Colecoman1982’s Recent Comments

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  Follow-up

  Thanks for the response. If you get around to hooking an amp meter up please post the results.

  I have some follow-up info.  After I posted my message I came across another forum where someone pointed out that if you take DeWalts hammerdrill spec of 750Watts of output power at the bit and assume a conservative 5% loss from the motor and the gearbox you come up with an amperage rating of ~23amps coming from the battery.  So, it looks like the packs are, at least, capable of producing 10C. Now, whether that is continuous or burst is another story.

  Also, if you read the DeWalt hammerdrill manual posted on their support site they specifically mention that the trigger is a variable speed control.  This, along with the parts diagram, on the same site, that shows the trigger module wired to the battery, lends more credence to the idea that there is some sort of motor controller built into the battery pack.

  As for the possibility of damaging the packs by running them in parallel; I can only say that, while I seem to remember seeing a site where someone tried to run them in serial and had a pack stop working, I see no reason why they would suffer from a parallel configuration (with the possible exception of the battery balance issue you mentioned).  I don't think you would have any more voltage or current running through each individual battery pack compared to running them alone.  Then again, I can't claim to be much more than an interested tinkerer as my background is in software development so please don't use me as an authority on electronics.

  If you're interested in hot rod electric cars, I can recommend this site:

  http://www.poormansev.com/index.html

  I found something about the way the guy managed to piece together a pretty fast electric drag car on a, relatively, tiny budget impressive and inspiring.  I especially like the way he pieced together the motor controller from $85 in part (though it’s a little crude for my tastes).

  -Colecoman1982
  On A home-built electric bike is working like a champ posted 3 years, 2 months ago 35 Responses

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  Current draw and other DeWalt pack stuff

  Hi,

  I stumbled across your posts while roaming the net looking for info on the DeWalt 36V packs.  They seem to be attracting a lot of attention from various groups such as RC vehicle groups, Electric Car groups; and, of course, electric bike groups.  My personal interests lie in electric bikes and, potentially, an electric car conversion.

  You seem to be one of the only people working on using the DeWalt packs without gutting them.  I was hoping I could pick your brain about the limitations of the, unmodified, DeWalt packs.

  According to a123, the cells inside the pack are rated to provide amperages in he range of 30C continuous and up to 100C in pulses (30 x 2.2Ah and 100 x 2.2Ah respectively).  However, inside the packs DeWalt has included a PCB that most people working on them assume to be a battery management system and, possibly, a motor controller.  This is supported by the exploded parts diagram on the DeWalt support site that shows what looks like a potentiometer attached to the tool trigger of the hammerdrill with it's wires going to the extra input on the battery.

  What I'm wondering is whether DeWalt has included amp limits on the PCB that limit the pack's output below the a123 limits.  Can you tell me what the highest amp output you've pushed the pack to is?  Also, have you ever tried messing with the extra terminal on the battery pack?

  My end goal, assuming DeWalt hasn't limited the amp output to much, would be to use the built in electronics to eliminate expensive/specialized motor controllers and battery management systems in electric bikes/cars.

  Thanks for any help you can provide.

  -Colecoman1982
  On A home-built electric bike is working like a champ posted 3 years, 2 months ago 35 Responses