Hmm, interesting. I just did it the easy way because it was easy. lol

 

Ok, two new questions based on that...

1) If I don't have any battery connectors can I just use a sheet of .008" copper and cut little ones?

2) If I accidentally touched + to - and sparks flew, have I messed anything up? I did it on two separate occasions...

Thanks for the info so far guys!

 

.008" ?! that's 0.2 mm ! Nope... Definetly not... That won't carry enough current to start a bike...

Look at it this way, the DeWalt connections are marginal, meaning you want thicker connectors between the cells than that ideally... The busbars should as absolute minimum be 1 mm thick and more than 6 mm wide if in copper... Ideally they should actually be 1 x 10 mm or equivalent... And just for making me convert inches to mm, you get to do the opposite on your own as punishment...

As for the second question, well... Yes and no... The cells are unhurt... And since you did the sparky thing you obviously avoided welding whatever to the cell which is a definete worry... So form now on, no sparks, OK!

However doing that puts you in a little dilemma... The cells you made sparks with are now less charged than the others, and putting them in the pack means the pack is unbalanced... Bad idea...

So to fix that problem, put one sparky with another cell that hasn't been sparked in a pair and they balance out to the point where it becomes irrelevant...

Or balance the cells... Ie connect the whole bunch together across all the positive poles and the negative poles and leave them over night to equalize, then discharge and charge them in that state... Since I doubt you have the tools for this, the above method is your best bet...

And... Remember, from now on, no sparks!

 

come on buddy, conversion isnt that tough. I do agree that metric is easier, but for simplicity you can substitute .040" for 1mm. So, by that measure you want .040x.400 as a bus bar. And the conversion back from .008" is 1/5mm, or .2mm. I wouldnt have to know anything of the sort if cars were done in anything that made sense, i.e. american cars using metric as well as inch, and odd sized metric to boot. This means that you actually need every single socket and wrench in both metric and inch to work on the stupid piles. I wish it were like the japanese: 8, 10, 12, 14, 17, 19, 21, 22, 24, 27, 30, 32mm. Much easier, and less than half the wrenches and sockets necessary to work on US made vehicles.

 

I'll try to find some 1mm or equivalent stuff . It will be much bigger than the DeWalt ones... they're reading at .3 mm. Here's another one for ya- will it matter if I use different sized bars (DeWalt vs self made) or do I need to make them all the same? In terms of hours here I'd probably be better off just working a few overtime ones and buying another pack with all the circles I'm running!

And, yeah, I work in metric whenever anyone lets me. Problem is that over here standard is, well, standard.

OK- no more sparks. Glad I didn't ruin it, figured the balance would be out, I may finish this one and see how it goes and get another in a few months and do a cleaner job of it!

When I'm done I'll be able to make a "how not to" thread!

 

Heh, I know Bill... Mostly I can do the conversions in my head, but it's still a PITA... As fer sockets... Well, add some cars and bikes from old English manufacturers to you garage as well, and you get the fun of figuring out sockets for 'merican cars times five... Not to mention the fun of trying to figure out what damned thread various bolts are... By now I have a full set, so that's not really a problem, but oh, do they enjoy making it complicated...

 

Well, learning takes a little time and a few circles... But then usually once you learned and more importantly understood things, you remember them...

As for your question... Since this is starting to resemble when I babysit EE's on lab hours, I'll answer that question the same way I use to do then... I'll sigh, shake my head and walk away, since I'm pretty sure you know the answer to that one already...

BTW the weakest link determine the current...

 

are things like "DeWalt DC9360 Heavy-Duty 36V Nano Phosphate Lithium Ion Battery Pack" use-able? there are 14.4V, 18V, 24V... it looks like they are 3.6V cells. 8-cell pack makes 14.4V battery.

 

That's the one to get... the 28v (DC9280) one has the 8 cells:

http://www.amazon.com/DEWALT-DC9280-.../dp/B000X1Q07I

 

it means they are all 3.3V cells and difference is only - labels on devices?
36V is actually 33V, 28V = 26.4V and so on...

 

A123 are 3.6v IIRC

 

3.3v

• Nominal voltage: 3.3V
• Nominal capacity: 2.3Ah
• Core cell weight: 70 grams
• Internal impedance: (1kHz AC) 8 mΩ typical
• Typical fast charge current: 10A to 3.6V CCCV
• 70A continuous discharge
• 120A, 10 sec pulse discharge
• Cycle life at 10C discharge, 100% DOD: over 1,000 cycles
• http://www.a123systems.com/a123/products

 

Actually you are both kind of right... When fully charged it peaks at 3.6V... And in the band where it's charged but not absolutely full or about to run out it stays 3.3V...

But dumbass manufacturers prefer the higher number... They seem to always do...

