For ES not facebook group users (DIY 48V pack)

I've just finished a 48V 18650 13s15p cells battery pack from tumich rejected Bosch packs, I'm use to share things on the ES Facebook group (because is quickier and easier for me to answer and make questions) I've couldn't done the Job without tons of coffee and hours of reading this awesome forum, so I'm pretty greatful and an honor for me to share this low cost battery pack building with all of You. These are my 2 cents on battery building

[youtube]5L9hOVG_0RQ[/youtube]

Nicely done .. the bus bars seem a bit excessive as well as the extra hot glue ( the weight adds up !!!.. and word of caution, hot glue softens up if/when the cells get hot .. and it can run and settle with gravity lol.. ) but that looks like a solid pack. 8)

details on the spot welder ?

Very professional build. Heat gun and an 80w iron would be worth getting. I use silicone for the adhesive, provides some vibration and won't run. Cheap house caulk. I was on track to build a spot welder, but never got around to finishing it. Ended up just soldering my last few packs, which can be fine if you do it quick.

good video - thanks for sharing.

...When you are soldering you need to get more heat into the job - looks like your soldered wires may be 'dry-jointed' - which can be problematic. The solder wants to be in a completely liquid state - then cool and solidify in one mass.

Ypedal said:

Nicely done .. the bus bars seem a bit excessive as well as the extra hot glue ( the weight adds up !!!.. and word of caution, hot glue softens up if/when the cells get hot .. and it can run and settle with gravity lol.. ) but that looks like a solid pack. 8)

details on the spot welder ?

Click to expand...

Thank You, indeed I wanted to reduce electrical resistance to the minimun and get nickel strips cooler, so of course, it's paid with a little more weight. As I tested, charging the battery at 0.15C (6A) doesn't let me feel even a bit warm, for 10A-20A EV purposes I can't notice anyting too (will see how it goes in summer). Only the 1000W hub motor gets warm. I hope I can upload soon a video with the EV.

This is the cheapest spot welder junk You can buy, and I did:
http://aliexpress.com/item/Hand-hel...attery-Pack/594538510.html?recommendVersion=1

kfong said:

Very professional build. Heat gun and an 80w iron would be worth getting. I use silicone for the adhesive, provides some vibration and won't run. Cheap house caulk. I was on track to build a spot welder, but never got around to finishing it. Ended up just soldering my last few packs, which can be fine if you do it quick.

Click to expand...

This is a low cost build.. :wink: but I hope I can get soon a hot gun and a relgulable iron solderer. The magic about spot welding 18650 is that takes a very thin space, just 0.15 in this case milimeters and is really stone strong solded. I guess silicone is better choice

Willow said:

good video - thanks for sharing.

...When you are soldering you need to get more heat into the job - looks like your soldered wires may be 'dry-jointed' - which can be problematic. The solder wants to be in a completely liquid state - then cool and solidify in one mass.

Click to expand...

Completely agree with You, but I am mad to avoiding heating up the cells, I checked that soldered wires where enough strong before wrapping.

Hi Damian, I'm also waiting on some LG cells from Tumich and have a few questions with your build:

Where did you get / build the capacity meter ?
Where did you get the shrink tubing from ?
What kinds of problems did you run into when spot-welding etc. ?

Any chance also of a closeup of how you routed the battery balance leads?

I may copy your design although i have a very tight frame size to fit it all in

Regards,
Jazzman56

Well done nice battery build there and also respect for the quality video work topped off with one of my favorite tunes, M83 Midnight City.
I'm also interested in that capacity meter.
Cheers

It reminds me of a pack made by another member who didn't use bracket and glue it all a year ago:
http://endless-sphere.com/forums/viewtopic.php?f=14&t=52710

His pack has lost 30% capacity in a year time. A couple of reason come to my mind but the key one is that the pack was probably getting too hot. Also, there is a risk that glue become loose over time with bike vibration.

I hope it will hold over time and not have the same destiny as the previous member... who decided to go back to A123

Jazzman56 said:

Hi Damian, I'm also waiting on some LG cells from Tumich and have a few questions with your build:

Where did you get / build the capacity meter ?
Where did you get the shrink tubing from ?
What kinds of problems did you run into when spot-welding etc. ?

