Testing 36v DeWalt packs

Yeah, I am probably going to go to dewalt. I am just trying to get as much info as possible before leaving my feedback.
 
I heard back from the battery guy. He told me that he got one bad batch and they went out without being checked. The new 1 I ordered is fine so that should be good. He will pay to have us ship back the bad batts so he can get them back to his supplier. He is checking to make sure he has 2 packs of the new ones so he can ship them out to us asap. He will let me know tomorrow morning. If he can't get them he will refund the money. He was very apologetic and wants to make it right.
That is what I was hoping to hear from the guy. As far as I'm concerned at this point, if he doesn't have the packs, I would rather keep the packs and take them into the dewalt service center then get a refund on my money. As far as I'm concerned, with this response, if I keep them and take them into the service center then I will leave positive feedback from him because of his response to the situation. Bad situation can always happen, as far as I'm concerned it is how companies deal with it that counts to me.
 
Yeah! I found most folks on Ebay are just folks tryin' to make a livin and doin the best that they can! Thats a song,isnt it!???????
otherDoc
 
Yeah, he did get them through someone else. But good news. he just sent me another set of 4 batteries and all 4 of them charge up. I also got that 5th one that I ordered, which also charges up. However, there is a difference of total voltage between the packs after charging. The highest one is over 37v and the lowest one is a little over 35v.
 
That won't last. Those Dewalt BMS boards are all crap. DeWalt's decision to series string 10 cells together in single file to get 33V was probably not a good one, IMO.

One battery will freak out the BMS, and the puppy will refuse to charge. The only good way to put together A123 batteries is to parallel cells first, and then series these banks to the desired voltage.
 
What won't last? The difference of 2v between the best and worst packs?
 
I understand that the dewalt bms is crap-- not because it breaks easily but because it's a bit too finely tuned. It does not take much of a difference of voltage between two cells before the bms declares the WHOLE pack to be bad and refuses to charge.
 
I would like to build a 72V pack out of the a123 cells for a high power motorcycle conversion.

What is the max current in allowed on the cells? IE: if I used a regen controller that doesn't spike too high, would I kill the cells, or could I risk it?

What about a123 chargers? I don't want to use the stock 36V dewalt packs as they are too limited. I can get the individual a123 cells and build my own pack, but I need a bulletproof charger for them and I am kinda confused as to what is available and being used. Most of what I have found is for electric model airplanes, which are much smaller packs than I am anticipating.

Money is not really an issue. I just want something that is bulletproof and reliable for charging a 72V pack of a123 cells at a fast(ish) rate. Ideally, I'd like to charge in under an hour. Two hours at the absolute most. I know the dewalt tool packs are one hour (at most) fast chargers and I know that the cells can be recharged in as little as 5 minutes, so an hour seems like a reasonable time frame for recharging.

Also, I have another project for these cells at 24-48 volts. Ideally, I would like a charger that can do anything from 24V-72V so that I can have one charger for several rides.

Any insights or infos are appreciated
 
if the dewalt packs are 36V each, and if the packs recharge in an hour on the stock tool pack charger, can't you use two chargers and charge a 72V pack in an hour (2x36V packs in series)? Double the pack capacity by wiring a second series pair in parallel with the first and use four chargers to bring all four tool packs up in under an hour off of a single 15A outlet.

I read this report at another forum:
I finally got around to nearly finishing my Dewalt multi-pack and was able to test the concept of using Multiple Chargers...
I was able to use two Dewalt Chargers in Parallel to simultaneously charge 6 "paralleled" Dewalt Battery Packs. Charging proceeded normally from a slightly discharged state - one light on and one light flashing in each, to two lights on and one light flashing, to a full charge with all lights on. No warning flashing even after the balancing cycle overnight! These chargers have no idea that they are sharing the battery load from 6 packs
My configuration: Two Fully Intact 36V Dewalt Battery packs (with BMS modules in place) with main power and the 9 BMS lines routed externally and wired in parallel to 4 other 36V Dewalt Batteries (without BMS modules). The intact Battery packs, used to plug into the chargers, were located on opposite ends of the parallel string.
Itan - This leads me to believe that there is a good chance that you could use 5 Dewalt chargers to charge 5 Dewalt packs wired in parallel and charge them all in 1 hour.
I myself am happy with being able to charge 6 packs in 3 hours - it only cost me about $60 for these two chargers on eBay. Others have pointed out that the Dewalt chargers don't do such a great job of balancing, but I am hoping that the multiple parallel packs will compensate by self-balancing. How well this will work in practice is still TBD...
Click to expand...

Obviously the balancing aspect is a separate issue, but it at least appears possible....
 
You are correct to some degree... I assumed you meant significant high-power for a motorcycle. THe least I can imagine being anywhere near your goals (80mph, etc.) would be 20p. Being that the DeWalt charger can draw 2 amps- that's 40 amps there?

Do more research. Go check out the builds on EV Album. I say this because there are more "high-power cycles and such there.
 
SuperSumoYakuza, if you plan to use the Dewalt charger & BMS to charge your rig, keep the wires from your BMS to each cell short and relatively equal. I've wasted hours on end trying to resolve the stupid blinky lights.

If money is no object then I would get couple Mastech 5020 to charge your system. My friend's custom motorcycle that we're building is a 2.5 kWh system which utilize ~30 Dewalt packs which can be charge in less than one hour from two of these power supply.

BTW: Our estimate is somewhere around 15-20 miles range with his driving habit.
 
Fantastic tip! That looks like what I need in a nutshell. Thanks! I'll use a dual Mastech 5020 setup at home for fast recharging.. Looks like the perfect tool for the job. Price is up there for sure, but with gas going crazy, expenses like this are easy to justify.

Thanks again!
 
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