Makita battery runtime...

[neds]

I have got myself a decent set of Makita 18V power tools including MXT drill, Impact driver and a combi. They came with 1.3Ah Nicd batts but I upgraded with some brand new 3.0Ah NiMh bats. This is where the problem begins!

When I was using my 1.3Ah bats they seemed to have a longer runtime than these new bats I got! These NiMh bats on a full charge will drive in about 30 or so 2 1/2" screws with the impact driver and start to fade, my 1.3Ah bats used to do better than that!
Also using my MXT drill for drilling and it seems to fade after a few holes. This doesn't seem right to me. Also I know the drills are meant to get hot but how hot do yours get? mine seem to get veeery hot after a few uses.

Any ideas?

 

[gcol]

Something wrong there cockle. I've got the same drill and batteries and my 3ah batteries last ages. To get the drill hot, you'd have to give it a hard and continuous workout for quite some time. A few screws wouldn't do it.
Is your charger compatible with NiMh batteries? Don't think that would suggest why your drill is getting hot though.

 

[Hitachimad]

Sounds like a charger problem Im not familiar with the Makita stuff. Id expect some cheap chargers only cope with low capacity nicads, where as some will cope with all types any capacity.

Check that out.

 

[neds]

OK hot drill is worrying me now if yours don't get that hot?
The charger I'm using is the Makita DC1804T which charges 7.2v -18V NiCd/NiMh. This is a pukka charger which came with my 1.3Ah bats but this is the same charger they supply for the 3.0Ah bats so I hope thats not faulty. It does take about 65 minutes for a full charge which according to the makita guide about right (70 mins for 3.0Ah bats)

I'm not sure if it is the discharge rate as granted this is over like 2 days, but I wouldn't have thought the discharge rate would be that bad over a few days?

 

[gcol]

My batteries hold their charge for a good few months - I've never come to them and found them wanting - basically they're brilliant. If you have no problems with your 1.3ah batteries then I would suggest there might be something amiss with the new 3ah ones.

 

[neds]

Might be getting getting some replacement ones then, but surely its a bit of a coincidence that all 3 bats are doing the same thing? Well confusing. These don't need running in or anything do they? have I missed a trick here?

Also I have noticed on a full charge the drill will spin up to a max rpm, after a few bursts with the drill it will drop to a slower max rpm, you can hear the difference, and it will stay like that until it totally drains. So maybe I am expecting too much from these batts.

 

[gcol]

The batteries should be basically full power with little or no difference until they stop - they're not like Ni-cads where they gradually give up. It's more all or nothing with NI-Mh.
It's either a bad batch of batteries you have or a dodgy drill. The fact that it seems to work ok with your 1.3ah batteries would suggest to me that it's a fault with the 3.0ah batteries.

 

[andy2306]

Did you buy from a reputable supplier? possibility of fakes!

 

[neds]

Right I think I have narrowed it down and found the culprit!

Its the bloody Impact drill I'm using, The problem I was having before was swapping the bats from drill to drill when they ran low so immediately assumed it was the bats (They are pukka Makita bats too from screwfix). Now I have kept the same battery in one of the drills and its still going strong after a lot of abuse.

The Impact drill however on a full charge has lost half its power after driving a few screws in! I know the battery drain on an impact drill is higher than say a normal drill but not this bad surely? Have I got a dud one? Anything obvious in the drill that could be causing this unusually high battery drain?