Charging 12 volt portable tool batteries?

[493mike]

Hi fellas,
I have a older, good 12 volt Porter Cable drill set with 2 (rebuilt) batteries. My charger has died and I haven't been able to replace it. Can I adapt the old charger case to hook up to one of my Battery Tender Junior chargers? The OEM charger is rated 1.6 amps while the Tender is rated 1.5 amps. Any experience with a similar situation here? Thanks.
Mike

 

[CGarage]

Converting one of my 12V cordless drills to corded this week.

 

[PassnThru]

Are your 12V batteries NiCad?
Your Battery Tender is designed to charge a lead acid battery.
I'm not a battery expert but that would stop me from trying.

 

[493mike]

I hadn't thought about battery construction. Yes, this gives me pause. Thanks!
Mike

 

[mc4life27]

What type of cells are in your battery. If they use say the 18650 cell you can buy charging boards and make your own 18650 battery charger and just had either like a little flush mount plug or have a little like 3/4 of an inch pig tail sticking out of the battery pack. And just use that. Not sure what type of cells your 12volt uses. But I’m going to be making my own lithium battery pack for my Snapon screw gun and make my own charge for it.


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[TuxThePenguin]

NiCd and lead acid chargers are both pretty simple, and their nominal cell voltages do both allow for 12v (1.2v per cell for NiCd - 10 cells to 12v; 2v per cell for lead acid - 6 cells for 12v). But they probably don't charge at the exact same voltage. Also the battery tender might not be able to tell when a NiCd has reached full capacity, so it might damage it by overcharging, something that NiCd batteries were actually pretty susceptible to. If they charge at even a quarter of a volt difference, that could be the difference between damaging the battery or not (or significantly under-charging it such that it doesn't have good runtime in use).

If converting to lithium as previously suggested then I would personally add an extra "charging specific" connector to the battery pack and I would use a generic balance charger (like an imax B6) to charge.

For 12v, with lithium ion, you will be running a little bit more or a little bit less than 12v as 12 isn't divisible by 3.6 (the nominal voltage of most common types of lithium ion cell). You can do 3 in series for 10.8v nominal or 4 in series for 14.4v. I'd be willing to run most 12v tools at 14.4v, personally, but some tools might be more okay with it than others. (Could do 14.4v+ and convert/regulate it to 12v, but I wouldn't bother, personally)