Electric Bikes - dewalt 36v lithium

has anyone used/ researched the dc9360 36v Nano-Phosphate Lithium-ion batteries. i couldn't find out how many amp hours they pump out and am having trouble figuring out how many to use. 4 in series? to replace my 3 12v 10ah sla's?
what i know so far
Features:
* DeWalt exclusive Nano-Phosphate Lithium-ion cells provide high power for corded performance
* Deliver 2-3x more run time vs 18v batteries
* Offer long battery life & durability (2000 charges)
* 1.09kg same as 18v Dewalt Battery
* No memory and virtually no self discharge
of course they refer to power tool usage tho......

2.3ah each

If you google on dewalt 36 volt lithium ion you will get bazillion hits...they are hotter than Paris Hilton

You'll need 10qty cells to acheive 36V @ 2.3Ah with the A123 System/Dewalt batteries. But, the good news is that based on my use of the same cells - in the real world they deliver about as much range as 4Ah SLA. Bad news is that when they're empty they're EMPTY and you should never discharge those individual cells below 2.5V. Spec sheet says 2Vmin. per cell but the temperature really shoots-up so quickly that I shut my 36V pack down when it reaches 25-28V. Also, cell balance can be a mess to keep up with so you must either design your own charger and BMS circuit or use the Dewalt charger. Of course, you'll have to bypass the internal BMS for discharge only since the Dewalt tools operate through that circuit.

You'll need 10qty cells to acheive 36V @ 2.3Ah with the A123 System/Dewalt batteries. But, the good news is that based on my use of the same cells - in the real world they deliver about as much range as 4Ah SLA. Bad news is that when they're empty they're EMPTY and you should never discharge those individual cells below 2.5V. Spec sheet says 2Vmin. per cell but the temperature really shoots-up so quickly that I shut my 36V pack down when it reaches 25-28V. Also, cell balance can be a mess to keep up with so you must either design your own charger and BMS circuit or use the Dewalt charger. Of course, you'll have to bypass the internal BMS for discharge only since the Dewalt tools operate through that circuit.

The A123s seem like really good batteries, but in the end once you have to extract the batteries from the plastic battery cases and rework them into a shrink pack (or use them in those plastic containers, which would probably add up a bit in weight?), rewire them and figure out a way to properly charge and discharge them evenly and safely, isn't it a bigger time investment than simply getting yourself a premade pack, or is it not as bad as it sounds?

The A123s seem like really good batteries, but in the end once you have to extract the batteries from the plastic battery cases and rework them into a shrink pack (or use them in those plastic containers, which would probably add up a bit in weight?), rewire them and figure out a way to properly charge and discharge them evenly and safely, isn't it a bigger time investment than simply getting yourself a premade pack, or is it not as bad as it sounds?

Many Dewalt pack scavengers use the original housing but they open it up to bypass wire the BMS for discharge. Very simple to do that - just run a pair of decent guage wires directly off the cells and out of the housing. The charger will still use the internal BMS and hopefully perform all of it's balancing duties. Trouble is, you can only EASILY charge one pack at a time with this method - not a big deal if you have another charger and remember these packs charge very fast so...

You're correct about some other options though - LiPo is starting to come in many turn key packages and for eBikes most would be suitable. The cool thing about A123 cells is the current they can deliver. I'm not exagerating when I say they can handle +100A with welded tabs. Most eBikes will never get close to that much current demand but - this also translates into insane charge rates!

When you consider $100-$150 or so for Dewalt battery pack with charger - for well under $600 you can have roughly 10Ah which is comparable to 14-15AH SLA. Also, you can piece the Dewalt thing along by buying a pack or two at a time so it's not as much upfront cost to get into this chemistry. When you consider the weight savings and discharge characteristics compared to SLA - 5AH A123 will get most folks to where they need to be in a compact and lightweight package. $200-$300 or so to get started???

Of course, being a tinkering type of person is required but if you got the chops - the Dewalt hack can save some gosh...

Well, I can buy 10ah of LiFePO4 from the local store here for $525 /w charger, but it doesn't have the same delivery/charge ability. The top rating on them is just over 20amps, good for running with the stock 36/20 controller, but not for anything extreme. One thing on the housing though, it probably adds quite a bit more size since its putting bulk in between your batteries, but on the other hand i'd imagine that those casings are quite durable and good for protecting the batteries.

20 amp controller can be a bit unexciting and remember - battery cycle life and cell string balance doesn't improve when you draw near maximum rated current. This is true of practically any battery chemistry. A123 cells gotta lot of reserve and seem to be very stable/durable. Mine can sit for weeks and still feel like they just came off the charger!

The pack housing isn't too bulky IMO and offers some armor protection you don't get with shrinkwrap packs. Some folks drop 'em couple into saddlebags, run the wires out and call it day.

The good news is that by next spring I think we're gonna see more and more lightweight, high power battery packs - hopefully, prices will get better too!

