Reviving 12V dewalt?

[bishopNlouisiana]

I was talking to a friend of mine last week about the dozen or so 12V cordless drill batteries I have in a container in my barn along with 3 12V dewalt drills, 1 dewalt 12V flashlight, and a dewalt 12V circular saw.

I stepped up to 18V several years back and didn't have the heart to dump all my 12V stuff.

The friend said I could revive the 12V batteries by touch connecting 12 volt car battery to each of the 12V drill batteries for a second three times to burn off the calcium buildup on the 12V batteries.

He said he has done this in the past and it worked. I'm thinking I'll explode the battery.

Anyone ever heard of the method?

 

[Tom from Buckeye Lake]

I've done that with ni-cad 18v Ryobi batteries. However I pulsed them off my golf cart system, 36v. They worked, but never reached over 50% usage compared to new.

I've now gone to Li-on batts.

 

[pete black]

do not know about the calcium buildup but the batteries' voltage decreases to a point that the battery charger reads it as a faulty battery. touching a hot battery terminals momentarily brings battery voltage back to a point where the battery charger will recognize it as a chargeable battery. I have done it and it worked but as stated the battery's use is limited.

 

[guido]

Hello BishopNlousiana,

Kill them deader then a door nail 100% dead, zero voltage at the terminals. Your 18 volt charger will-should charge them. Much safer way. You should charge them until warm to the touch. Sometimes the packs stop charging before they are fully charged. You can remove and reinsert a pack back in untill is warm to the touch, or stops taking a charge. You way may let all the smoke out trying your way!
Try my way first! Bet you some of the packs will come back to life......recycle the rest,

Guido.

 

[Stephen Newell]

New batteries is the only solution. I had a customer give me a 12v drill he never used so the batteries when bad. I checked into replacing the batteries and it made more economic sense to replace the whole drill. The batteries are too high. Anyway the experience I've had with replacement batteries is they are junk. I bought a couple for an 18v dewalt one time and they wouldn't hold a charge half the time as the originals.

 

[Russ from MN]

I'v done that, gotten a little more time out of a battery, but if their over 5 years old they're probably shot!

 

[jon_schram]

You are never going to bring them back to full strength, but you might get them to at least take a charge again. If you have a battery store (Batteries Plus, Interstate, etc) they can rebuild them for you for just a few dollars more than rebuilding them yourself with e-bay or Amazon batteries.

I'm going through this myself right now. I have a pile of 14 or 15 dead and/or dying 18v DeWalt batteries that the Dairy was going to throw out. I'm hoping a good number of them end up being OK once I get them on a charger. I'll probably have Batteries Plus refurbish whatever ends up not holding a charge.

 

[Geo-TH,In]

Nothing works to bring back old batteries.
It's cheaper to buy new batteries off ebay with a 3 year squaredeal warranty than it is to have batteryplus rebuild them. No warranty from batteryplus.
Been there , done that, ebay is the best way to go.

 

[Bret4207]

So, if I follow Georges advice and buy off Ebay, which is fine by me, what is the effective users difference between a 2K m amp hour and 3k m amp hour battery? Is the 3 a lot better or just a little?

 

[guido]

Hello Bret4207,

Lot better for sure. Probably double the battery useful
capacity. It's like horse power more is always better.what
most people think though, is that all those milliamps is
useful power, not!

Guido.

 

[Determined]

No experience with the method you describe.

I gutted a battery pack and hooked an old extension cord with alligator clips on the other end to it.

Not as handy as fully cordless but being able to run it off the battery in the truck or tractor where power is not available still comes in handy.

 

[TimV]

That's been my experience as well--yes, it DOES work, but no, it does NOT bring back anything resembling full battery life. It also does not work on all batteries--I assume some are just too far gone for anything to help. In general, as noted, you're better off just buying new batteries, though if you have a pile of old ones it only takes a few minutes to do and you might find a few that it helps enough to be worth putting off buying new ones for a bit.

 

[BarnyardEngineering]

milliAmp-hours is the capacity of the battery, how long it will run the tool. 3000 is 50% more than 2000%.

The people are telling you that touching a 12V power tool battery to a 12V car battery will somehow cause problems are ill-advised. They're the same nominal voltage. The 12V car battery cannot possibly overcharge the 12V tool battery to cause an "explosion."

If you're worried about excessive current flow, the wires inside the battery pack aren't heavy enough to conduct that much current, and it is not likely that you will be using 00 gauge battery cables to make the connection either.

 

[bishopNlouisiana]

I just called Batteries Plus and they wanted $60 to rebuild a 12V dewalt battery pack.

The last time I looked at Lowes the new 12V dewalt battery was $55.

I believe I'll just put a new 18V or larger Dewalt Drill with charger and two batteries on my Christmas list every two years. That should do it.