AliExpress battery pack unboxing (for my eZuma project)

Batteries, Chargers, and Battery Management Systems.
Post Reply
User avatar
MJSfoto1956   10 kW

10 kW
Posts: 959
Joined: Jul 28 2010 9:28pm
Location: Boston, MA

AliExpress battery pack unboxing (for my eZuma project)

Post by MJSfoto1956 » Jan 27 2019 4:28pm

So I took a chance and purchased a 57Ah Li-ion battery pack from an AliExpress vendor touting 8 years experience. The nice thing was how easy it was to work with them -- I requested a custom configuration not shown on their web store (i.e. 20s17p/120A BMS) and within a day they gave me a link to finalize the purchase. Took more than 4 weeks to get here, but I expected that. Here is the actual pack after it arrived via Fedex Ground (N.B. I Photoshopped the background out):

AliExpress battery IMG_6796.1200.jpg
AliExpress battery IMG_6796.1200.jpg (168.06 KiB) Viewed 5884 times

Being the curious type, I wanted to see how this battery was constructed. So off came the PVC shrink wrap et voilá. Interesting how little Kapton tape they used. Instead opting for double-stick + six plastic panels. They used hot glue to glue the cells together into a grid pattern. The Anderson plugs are soldered not crimped. Not shown, but there are 140mm long serial bus bars on the bottom that carry the load from one side of the battery to the other (essentially two 10s17p batteries in series). Another weakness I can see is that all the power flows through just the very end of a single nickel strip. And finally, the dumb BMS they installed on this pack is this one: http://www.best-way.cn/html/product/580.html.

20s17p AliExpress Battery Pack IMG_6804.1200.jpg
20s17p AliExpress Battery Pack IMG_6804.1200.jpg (450.69 KiB) Viewed 5539 times

Looking for ideas here, but I think I will solder in a beefier terminus for the positive and negative leads. I might also change out the BMS to something with Bluetooth, add a heatsink, then mount it external to the pack. Finally, I'm thinking it would be a good idea to add some silicone thermal pads to the sides to absorb some heat.

20s17p AliExpress Battery Pack IMG_6806.1200.jpg
20s17p AliExpress Battery Pack IMG_6806.1200.jpg (431.86 KiB) Viewed 5539 times

So that's it for now. Any cheap and easy ideas to improve this pack will be greatly appreciated.

M
Last edited by MJSfoto1956 on Aug 15 2019 11:04am, edited 8 times in total.
Bois and their fancy tacticool ain't cool -- it's a pathetic circle jerk

QANON is a sick cult: https://www.rollingstone.com/culture/cu ... e-1064076/

hemo   100 W

100 W
Posts: 198
Joined: Mar 30 2016 5:13pm
Location: England, GB ( UK).

Re: AliExpress battery pack unboxing

Post by hemo » Jan 27 2019 6:17pm

120a BMS what is the nickel size as there are only seven series buss, might be well worth adding one for every series link to carry the loading if you are able to separate the pack to get to the middle.

999zip999   100 GW

100 GW
Posts: 10198
Joined: Jan 10 2010 1:40pm
Location: Dana Point So. Cal

Re: AliExpress battery pack unboxing

Post by 999zip999 » Jan 27 2019 8:25pm

How much did you pay ? What cells ? I agree more series buss bars can only help. What amps will you be using it at ?

User avatar
MJSfoto1956   10 kW

10 kW
Posts: 959
Joined: Jul 28 2010 9:28pm
Location: Boston, MA

Re: AliExpress battery pack unboxing

Post by MJSfoto1956 » Jan 27 2019 11:01pm

999zip999 wrote:
Jan 27 2019 8:25pm
How much did you pay ? What cells ? I agree more series buss bars can only help. What amps will you be using it at ?
  • I paid $1692.00
  • (340) LG 3350mAh cells
  • I plan on running it @ 83A, or approx 1.5C
Michael
Bois and their fancy tacticool ain't cool -- it's a pathetic circle jerk

QANON is a sick cult: https://www.rollingstone.com/culture/cu ... e-1064076/

User avatar
MJSfoto1956   10 kW

10 kW
Posts: 959
Joined: Jul 28 2010 9:28pm
Location: Boston, MA

Re: AliExpress battery pack unboxing

Post by MJSfoto1956 » Jan 27 2019 11:10pm

Given that I will be using a PowerVelocity 20kWh controller with this pack and that PV's new iPhone App now supports "smart" BMS's, I'm definitely leaning towards replacing the supplied "dumb" 120A controller with a "smart" 150A controller and then perhaps mount it external to the battery, optionally with a heatsink. Something like this:

