Reviving an old 18V Ryobi Battery Pack

Got some chuckles a couple days ago after mentioning trying to revive an older battery pack by using two 12V batteries connected in series -/+to-/+ making it 24V total. These batteries were so far gone they wouldn't charge under any circumstances, or no matter how long it was left in the charger. Neither would give any charging indications, just a green and orange(error) light. I recently picked up a couple old riding mowers and managed to get both batteries to charge, so I finally had my two 12V batteries to try this with.

I went back today looking for the website where I'd found this explained. It's at How to Fix 18V Ryobi Batteries | eHow.com

I hooked up the mower batteries, got a sleeved shirt and safety glasses, and followed the procedure to a t, connect- one thousand one- disconnect, connect-one thousand two- disconnect. Three one second 24V surges into the dead 18V non-charge-able battery. It was so eventless that after doing the second battery I even had to tap the wires together to check if they would even spark, yeppers, sparks!



Brought em in to the charger, put the first one in, green light/orange light-blink-Red charge light came on! It's already charged and gone to green now, turning the cordless like new

Soon as the charger cools a bit I'll see how the other one fares

Bear. Thank You so much for this post!!! I was just given two 18v cordless drills both batteries and both chargers, supposedly because the batteries would nottake or hold a charge. I am going to try this trick to see if I can get new life out of two older drills. One is a good model DeWalt and the other is a Ryobi knock-off.

I recently read an old post, I think it was from Easy that had a video showing how to revive old batteries with a buzzbox welder. Looked like it actually works. If the Bears/Packers game wasn't on in a few minutes I'd find the link.

Originally Posted by theelectronrecycler

Bear. Thank You so much for this post!!! I was just given two 18v cordless drills both batteries and both chargers, supposedly because the batteries would nottake or hold a charge. I am going to try this trick to see if I can get new life out of two older drills. One is a good model DeWalt and the other is a Ryobi knock-off.

Be sure and read the details on that page electron, they say it only works on particular batteries

Somebody put a post that said it only lasted about a week, not sure what happened to that, but I'm still using these batteries. I have to "bump" em again every once in awhile, but then they charge up like new again, and last for days(on easy stuff) Sure beats having to do without ; )

Still going 4 months later Great way to prolong the life of these things, if you have a couple old 12V batteries, and an 18V cordless on the wane, and you can't just run out and go buy a new set.
I'm using an old motorcycle battery which holds a good charge, and an old lawnmower battery, that doesn't hold enough amps to turn a motor, but holds enough to reset the 18V. I just leave em set up in the back for when it needs another hit. That green "charged" light sure looks better than seeing the orange(error) one

That's good info to know given the number of cordless drill batteries that I've discarded. I'd be willing to try this on a bad car battery being that principle is probably the same.

I see comments of feeling canniballistic as someone has just scrapped an old trusty tool. Today I experienced what could possibly have been the ultimate. After leaving a battery in the charger overnight, before heading out to the shed this morning, where I've been stripping TV and electronics boards( I'd even began pulling the fuses to save for possible replacement in other contraptions), I removed the charged battery and replaced it with the spent one (even thinking maybe I should let the charger cool a bit, but stuck it on there anyway). The lights came on, but not the charging ones, but sometimes it'll plop over to charge cycle after a short while.
I looked back later and there were no lights at all, and just figured welp! I guess that's about it, and headed out to use the remaining charged battery for this mornings work, and thinking now it'll be cords and corded for awhile. The battery was winding down as I wrapped up the pile around lunchtime, so I brought it in to pull the charger down to look inside.
That's when it hit me, that cannibalistic feeling, using a batteries last gasp to tear down the charger that had charged it ; )
Inside the charger were some small cobwebs(not sure where those came from, it's been on the cleanest tool shelves for years ; ) which I wiped away, but saw no burned places, and kinda figured that's it. While leaving the workroom that fuse pile came to mind. I turned around and looked at it again, pulled the fuse and sure enough, it was blown.
The fuses I'd just pulled from TVs were the same size but I replaced a 125V/4A with a 250V/2.5A. It's charging once again, but do you think that's a suitable swap ?

Originally Posted by Mechanic688

It's a little light on the fuse, you just went down a couple of sizes is all. Might just blow a little quicker.

doesn't the 125/250 factor in effect double it? I guessed the 250V/2.5A would sorta equal a 125V/5A making it actually a bit stronger than a 125V/4A

mostly hoped I wasn't plum out of the ballpark with my guess, or my "test". So far it's looking good, already charged both batteries

Originally Posted by Mechanic688

It's a little light on the fuse, you just went down a couple of sizes is all. Might just blow a little quicker.

You mighta been right there Mech. It blew the 2.5. I stepped it up to a 3.0 and it charged one overnight.
Reckon I'll be looking back through that pile of boards and gathering fuses for sure ; )