dewalt batteries in firestorm drills.

[ant]

disclaimer: i checked out the google archives. there are a few threads that address this. everyone seems to think it is OK. that said..

a friend sold me two dewalt 18v batteries which are almost identical to my firestorm 18v batteries. the only difference is a plastic tab which prevents proper insertion, but i can take care of that. i picked up my firestorm from the service place today after a recall repair, and asked the fellow at the counter if a dewalt battery was ok in the FS drill. he said that because the dewalt battery kicks out more current it could damage the FS drill.

before i left my drill for repairs, i had used the dewalt batteries a couple times and the motor had been sparking up a storm. i dont know whether this was some other problem, or a dewalt battery incompatibility problem.

any thoughts?

anthony

[Leon]

i picked

That guy was an does not know what he is talking about.

Normal for a universal motor. It will do that with the FS battery also.

[toller]

Current equals voltage divided by resistance. Since resistance is the same and they are both 18v, then the current is the same.

Since they fit, and the drill runs, they are the same.

[Paul Kierstead]

Well, I dunno about the dewalt battery situation, but your answer is overly simplistic and not accurate; batteries have different internal resistances/maximum current capabilities so it is quite possible that two batteries of the same voltage will have vastly different current outputs in some situations, particularly when driving a heavy load. It is because of this -- for example -- that some old photographic flashes can be damaged by some of the new rechargables.

Now I will admit that most likely it will work out fine, just wanted to point out that your logic can backfire.

PK

[Mike Marlow]

Wrong. Current is only constant at a constant load. Hog the drill down and you'll draw more current. It's possible that the DeWalt batteries supply enough more current than the FS batteries to damage the motor if you really load it down. Don't know for sure, since I don't know what the difference between the batteries is.

[toller]

You are suggesting the FS batteries are really lousy and can't supply enough current at low resistances. The drill was designed with that in mind, so the higher capacity DW batteries will damage it. Gosh, I hope you are not serious.

[Leon]

Um the problem with that is that if you bog the drill down with a weak battery you will stand the chance of burning up the motor. If you have enough power in a stronger battery the drill may not bog down at all. Sorta like the advantage of 220 volt over 110 bolt. Less voltage drop and the motor runs cooler when strained.

[Mike Marlow]

I'm saying that a battery designed to supply a higher mAH rating than another is not the same battery despite the fact that both provide the same output voltage. Read my last sentence before you jump - I clearly stated that I don't know what the rated difference between the batteries is.

[Edwin Pawlowski]

Why is that? I've seen where some independent rebuilders (such as Primecell) offer higher capacity batteries for replacement of factory packs. Given the voltage is the same, what does a higher output do?

If you plug a corded drill into a 110 outlet, it works the same on a 15a or a 20a circuit.

[toller]

Uh, maybe it runs longer without needing to be recharged? Or, in some circumstances it might be designed to support higher amp outputs. The classic example is a battery made for starting a car and a battery made for a trolling motor. They might be identical voltages and amphours, but have completely different output capacities.

OTOH, since the DW battery and the the FS batteries are both made to power pretty similar drills, it is absurd to think that a DW battery could fit a FS drill, yet damage it somehow.

Not if it is an 18a drill it doesn't.

[Edwin Pawlowski]

That's what I thought but did not want "ass u me" anything.

[Mike Marlow]

No, but if you plug a drill rated for 15A into a circuit with a 20A breaker and bog it down it will draw more than it's rated current. Drills don't typically have thermal protection built in.

[Mike Marlow]

Hope you're not still referring to my post.

[Leon]

I can assure you that if you plug a 15 amp drill into a 15 amp circuit and bog it down it too will burn up. The rated circuit is not to protect the tool.

[ant]

well, i wasnt clear enough. yes, you can see my drill sparking a bit in normal operation if you peek through the grill, but before i brough it in to be repaired it was sparking and *smoking*. enough to make the whole room smell. i've gotten good use out of this drill, and wanted it repaired. i went to the dewalt service center, ready to pay up, and they told me it was under recall warranty and replaced both the recall-defective switch, *and* the motor and pinion assembly, which i assume was becuase it was damaged and/or charred;)

they did not do the work themselves, so i couldnt ask what the motor was replaced for, but im pretty sure it has nothing to do with the recall.

thank you for all the posts, youve helped me understand the issues. i think that we have no definitive answer yet. as a car battery analogy, i guess that the dewalt battery has not only a higher Ah rating, but also a higher 'cranking' amp rating, and that under high load conditions this could be too much for hte motor. when the motor went smoky on me i was driving 3" drywall screws into hardwood with undersized pilots, so this might come as a surprise to no one.

thanks for your advice, anthony

[Lawrence Wasserman]

I don't think the DW batteries would cause any problems with the B&D drill, but, simply applying Ohms law to the load in a battery powered circuit is a little bit of an over simplification. It's quite possible, and actually likely, that the higher-rated DeWalt 18V batteries will allow the drill to draw more current, (and produce more heat & sparks) than the stock B&D batteries.

[ant]

thanks for the advice, all. i called b&d and they warned that the dewalt batteries can supply more current, and there is a chance that it will burn the motor up. given what i learned in this thread, and my past experience, id say that is exactly what i did with my drill. good thing the 40 dollar repair was covered becuase the drill was in for a recall.

that said, i guess ill stick with my FS batteries. if anyone wants to buy a couple used 18v dewalt batteries (old post style) let me know.

anthony

[Leon]

thanks for the advice, all. i called b&d and they warned that the

Um, B&D in in business to sell and make money. How much money do you think the B&D division will make if you buy DeWalt batteries. That said, I know that DeWalt offers higher amp rate batteries in the same voltages. Funny the highter amp replacement batteries have no ill effect on the older drills.

[Edwin Pawlowski]

I don't understand that. 18V is still 18V.

[ant]

well, given the profit motive i asked here first to get a little edjucashun. but given all i know now i think they're telling it straight. besides, i cant imagine the bd division is really in heated competition with the dewalt folks.

dewalt drills might have better components ('might?' im sure they do) that can handle a battery upgrade. the new batteries are longer life (more Ah) or as you suggest- more current per unit time? i know that there are long life batteries out for a variety of cordless tools, but that doesnt necessarily mean their batteries will put out higher currents, and therefore wouldnt necessarily be burning motors like my own out.