Any chance also of a closeup of how you routed the battery balance leads?

I may copy your design although i have a very tight frame size to fit it all in

Regards,
Jazzman56

Click to expand...

I got this capatity meter, it is configurable for different chemistries and between 2s and 13s according to description but the display admits more, so maybe till 16s
http://aliexpress.com/item/-/2006977930.html?recommendVersion=1

The heat shrink tubes are very easy to get everywhere. I guess you mean the battery shrink wrap? this one: http://aliexpress.com/item/10pcs-wi...gth-1000mm/1858382198.html?recommendVersion=1

When Spot welding the main problem is that it is not hand probes built-in, so You will have to be very imaginative on the nickel strips configuration/steps to spot solder all the battery pack. Another problem is that You must test the right current to the specific nickel strip You use, because the nickel would stick to the electrodes, make weak solder, desintegrate it with a hole, also it requires a large amount of current that can make continuosly blackout if You work at home. I highly recommend hand probes spot welder to reduce time and simplify the welding.

The diamond nickel strip pattern acts as balance leads, if You mean the BMS wires routing, simply as connected between each paralelled group and main leads (as usually is done).

Are You going to copy my desing? are You sure You will pay the pantent royalties? hahah just kidding!, Of course it would be an honor if You copy my desing, in fact it has been made with ideas from everywhere except the way I spot weld everything with that spot welder, that was my very own thing.

1000w said:

Well done nice battery build there and also respect for the quality video work topped off with one of my favorite tunes, M83 Midnight City.
I'm also interested in that capacity meter.
Cheers

Click to expand...

Thank You!, awesome band I follow since "Don't save us from the flames" gem. This is the metter. http://aliexpress.com/item/-/2006977930.html?recommendVersion=1

cwah said:

It reminds me of a pack made by another member who didn't use bracket and glue it all a year ago:
http://endless-sphere.com/forums/viewtopic.php?f=14&t=52710

His pack has lost 30% capacity in a year time. A couple of reason come to my mind but the key one is that the pack was probably getting too hot. Also, there is a risk that glue become loose over time with bike vibration.

I hope it will hold over time and not have the same destiny as the previous member... who decided to go back to A123

Click to expand...

similar? maybe the hot glue and the color of the cells haha, I will report for good or for bad how it response over time, for now I have no heat on charge or discharge as I wrote on the updated description.

As I've experimented the glue sticks to the cells cover extremely hard, as the point almost destroy one cell trying to take out a not thick enough glue strap. The battery has some pads to balance the weight and absorb vibrations (there is more flexible pad on the ending installation)

Nice build!

I wouldn't recommend silicone for two reasons. 1. Silicone draws water to it from the air. 2. Replacing bad cells would be a nightmare!
If the battery is getting hot enough to melt hot glue, it's being pushed way too hard.

Very nice job. Spot welder no longer available?

Dan

Thankyou Damian,

Definitely liking that capacity meter for the price
I'll have to look into getting hand held probes for spot-welding and make sure to dial the current in first

Jazzman

DAND214 said:

Very nice job. Spot welder no longer available?

Dan

Click to expand...

It looks that is gone, but there are other sellers on ebay or Aliexpress that sells exactly the same spot welder. Don't pay more than 140$ for that junk

ErnestoA said:

Nice build!

I wouldn't recommend silicone for two reasons. 1. Silicone draws water to it from the air. 2. Replacing bad cells would be a nightmare!
If the battery is getting hot enough to melt hot glue, it's being pushed way too hard.

Click to expand...

I will take that into account, I will report if something go wrong with the glue. At the moment neither charge or discharge makes the battery even a little warm, we'll see at summer time..

Jazzman56 said:

Thankyou Damian,

Definitely liking that capacity meter for the price
I'll have to look into getting hand held probes for spot-welding and make sure to dial the current in first

Jazzman

Click to expand...

It works as perfectly as You can imagine, I've tested it with a multimeter and shows 50% exactly at 48V and 100% at 54V. Even the power consumption is barely apreciable, I recomend to use with a switch, or buy the momentary button that fits the hole in the screen.

pick super size wires or the welding will be far away than from electrodes (~6AWG)