Bosch 36V fatpacks opened up

I personally have over 1500 konion cells, so if I was approaching this as a business, 50k cells would be nothing. WRT to cell matching, just like with the tool packs, the only matching required is for cells in each small series string. Entire packs do not need to be composed of matched cells, just the individual strings. Selling to the general public would definitely require heat sensors that can turn the pack off, which wouldn't be so mandatory with hobbyists. I have an ideal product application that I'm certain would be a use approved by Sony for 2p10s strings and include a requirement of waterproof packaging as an added bonus for our use. What I lack is a good route in via a high level contact in order to obtain great pricing right off the bat.

John
 
Just curious John, with these 're-cycled' packs you pick up
how do you know the cells aren't on their last legs? Like, i read
Ductorbass picks up these packs and they often only have one or two dead cells,
are these packs people have bought and returned or are they ones
that were DOA right from the factory? If not then is it possible someone could have had
the pack thrashed the bejeesus out of it for 2 years return it with a dead cell.
How can you be sure that the packs you get contain cells that have heaps of capacity left
and wont shit themselves in a week or two i guess is what i'm asking? Just curious


KiM
 
AussieJester said:
Just curious John, with these 're-cycled' packs you pick up
how do you know the cells aren't on their last legs? Like, i read
Ductorbass picks up these packs and they often only have one or two dead cells,
are these packs people have bought and returned or are they ones
that were DOA right from the factory? If not then is it possible someone could have had
the pack thrashed the bejeesus out of it for 2 years return it with a dead cell.
How can you be sure that the packs you get contain cells that have heaps of capacity left
and wont shit themselves in a week or two i guess is what i'm asking? Just curious

KiM
Click to expand...

Makita packs have an internal counter that reports the number of cycles. Doc has some way of reading it and doesn't sell the high cycle stuff. I bought some last year from Marty, but his were apparently from a recycling center so the quality of the used packs was much lower, as was his price. Makita had some kind of tab welding problem with one of its robots, and with temperature changes or whatever, one of the cells would come loose, which killed the other cell within a few cycles. Once that happens the charger and/or tool rejects the pack, leaving the other cells good. They made some kind of change, so I rarely see the loose cell anymore, but I guess they went too far the other way, because on most of the packs, it's still a problem with just the end pair of cells, which makes for much easier processing. Then on about 25% of the packs something fails in the electronic board, leaving a full pack of good cells, which are even easier to process.

With well worn packs things get more difficult, because it's cells in the center of the pack that fail and sometime cook the adjacent cells in the process of dying. I've got about 200 good cells in packs with central cell failures, which I haven't done anything with other than partially charge to make sure the voltage doesn't drop too low over time on the good cells. At some point I'm going to process all of those cells in one shot. I've just put it off, because it's more than double the work compared to end of the pack cell failures, though I'm sure I'll come up with an easier way to process them once I get around to it.

John
 
John in CR said:
Makita packs have an internal counter that reports the number of cycles.
Click to expand...

I would like to see that tool for the Makitas. I've seen the Milwaukee service reader in person and it was so cool I almost bought one when I was using V28s (~$150 direct from Milwaukee IIRC). Cycle count, individual cell voltage readings, max temperature the pack had recorded and more. It was badass.
 
You get the tool. All I want are cells. I've only killed one cell in over a year and a half. That required a plasma flash the first time I forgot to switch my multimeter leads after measuring current. The flash melted a hole in the rim of the nearest cell, and it still took 2 weeks of use for the cell to die. Since the string was 20s and I don't charge to max voltage, the other cells had no problem covering 0.2v/ea for the damaged cell, so the string had no problem paralleled with the other strings only at the ends. Since that was a pack of oddball cells, I left it with the dead cell for an extra week just to see what would happen, and the only thing that happened was a bit of heating from that one cell that wasn't hot enough for concern.

That was proof enough for me that my approach of paralleling strings only at the ends is the correct one in my case. As long as you don't have to balance, and you have a long enough series string, you shouldn't tie them together in parallel at the cell level. Had I done so, that cell would have killed all 10.
 
So, I've privately called people goobers for leaving their pack plugged in to the CA accidentally. I said "how hard is it just to pull the plug just before putting the bike into storage."

Well now I'm the goober.

I have 7 fatpacks paralleled for 14ah of Bosch goodness, and I left them plugged in when I stored the bike.

