Emag charging problems

[athomas]

Well I left the battery in for maybe an hour and now I can't get the LED screen to display anything... when I touch the positive end of the meter to the bolt where the battery connects to the frame and the negative end to the grounding screw on the bottom of the board i get something in the neighborhood of 2.5 volts. Battery is still showing 18.

This looks like a connection issue. Have you cleaned out the screw hole where the board fastens to the frame. These holes sometimes get corroded and lose connection. Use a tap if necessary, to cut into the threads, especially if the hole is partially annodized.

[fhawkeye]

This looks like a connection issue. Have you cleaned out the screw hole where the board fastens to the frame. These holes sometimes get corroded and lose connection. Use a tap if necessary, to cut into the threads, especially if the hole is partially annodized.

Actually that's one of the first things I checked before posting because I've had that screw come loose on me once before. Neither the grounding screw or hole show corrosion when i cleaned it out i got a little residue but no luck on fixing the problem.

I ended up dropping the battery off at a shop to get the resistance tested (was only $5). They said it would take 24 hours to do so I'll let you guys know if we can rule that out when I pick it up.

[fhawkeye]

So apparently the battery failed every conceivable test they could load it with - bad cell just won't hold a charge. Which is weird because I don't believe a a full case of paint even went through the battery since I got it. But at least we know where to go from here. Thanks for helping to point me in the right direction, everyone. Much appreciated.

[athomas]

So apparently the battery failed every conceivable test they could load it with - bad cell just won't hold a charge. Which is weird because I don't believe a a full case of paint even went through the battery since I got it. But at least we know where to go from here. Thanks for helping to point me in the right direction, everyone. Much appreciated.

Probably one bad cell in the pack. You can build a completely new pack, or take yours apart and find which cell is bad and replace it with a cell of the same type. It won't make the pack as good as new, but it will provide some good life and let you use the pack at a slightly reduced capacity.

If you have any NiMh battery packs, make sure you keep them topped up. The voltage will decrease over time while in storage. Letting them leak down and sit without charge for a long period of time is one of the biggest killers of this type of battery. It causes the electrodes to oxidize which results in high internal resistance and it reduces the capability of the cells to take and hold a charge.

[Cyco-Dude]

So apparently the battery failed every conceivable test they could load it with - bad cell just won't hold a charge. Which is weird because I don't believe a a full case of paint even went through the battery since I got it. But at least we know where to go from here. Thanks for helping to point me in the right direction, everyone. Much appreciated.

age matters. you can have a brand new pack, but if the cells are 10 years old and it's just been sitting, it'll still go bad. this is why i wonder about any new packs agd or tuna have...gotta know when the cells were manufactured and when the packs were assembled.

[fhawkeye]

Probably one bad cell in the pack. You can build a completely new pack, or take yours apart and find which cell is bad and replace it with a cell of the same type. It won't make the pack as good as new, but it will provide some good life and let you use the pack at a slightly reduced capacity.

If you have any NiMh battery packs, make sure you keep them topped up. The voltage will decrease over time while in storage. Letting them leak down and sit without charge for a long period of time is one of the biggest killers of this type of battery. It causes the electrodes to oxidize which results in high internal resistance and it reduces the capability of the cells to take and hold a charge.

Ah, you know I'd probably elect to try with a fresh new battery despite I know they are pricey (and possibly old depending on when they were stocked). Is it recommended then to keep charging it up every couple weeks regardless of the total usage to prevent the oxidation? Until now I thought it was better to drain it all the way before giving it a full charge every time.

[Tunaman]

age matters. you can have a brand new pack, but if the cells are 10 years old and it's just been sitting, it'll still go bad. this is why i wonder about any new packs agd or tuna have...gotta know when the cells were manufactured and when the packs were assembled.

all the batteries/cells are brand new and being assembled every month or so. Even though they are high quality you do get a bad one once in a while. You dont have to wonder any more.

[athomas]

Ah, you know I'd probably elect to try with a fresh new battery despite I know they are pricey (and possibly old depending on when they were stocked). Is it recommended then to keep charging it up every couple weeks regardless of the total usage to prevent the oxidation? Until now I thought it was better to drain it all the way before giving it a full charge every time.

I incorrectly referenced oxidization of the electrodes. Its more of a crystalization. Oxidization is actually part of the process of chemically producing electricity in the cells.

It is recommended for normal average users to keep all batteries topped up when in storage. I mention normal average users, because the average person just puts a battery on the charger when it needs to be charged and uses it when fully charged. The exception is Lithium based cells. Lithium cells are best stored at about 40% charge if not being used for a period of time. In reality, all nickle based batteries can be stored at any charge state as well. The problem with nickle based cells, is that you run the risk of overdischarging them if they start low and leak down from there. Also, if you store a cell for long periods of time in a discharged state or let them gently leak out for long periods of time without any conditioning, and they develop a crystal structure on the plates/anodes/cathodes, then you need to prime the cells before use. That involves a couple of full charge and discharge cycles at a high rate of charge/discharge. If you let the cells go too low, they can become damaged(?) and cannot be recovered by normal means (the average fast charger). To avoid this, keep them topped up. Its just easier for the average person to manage.

When managing your battery packs, you don't need to fully discharge before charging. A pack will charge just fine from any percent of charge. A cell or pack has a finite amount of charge cycles before is will stop accepting and storing a charge. That number is based on a full charge/discharge cycle. If you only discharge half way and then do a full charge, then that only counts as a half a cycle. On a pack that has a 500 cycle life expectancy, you can get 1000 half cycle charges, or 2000 charges starting at 75% charge. However, you should do a full discharge/charge maintenance cycle every few months, just to break up any crystaline structures that form on the electrodes.