Battery drill hack

[seanpk]

I'm fed up with having to replace the whole drill every time the batteries expire and the format is obsolete.

Any reason why I couldn't use standard re-chargeables hacked into the battery case and then use a standard re-charger to charge the cells? Not concerned with the fitting side, it's the electrical side of the hack I'm questioning.

I've found an 8 cell charger, I presume I can hack into the connections in that but it will just take longer to charge 12 cells rather than 8?

Current cells:
//media.diynot.com/123000_122933_44136_52702730_thumb.jpg

It's a 14.4v drill, 12 NiCd 1500mAh cells I presume nominal 1.5v,

Cheers,

 

[Sam Gangee]

14.4/12 = 1.2 volts, which is the nominal voltage of a NiCad cell. Definitely not 1.5 volts.

NiCad are out of fashion because of their "memory effect". They have generally been replaced by Lithium and NiMH Nickel metal hydride cells.

You could even use a lead-acid gel type battery, I guess.

There are two main considerations:
1. provide sufficient voltage and current for the motor.
2. provide a charger that is matched to the batteries.

In general the battery cells are charged in series because that's how they are connected in the pack. But it's not ideal. They will last longer if removed and charged individually - but that's not practical.

 

[big-all]

look up recell batteries
loads off places to do it for you

untill recently dewalt have made all tools and batteries compatible
indeed you can still by the tools that fit nicad/nmh and li-ion batteries i have all 3 battery sorts but you need an up to date charger to charge all the batteries

so a li-ion charger will charge all 3 a nmh charger will do nmh and nicads

ryobi are are also fully forward and backward compatable with the one plus system
http://uk.ryobitools.eu/one-plus-the-world-s-most-flexible-cordless-tool-system.htm

 

[JohnW2]

I'm fed up with having to replace the whole drill every time the batteries expire and the format is obsolete.

You're not alone - it's absolutely infurating!

Any reason why I couldn't use standard re-chargeables hacked into the battery case and then use a standard re-charger to charge the cells?

One problem is cost. 12 good quality high capacity 'standard rechargeables' could cost you a lot more than a new drill.

As has been pointed out to you, a 14.4V drill requires 12 x 1.2V rechargeables and if you're planning to charge them in series (i.e.'in situ'), rather than separately, you'll need a charger designed to do that - on the face of it, I can't see why you couldn't use/adapt the drill's existing charger.

Kind Regards, John.

 

[davelx]

I've found replacements for many older types here:

http://www.batteryonline.org.uk/

 

[theprinceofdarkness]

Batteries in electric drill tend to be 4/5 C cells or such like, same diameter, but shorter in length. best thing to do is to open up the battery and find out which cells are low in volts and just replace them. If a cell is showing no voltage at all after charging the battery, it could be that it is a NiCad and has has a finger of iron grow inside it shorting it out. A brief current pulse will blow this off (like a fuse) and the cell will spring into life. I look in the junk section in supermarkets where you can some times find unused battery packs for obsolete tools going for £1, which I then open up for spares. - You need to know how to solder.
Frank

 

[ericmark]

Using the battery is not a problem. Charging is another thing. The old NiCad had three basic ways of charging.

1) Very slow 16 hours or more often used with cheaper drills.
2) Temperature controlled some times with a start button some times the button is built into holder but idea is once the temperature reaches a set level the charger switches off and latches so it will not re-start charging even when it cools. Idea is while charging electrical energy is converted into chemical energy as soon as charged however electrical energy converts to heat so a sensor in battery opens once the heat reaches the level selected.
3) This last is a very expensive method called DeltaV and it watches for the voltage dip once fully charged. This worked OK on a NiCad Battery or a single cell what ever type but with a battery of NiMh the dip is not enough to detect when more than two cells are charged together.

The first is very voltage dependent. The others often have a range as it's the current which is carefully controlled not voltage. However after a point it will stop the control system working and could over charge the battery or under charge the battery.

I have replaced cells in Radios where the radio would cost £100's of pounds but the cost of many drills as such that even from new it can cost more for a replacement battery than a whole new drill costs.

I have had in my Radio the batteries fry the battery carrier and so I would advise one is very careful.

 

[plugwash]

There are multi-cell NiMH chargers that use -DeltaV. IIRC it works as long as you charge the cells fast enough (the slower you charge the less apparent the voltage bump is.

Still as long as you replace the cells with something reasonablly similar to the originals i'd expect the original charger to still be usable.

 

[ericmark]

There are multi-cell NiMH chargers that use -DeltaV. IIRC it works as long as you charge the cells fast enough (the slower you charge the less apparent the voltage bump is.

Still as long as you replace the cells with something reasonablly similar to the originals i'd expect the original charger to still be usable.

I would agree there are some chargers that can handle the NiMH batteries but to use a charger designed for NiCad can cause problems the main point is there will be nothing to say on the charger that it will not work with NiMH as if it's that old the manufacturer would not have expected at that time that anyone would try to use them.

There are warnings in the reverse I have seen cameras which stipulate NiCad should not be used.

There was also for a short time 1.5v rechargeable cells on the market which again can cause problems.

 

[plugwash]

Indeed, if the original cells are NiCd you need to either replace them with NiCd (which may be tricky as while some NiCd batteries are still available they seem to be getting difficult to find, RS still have quite a range though) or replace the charger.

 

[ericmark]

It seems NiCads are now banned except for forces and hospitals something to do with toxic waste.

 

[roberta1000]

I don't believe that NiCads are banned, but importing them is banned so they are slowly becoming unavailable. There are lots of NiCads still on the market though.