I measured 2V on the entire pack... :( :( :( :( :(

My charger would not recognize the pack, so I got the rc charger out, set it to Pb 8V and charged until it stopped, reset to 12v, charged, set to 18v, charged and repeated until my regular charger recognized the pack.

It is currently charging and has taken 13Ah so far.

Hope I didn't kill some cells. :oops:
 
Batteries took 15.7Ah. About what would be expected from totally drained to 40.9V

Now for a discharge....
 
Went for a long ride.

took 11.74 Ah out of the pack according to Cycle Analyst.

Put 11.34 Ah back in according to Watts up.

This is not looking good. Hopefully it is just a case of difference between meters.

Worst case scenario, I upgrade everything to lipo and turnigy 4x6 chargers.

Not too bad for worst case scenario... :wink:
 
I've run a couple of my BFPs down to "0" and have recharged them back up to what I would consider full health. After I got them recharged which was as simple as plugging them into my Tenergy 10 cell LiFEPo4 charger, I tested them using my LBD and they tested out to be 2.0AH. I've put a couple of cycles on them since and they are doing fine. These Sony/Konion cells are simply amazing!

Ambrose
 
round 2

My ride today depleted 11.11Ah according to CA.

Recharged 10.72Ah by the Watts up meter.

That is a 3.5% difference this time and a 3.4% difference last time.

Kinda looks like a difference in measuring devices, or could it be a steady rate of decay?

Here's to hoping...
 
Can you charge thru the CA (with the WU in series to see both measurements)? Even if you don't reverse the connections it'll show up as regen current in the CA.

I'd suspect a calibration issue with one of the two.
 
Have you checked each pack separately before and after a ride to see if any one is off? I've had that happen where one pack will drain faster and drag down others.

Ambrose

TPA said:
round 2

My ride today depleted 11.11Ah according to CA.

Recharged 10.72Ah by the Watts up meter.

That is a 3.5% difference this time and a 3.4% difference last time.

Kinda looks like a difference in measuring devices, or could it be a steady rate of decay?

Here's to hoping...
Click to expand...
 
On a slightly separate note,

Does anyone know if the Cell-Log 8S can be used with Bosch Fat Packs? I would love to be able to monitor each pack separately while riding!

http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=9282

Thanks,
Ambrose
 
amberwolf said:
Can you charge thru the CA (with the WU in series to see both measurements)? Even if you don't reverse the connections it'll show up as regen current in the CA.

I'd suspect a calibration issue with one of the two.
Click to expand...
This evening I plan on trying a discharge by this method (both meters in series). :wink:
 
Just thought I'd mention that I've had 2 packs sitting at 40.3 volts for 6 months, just checked them and they're at 40.1 after storage. seems they hold a charge quite well too.
 
Just as suspected. I took a long ride today, with both the CA and WU connected.

CA reports 11.71Ah used
WU reports 11.23Ah used

A ~4.5% difference Which means one or both meters are not accurate. I tend to suspect the WU meter for the majority of it.

However it reported 11.25Ah recharge, so it is consistent.

These Bosch packs are bullet proof.
 
+1 for Fatpacks!
otherDoc
 
I found my SLA charger that didn't have an XLR adapter, and I started charging a fatpack that was down to 1.4V. In less than a minute, it was already up to 5V. In just a few minutes it was already past 20V! At that point, my Bosch charger accepted the batteries. I wonder at what point it will allow you to charge. It defnitely didn't like them at the 1.4V or the 5V.

My ride to work uses about 2Ah. Having taken these guys down to the lower depths, do you think enough of the 4.4Ah will still be usable for my ride?
 
I have had no noticeable loss in capacity since my incident.
 
As of today the "buy it now" price for Bat836 Fatpacks is 90 bucks! That is gettin' to be a bit high when it comes time for replacements. Lipo is looking better and better.
otherDoc
 
yeah, the price has gone up. I saw a steal at $70 shipped yesterday, so I had to buy it! How ironic that I was able to bring my 2 packs back to life on the same day.
 
I guess I got a decent deal on them when they were at 70/75 shipped. I would not pay more than that.

Lipo is a fraction of the cost, just more hassle with charging/balancing.
 
Wow, thanks for that pic! I think I'm going to take the cover off and make my own little covering for it so I can transport it easier on the bike.
 
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