18v Drill Charging

[laika]

[EDIT: Utterly wrong premise to the question: Mis-calclated in a moment of madness based on 240v cos it's a 240v charger innit. But of course it's an 18v battery.... Please ignore]

I have a truly rubbish drill my father bought in aldi and gave me. I've always wanted a decent one. Today was spent researching the Makita range and I was just about to hit "buy" when it occurred to me to work out whether my inverter would handle the charging.

The Makita battery charger specs don't give power draw but interpolating from battery capacity and charge time the charger looks to be pulling an average of at least 1.6kW charging a 4Ah battery.

Is the deal with cordless tools generally that you need a generator or an enormous inverter to recharge the batteries?

I do actually have a generator but I'd *really* like to get rid of it in favour of solar/hydro

 

[Kelpie]

What model of charger is that?
My Makita stuff (4Ah batteries) charges on a RC18 which draws about 250w and runs quite happily on a cheap 300/600w inverter.

 

[Richard10002]

When I charge my Makita batteries I don't even think about what they are drawing via the inverter. Insignificant really.

 

[NickRobinson]

Hang on to the 18v Lidadl one too. Dump the battery pack and wire up to a flylead and croc clips. Not a crafter tool but works Ok to keep on the boat for small jobs.

 

[laika]

OK my calculations were *way* out. Thanks to Kelpie and Richard10002 for making me rethink it. Back to planning de-installation of the generator then.

 

[rogerthebodger]

I lost the charger for my 18V battery some time ago and following discussions on this fora I now charge my NiCad battery direct from 12vDC but using a 1A dc dc buck converter set to output 20Vdc with a low ohm high wattage current limiting resistor. Cannot remember the value as charger is on boat but a search may find the thread.

 

[Kelpie]

I lost the charger for my 18V battery some time ago and following discussions on this fora I now charge my NiCad battery direct from 12vDC but using a 1A dc dc buck converter set to output 20Vdc with a low ohm high wattage current limiting resistor. Cannot remember the value as charger is on boat but a search may find the thread.

At about £60 per battery I wouldn't try that on my Makita stuff! Their current battery packs have some sort of chips in them which are supposedly able to sense things like incorrect charging and also prevent the tool from discharging them too deeply. Some would say it's too much complexity, which I sort of agree with, but it hasn't caused me any issues personally (yet).

By the way, there is a 12v Makita charger designed for use in vehicles, but it costs twice what the regular one costs- you can easily buy a suitable inverter with the difference, have change left over, and of course you can use the inverter for other things too.

 

[rogerthebodger]

Mine is a cheap badge engineered job that I had the battery's replaced but a local company specializing the that and not having the correct charger I just tried it to save throwing it away.

I dont leave it on charge all the time just to get enough charge to do the job in hand. The battery life will be shorter than with the correct charger but I wont have lost anything.

 

[William_H]

Much depends on the type of batteries in the drill regarding recharging. Lithium perform much better with greater capacity than the older more common NiMH batteries. Vital you know what sort of battery is fitted. Lithium are said to be 3.7 volt cells while NiMH are 1.2 volts per cell.
Lithium are quite critical on charging especially fast charging and some types can burst into flames if it is overdone. Likewise they do not like being excessively discharged hence the electronics to control charge and discharge.
It would be foolish to just supply 18volts or more to the batteries in lieu of the mains charger if the control electronics are in the charger.
NiMH are less critical of charging and a small constant current slow charge is easily produced using one of the cheap up converters. A NiMH cell loves to be completely discharged occasionally. However when wired into a battery one cell will first go to zero volts when discharging the subsequent current tends to charge the cell in reverse causing damage.
So with NIMH batteries they have a pretty constant voltage until near discharged so as soon as a drill starts to slow down even slightly due to discharge stop using it until recharged.

For an old drill a wire connection to the ships 12v system can be really useful. good luck olewill