great thanks

 

I bought a turntech a while back and mine works great. My buddy rode his R6 the other day and he a a Moty battery in his. It was slightly smaller and had a built in voltmeter that measured each cell, so of course I had to try his out. I rode all day with it and my hawk started right up everytime. He did a group buy over on he R6 forum and got his for $160 shipped. Here is the link. http://www.motydesign.com/

 

I am thinking about trying this battery, did he have the 8 cell or the 12 cell? Im thinking the 8 cell would work.

 

8 cell is plenty- it's actually been done with 4 before, but that's not really necessary unless you're racing or unnecessarily cheap!

BTW for those interested, The date on the DeWalt A123 packs that I ordered is 2007, so you're getting batteries that are a few years old. Quality batteries, but not as fresh as if you were to order from a direct source...

 

Stumplove, he had the eight cell. 12 cells is just overkill.

 

So, for our applications, (this is for Tweety or another of the electrical guys) that 12 cell pack would be made as a 4S3P pack?

 

It still could be made either way. Cells combined in 4 packs of 3 or 3 packs of 4.. Either way would work. But my guess 4 packs of 3 would be better.. I defer to Tweety's knowledge on this. (fyi a DeWalt 36V Nano battery pack could be converted into one of these)

 

How would you write the configuration for the battery that you made by cutting one terminal on the DeWalt 28v pack, lazn? The way I am understanding it it is two 4S packs.

 

Two packs of four.. 4s works too.

 

Yep, paralell in 3's first and then string 4 of them together to form the pack is considerably better...

The thing to notice though is that putting two cells in paralell is easy, both mechanically and in terms of finding two evenly matched cells... 3 is a bit more challenging, and 4 becomes a PITA... So if you go to a 16 cell pack, i'd actually advice making two 8 cell packs with paralell pairs and then putting the packs in paralell... Are you confused yet?

The reasoning is simple... If you pair two cells with very different capacity, the larger capacity cell will spend it's entire life charging it's partner, and will soon gain internal resistance as it's never fully charged... As a result, it will die an early death and make the whole pack useless...

And if you need pack's larger than 16 cells, use larger cells... Or a battery managment system, ie the expensive kind...

 

Surprisingly, Tweety, this is all making sense. High school physics did nothing. Real world use makes me want to learn it!

 

Heh... Lemme know if you want me to make it more complicated... I can probably manage it pretty easy...

Nah, just kidding... The same applies to me, reading stuff in a book makes me able to know the fact's, but not neccesarily understand them... Putting my hands on stuff makes me understand them... The thing is, with a photographic memory, understanding things that you have read about earlier is a snap...

 

I used to have a nearly eidetic (photographic) memory, but by the end of my 2nd year of college it was gone. I remember how easy it was to learn stuff, and now it is quite a bit more effort.. Oh well, such is life, not going to let it bother me.

 

Maybe one side of your brain was slightly larger than the other and after a lifetime of charging the other side it started building internal resistance...soon the whole pack will be bad...

 

Good God that's funny! ^^

 

Wouldn't surprise me

 

Hi all, I wonder nobody´s asked yet. What do you think about this one from ebay omg? Looks pretty similar to your specs. Thanks.

http://cgi.ebay.com/A123-4S2P-motorc...item2c58d28c53

 

https://www.superhawkforum.com/forum...637#post288637

It's even in the same thread...

To add to what I wrote in response to that, on a IL4 with a smaller starter motor, say a 600... This would work quite nicely... On a VTR that does need a lot of juice, marginal but could work nicely, dunno until somebody tries it...

 

this one is diferrent Though I read whole thread I missed it, thanks for reply.

 

I had an exciting experience with a pack (that I was making for a different project) over the weekend, I was putting them into a custom steel battery container when one of my insulators failed and shorted the whole pack out, it took me long enough to disconnect it that the cells failed in a spectacular, messy and HOT fashion.. Didn't catch fire though so that was a good thing.

Now to rethink my design and get some more cells.

 

what do you think about this:
Model : Headway 38120S 10AH cell with Screw Terminal Nominal Capacity 10AH @1C discharge rate Operating Voltage 2.5V-3.65V Dimensions diameter of 38 (mm) height of 146 (mm) weight 307g IR 1.8 Max continuous discharge 5C Max pulse discharge 15C
looks like this 4 cells have more power then 8 DeWalt cells and less difficult in connecting and balancing
http://currentevtech.com/Lithium-Bat...FePO4-p40.html

 

Thanks guys, especially Tweety. Battery to your specs my friend did:

 

Looks sweet!