External BMS.1024.jpg
External BMS.1024.jpg (368.08 KiB) Viewed 5834 times
M
Last edited by MJSfoto1956 on Jan 30 2019 6:15pm, edited 1 time in total.
Bois and their fancy tacticool ain't cool -- it's a pathetic circle jerk

QANON is a sick cult: https://www.rollingstone.com/culture/cu ... e-1064076/

armandd   100 W

100 W
Posts: 110
Joined: Jan 18 2018 4:46am
Location: Malaysia

Re: AliExpress battery pack unboxing

Post by armandd » Jan 28 2019 12:31am

Interesting... subbed. :bigthumb:

TilmanBaumann   100 W

100 W
Posts: 120
Joined: Feb 15 2018 10:32am

Re: AliExpress battery pack unboxing

Post by TilmanBaumann » Jan 28 2019 3:36am

That nickel strip is a bit unfortunate. But you'd be putting in a lot of heat trying to solder on a copper busbar.
Perhaps just add a second tap off on the other end of the strip.

Silicone cooling pad is a great idea. It's always best to suck the heat from the terminals.

The smart BMS has one great benefit, you can watch the cell temperatures and adapt your driving accordingly.
Just in case those cells aren't what they say they are...

hemo   100 W

100 W
Posts: 198
Joined: Mar 30 2016 5:13pm
Location: England, GB ( UK).

Re: AliExpress battery pack unboxing

Post by hemo » Jan 28 2019 6:39am

Add one more series buss to each unconnected cell as you have an odd cell count number in parallel, it will help to carry/share the load equally.

Where yo have depicted a 2awg rod/wire. If you only plan on about 80-90a draw you can solder 4 smaller lengths of 12 awg buss along the parallel strip (3 strips to cover 4 cells & 1 to cover 5 cells) firstly solder them along one edge of a wider nickel strip 18/20mm. Then add a discharge lead to the center of each of the small awg buss strips, terminate the four discharge leads in to one larger 6 or 8awg lead. Having done this spot weld the nickel to the existing parallel strip. That way instead of discharge going thru the very end cell, you take the discharge from 4 smaller cell groups in the parallel row for less cell stress.

Do the same for both negative lead as well.

User avatar
MJSfoto1956   10 kW

10 kW
Posts: 959
Joined: Jul 28 2010 9:28pm
Location: Boston, MA

Re: AliExpress battery pack unboxing

Post by MJSfoto1956 » Jan 28 2019 8:43am

hemo wrote:
Jan 28 2019 6:39am
...you can solder 4 smaller lengths of 12 awg buss along the parallel strip (3 strips to cover 4 cells & 1 to cover 5 cells) firstly solder them along one edge of a wider nickel strip 18/20mm. Then add a discharge lead to the center of each of the small awg buss strips, terminate the four discharge leads in to one larger 6 or 8awg lead. Having done this spot weld the nickel to the existing parallel strip. That way instead of discharge going thru the very end cell, you take the discharge from 4 smaller cell groups in the parallel row for less cell stress.
While the description above is great, a picture would help me understand things a bit better. I'll bet there already is a photo somewhere here on ES, but try as I might, I can't seem to find something that matches your description.

Cheers
Michael

P.S. I don't have access to a spot welder, so I will be looking for something that is a pure solder approach
Bois and their fancy tacticool ain't cool -- it's a pathetic circle jerk

QANON is a sick cult: https://www.rollingstone.com/culture/cu ... e-1064076/

User avatar
MJSfoto1956   10 kW

10 kW
Posts: 959
Joined: Jul 28 2010 9:28pm
Location: Boston, MA

Re: AliExpress battery pack unboxing

Post by MJSfoto1956 » Jan 28 2019 8:47am

TilmanBaumann wrote:
Jan 28 2019 3:36am
That nickel strip is a bit unfortunate. But you'd be putting in a lot of heat trying to solder on a copper busbar.
Perhaps just add a second tap off on the other end of the strip.
I like that idea. I wonder if a woven grounding strap might not be easier to solder?
Something like this: https://www.zoro.com/quickcable-ground- ... /G7626936/