 

Ahh, look again at what I posted... the manufacture of A123 cells states the lower number of 3.3v

 

Yeah, A123 does... But how do you make a 14.4V battery out of 3.3V cells? Or a 28V... So when you look at DeWalt packs, you need to calculate with the fact that they use anything between those values as their "preferred" truth... Ie what makes a snazzy number to put on the box, not what's actually inside...

 

ahh, got it, you were talking what the end user marketing says.. gotcha

I was referencing the folks that make and market the battery itself.

Rounding up is common marketing as I'm sure you know,, CC size of engines, HP and TQ numbers, capacity of an after market fuel tank to name a few.

Marketing is one thing.. But when I see a spec sheet,Or technical reference document , it had better have the clear unvarnished truth...

 

I agree totally... I prefer a spec sheet, so I can figure out the what, why and how for myself...

I was just trying to give both numbers, since I think a lot of people will go for the DeWalt cells if they try this... Which actually for the price is considerably better than most of the dubious copies you can find on eBay...

Yep, rounding up is standard, and in this case actually somewhat true, since the final resting voltage on a full charge is potentially 3.6V... But I still recommend not charging above 3.45-3.5V... Since then you aren't top filling the cells and getting them unbalanced... Plus it doubles the cycle lifetime...

 

I'm looking for a direct source of A123 cell at reasonable cost,, nothing is coming up though.

The responsible priced Dewalt 28 packs are 2007 or older from what i can find... making them not that great a choice as well.
So you have fresh genuine A123 cells though there direct retailers. http://www.bphobbies.com/view.asp?id=V819427
and
http://www.rclipos.com/

at $16.50 a cell
http://www.rclipos.com/A123_Cells.htm
Or old Dewalt schavenged A123 cells for about $10 each after shipping.
Or Old / second condition A123 cells sold though Ebay.

 

I have bought cells from here http://stores.ebay.com/OMG-Battery, and they are legitimate, new and from A123... Roughly $10 per cell for or less if you get them 100 at the time (which I did)... They also check out on internal resistance (Measured at 1kHz AC, like spec) which none of the others I tried buying from check out on... Ie not secong grade...

 

Rounding up is great in marketing, not in real bike. 13.2 and 14.4 are not the same, especially with common "R/R not charging battery" problems.

 

Very, very true... one of the reasons I'd recommend having a look at this thread... https://www.superhawkforum.com/forum...arge+indicator

Changing the diode and some resistance values will give you a indicator that tells you when your bike is in fact charging the A123 pack... Works exactly the same as with a lead battery, just changes the voltage levels that the LED's turn on at...

If you don't like to solder small stuff, let me know, I can easily make them and stick them in an envelope and mail to you... I do however use SMD parts, so mine are considerably smaller in size... They work the same as the DIY version though... Oh, I'll gladly make either for lead or LiFePo4 voltages, the cost is the same and the benefits are identical, you know it you have charge voltage and when not...

Oh, btw... I have provided on numerous threads info on how to best charge the packs, not just all listed in this thread... Go read up, most of it is pretty usefull...

 

Thank you very much. It is very interesting to me.
Miksrt and JamieDaugherty have a problems with this kind of battery. Somebody of your Sweden friends have this problems?

 

I have made a total of 23 packs, two of which has gone to members of this forum in the US, and I have myself covered some 400 miles using a smaller 4 cell pack without any problems... And as far as I know nobody have had problems that where directly related to the pack... Some have had problems that would have occured anyway and might have been less obvious with a standard type battery though...

As for me... Well, trying to start the bike with the killswitch pushed and the headlight on doesn't really count as a problem... I'd say it just classifies me as an dumbass... Plus once I figured it out, swapping over to the 8 cell pack started the bike easily enough... And besides, with a lead battery, I wouldn't have gotten half the amount of attempts anyways, so it didn't really change the outcome...

One of the guys that bought a pack from me had problems when his bike failed to charge correctly, but with a charging indicator in place it was just a simple matter of swapping the R/R, bumping the bike and keep riding... Again, not the pack at fault, and it would have happened just the same with the OEM battery or any replacement...

Also one other reported that going at freeway speeds while lugging the engine (2000-2500 RPM) managed to almost drain his pack, but at the time he was doing driving training with someone on a cruiser and a couple of kilometers at normal RPM's charged the pack back up... He didn't have a charge indicator, so I can't say for sure what his voltages where, but not enough to charge the pack continously since it started complaining after 3-4 hours and he caught the problem... Also, his solution wasn't to repair anything (not yet anyways) but just "don't do that, because it's stupid", which is a fairly correct translation of a direct quote from him...

 

what are the thoughts on this? seems like a reasonable price and hardly any work.... http://cgi.ebay.com/8-cell-A123-moto...#ht_3835wt_905

 

Some good, some bad...

The good is that it's good cells, the configuration is good with cells in pairs and the wires are of the right size... Just add ring connectors or a quick disconnect and it's good to go...

The bad, the welded on tabs are less than 1 mm thick, and less than 10 mm wide, also they aren't copper, so higher resistance... Plus resistance welding tabs doesn't give a connection with as good characteristics as a soldered one... My estimation is that it's doubtful if it supports 25A of current...

It's most decidedly better than using the DeWalt cells with the connectors intact... But if it's as good as having the cells soldered... Dunno for sure, and the only way to know is measuring it...

 

I hate to bring the whole of the discussion back to my personal setup but am a little curious about two more things!

First, having "sparked" a couple of cells, I have discharged them a bit... I plan on reading into this more over the holidays because it has peaked my interest... but for now, have I greatly deterred the performance of the battery due to the unbalancing? Is this in any way dangerous, or will it just wear out sooner, not hold as much charge, or something like that? You answered before saying I was fine, I just kind of want to know what the little magic battery juices are up to in there.

Second, just so I understand what's going on (I'm trying my best to measure twice and solder once this time!) I have paired the batteries up and am going to connect those pairs up in a row of four, alternating the + and - of the packs, and only connecting one side of those... I am visualizing that if I were to just stack the batteries vertically instead of in a row I would be connecting the parts that touch in the stack. I am also visualizing that if I do this it will have a subtle accordion effect if I were to pull on the ends of the pack before I secure them together...

This is all really great stuff... too much to learn in too short of time, but thanks for being patient!

 

What is the date code on the cells you received?

 

Question one, nope this has absolutely nothing to do with the performance of the battery, either the pack or the cell... The sparks is completely irrelevant as long as you don't weld stuff together when they occur (yes, it's definetly possible)... Other than that, the only effect this has is to discharge the cells... Not anymore harmfull than connecting a lightbulb to one ot two cells and using the power to light the bulb...

The problem occurs from the imbalance... Think of it this way, you have several water tanks... Connect two of them with a pipe at the bottom edge, add an inlet to one and an outlet to the other... Whatever level of water is in there will be equal... When one is empty, both are... This is two cells in balance by being in a pair...

Now do the same, but connect the cells with a pipe at any other point than the bottom... Now you need to fill them above the pipe for them to balance... The one with the inlet will empty out while there is still water in the other cell... This is what you got with two cells that have a different charge...

Now, unlike the water, when you empty one cell until it is completely flat, the other one tries to compensate and can end up charging the empty one... When that occurs you end up with a cell with reversed polarity... That means that the marked positive pole now has become the negative pole... That cell is now permanently damaged... If it's loose cell it's not a problem, you just junk it... If it's in a pack, then you have a problem...

If you take a fresh cell and put it with a sparked one, they end up being in between where they started... That means the difference between the 4 cells in the string is less than if you pair up two sparked ones and then string them with a pair of fresh...

The best option, balance them... Hook all + to one point and all - to one... Then they all become one big cell and all equal out, but it takes some time unless you cycle them, and for that you need a variable powersupply and some way to discharge them...

For the second one... I dunno... I know the right way to solder this up... But after reading your description on how you think it's supposed to work, i ended up being confused... Thanks! You bastard, you killed Kenny!

The best way to describe things... You hook 4 cells of 3.3V each together in a string, + to - so that you end up with one + connnected to a wire, and one - to another wire... The other junctions are + to -... Does that make sense?

To make it even clearer, those 4 cells can consist of single cells, making it 4 cells in the pack, or pairs of cells that are in the pair connected together by both poles, + to + and - to -... Makes no difference...

The correct terminology is that if you hook two cells + to + and - to - they are in paralell, and if you hook two cells in a string with one + to - junction and one of each pole accessible, they are in series...

Let me know if it's unclear...

 

Well, I can't tell you the exact date for manufacture of the top of my head, but I can tell you that of all the cells I have bought, the oldest was at the time of delivery around 6 months old... To me, that seems fairly reasonable...

Last batch was with the hologram patch, all the others (prior to the hologram being introduced) have had both the barcode and the laser engraving, with the two matching up to each other as correct from A123 (including the readout of the barcode)... This plus measurements of the cells that pass all the parameters with margin, makes me believe the statement that they are in fact legitimate cells, destined to be sold to OEM's...

Another clue... A123 has stipulated to it's resellers that the cells can only be sold to the end customer as welded in packs, selling the cells with the tabs welded on as they are offering free of charge circumvents that demand... I'm pretty sure there are other eBay sellers with the same quality off cells, with the same way of circumventing it (I have seen others) but these I have tested, the others I have not tested...

 

All of it made sense to this point

Even the part where I confused you... I'm pretty sure the way I'm thinking is correct, I just explained it poorly... if I drew a picture I could explain my thinking better.

I could hook them all up to make a big pack, then discharge them by sparking them a whole bunch to balance them..
haha, jk I won't do that. don't worry