NiCd or NiMH?

[Kyle Kraft]

Need some advice here!! I will be sending my 14.4v DeWalt batteries out for a rebuild, and my choices for new cells are in the title of this thread. Should I go for the NiCd cells and get another 5 years out of them or invest a bit more for the NiMH? What are the benefits and drawbacks of either? As Jim B stated earlier LiON batteries are not a consideration at this time. Thanks!!

[Matt Moore]

I don't know any reason why not to choose NiMH except for the cost. If you will be wanting to replace the DeWalt tools within or less than the time that the NiCd batteries will last then that probably is the best option.

[Randal Stevenson]

Verify your charger can/will do both BEFORE you order NIMH.

[Stan Terrell]

How do you verify that?

[glenn bradley]

How do you verify that?

The manual should state clearly if both types are supported. Manufacturers have gotten pretty careful about this after a few 'incidents'.

For example, this guy, a DW9116 would not:

< snip from online manual >

Multivolt 9.6-18-volt NiCad charger
Works with any DEWALT 9.6 to 18-volt NiCad battery

[Kyle Kraft]

Glen,
I checked the battery rebuilding outfit and they stated that as long as the battery cells had an amp/hour rating which was higher than the charger output, then the charger would be ok. In other words, if the charger puts out more amp hours than the rating of the battery, don't use it.

[Rick Christopherson]

Glen,
I checked the battery rebuilding outfit and they stated that as long as the battery cells had an amp/hour rating which was higher than the charger output, then the charger would be ok. In other words, if the charger puts out more amp hours than the rating of the battery, don't use it.

I would be a little more cautious about this. The circuitry and method for detecting a full charge may be different between the two type. however, what I do know is that the NiMH batteries need to be charged at a slower rate than the NiCd's. For example, when Festool introduced the C12 drill, they artificially slowed down the charge rate for all batteries to accommodate having the same charger for both NiCd and NiMH. The previous model charger operated in 1/2 the time on the same size NiCd's because NiMH was not an option for that drill.

[Mark Engel]

Leave well enough alone.

Replace the cells with the same type and you should have no problems. Replace the cells with a different type and you 'might' have a problem.

Why introduce a possible problem? To get a little more than 5 years? Wondering the whole time, 'Is this going to blow up in my face', or maybe something less sinister, but, you get the point.

[Eric Gustafson]

Leave well enough alone.

Replace the cells with the same type and you should have no problems. Replace the cells with a different type and you 'might' have a problem.

Why introduce a possible problem? To get a little more than 5 years? Wondering the whole time, 'Is this going to blow up in my face', or maybe something less sinister, but, you get the point.

I have to agree with Mark. Nicads are better batteries for power tools because they have a lower internal impedance. In English that means at full load more of the battery's voltage is supplied to the motor. This means more power when you need it. That is the science.

I bought NIMH batteries for my old faithful craftsman drill that should have had far more capacity than the NiCad battery Sears supplied, AND they were way less expensive. However, that internal resistance got in the way and the battery does not last as long as I expected. I still use them, but the drill is not as powerful. That is the practical.

[glenn bradley]

Glen,
I checked the battery rebuilding outfit and they stated that as long as the battery cells had an amp/hour rating which was higher than the charger output, then the charger would be ok. In other words, if the charger puts out more amp hours than the rating of the battery, don't use it.

Ahhh, excellent info. Thanks.

[daniel lane]

I would be a little more cautious about this. The circuitry and method for detecting a full charge may be different between the two type.

I agree with Rick on this one. I used to fly R/C aircraft back when NiCd was the standard and NiMH were just starting to come out. The charger electronics would vary significantly from brand to brand, and some of the chargers couldn't handle NiMH. It's not an insignificant thing, so make sure you know the answer to this before making a switch. Also on the surface, I would have to agree with Mark and say that replacing the batteries with the same type that was in there is the best approach, unless you specifically need the benefit that comes with NiMH.



daniel

[Kyle Kraft]

Thanks for all the helpful advice. I think I'll go with the slightly higher amp/hr NiCad cells and keep things more like OEM.

[Jason Abel]

Alot of the information provided above may be true and may not be based on who's NiMH batteries are being used. The NiMH I offer have about 1/3 the internal resistance that my NiCads have. They will also accept a charge rate of 6A compared to the NiCads which will take up to 3A. My NiMH batteries will function on any NiCad charger without problems with charger compatability or knowing when to turn off. There are many different grades of NiMH and the generic ones will certainly meet much of the criteria listed above. I would clarify that with the company you are looking to send them off to. Many rebuilders off Ebay and through some websites are not using fast charge/high rate output cells. Be sure to look for that as well.

Regards,
Jason
MTO Battery