 

The light green label indicates those are the higher-end A123 cells. The ones you get on eBay are the same as used in the DeWalt drills and such - they can be identified by their white paper covering. The industrial grade cells are ok (that's what I've been using) but the quality will vary more. For example, I lost a cell in one of my packs so I had to dig into it and replace the offending party. This is the risk you run with the white cells, the down side of the green ones is they are considerably more expensive.

 

As A123 cells from OMGBattery are quite cheap, there was no reason for finding the other way, but to be honest I didn´t look for white cheaper one´s.

 

I guess that I don't consider ~$10 per cell cheap, when I've built packs I've tried to keep it down to around $5 per cell. The only way to get that kind of pricing is with the industrial grade cells. As mentioned, with only one exception I've found them to work just fine. In fact, the one cell that went bad was probably my fault and not the cell's (I let the pack go totally drained - not good). That pack is now in my wife's bike. I trust it that much!

 

I thought it was discussed before that this wasn't true. My understanding of it was that the green/white A123 cells are exactly the same from the factory- and both have a label wrapped around them.

Actually, somewhere it was talked about that the green ones are sometimes white ones that are stripped and then re-wrapped. All are made by the same company as they have the copyright on the technology.

The only part of the green ones that I understood to be better is that they are more likely newer as the DeWalt ones are a couple of years old. But DeWalt has better quality control than some other third party e-bay sources. Buying direct from a battery source would likely make this a non-issue, but if you're only buying 8 cells, then by all of this the DeWalt packs are a good investment.

Just saying what I remember, I could be corrected on all of this...

Oh and super clean pack! That sucker looks purdy

 

Well... You are both kind of right...

The cells where when they where new and left the factory the same... Same quality, same-same... Only difference was that those branded under DeWalt got the white paper sleeve, and those branded under A123 got the green...

However the one's you buy on eBay with green sleeves can be several different things...

1. Brand new from the factory with 2009-2011 as manufacturing date and after 2010 also a holo marking... Which means top notch, new cells...

2. Older cells, but top notch once new...

3. DeWalt cells in a green sleeve... (These are usually made pre 2008, same as no.2)

4. Lower grade factory rejects that got picked up by an unscrupulous eBay scumbag and given green sleeves and sold at premium price...

5. Cells produced by an entirely different manufacturer... Might actually be good cells, but the characteristics are usually way off...

The best way to tell... Peel of the green sleeve, there is an etched barcode and date on the metal shell... if the markings and sleeve are identical, it's a good A123 cell (and you know the manufacturing date)... If not, it's dodgy... A123 added the holomarking in 2010 to all premium cells, ie no holo marking and 2010+ date = reject...

The good thing about buying the DeWalt cells in paper sleeves is that you kind of know what you get, factory cells of good quality, slightly older, but still good to use... The thing is, scammers prefer to go for the green sleeve, easier to fake and more money...

However I can say from personal experience that all cells I have bought from OMGBattery (500+) have been A123 cells, fresh from factory, top grade... And when two of them where DOA I got five new cells expressed to me, no questions asked... So I can honestly recommend them... and while it wont be $5 per cell, it's closer to that than $10 if you buy in bulk...

If someone want's the list of dodgy sellers that sells type 2-5 on my list, lemme know... I tried a few before finding OMGBattery...

 

im very impressed that these little double a looking batteries are that powerful. if i didnt have a brand new battery id have one of these. infact when mine dies im gonna end up with something like this, maybe see if tweety has the resources to make one when im ready

maybe its been discussed and i missed it. how do these batteries react to the rr when it goes bad? will it kill them? and what do you think the life is like before the battery stops charging properly or holding a charge? i know the with lithium cell phone batteries theyre great for a while but slowly hold the charge less and less. is it the same with these things? and you had mentioned unplugging the battery for the winter and not worrying about using a battery tender. how long is too long to leave these connected to a bike without using them? if the bike sits for a month or a few weeks with this thing in it should it be un hooked?

im sure some of this has been answered but my brain has slowly melted from trying to wrap it around all the numbers and specs and things i dont understand being thrown around by you guys, lol

 

The industrial grade cells are not held to the same tolerances. You'll notice that Tweety "matched" his packs because of the variance between cells. Although I've not found it necessary to do this, it's not a bad idea. The LiFePO4 chemistry was specifically designed to be more tolerance of balance issues.

There is a reason the green ones cost twice as much!