Repurposing an old drill charger

[Nick1994]

I have an old Makita drill and impact set, I overheated the drill and it killed it and kind of melted the battery. Bought a new set.

If this is not safe, I won't do it. Just thought I might be able to repurpose the charger.

I opened the old charger and there's a few wires going to other prongs, and 2 that are obvious- Positive and Negative.

Can I just extend the positive and negative wires, drill a small hole in the plastic to stick the wires out of, and stick some alligator clips on there and use to charge batteries? I was thinking of using this to charge my ATV battery since it's "smart".

Once again, if the ATV battery isn't the right type to use this charger on I won't do it.

Here's some pictures I took. The last one is where someone labeled a similar battery but 18V, I'll post the link below to what that guy was talking about below too, found it on Google.

Link

 

[Gasbuggy]

Interesting idea. I can't comment on if it is safe, but I think my dad has one of these laying around too. Would be cool if it could make a useful battery tender.

 

[Kira]

The charging circuit would work if the "smarts" cooperated. By that I mean the other terminals are for overheat/overcharge protection.

A battery pack can be designed so it won't accept a charge in the absence of protection circuitry.

I'd give it a go for outdoor trials using the positive and negative terminals.

Once or twice I've smelled hot, damaged Makita batteries and their chemistry will give you a headache.

ERGO do it outside.

 

[The_Jeff]

Give it a shot. You can get similar results from an old "wall wart" transformer rated 14-18VDC with
The thing to do is monitor the battery voltage while charging, with either rigged system.

There's always the $5 HF maintainer.

 

[JetStar]

It may work as a current source if the built in charge profile lets it. I see it's intended for Ni-Cad / Ni-Mh chemistry. Your ATV battery is likely lead acid, which is probably a different charge profile. I'd have to look it up. I think I'd start by monitoring the voltage and the current to see what it does, and wouldn't leave it unattended.

 

[JMJNet]

I have that same set with same charger.

I am probably not adding to the discussion on the topic.

If you have something similar like that Makita charger, notice there is no air hole to dissipat the heat that cause melting the batteries.
What I did is drill some hole so the hot air can go out during charging and that reduce the temp by a lot.

So, whatever charger you have make sure there is air hole otherwise it won't hurt to drill them yourself.

I saw this suggestion from search online.

 

[racer12306]

Originally Posted By: JetStar
It may work as a current source if the built in charge profile lets it. I see it's intended for Ni-Cad / Ni-Mh chemistry. Your ATV battery is likely lead acid, which is probably a different charge profile. I'd have to look it up. I think I'd start by monitoring the voltage and the current to see what it does, and wouldn't leave it unattended.


This was my thinking as well. I know LiIon and NiCd/NiMH have very different profiles, but I don't know how a lead acid plays into it. Personally, I wouldn't do it. I like the idea of the project, but I wouldn't want to try it unless I was able to encase the battery and charger in a very sturdy boom box.

 

[HerrStig]

Charging a 12 volt lead acid battery with an 18 volt NiCd/NMH charger? Better disconnect the vechicle + terminal first.

 

[andyd]

hEH heh Nick I admire your DIY energy. I have a > 10$ HF tender that works fine on the two cars I use it on. One of these days I'm gonna get another. They are purpose built to float a battery. But you sure don't want an overcharged car battery

 

[NMBurb02]

Originally Posted By: HerrStig
Charging a 12 volt lead acid battery with an 18 volt NiCd/NMH charger? Better disconnect the vechicle + terminal first.

I assume the ATV battery is not meant to be charged to 18V so the charger's "smarts" will not work in your favor.

 

[Nick1994]

Originally Posted By: NMBurb02
Originally Posted By: HerrStig
Charging a 12 volt lead acid battery with an 18 volt NiCd/NMH charger? Better disconnect the vechicle + terminal first.

I assume the ATV battery is not meant to be charged to 18V so the charger's "smarts" will not work in your favor.
The charger has an output of 14.4V as you can see in the 2nd picture, the drill set was a 12V system.

 

[JHZR2]

This is precisely how battery fires start.

Without any smarts, it either will not charge, or it will overcharge, potentially to the point that the battery thermally runs away (yes, lead batteries do burn), or at least dries out or is irreversibly damaged.

14.4V is not a float voltage for lead acid unless very cold. If the dv/dt or impedance behavior doesn't match, it may never change modes... charge termination logic can be quite different.

 

[Nick1994]

Originally Posted By: JHZR2
This is precisely how battery fires start.

Without any smarts, it either will not charge, or it will overcharge, potentially to the point that the battery thermally runs away (yes, lead batteries do burn), or at least dries out or is irreversibly damaged.

14.4V is not a float voltage for lead acid unless very cold. If the dv/dt or impedance behavior doesn't match, it may never change modes... charge termination logic can be quite different.
Thanks for the help! I bought some alligator clips today and will return them, not going to risk a fire.

 

[spasm3]

You can buy a battery minder for like $24 at northern too. Safer option.