If you have a few of these hooked together on a bike can they be recharged with one charger at the same time, perhaps connected in series or parallel? Given the lightness of the set of batteries and the fact that I often do not end up in the same place every night I would like to be able to build a battery charger into some part of the bike but it would only be weight/cost effective if one charger could do the trick with 4 or 5 packs and would be able to do it in 5-6 hours.

If you have a few of these hooked together on a bike can they be recharged with one charger at the same time, perhaps connected in series or parallel?

Given the lightness of the set of batteries and the fact that I often do not end up in the same place every night I would like to be able to build a battery charger into some part of the bike but it would only be weight/cost effective if one charger could do the trick with 4 or 5 packs and would be able to do it in 5-6 hours.

Probably not with the Dewalt charger. I've heard of trying to parallel charge more than one pack at a time but I don't think the balancing circuit functions properly if you do.

Perfect example of why there are so many different REASONS for various eBike designs! 'Seems like you would be better off with an onboard charger. In contrast, I'm fine keeping a charger both at home and at work and save the weight on my eBike. Different needs, different ways! eBikes have narrow application requirements. What's good for one person might not make sense for others.

So, if you gotta carry chargers - they all gonna weigh about the same for similar ampere output. SLA, NiMh, LiPo - don't much matter which chemistry in regard to weight of the chargers. The Dewalt chargers are fairly lightweight so even if you had to carry more than one - it's probably better than hauling SLA around...

seems like alot of messing about to get a battery these dewalt setups and i costed it in sydney and it works out more expensive ,i am gunna stick with my old heavy lead acid simply because of the price and those lithum ones well no one here wants to take money off the public i have tried to buy some lithiums here and no one will sell them to the general public,the lead acid ones are very cheap and allways available so ill stay with them and just put up with the extra wieght.i couldnt even buy single lithium cells to make my own

seems like alot of messing about to get a battery these dewalt setups and i costed it in sydney and it works out more expensive ,i am gunna stick with my old heavy lead acid simply because of the price and those lithum ones well no one here wants to take money off the public i have tried to buy some lithiums here and no one will sell them to the general public,the lead acid ones are very cheap and allways available so ill stay with them and just put up with the extra wieght.i couldnt even buy single lithium cells to make my own

Please don't assume I think SLA is junk. It's not and in my original conversations with newer eBike riders I often suggest they plan to build using SLA and then work into more exotic chemistry if it makes sense for an application. In many cases, SLA is just fine, long-term tested, cost effective and so simple to work with it's hardly worth messing with anything else.

However, if you need more range, less weight and have the money/skill to play lab, high-power lithium is an exciting battery technology. I can see no reason why you can't buy developer kits directly from A123 Systems? Maybe they don't sell outside the USA? Where in the free world can you NOT buy Dewalt products?

Not arguing - just pointing out that some folks need/prefer other ways of doing things. Older, tried and true methods are often the best but I like to pioneer a bit and that's what drives my messing with such things.

all the best...

Please don't assume I think SLA is junk. It's not and in my original conversations with newer eBike riders I often suggest they plan to build using SLA and then work into more exotic chemistry if it makes sense for an application. In many cases, SLA is just fine, long-term tested, cost effective and so simple to work with it's hardly worth messing with anything else.

However, if you need more range, less weight and have the money/skill to play lab, high-power lithium is an exciting battery technology. I can see no reason why you can't buy developer kits directly from A123 Systems? Maybe they don't sell outside the USA? Where in the free world can you NOT buy Dewalt products?

Not arguing - just pointing out that some folks need/prefer other ways of doing things. Older, tried and true methods are often the best but I like to pioneer a bit and that's what drives my messing with such things.

all the best...

Personally, I see little reason to purchase SLA aside from the low entry cost, but thats just me. You can pick up a NiMH pack for about twice the cost, but it'll last three times as long (or more), making NiMH more economically practical than SLA, as well as more convenient from a discharge characteristic/weight standpoint. Still, the introductory cost can't be beat.

Personally, I see little reason to purchase SLA aside from the low entry cost, but thats just me. You can pick up a NiMH pack for about twice the cost, but it'll last three times as long (or more), making NiMH more economically practical than SLA, as well as more convenient from a discharge characteristic/weight standpoint. Still, the introductory cost can't be beat.

And for me - NiMh is not my favorite. I got 2qty F cell packs 24V x 13AH. They don't handle high current +40A very well, sit for a couple days and the charge state really suffers. Unless they're excersized daily I need more AH than SLA to go the same distances. And, cell balance is much worse than my A123 Systems packs. By the time I carry enough AH to make up for the rapid charge loss if not used regularly - I realize no actual weight savings between NiMh and SLA.

Obviously, many folks will feel differently and rightly so. Daily NiMh users will see more benefit than someone using them like I do. I do like the shelf life but they take several cycles to wake up from their slumber and then - cell balance is usually off enough that I must balance each cell charge or monitor each cell voltage until things are stable again.

