Zebralight for the past six months. I now want to buy a flashlight that takes three 18650 cells. Would it be okay to just buy two more Orbtronic 18650 cells of the same capacity and add one of my existing cells? In other words, can I use one older and two new batteries in the new light, given that they are the same brand and model? Thanks.

Re: Okay to use used battery with new one

All of your cells used in the one flashlight need to be identical, age and condition included. You answer is a definite NO.

Norm