Using DeWalt 36v Packs in high amp application...

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noahmrogers
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Using DeWalt 36v Packs in high amp application...

*I'm new to this kind of stuff, so forgive me if I sound ignorant*

I am putting together an electric vehicle using an AXI 5345/18 3000w motor.
It is designed to run off 30-40v and uses a Jeti 90 amp controller.
I am planning to use three 36v DeWalt battery packs in parallel.

Hopefully this will give me a range of at least 20miles at 75% power. (wish I could find a controller with regenerative braking!)

I am worried about blowing a fuse in the packs, overheating, or bad balancing with the DeWalt chargers. From what I understand, the packs have a 15 amp fuse in them, and at stall I could be pulling close to 90 amps. I would hard wire the batteries to the controller, but that would make using the DeWalt chargers I already purchased useless.... and then how would I balance the packs?

My main question is, what kind of modifications, if any, will be necessary to use the DeWalt packs in this (high amperage) application?

Noah

LinkOfHyrule
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Re: Using DeWalt 36v Packs in high amp application...

It's easy enough to do. Just open up the packs and stick some wires on the + and - of the pack itself (before it connects to the BMS). Make some holes in the case to feed them through and voila. You'll need some sort of LVC (I suggest using a Cycle Analyst) to keep from draining them too low, though.

You're not going to make 20 miles on only three packs, though. That's a total of only about 7Ah, so your system efficiency would have to be better than 11.55Wh/mi, which is very difficult to do. 20Wh/mi is the bottom-end of normal, with 25-30Wh/mi being typical of bikes capable of more than about 20mph.

Regen isn't really all that great. It seems to add around only 5% to range depending on how many hills or stops you have.

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colin9876
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Re: Using DeWalt 36v Packs in high amp application...

? lol! this reminds me of my younger days when I thought I could run a bike off some 30 'D' cells in series. Its all about current delivery - they just cant do it!

Why try and make a bike from small Power Drill batteries

For the same money you could get a 20ahr lifepo4 pack, or just stick with 3 x 40ahr SLA batteries - at least they work!

p.s. if its a 3000w motor then ull need even more power than the above. At 36v ull be pulling 90A minimum, much more than this while loaded

noahmrogers
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Re: Using DeWalt 36v Packs in high amp application...

So essentially I'm splicing the wires to bypass the BMS while I'm using the batteries, but I still have the BMW connected for when I'm charging?
That is more simple than I thought.

It is 15 miles round trip and I'll probably be using only 50% throttle. I'll probably be drawing less than 30 amps at any given time.

How did you calculate the system efficiency? How many batteries would it take to get me 20 miles?

Are there any 90amp controllers around with regen? I would definitely consider it because there are quite a few hills in my commute.

noahmrogers
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Re: Using DeWalt 36v Packs in high amp application...

I wish I could afford a 1000+ dollar lifepo4 pack....

And lead acids are a bit too heavy for this....

I know someone that is running this same motor in a scooter off 40v of a123s so help me understand why they won't work? http://www.youtube.com/watch?v=BQ1ZtsEdYno

LinkOfHyrule
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Re: Using DeWalt 36v Packs in high amp application...

7Ah of A123 is capable of 210A continuously and 420A burst, Colin. ;)

Yeah, you're just avoiding the BMS and adding your own connector. You still use the normal chargers and the BMS still does its job while charging.

It might barely do 15 miles if you pedal a lot.

Calculating efficiency is easy, but the problem is that it can't be done without actually putting the bike together and having a Watts Up/Cycle Analyst monitor how much power you've used to go a certain distance.

With four packs, you would be able to go 20 miles if you got about 15Wh/mi. Doable under normal conditions, but you're going to be helping out a lot, and, since I live in a totally flat area (no hills except for the occasional freeway overpass), I can't really say how much the hills are going to affect you. From what I've read, however, those who live in hilly areas use around 30%-50% more energy to go the same distance, so you might need five or six packs. Some who have uphill climbs to do may use two or three times what someone in a flat area would.