Image

M
Bois and their fancy tacticool ain't cool -- it's a pathetic circle jerk

QANON is a sick cult: https://www.rollingstone.com/culture/cu ... e-1064076/

999zip999   100 GW

100 GW
Posts: 10198
Joined: Jan 10 2010 1:40pm
Location: Dana Point So. Cal

Re: AliExpress battery pack unboxing

Post by 999zip999 » Jan 28 2019 11:24am

What I use is a 80amp weller big fat tip iron and a very little solder paste. Use can use multi strand insulated copper wire and just pretin the ends. Can use a dabbing sponge to pull away the heat if worried.
Last edited by 999zip999 on Jan 28 2019 5:33pm, edited 1 time in total.

User avatar
MJSfoto1956   10 kW

10 kW
Posts: 959
Joined: Jul 28 2010 9:28pm
Location: Boston, MA

Re: AliExpress battery pack unboxing

Post by MJSfoto1956 » Jan 28 2019 4:22pm

999zip999 wrote:
Jan 28 2019 11:24am
What I use is a 80amp weller big fat tip iron...
I assume you mean Weller 80W. Yeah, I'll need to pick one up. Amazon has one for $20: https://www.amazon.com/Weller-SP80NUS-8 ... B00B3SG796

Is that what you mean?

M
Bois and their fancy tacticool ain't cool -- it's a pathetic circle jerk

QANON is a sick cult: https://www.rollingstone.com/culture/cu ... e-1064076/

User avatar
MJSfoto1956   10 kW

10 kW
Posts: 959
Joined: Jul 28 2010 9:28pm
Location: Boston, MA

Re: AliExpress battery pack unboxing

Post by MJSfoto1956 » Jan 28 2019 4:34pm

999zip999 wrote:
Jan 28 2019 11:24am
What I use is a 80amp weller big fat tip iron and a very little solder paste. Use can use multi strand insulated copper wire and just pretend the ends. Can use a dabbing sponge to pull away the heat if worried.
WRT using braided wire, I was inspired by an earlier thread here on ES: viewtopic.php?t=81928. Notice how he only solders the braid in-between the cells.

Image
Bois and their fancy tacticool ain't cool -- it's a pathetic circle jerk

QANON is a sick cult: https://www.rollingstone.com/culture/cu ... e-1064076/

999zip999   100 GW

100 GW
Posts: 10198
Joined: Jan 10 2010 1:40pm
Location: Dana Point So. Cal

Re: AliExpress battery pack unboxing

Post by 999zip999 » Jan 28 2019 5:40pm

Yea it holds solder like a and can be used as solder wick. Maybe I would feel better with it being insulated after. With fiber board or a tape. Plus I like gaskets on pos end. A.W. and DrAngle like the braided stuff. I always wear a rubber. 25 cent of rubber can save alot of money over time.

User avatar
MJSfoto1956   10 kW

10 kW
Posts: 959
Joined: Jul 28 2010 9:28pm
Location: Boston, MA

Re: AliExpress battery pack unboxing

Post by MJSfoto1956 » Jan 28 2019 5:50pm

999zip999 wrote:
Jan 28 2019 5:40pm
... Maybe I would feel better with it being insulated after...
Isn't that what Kapton tape is for? :P

(Also, don't forget the yellow plastic insulation boards that came with my battery. See earlier photos.)

M
Bois and their fancy tacticool ain't cool -- it's a pathetic circle jerk

QANON is a sick cult: https://www.rollingstone.com/culture/cu ... e-1064076/

999zip999   100 GW

100 GW
Posts: 10198
Joined: Jan 10 2010 1:40pm
Location: Dana Point So. Cal

Re: AliExpress battery pack unboxing

Post by 999zip999 » Jan 29 2019 1:22am

Ok. I agree. Just saying. That big of pack has lots of stored energy 54ah. Wow... Let's us know how that work. I do like my powervelicty. Controllers 18fet and 15 fet. But bt bms also ? Wow.
I'm looking for a 20s 9p or 10p Samsung 30q just looking to find a good supplier.

Tolkano   100 W

100 W
Posts: 154
Joined: Dec 29 2017 4:28am
Location: South Australia

Re: AliExpress battery pack unboxing

Post by Tolkano » Jan 29 2019 1:40am

Isn't that pack built pretty badly?