SLA is so easy and affordable by comparison. A daily user could afford to own several smaller SLA's and chargers, keeping some at home and another set at work for return trips. Once again, it all depends on the individual needs of the rider and their desired use.

Pretty good counterpoint there, I must say :)

NiMH batteries often suffer from some pretty low C rates. And the chemistry is *definetly* best suited to those who use often and use the charge up.
I've got not personal need for high current, currently running a 36/20 controller and thinking about using a 36v pack and/or a smaller motor on the next bike.

Currently thinking about integrating solar into the mix, as mentioned before more so for portable device charging capability which is nice on the tours, but i've been thinking about using SLA on the upcoming Xtracycle design, I won't end up feeling shanked if someone nabs $70 worth of batteries, and I don't think there are many thieves who would consider them a prime steal. SLA would also be able to take advantage of the solar, permitting that I could leave it somewhere theft of the panel wouldn't be a concern.

yes lead acid still have a good side and being so easy and cheap to buy is a big bonus and they are cheap ebough to buy a few spares for more range the down side is the wieght ofcourse but not a big issue if you dont have to pedal,i see other types of batteries as too complicated and far too expensive you may as well go and buy a motor bike for the same price

[...]Of course, you'll have to bypass the internal BMS for discharge only since the Dewalt tools operate through that circuit.

If you search for these on Power-Assist and probably all over the web using google, you'll find it's quite easy to take advantage of the built-in BMS. If you don't use it you're not using a Dewalt pack but rather a bunch of cells that used to be one.

If you search for these on Power-Assist and probably all over the web using google, you'll find it's quite easy to take advantage of the built-in BMS. If you don't use it you're not using a Dewalt pack but rather a bunch of cells that used to be one.

Why not post the links instead of jawing your mouth? You gotta problem with me Jean? Take it to PM...

WTF are you on about?

You said the BMS needs to be bypassed and I knew this wasn't true so I pointed it out, along with a hint to where I'd read about it in case anyone wanted to look it up. I don't see how this leads to you acting all butthurt about it. But since you've chosen to take it that way...


I don't care about the intricate details of these batteries since I got lead and by the time I go to lithium the scene's almost certainly going to have evolved. This why I didn't have exact links to stuff, while having read about it allowed me to give an indication where I'd read about it, in case anyone wanted to find that info.

I'll also point out this dead giveaway pengyou mentioned earlier in this thread:

If you google on dewalt 36 volt lithium ion you will get bazillion hits...they are hotter than Paris Hilton

So then, I hit google and came up with this in ~5-10m:



Two threads with details about using an unadultered pack, complete with pics, pdf's, schematics, etc:
http://endless-sphere.com/forums/viewtopic.php?t=2339
http://endless-sphere.com/forums/viewtopic.php?t=2050

A post suggesting different resistor network values then described above:
http://tech.groups.yahoo.com/group/power-assist/message/67705

A follow up to the above, more specific on how to use it:
http://tech.groups.yahoo.com/group/power-assist/message/67678

A vid showing a DeWalt pack cutting off on low V:
http://www.youtube.com/watch?v=vituFUmEnU8

What to do with a pack that blewfuse off the unswitched tab:
http://endless-sphere.com/forums/viewtopic.php?t=1427


More wisdom regarding the use of the BMS:
http://tech.groups.yahoo.com/group/power-assist/message/66473

"The A123 cells are great, but that is only half of the solution.
DeWalt spent millions of dollars developing a BMS and charging system
that keeps the cells safe and insures that they last a long time. It
seems crazy to me to tear open a DeWalt pack and throw away half of
what you need for your bicycle power source."


I'll add that these packs come with an outstanding warranty, and modifying them (such as bypassing the BMS) ruins it.



*****ing at people to get them to feed you delicious copypasta is so much more rewarding then bothering to check **** up yourself, isn't it?

http://i181.photobucket.com/albums/x25/coutujean/086c122a.jpg

and then theres this batt pack.... http://www.cyclone-tw.com/lithium.htm

Sheriff Jean - I said BMS bypassed for DISCHARGE - did you get that? Of course maybe they use BMS now - I wasn't trying to be Google correct. Just offering what I know by hands-on experience but I'm done with this forum - thanks to you. Bag on me all you want but you ain't gonna like it if/when we ever meet in person.

Sheriff Jean - I said BMS bypassed for DISCHARGE - did you get that? Of course maybe they use BMS now - I wasn't trying to be Google correct. Just offering what I know by hands-on experience but I'm done with this forum - thanks to you. Bag on me all you want but you ain't gonna like it if/when we ever meet in person.

Sherrif JeanCoutu, great answers. Thank you for your maturity and informative information. I was really enjoying BroadwayJoe's posts, until he got all butthurt and ran away with his tail between his legs. He REALLY has something against BMS, huh? :lol: