DeWalt 14v Drill Driver losing power

sammy1990 · 16 Apr 2015

Hello, i would be greatful for some advice. I purchased a DeWalt drill driver about 3 years ago, 14v. It worked perfectly fine until about 2 months ago when it gradually began losing power. Now even after a full 1 hour charge the batteries only let me drive in 5 or 6 screws until it loses most of its charge.

But even when both batteries are fully charged, the drills power seems very weak. A 6mm wood bit barely goes through wood.

Is this normal on a dewalt which is 3 years old and used lightly 3 or 4 times a week?

ntb · 16 Apr 2015

It's not abnormal with NiCad batteries which I'm going to guess they are? The long and short of it is that your batteries need to be replaced. That may prove to be as expensive as buying a new drill and if you do that, make sure you get one with Li Ion batteries.

big-all · 16 Apr 2015

i am guessing they are 1.3ah ??
batteries tend to loose 10-25% off there capacity every year dependent on quality use and storage

sammy1990 · 17 Apr 2015

Thanks for the replies lads.

Yes, its Nicad batteries, 1.3ah.

Do Li-on batteries work better over a long period of time? I dont really want to have to buy a new pack of batteries every couple of years considering im a light trade user.

Ive seen some sites saying they can refurbish old batteries for about £30, not sure if this is worth doing. Has anyone tried such a service and if so any luck?

big-all · 17 Apr 2015

in my opinion
if you take a battery as a fuel tank and the voltage as the engine
in general there is an amount off a battery you cannot use as this part overcomes all the resistance in the battery and in the motor and drive train in the drill
where you have a say 1.3ah battery this may be 20% loss so a lot off the capacity available as new at say .25ah leaving 1ah to power
i have several 2-2.6 ah dewalts so the .25ah removed from the battery would give you 1.75ah-2.3 ah power available
now the point i am making is i have 8 batteries 2-2.6ah minimum 5 -12years old giving around 40% power minimum so around the capacity off your battery in year two
so go for higher power batteries
are your reviving options new cells ??
if so go for the same chemistry as you charger [may be nicad or nicad and nmh ]and go for no more than 3ah unless you know your charger will fully charge the capacity

sammy1990 · 17 Apr 2015

Thanks Big All, thats some great info! Yes i was considering reviving the batteries. But ive seen a dewalt drill at screwfix, 18v, with a li-ion battery thats giving 4.0 Ah! That seems very high, is that a ginmick or worth getting? Its priced at £150 at screwfix!

http://m.screwfix.com/p/dewalt-dcd7...n-cordless-combi-drill-xr/1544f?filtered=true

joe-90 · 17 Apr 2015

I bought an Hitachi 18v drill plus impact driver with two 1.5 lithium batteries for £169. I love it. From Screwfix.

ntb · 17 Apr 2015

sammy1990 said:
Thanks Big All, thats some great info! Yes i was considering reviving the batteries. But ive seen a dewalt drill at screwfix, 18v, with a li-ion battery thats giving 4.0 Ah! That seems very high, is that a ginmick or worth getting? Its priced at £150 at screwfix!

http://m.screwfix.com/p/dewalt-dcd7...ss-combi-drill-xr/1544f?filtered=true[/QUOTE]
It's no gimmick - all my Makita 18v batteries are 4Ah. It's way better to get one big battery than two smaller ones, especially if you are trade. The 1.5Ah batteries have 5 cells, the 3 & 4Ah batteries have 10 cells. This means double the current capacity and twice the power as well as the extra run time.

big-all · 17 Apr 2015

i always go for the larger batteries unless the cost is disproportionate
they tend to be cheaper per extra ah as in 2ah say £50 and 4 ah £80 so less than double

a brand new 4ah battery will give you around 4 times the run time off a 1.3ah battery
you will also have far more off a sweet spot on the battery
by sweet spot i mean when you charge a battery in around an hour you get a charge rate off around 20% more than the battery rating so your 14.4 will be around 17v when fully charged for a short while before it drops down towards and then below 14.4v as it flattens

Monkeh · 17 Apr 2015

Just because it measures higher on a high impedance multimeter doesn't mean you magically get more power.

sammy1990 · 17 Apr 2015

Monkeh said:
Just because it measures higher on a high impedance multimeter doesn't mean you magically get more power.

Please explain, as I would assume the higher Amps being generated would translate into more power?

Monkeh · 17 Apr 2015

sammy1990 said:
Monkeh said:

Just because it measures higher on a high impedance multimeter doesn't mean you magically get more power.

Click to expand...

Please explain, as I would assume the higher Amps being generated would translate into more power?

Batteries show a high voltage into no load after a charge. This voltage immediately vanishes under significant load, it does not relate to stored energy.

Under unloaded conditions you'll get a drill spinning faster. As soon as you load it down it becomes irrelevant.

ntb · 17 Apr 2015

Yes, the cells are nominally 3.6V but can show 4.1V after a charge. Americans being optimists use the higher figure which is why a 10.8V drill over here is a 12V drill over there despite them being identical.

Monkeh · 17 Apr 2015

ntb said:
Yes, the cells are nominally 3.6V but can show 4.1V after a charge. Americans being optimists use the higher figure which is why a 10.8V drill over here is a 12V drill over there despite them being identical.

Something they don't get away with here.. something to do with laws about false advertising.

big-all · 17 Apr 2015

sammy1990 said:
I would assume the higher Amps being generated would translate into more power?

think off a car
voltage is the engine
amps is the fuel tank

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DeWalt 14v Drill Driver losing power

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