I believe Kelly sells a controller capable of regen, but, if you already have the controller, I wouldn't bother getting the Kelly. What little regen has to offer isn't worth the money. In most people's opinion, regen's primary value on a bike is a combination of reduced brake wear and novelty. :/

Oh, if you haven't already looked, each DeWalt pack will run you like $150. What IS your budget for a pack, anyway?

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colin9876
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Re: Using DeWalt 36v Packs in high amp application...

NoahmRogers - hilarious that video shows a childs 150watt scooter - which u can run from a 7ahr source
The origonal post mentioned a 3000w vehicle!

noahmrogers
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Re: Using DeWalt 36v Packs in high amp application...

I have the motor, gearing parts, souped up vehicle, 10k pot, and a dewalt charger.
I still need the analyst, controller, some wiring, and batteries.

The Kelly controller is $50 cheaper and has regen, so I'll it though it is 4lbs and huge.
Jeti- http://www.electricwingman.com/jeti/advance-90-plus.aspx
Kelly- https://www.kellycontroller.com/shop/?mod=product&product_id=161&cat_id=26,23

I'm trying to keep the cost below 1500 and I'm at 1000 with the controller and analyst. I think I'd cut myself off at 4 batteries. I'm a student and this will be used for commuting to college as I don't live on campus.

It looks like a123's are about 1 lb/amphour and SLAs are about 2.2 lbs/amphour in this application. I'm looking at about 20lbs for 6 lipos or 40lbs for 3 SLAs and about $700 or $120 respectively.

I may just go SLA for now since it's so cheap, and I can always easily upgrade later.

I was planning on using a house style 80 amp circut breaker or something along those lines for a power switch/fuse. Think that will work?

Noah

colin9876
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Re: Using DeWalt 36v Packs in high amp application...

have u already got the vehicle built?

I dont really understand why ur doing a DIY job when for $350 you can get a machine like a Razor650, or a commercial electric scooter?

noahmrogers
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Re: Using DeWalt 36v Packs in high amp application...

Because I'm not making a scooter.
Because commercial scooters are slow.
Because it is more fun to build it yourself.
Because I wanted to learn about it.
and
Because commercial scooters are slow

It's not built, but everything is drawn up in solidworks and I've done what I can without the motor.

So if I'm using 3 SLA's in series, can someone point me in the direction of where I can buy a 36v charger for them?

LinkOfHyrule
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Re: Using DeWalt 36v Packs in high amp application...

If I were you, I'd give some thought to LiFeBatt/PSI cells. They aren't capable of the discharge rates A123s are, but I think they're cheaper per Wh. If I'm thinking of the right specs, a 10Ah pack would be enough to run a 100A controller.

SLAs might be a good idea if you really want a good pack but don't have the money right now and need to tide yourself over. Assuming you can handle the weight, of course. Remember that you need to account for Peukert with SLA.

I use a 50A house breaker on one of my bikes. It was a pain to solder to because its top connector was a sort of recessed clip thing, so I'd recommend using a breaker made for this just for that reason.

If you go with SLAs, chargers can be had any place that sells scooter stuff. I got most of mine from eBay, though.

The author of this post isn't responsible for any injury, disability or dismemberment, death, financial loss, illness, addiction, hereditary disease, or any other undesirable consequence or general misfortune resulting from use of the "information" contai

colin9876
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Re: Using DeWalt 36v Packs in high amp application...

36v SLA chargers are really easy to get - $10 from ebay

Good luck with the build
Is it a car / trike?
Are u doing the welding of motor etc yourself

Im interested - ive built loads of bikes so if u need any help just ask - keep me informed

p.s. I never bother with circut breakers. Theres only so many amps a 12ahr bat can deliver anyway, and at less than 50v as long as ur careful its ok

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