LG ICR18650D1 battery pack build

This was just very quickly soldering some copper solder wick (the stuff you use to de solder something) onto a cell. It took less than a second to hear the bubbl'ing in at the top of the cell.
 
I've seen many homemade batery packs and they are only getting better, this makes me think that when i build my own e-bike i'll build the pack too, instead of buyinf it already made up. Nice pack!
 
Wheazel said:
I did send LSBW a pm and asked if he could comment in this thread.
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I guess there's no update from LSBW?

I don't think it's good idea to solder directly to the cells, better make no solder/weld pack (like Snatch design http://endless-sphere.com/forums/viewtopic.php?f=14&t=57810), buy welder (not that expensive, http://endless-sphere.com/forums/viewtopic.php?f=14&t=57291&start=175#p894035) or make it yourself even cheaper (http://endless-sphere.com/forums/viewtopic.php?f=14&t=59383). But if you really want to solder, then a few words of advice.

I've never try to solder cells, but have a lot of experience with other things.
To get two items soldered you need to heat them up to solder melting temperature which is the problem if items are heavy. So I can say it should be easier to use leaded solder SN63/PB37 instead of the one LSBW use (SAC800) because leaded solder melting temperature is 183°C instead of ~217°C for most lead free solders. There are solder alloys with even lower melting temperature (e.g. Bi58/Sn42 138°C, In52/Sn48 118°C and other) but may be hard to get/expensive/not strong enough. Also common technique is preheating of soldered items. Obviously not good for the cells, but even preheating to 60-80°C will be better than nothing.

Re flux - looks like it's key factor for soldering batteries. Because battery case is nickel plated in fact it's like soldering to nickel. Flux needs to be corrosive to clean nickel oxide, look for special nickel/stainless steel flux like Indium 42-SS or this one: http://www.superiorflux.com/superior_30_supersafe_industrial_soldering_flux.html, or diluted solution of sulfamic acid.
 
Sorry guys, I was quite busy with some other stuff, and wasn't paying much attention to ebike world.

This is almost one year, since I've put together my LG pack.

Still running good, however, nowhere near 70 km range I was getting 1 year ago. 30-40 km, and I would recharge.
No big deal, my daily commute is only 9 km.
I did manage to get 60 km couple months ago, bunch of ppl test rode my bike during BBQ in the nearby park, but battery afterwards was almost dead. Cells around 3.5 volt or even lower.
In the conclusion, I think tons of cells coming from China are fake. Especially ones which are really cheap.
Think about it, by wrapping fake plastic wrapper on no-name cell they can make 100-200% profit.
So, for my project #2 I've already bought 210 pcs of A123 26650 cells, refurbs, directly from the factory in US.
Now looking for the spot welder in Toronto :)

2mrd73c.jpg
 
Let us know what spot welder you end up with. They seem hard to find. Those batteries should be nice.
 
LSBW said:
This is almost one year, since I've put together my LG pack.

Still running good, however, nowhere near 70 km range I was getting 1 year ago. 30-40 km, and I would recharge.
No big deal, my daily commute is only 9 km.
I did manage to get 60 km couple months ago, bunch of ppl tried my bike during BBQ nearby, but battery was almost dead. Cells around 3.5 volt or even lower.
Click to expand...

It is very interesting to read about your experience. It would be very useful for community if you could answer this short questionnaire. :)
1. How many kilometers did you travel in total and how many times charged?
2. What was your average and peak discharge rate (C)? Charging rate (C), cutoff condition (voltage, C)?
3. Any disbalance issues? How well did it stay in balance?
4. Did you use a BMS? Any failures that could cause overcharge/overdischarge?
5. Charging in cold?
6. Cells connected by soldering?
7. Any thermal management used? Like cooling or heating in cold.
8. What are your habits: charge before ride, or charge fully and store until next ride? Did you do multiple rides on single charge, of did you recharge fully after each ride?
 
So, here it goes.
1. Total distance traveled is 2700 km, and I roughly charged 110 times
2. For the winter time I limited discharge with CA to 45 Amp, so it was 1.5C, I don't have cut-off voltage, but usually I never went below 3.7 volt per cell
I have 16" moto tires, so bike is quick enough as it is.
For charging I always use dual Hyperions 1420 with balancing, its slow (2 hours on average), but I don't care. Charge rate is 0.5C at most
3. My pack is split in 10S and 8S. 10S usually has 0.030-0.035 v disbalance, but 8S is always within 0.003-0.005, so it never needs balancing.
4. I have CA and balance charge every time, so no BMS. Plus after reading some horror stories about failing BMS and whatnot, I think Im better off without one.
5. I keep and charge my bike indoors 99% of the time, no issues there. Battery does lose a lot of capacity when temperature outside falls below 0 C, but this is totally expected.
6. Cells connected by soldering, pls see my original post and pics :)
7. No thermal management, pack does get warm after prolonged (30 min and up) rides during summer, with temperature outside being 25 C and up.
8. Usually Im trying to recharge after 20 km distance covered, so the cells are at 3.8-3.9 volts.
Another thing is, these LGs are fully charged at 4.35 volt, but since there's no chargers available yet for this voltage, I just override Hyperion to 4.28, and by not fully charging my pack, I would somewhat prolong its life.
 
circuit said:
Thanks, that is very useful information. Looks like this is bad news about LG...
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Perhaps it's because they are not original, but I'm intrigued by what LSBW said in the first post "its time to upgrade from crappy konions" - Konions are AFAIK quite good. LSBW, did you buy them from the same seller?
 
LSBW said:
Sorry guys, I was quite busy with some other stuff, and wasn't paying much attention to ebike world.

This is almost one year, since I've put together my LG pack.

Still running good, however, nowhere near 70 km range I was getting 1 year ago. 30-40 km, and I would recharge.
No big deal, my daily commute is only 9 km.
I did manage to get 60 km couple months ago, bunch of ppl test rode my bike during BBQ in the nearby park, but battery afterwards was almost dead. Cells around 3.5 volt or even lower.
In the conclusion, I think tons of cells coming from China are fake. Especially ones which are really cheap.
Think about it, by wrapping fake plastic wrapper on no-name cell they can make 100-200% profit.
So, for my project #2 I've already bought 210 pcs of A123 26650 cells, refurbs, directly from the factory in US.
Now looking for the spot welder in Toronto :)

2mrd73c.jpg
Click to expand...

Ouch that is painful. Almost 50% capacity loss after 1 year... and now back to A123..... :/

Damn Founding power (Ex-victpower) is not someone trustable??


My key criticism about your battery is that you left them almost always at fully charged state (4.28V), which is famous to degrade cell capacity extremely quickly for any lipo cells (except A123 and some lifepo4 I suppose). So maybe if you left them most of the time at 4.15V, which shouldn't be such a voltage difference, you would still have decent capacity?
 
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