How to test AA batterys to see if they have a problem ?

[buckyball]

hi i use lots of trail cameras ( bushnell and Campark brand mostly) they use 8 to 12 x AA each so i use lots of rechargables eg tensai or eneloop branded ones, the other day one of my trail cams only lasted 1 day with what i thought was 8x fully charged AA batterys and got 32 x 1min long videos before it stopped recording,( i was expecting it to get about 200 1min videos in 5 or 6 days using 8x AA before they would be spent ) when home i put the 8x tensai batterys in my MAHA recharger and noticed 2 of them seemed to recharge way faster than the other 6 , so my question is how can i find out if something is wrong with batterys ? ( my MAHA branded charger show me when batterys are fully charged and i have a silverline battery tester ( cheap maybe £5 on ebay) that runs off 1x 9v battery that has a needle that moves to show if a battery has good voltage , i also own a LiitoKala lii-500 charger but dont really know much about using it ..so please help me if you can to figure out a way to know if any AA batterys are bad , i really need to weed out the bad ones as its a pain to set up cameras and leave them miles from home only to find out days later they didnt record ok !

many thanks,,ps video showing how to use and device you mention would be really helpful

 

[ChrisGarrett]

Charge them all up, measure their state of charge after an hour, clean all contacts (charger, batteries and camera,) do a 1A discharge on the chargers, charge them back and see what you see?

I'd first focus on the Eneloops, for now.

Chris

 

[buckyball]

Charge them all up, measure their state of charge after an hour, clean all contacts (charger, batteries and camera,) do a 1A discharge on the chargers, charge them back and see what you see?

I'd first focus on the Eneloops, for now.

Chris

ok thanks ill see if i can figure out how to do that, thank you

 

[Lynx_Arc]

First thing to do when the pack is no longer able to deliver enough power is to disconnect it and measure the voltage of each cell. Typically the highest voltage ones will be the healthiest but not always that if you have a lot of unhealthy cells, the lowest voltage cells will likely be the problematic as they often have lower capacity and discharge totally before the others discharge I would mark these cells and set them aside and use known good ones in place and see if the performance improves. I would consider investing in a charger that can do a refresh cycle to measure capacity. If you can get the capacity try and use cells in the same range of capacity in the same devices. If you can spot how long it takes a set of good batteries to deplete noting that time and see a set that doesn't last as long you can get an estimate of the capacity of the weaker cells and removing them from that set you should see a longer run time. As Buckyball said weaker batteries often have higher self discharge rate if it gets high enough you can measure the voltage loss over time and compare it to known good cells. Higher internal resistance in cells is also a sign of problems and higher self discharge can be associated with it also you can see these culprits taking super long to complete charge and get a lot hotter than other cells and end up with considerably lower capacity. If you have all 8 cells in a set working together when you recharge them all it should take about the same amount of time to complete so the cells that take considerably shorter time and longer time than the average can be suspect and should be noted. I use a red sharpie to mark cells that I suspect as problematic or know they are are bad. I have an charger that can test capacity and I sometimes mark the tested capacity on cells.

 

[alpg88]

How cold was "the other day"? nimh do not like cold, i noticed weak nimh cells fail much sooner in cold. how many cycles are on your pack?

 

[Timothybil]

The MINI-MBT by ZTS is the best cell tester I have found. It uses a real pulsed load to test the cell capacity and ability to deliver real power. It uses 5 LEDs to signal cell state. It's not cheap, $60 on Amazon, but to me is worth it.

 

[Dave_H]

Problem with so many NiMH cells is series is they need to be initially well-matched but even so over time differences show up, and you end up with at least one weak cell which runs down before the rest. If load continues and cell is dead it starts getting reverse-charged which is usually the end of that cell. You can't just replace with a new one as its condition does not match the others; best to replace the lot and move old good cells to another device which can use them, a kind of hand-me-down.

Many devices do not have low-voltage cutoff sensitive enough (if at all) to prevent the above.
Even "matched" cells can have some difference in capacity. I recall reading about radio (NiCd) battery packs costing a lot because the cells were "graded" i.e. capacity-tested and matched to each other; may be more effort than the average cell user wants to employ.

Make sure initially all cells per device are same brand, type, capacity, and age (don't mix new with used). Charge them all on the same charger and don't mix up with other (otherwise similar) cells from other devices.

For checking state without a fancy charger/tester, just run device until it shows first signs of lower voltage (if it does) then check each cell voltage; otherwise just run and check periodically.

Dave