Panasonic 15.6V and 14.4V NiMH battery self discharge issues

[Joe Jensen]

I have a Panasonic 15.6V Drill/driver and a Pansonic 14.4V impact driver and I love them except that the batteries seem to self discharge within a few days of non use. I'm a hobbiest, and if I have them freshly charged one weekend, the next friday night, they are dead. Freshly charged, and in use, they run forever. I've tried having them in and out of the drill and impact driver and I have the same problem. Did I get bum batteries, or somehow ruin them? I live in AZ and the live in the very hot garage. Is that a factor? The self discharge happens in the winter too...joe

[Doug Shepard]

I've had that problem too with one of the 2 that came with my 15.6. The other one seems fine, but it tends to get used more consistently than te other one that may be affecting something? I'll be watching to see what everybody else thinks.

[Karl Brogger]

How old are they? I've got 8 batteries laying around the shop, the old ones behave like that, as in 4+ years old. To me thats an acceptable life span.

[Joe Jensen]

How old are they? I've got 8 batteries laying around the shop, the old ones behave like that, as in 4+ years old. To me thats an acceptable life span.

Both the 15.6V pair of batteries and the 14.4V pair behaved this way from very early on. I love the drills, but for the cost of new batteries, I can buy a new set of tools.

[Karl Brogger]

Try one of the places like "Batteries Plus" Sometimes they can replace the batteries, as in dissassemble the case and put new rechargeables in. I know it works with some DeFalt stuff.

It isn't the charger is it? Ni-MH batteries aren't supposed to have a memory.

[Joe Jensen]

Try one of the places like "Batteries Plus" Sometimes they can replace the batteries, as in dissassemble the case and put new rechargeables in. I know it works with some DeFalt stuff.

It isn't the charger is it? Ni-MH batteries aren't supposed to have a memory.

Not a memory problem. NiMH will lose 30% of their charge per week sitting on the shelf. Fully charged, they hold all of their original capacity, they just leak. These seem to lose their charge much faster. I suspect that Panasonic had issues as I bought the NiMH soon after they were launched. I think mine lose nearly 100% in a week just sitting there...joe

[Randal Stevenson]

Stupid question, but where do you store them? (in the tool, in the charger, seperate from both)

[Joe Jensen]

Stupid question, but where do you store them? (in the tool, in the charger, seperate from both)

I used to keep one in the tool, and one on the bench out of the charger. Now, any battery that has been out of the charger more than a few days won't even drive a screw. If run them through a charge cycle, they seem to have tons of capacity.

Maybe the heat in AZ killed them?

It's a pain, because every time I want to use the tool it's dead and I have to recharge. I've started leaving a battery in the charger all the time so I can use the tools at will...joe

[Rich Konopka]

I have noticed some leakage in my Panasonic 15.6 batteries. However, I have a backup always in the charger and I just witch them in and out. My Drill/batteries are 5 years old. I love the drill and would consider a new one in the future.

Cheers

[Curt Harms]

I have a lightly used P-C 14.4 volt. The batteries got to where they wouldn't hold a charge for more than a couple weeks. I sent both packs to battery builders and had them rebuilt. They can now sit a couple months and seem to hold a charge fine. These are NiCad. I wonder if more recent chemistry or manufacturing has improved on the self discharge problem? These seem better than the originals were when new.

Curt

How old are they? I've got 8 batteries laying around the shop, the old ones behave like that, as in 4+ years old. To me thats an acceptable life span.