I have some AA rechargeable batteries and I suspect one or two of them are weak and do not fully recharge but I'm not sure how I can test them or isolate the one or two poor ones out of many good ones. Does anyone know how to do this?
Testing Rechargeable Batteries
- Thread starter Garry G.
- Start date
Help Support vftt.org:
Quietman
Well-known member
I have a cheap $5 battery tester from Radio Shack. Works for me!
PeterM
New member
Garry-
Take your batteries into Radio Shack, see if they'll test them there. You didn't say what type - if theyre the old Ni-Cad, I'd get rid of them (properly) and move to NiMH which are alot better ( and require a different charger )
If you had a single cell flashlight you could run them way down - not quite dead - recharge and check them that way.
I'm using Sony NiMh in my cameras & GPS units - they seem fine but do tend to get pretty hot - and with all Sony's bad press on their laptop battery production being faulty I make sure my homeowners ins is paid up
good luck
Peter
Take your batteries into Radio Shack, see if they'll test them there. You didn't say what type - if theyre the old Ni-Cad, I'd get rid of them (properly) and move to NiMH which are alot better ( and require a different charger )
If you had a single cell flashlight you could run them way down - not quite dead - recharge and check them that way.
I'm using Sony NiMh in my cameras & GPS units - they seem fine but do tend to get pretty hot - and with all Sony's bad press on their laptop battery production being faulty I make sure my homeowners ins is paid up
good luck
Peter
Quietman
Well-known member
Yup, that's the tester I have. Worked fine for 5 years. I'd take the tester and the batteries to the shack. Not sure I'd buy NiMH from them though, as their prices are pricey.
If you want to invest $40, you should get one of these. I got mine at EMS a couple of years ago.
Basically, it is a charger/tester. It can give you a number representing the milliamp-hour (capacity) of the batteries under test.
I have one, and here are the pros/cons
-complex to operate, always seem to need to read the manual
+a good basic charger when not testing
I bought a package of new AA cells from a warehouse store, and tested them.
One cell had 20% less capacity. I could not believe this result. (I thought the charger/tester was inaccurate). So I moved this damaged cell to another position in the charger and repeated the test.
The results were exactly the same, so I stopped buying Panasonic branded nimh cells.
Basically, it is a charger/tester. It can give you a number representing the milliamp-hour (capacity) of the batteries under test.
I have one, and here are the pros/cons
-complex to operate, always seem to need to read the manual
+a good basic charger when not testing
I bought a package of new AA cells from a warehouse store, and tested them.
One cell had 20% less capacity. I could not believe this result. (I thought the charger/tester was inaccurate). So I moved this damaged cell to another position in the charger and repeated the test.
The results were exactly the same, so I stopped buying Panasonic branded nimh cells.
PeterM
New member
Remix-
If you bought NiMH rechargables and one was at 80% then just charge it up!
Think of it like a 1 liter container, coming with 80% water. Its capacity is still 100%. No reason there to fault Panasonic, NiMH tend to lose 1% per week if I have my facts straight. While I try to keep my gear ready to go I'll charge batteries before an important trip. And a special vacation I'll bring xtra sets of batteries and maybe lithiums too ( no rechargable but huge capacity )
Hope this helps
Peter
If you bought NiMH rechargables and one was at 80% then just charge it up!
Think of it like a 1 liter container, coming with 80% water. Its capacity is still 100%. No reason there to fault Panasonic, NiMH tend to lose 1% per week if I have my facts straight. While I try to keep my gear ready to go I'll charge batteries before an important trip. And a special vacation I'll bring xtra sets of batteries and maybe lithiums too ( no rechargable but huge capacity )
Hope this helps
Peter
DougPaul
Well-known member
The only way to test NiMH cells is to put them through a charge and discharge cycle, measuring the amp-hours delivered during the discharge.
If one or more cells are found to be deficient, then one can try to restore them and retest.
NiMH cells can have the memory effect (which gives reduced usable capacity, but can be fixed by restoring). Depends on the type of charger.
The simple voltage measuring battery testers can tell you the approximate state of charge, but not the capacity of NiMHs.
For more info, see http://www.batteryuniversity.com/index.htm.
Doug
If one or more cells are found to be deficient, then one can try to restore them and retest.
NiMH cells can have the memory effect (which gives reduced usable capacity, but can be fixed by restoring). Depends on the type of charger.
The simple voltage measuring battery testers can tell you the approximate state of charge, but not the capacity of NiMHs.
For more info, see http://www.batteryuniversity.com/index.htm.
Doug
The charger/tester I referred to put the brand new batteries through a complete charge and discharge cycle. Basically, there was one cell in the pack of 6 that had 20% less capacity than the others.
The charger/tester is not a lab quality instrument, but the results were quite repeatable with the questionable battery in different slots.
Anyhow, the OP was looking for a battery test instrument that measures capacity, and this charger/tester will give him the info he wants.
PeterM- The charger reported 1800 maH for 3 of the brand new batteries and around 1400 maH for the 4th. Thats a pretty significant mismatch and a good enough reason for me to switch brands.
The charger/tester is not a lab quality instrument, but the results were quite repeatable with the questionable battery in different slots.
Anyhow, the OP was looking for a battery test instrument that measures capacity, and this charger/tester will give him the info he wants.
PeterM- The charger reported 1800 maH for 3 of the brand new batteries and around 1400 maH for the 4th. Thats a pretty significant mismatch and a good enough reason for me to switch brands.
Last edited:
PeterM
New member
Remix-
let us know how your next brand is for consistency. This is interesting, and the weak cell in a set would pull the set down. Its good you found & reported this
Peter
let us know how your next brand is for consistency. This is interesting, and the weak cell in a set would pull the set down. Its good you found & reported this
Peter
DougPaul
Well-known member
Sounds like a reasonable consumer-quality instrument.Remix said:
One should note that the capacity is a function of the current draw. (Higher currents yield lower capacities.) Manufacturers have incentive to post the highest numbers they can get, so your measured or practical capacity may be lower.
Doug
PS. Remix: put the cell
Last edited:
Neil
Well-known member
- Joined
- Apr 26, 2004
- Messages
- 3,434
- Reaction score
- 487
I suspected a battery was at the end of its usefull life so I fully charged it and some other good ones. Then I left them out for a day and put them back in the charger. The others charged back up quickly but the suspected one took hours and hours. I'm not sure what this means in precise electrochemical terms but I removed it from the lineup.
DougPaul
Well-known member
Could be bad, but not necessarily.Neil said:
I have a cell that occasionally acts like this that I can charge and use.
These chargers typically sense when the cell is fully charged by monitoring the voltage during the charge. (It rises slowly during charging and then drops a bit when the cell is fully charged. Better chargers also montor the cell temp which rises after the cell is fully charged.) If for some reason, a cell has an abnormal charging voltage curve, the charger might not detect when to stop. (Warning--continuing to charge a fully charged cell will heat it up and possibly damage it.)
I can usually handle the flaky cell by removing it from the charger, letting it cool and then inserting back in the charger. The charger then usually shuts down after a few minutes suggesting that the cell was fully charged.
The chargers also perform a quick test on the cell before charging it. This test sometimes rejects a fully discharged, but ok cell. It usually passes the second time, I can charge it in a different charger, or it will charge after an initial trickle charge.
And even cells in bad shape can sometimes be charged using a trickle charger. These cells may exhibit a greatly reduced capacity, but it is enough for some applications.
Doug