7 series connections per 34 cells?
Main positive and negative soldered to 1 single cell at the end

I think the entire layout should be different too

hemo   100 W

100 W
Posts: 198
Joined: Mar 30 2016 5:13pm
Location: England, GB ( UK).

Re: AliExpress battery pack unboxing

Post by hemo » Jan 29 2019 8:04am

MJSfoto1956 wrote:
Jan 28 2019 8:43am
hemo wrote:
Jan 28 2019 6:39am
...you can solder 4 smaller lengths of 12 awg buss along the parallel strip (3 strips to cover 4 cells & 1 to cover 5 cells) firstly solder them along one edge of a wider nickel strip 18/20mm. Then add a discharge lead to the center of each of the small awg buss strips, terminate the four discharge leads in to one larger 6 or 8awg lead. Having done this spot weld the nickel to the existing parallel strip. That way instead of discharge going thru the very end cell, you take the discharge from 4 smaller cell groups in the parallel row for less cell stress.
While the description above is great, a picture would help me understand things a bit better. I'll bet there already is a photo somewhere here on ES, but try as I might, I can't seem to find something that matches your description.

Cheers
Michael

P.S. I don't have access to a spot welder, so I will be looking for something that is a pure solder approach

I tried to draw on your batt pic but size was too large for me to upload, so excuse my crude sketch/drawing.

For improved current share/flow you will need to improve the series buss connections, 5 buss for a 17p configuration isn't going to cut it for nickel assuming the nickel is 12mm x 0.15 or 0.2mm. An even number of cells in parallel would have been better then an odd count.
To do this work will take a bit of time to carry out and tries to utilise the battery as it is without pulling it apart completely.
DSCF0935.jpg
DSCF0935.jpg (86.04 KiB) Viewed 5656 times
Each neighbour cell in series needs a buss/link, in my pic Green is the buss. You are soldering so use 16 or 18awg wire to prevent excessive heat to cell ends,though the parallel buss will help to dissipate/soak up some heat. Or you could use 10/15a rated tinned copper braid 2mm x .5mm or 2.5mm x.5m. The new soldered series buss needs to ideally to have the same rating as the nickel buss currently used, then you only need to add twelve extra series buss per row, but still time consuming.

The Red indicates the four separate discharge take offs for the cells use 10 or 12awg for this, remove any outer covering and tin the each piece completely.
Once done solder to the existing nickel buss, solder the wire at the very end of each piece and the other solders in between the cells on the nickel. Below Green indicates the solder spots.
DSCF0938.JPG
DSCF0938.JPG (114.33 KiB) Viewed 5656 times
On the first sketch the Blue indicates the four discharge take offs from the four separate cell groups on the first and final parallel string, all though not perfect it will allow for better discharge current flow then the single take off of the original battey build. Again use 10 or 12awg for each take off and culminate them as one to a single 8awg wire for BMS and discharge connector, ideally the four takes off wires want to be the same length so the current flows the same length along the wire.


I suspect other members may offer there musings on how to improve your battery.

User avatar
MJSfoto1956   10 kW

10 kW
Posts: 959
Joined: Jul 28 2010 9:28pm
Location: Boston, MA

Re: AliExpress battery pack unboxing

Post by MJSfoto1956 » Jan 29 2019 2:13pm

tolkaNo wrote:
Jan 29 2019 1:40am
Isn't that pack built pretty badly?
Maybe. Certainly my unboxing has illustrated what someone is likely to receive from a typical AliExpress vendor -- one can only assume that this level of build would be considered "good enough" for the masses in China. I think the unveiling shows how they can and will cut corners wherever they can.

With some straightforward soldering of braided wire I can probably get this pack close to where I want it. And for me, the lesson learned was that I probably could have built my own for a similar price point. Still, I think the gamble was worth it: I know what I'm dealing with now, with the added benefit that others can learn from my experience.

OTOH, if there is a quality AliExpress builder out there, we would all like to learn about them (hint hint).

M
Bois and their fancy tacticool ain't cool -- it's a pathetic circle jerk

QANON is a sick cult: https://www.rollingstone.com/culture/cu ... e-1064076/

User avatar
MJSfoto1956   10 kW

10 kW
Posts: 959
Joined: Jul 28 2010 9:28pm
Location: Boston, MA

Re: AliExpress battery pack unboxing

Post by MJSfoto1956 » Jan 29 2019 3:22pm

So I'm leaning towards buying a bunch of 1" braided tinned copper cable and then solder it to the existing pack as shown below. Shouldn't be that hard to make happen. Probably can finish it over a weekend.

tinned braided wire IMG_6807.v2.1200.jpg
tinned braided wire IMG_6807.v2.1200.jpg (381.11 KiB) Viewed 5623 times
Thoughts?

