Pure nickel strips for battery pack

[Nearchos]

II.
Same questions as above for a Reention DP-9C at 52V 21AH containing 18650 3500mah LG lithium-ion cells arranged at 13S 6P LG.

This pack feeds a 1000W 48V Bafang M620 / MM G510.1000.C. mid motor.

 

[harryS]

Nearchos, your bike controller is what really determines the maximum current. For a 350W motor. I wouldn't expect more than a 20A controller. My Bafang BBS02 midmotor draws 26A, and while I don't know the M600, let's call that 30A. Let's call them both 30A,
.
.One battery is 10S-7P. The other is 13S-6P. Divide 30A by the above P number to get the current per cell. It's about 5 amps per cell, a good safe number, in my opinion,
.
You can look up the ampacity numbers for nickel if you know both width and thickness. Here. it's not critical, as 5 amps is light. Most charts say that ,15 mm nickel, if it is at least 8mm wide, easily handles 5A.
.
More important questions to ask the battery guy.
-Is it pure nickel? If it is, it's prolly a lie,
-Max current rating, even though we think 30 amps is enough,
-Does the BMS balance?
-Brand of cells. If they are name brand cells with datasheets (Samsung, Eve, LG, Sanyo Panasonic, etc), you can verify the quality,
.
By the way, balancing if it occurs, happens at very low currents. If you look at a BMS specification, it's about .05 amps. The balance wires can be very thin,
.
Only we amateur battery builders use multiple layers of nickel and that's only because we don't have the gear to weld one single thicker layer. Doing extra layers adds cost, and can be problematic. Despite what Micah Toll says in his videos, I think it's a band aid.

 

[Nearchos]

Nearchos, your bike controller is what really determines the maximum current. For a 350W motor. I wouldn't expect more than a 20A controller. My Bafang BBS02 midmotor draws 26A, and while I don't know the M600, let's call that 30A. Let's call them both 30A,
.
.One battery is 10S-7P. The other is 13S-6P. Divide 30A by the above P number to get the current per cell. It's about 5 amps per cell, a good safe number, in my opinion,
.
You can look up the ampacity numbers for nickel if you know both width and thickness. Here. it's not critical, as 5 amps is light. Most charts say that ,15 mm nickel, if it is at least 8mm wide, easily handles 5A.
.
More important questions to ask the battery guy.
-Is it pure nickel? If it is, it's prolly a lie,
-Max current rating, even though we think 30 amps is enough,
-Does the BMS balance?
-Brand of cells. If they are name brand cells with datasheets (Samsung, Eve, LG, Sanyom Panasonic, etc), you can verify the quality,

-Cell brand is LG. Do you mean ask for the cell model?

-The controller determines maximum current but isn't it the BMS that manages balanced charge? In addition to the charger if it is a good one. Excuse my ignorance.

-...why are you so sure that ''pure nickel'' for an answer is a lie if you don't know the price of the pack?

 

[harryS]

I beg your pardon then. LG cells are darn good, so if you have them, I wouldn't be worrying about the battery. They're probably MH1 or MJ1,
.
The BMS only limits short circuit current, like 80-100A. Otherwise, it would be pretty expensive to put in a circuit that sets max current and holds it there. Your controller does that anyway. A lot of BMS don't balance either, Saves them a couple of bucks. And some that do balance, as I have discovered, do a lousy job at it, causing my charger to flash on/off. Just my opinion, but for cheap batteries, when the cells start failing, having balance might only keep the battery working a little longer. Having good cells, like your battery, is a good measure of quality.

 

[Nearchos]

I beg your pardon then. LG cells are darn good, so if you have them, I wouldn't be worrying about the battery. They're probably MH1 or MJ1,
.
The BMS only limits short circuit current, like 80-100A. Otherwise, it would be pretty expensive to put in a circuit that sets max current and holds it there. Your controller does that anyway. A lot of BMS don't balance either, Saves them a couple of bucks. And some that do balance, as I have discovered, do a lousy job at it, causing my charger to flash on/off. Just my opinion, but for cheap batteries, when the cells start failing, having balance might only keep the battery working a little longer. Having good cells, like your battery, is a good measure of quality.

Any balancing BMS producer you have a preference for?


...any Chinese balancing BMS producer you have a preference for?

 

[tomjasz]

Please make it easy on yourself. Don't question tried and true methods. It's all been done before and IMO
it's best to just follow an excellent pattern. You have all the information. Use a decent BMS and DO USE THE WIRiNG!

My chinese pack builder asserts that modern cells are very consistent and it is not necessary for such a low voltage...

I'm not clear on what is considered a "second" set of wires. You should use the balance wire that plug into the BMS.
"0, 15" is good.

 

[tomjasz]

Looks like you're getting the same info on endless_sphere...

 

[Dorkyman]

I get nervous when I read threads such as this one. Admittedly, I'm new to the world of ebikes, but after seeing the effects of runaway/damaged cells on YouTube I have to conclude that we are playing a risky game--if thermal runaway ever should happen for any reason, it will happen big-time and the resulting fire will be very aggressive. It could be that cells or packs that are not UL certified would be banned from import in the future.

I've done a lot of electronics hobbying in the past, and built my own gear as a ham radio enthusiast as a kid, so I'm not immune to the satisfaction that comes from building something myself.

Today, I am owner of several rental properties. I wonder if any future leases will need to include a clause that "non-UL-certified rechargeable cells or batteries will not be kept indoors."

Thoughts, please.

 

[tomjasz]

I get nervous when I read threads such as this one. Admittedly, I'm new to the world of ebikes, but after seeing the effects of runaway/damaged cells on YouTube I have to conclude that we are playing a risky game--if thermal runaway ever should happen for any reason, it will happen big-time and the resulting fire will be very aggressive. It could be that cells or packs that are not UL certified would be banned from import in the future.

I've done a lot of electronics hobbying in the past, and built my own gear as a ham radio enthusiast as a kid, so I'm not immune to the satisfaction that comes from building something myself.

Today, I am owner of several rental properties. I wonder if any future leases will need to include a clause that "non-UL-certified rechargeable cells or batteries will not be kept indoors."

Thoughts, please.

Provide lockers for batteries?

 

[Nearchos]

Please make it easy on yourself. Don't question tried and true methods. It's all been done before and IMO
it's best to just follow an excellent pattern. You have all the information. Use a decent BMS and DO USE THE WIRiNG!

I'm not clear on what is considered a "second" set of wires. You should use the balance wire that plug into the BMS.
"0, 15" is good.

Thanks a lot for the input.

I am too ignorant to question anything about E-Bike batteries. This why I am here, to see what people who know more than me think when the Chinese battery pack assembler says that good nickel sheet connectors are enough and secondary wiring is not necessary below 70V...

 

[tomjasz]

Thanks a lot for the input.

I am too ignorant to question anything about E-Bike batteries. This why I am here, to see what people who know more than me think when the Chinese battery pack assembler says that good nickel sheet connectors are enough and secondary wiring is not necessary below 70V...

A great forum here but endless_sphere is a better spot for battery builders. FWIW