Replacing cordless screwdriver battery.

[rizky_p]

I have 7 year old Black and Decker cordless screwdriver it uses 3 NiCd batteries. Now one of the battery in the pack is dead, the problem is i dont know what type, it is only wrapped with brown paper. I only knows that it is NiCd.

The dimension is 22mm x 33mm give or take because i dont have caliper to measure exact number.

It is definately smaller than my SubC, could it be a 4/5 SubC?

here are the pictures of the battery(not sure if it helps)

Thanks.

 

[linterno]

You can find 4/5C NiCd with tabs here. I have used Tenergy NiMh batteries for a while with acceptable results.

EDITED:

Use coupon TenergyDeals to get free shipping on orders over $10

 

[rizky_p]

@linterno: too bad i lives 9000 miles away fortunately i found a local dealer who sell almost any type of batteries and it only cost $3.

I asked around, now i know it is a 4/5 Sub C, should i go for Ni-Mh for higher capacity or stick with NiCD?

 

[Lynx_Arc]

@linterno: too bad i lives 9000 miles away fortunately i found a local dealer who sell almost any type of batteries and it only cost $3.

I asked around, now i know it is a 4/5 Sub C, should i go for Ni-Mh for higher capacity or stick with NiCD?

unless you want to figure out how long to charge the nimh pack so you don't fry it over time by trickle charging it too much you may want to stick with NiCd.

 

[darkzero]

Might as well go NiMhs since they're cheap & especially if you use it alot.

Found these at the local hobby store that I'll be including with an upcoming light for sale.

 

[AlexLED]

NiMH would give you a longer drilling-time but a shorter life-time.
I would stick to NiCd since they have longer life-time and usually can provide higher currents.
And as posted above, not overcharging NiMH is not easy. If you switch to NiMH, I strongly suggest getting a intelligent charger !

And please don't mix NiCd and NiMH in the stack. You might even consider replacing all 3 NiCd because the older will probably have less capacity and might fail soon, too, especially if used together with one new battery.

 

[rizky_p]

Thanks for all the feedbacks, i tested two of the working batteries has around 600mah capacity left (@1A discharge) which is quite good considering the 7 years old of age. I cycles the dead battery few times and discharged capacity is around 500mah but soon losses its capacity faster then the other two.

The screw driver came with an dumb AC charger, yes the output is AC and being rectified by the diode inside the unit. That is why i have to remove the pack to cycle it.
I think i'll remove the diode and charge it with a hobby charger externally and buy a Ni-Mh since my shop only have the 2000mah capacity(i bet it is a NiMh, forgot to ask )

Regards
Rizki P

 

[MrAl]

Re: Agree, but

Hello there,

I had the same problem with one of my cordless shavers.
As per Silverfox's idea i used NiMH cells in it and it works
great (and i continue to do it this way using my OLDER cells
that i dont want anymore anyway). The only problem is
that the cells die after about 6 months using the charger
that came with the unit and charging 24/7. The charger
only puts out about 90ma and the cells are rated for over
2000 but still they only last about 6 months before they
become too weak to use anymore (energy dies down too fast)
so they have to be replaced again. I guess i dont mind too
much but with a better charger i would probably get at
least 2 years out of a set of cells. The charger that came with
it is built into the base unit and it is made for NiCd cells, not
NiMH, hence the quick die off time.
The problem is that chargers made for NiCd take BIG advantage
of the durability of the NiCd's as to their overcharging ability.
The NiCd can take a lot of overcharge before it dies but
the NiMH is much much more sensitive. From my tests i can
see that the NiMH is about four times more sensitive, meaning
that it dies in 1/4 the time a NiCd would die in an overcharging
situation, possibly even faster with higher charge current.

All this means that if you want to switch a device that now uses
NiCd's to NiMH's then you also have to switch the charger or
plan on buying lots more NiMH's in the near future <chuckle>.

BTW, as soon as my last set of OLD cells dies off in the shaver
i am going to either go back to NiCd's or more likely redesign
the charger to do NiMH cells instead (much nicer). The
NiMH cells really make that thing buzzzzzz when they are new.

 

[Ron Schroeder]

Re: Agree, but

Take 3 AA batteries and see if you can wiggle them around to fit the same space. If they will fit, make up a pack of 3 low self discharge Ni-MH AA batteries like Enloops to replace the dead pack.

 

[VidPro]

you will have to replace all of them, replacing only the bad one, will leave inbalances that will destroy more , unless it never gits fully discharged.

 

[rizky_p]

Re: Agree, but

Take 3 AA batteries and see if you can wiggle them around to fit the same space. If they will fit, make up a pack of 3 low self discharge Ni-MH AA batteries like Enloops to replace the dead pack.

i was thingking the same,but i have 4 14500 LiFePo4 and i managed to squeeze 4 of them(paralel) inside with some modification. After Discharging it @1A the total capacity is 1735mah which is close to the 4/5 SubC. I can always buy SubC or eneloops and replace it, but trying LiFePo4 is more interesting. Lets see how it performs. I know it has lower total under-load voltage and result in lower torque, but the good thing is i can charge it in under 30 mintues, with LiFePo4 it just sucks all the juice from the charger.

 

[Ron Schroeder]

Re: Agree, but

The reason that I didn't reccomend LiFePo4 was charge termination. The NiMH can probably handle the origional charger but the Lithium cells could be easily overcharged.

 

[rizky_p]

Re: Agree, but

The reason that I didn't reccomend LiFePo4 was charge termination. The NiMH can probably handle the origional charger but the Lithium cells could be easily overcharged.

i throw the old charger and using RC charger instead.