M
Bois and their fancy tacticool ain't cool -- it's a pathetic circle jerk

QANON is a sick cult: https://www.rollingstone.com/culture/cu ... e-1064076/

hemo   100 W

100 W
Posts: 198
Joined: Mar 30 2016 5:13pm
Location: England, GB ( UK).

Re: AliExpress battery pack unboxing

Post by hemo » Jan 29 2019 4:44pm

25mm braid usually means something like 2mm - 3mm thick so it's going to need a heck of a lot of heating for it to solder on, increasing the chance of cell heat damage.
Smaller braid using about 5mm x 0.7mm or 4mm x 0.8mm braid is about 1.75mm2 so about 25- 30a and much easier to solder, pack is glued so mech strength isn't required of the braid you could zigzag the thinner braid along the series cell group. Starting on the pos end then next solder alternately in between cells as you zig zag along.

User avatar
MJSfoto1956   10 kW

10 kW
Posts: 959
Joined: Jul 28 2010 9:28pm
Location: Boston, MA

Re: AliExpress battery pack unboxing

Post by MJSfoto1956 » Jan 29 2019 4:55pm

hemo wrote:
Jan 29 2019 4:44pm
25mm braid usually means something like 2mm - 3mm thick so it's going to need a heck of a lot of heating for it to solder on, increasing the chance of cell heat damage.
I was thinking that if I pre-soldered the entire length of braid, then placed a blob of solder at all the junctions, I could just hit the braid for a second or two (@ each blob) with a 200W soldering iron and it would go down pretty quickly and easily. Might need to do some testing first though I guess. Note that I would need a total of 27' of 1" braid to complete this design.

BTW, I was thinking of getting some of this stuff: https://www.ebay.com/itm/1-BRAIDED-GROU ... 2036589469. Note that the nominal thickness is just 0.045" (1.37mm).

Cheers
M
Last edited by MJSfoto1956 on Jan 30 2019 6:29pm, edited 1 time in total.
Bois and their fancy tacticool ain't cool -- it's a pathetic circle jerk

QANON is a sick cult: https://www.rollingstone.com/culture/cu ... e-1064076/

hemo   100 W

100 W
Posts: 198
Joined: Mar 30 2016 5:13pm
Location: England, GB ( UK).

Re: AliExpress battery pack unboxing

Post by hemo » Jan 29 2019 5:55pm

A practice on old cells in parallel is a good idea.

User avatar
MJSfoto1956   10 kW

10 kW
Posts: 959
Joined: Jul 28 2010 9:28pm
Location: Boston, MA

Re: AliExpress battery pack unboxing

Post by MJSfoto1956 » Jan 29 2019 8:24pm

I'm pretty satisfied with the following upgrade pattern (see below).
Last chance for any feedback/advice before I commit!

tinned braided wire IMG_6807.v5.1200.jpg
tinned braided wire IMG_6807.v5.1200.jpg (399.25 KiB) Viewed 5538 times
Michael
Bois and their fancy tacticool ain't cool -- it's a pathetic circle jerk

QANON is a sick cult: https://www.rollingstone.com/culture/cu ... e-1064076/

User avatar
MJSfoto1956   10 kW

10 kW
Posts: 959
Joined: Jul 28 2010 9:28pm
Location: Boston, MA

Re: AliExpress battery pack unboxing

Post by MJSfoto1956 » Jan 31 2019 12:31pm

hemo wrote:
Jan 29 2019 5:55pm
A practice on old cells in parallel is a good idea.
Would fabricating a bunch of pre-tinned 12AWG twisted copper wire "modules" as shown below do the trick to improve the inherent serial bus weakness of my pack? (please disregard the strapping tap -- this is just a sketch)

I'm thinking this might be cheaper and easier to implement than braided cable.
twisted wire bus bars.jpg
twisted wire bus bars.jpg (134.38 KiB) Viewed 5523 times
Bois and their fancy tacticool ain't cool -- it's a pathetic circle jerk

QANON is a sick cult: https://www.rollingstone.com/culture/cu ... e-1064076/

Post Reply