Shimano e-bike pack of murata vtc6 (10s4p) with nickel plated copper. Local e-bike mechanic didn’t want orphan packs in shop after warranty work.
40$ for 2 packs. Cool dude. All p’s balanced to the mV, bt-e8020 model. Bypassing bms to discharge and discover
Where else have y’all seen disassembled packs with nickel plated copper? That’s what’s going on here, right?
If you’re asking about the copper color at the weld points, that could just be copper that was deposited by the welding probes. Not necessarily nickel plated copper tabs.
I’d be embarrassed if I left that much probe on the pack. Contact area would get progressively wider.
I’ll cut on it and report.
Most BMS’ alternate between the even and odd numbered cells when balancing in order to prevent overheating of the balancing components for adjacent channels.
A side note…this results in the balancing current being a bit less (or a lot less) than 1/2 of the current that flows when balancing. For example, some BMS’ that say they have 50mA of balancing current but they’re actually balancing with about 20mA (average) of current because of this alternating of odd/even channels. It’s not exactly 1/2 because of the bit of time needed to sample the cell voltage between balancing current pulses.
Industrial welders (which that pack was probably made with) use straight cylindrical probes, not tapered probes like our hobby welders use. They can deposit copper on every weld, and never change the contact area or shape.
However I do agree with you, that would he an unusually large amount of copper to deposit on each weld. I’ve never seen that amount, or that regularity. I also dont know what it looks like to weld nickel plated copper, so that could very well be the case.
im trying to reuse some cells, is it relatively safe to sand the positive side of a cell with dust getting in the holes? is there any methods to prevent the dust getting in without shorting the cell?
Cover the top with tape and then just sand through the tape. It’s not perfect but it’s better than letting the metal dust build up otherwise.
Note that sanding removes the nickel plating that makes soldering (a little) easier. You’ll be trying to solder directly to steel.
We don’t solder cells!!!
We definitely don’t, but many do.
Mentioning that the sanded tops of salvaged cells just makes that method even harder might help persuade some to try a different method. 
Thanks! and yea i am spot welding them
Just a quick mention, I forgot earlier…you can hold the cell upside-down while sanding too so most of the dust drops away from the cell and can’t get under the top contact.
Not 100% guide but maybe helpful?
Dont mind me, i’m just caching this here for when we have another battery idiot that asks for advice and chooses not to listen to the things they dont wanna hear
Elitist snoot on the job
I have no reservations about gatekeeping battery safety.
According to my remote, my first Esk8 battery, a 10s2p of Dmegc 2600mah 15 amp cdr cells, now has 152 miles on it.
Only once did I ride to the point the remote buzzed or beeped I cant remember which.
I often charge to only 41v or 41.5v, then a half hour before a ride, might bring it to 42v.
I’ve charged it as high as a little over 1C rate, but usually 0.6c or less. Always with a fan blowing over enclosure and the CCCV voltage booster and inline wattmeters on either side of it.
Once, It seems the high voltage limit was exceeded on one or more p group, when I charged at just over 1c to 42.02v. The ammeter was reading 0.00, sooner than expected, and when I disconnected booster from battery, battery voltage fell to 41.63v, when usually it hovers just a few hundredths of a volt below my pre load chosen charge voltage, at this stage in its cycle life.
I ran the motors for a second, cranked the current pot way down, to 0.43 amps, hooked it back up, and a fairly long while later current had tapered to 0.19a at 42.02v, and I disconnected it.
So I believe the Daly non smart is functioning, at least at preventing overcharge.
I have no idea the Vdelta of the P groups, and whether it is indeed balancing those times I do charge to above 41.8v.
I worried that I damaged it, as I had attached it to total battery negative, before plugging in the balance cable, and later saw directions on a a different ebay seller’s website, to only hook it to total battery negative After seating the multi wire balance plug.
So, in what will likely be another regretted decision, I recently received another 20amp common port Daly BMS in the mail, in 10 days from China.
This time, there was paper instructions included in the baggie.
The usual poor translation.
Notice steps 5, where it says the B- blue wire can now be connected to total negative pole.of battery, where step 4 says the bms can be connected.
Here is the other side of the paper with directions for a smart Daly BMS.
I am really curious about my P group balance, but it ‘seems’ my reversal of steps 4 and 5, did not damage the BMS. But I have no proof.
Checking the voltages on the balance connector, without disconnecting the blue wire from battery - first, ‘might’ damage, or damage further, the BMS.
I dont know.
Opinions?
I don’t want to dig out my blue wire to snip it and then remove the balance connector in order to probe it, then have to try and add connector in a space not originally designed for it. I can, of course, but would prefer to not have to.
So I wonder how important the order of steps 4 and 5 are?
Opinions?
I will make the next battery, with a likely XT 30 connector on blue wire, so I can adhere to Daly’s order, if i decide to use the newly arrived BMS, or instead, employ the comparatively huge Smart JBD which is on a truck a few hundred miles somewhere north of me at the moment.
I could also remove the potentially partially damaged Daly on my Dmegc pack, and replace it with the newly arrived daly, adding a XT 30 inline beforehand.
Fitting the larger Smart JBD adds some complexity to the small enclosure for a mini kicktail, but I am at that enclosure layout stage, and trying to weigh my options to arrive at the best possible result.
It matters on some bms, but a lot of them can do both ways no dramas.
Having connectors is always a good idea. This way you can do whatever you need to with minimum hassle 
Personally i think the Daly you have is probably fine, but i do understand the peace of mind that comes from replacing a questionable part. Once that doubt is created it can be hard to shake.
Assess
Yea can’t assess if a battery is actually damaged. Too dangerous. Only the super smart people who know how to use a multimeter
