My experimental no-solder, no-weld battery pack

[Gary Shannon]

I'm building a cargo trike from a Schwinn Meridian. My enclosed cargo box will hold two battery packs, 18 volts each, flat against the left and right inside walls. I wanted the batteries to be as flat as possible, instead of the usual "boxy chunk" battery packs. So here's what I'm trying:

To connect the batteries without soldering or welding, I'm using aluminum angle pieces as bus bars:

On the side of the busbar that touches the positive terminal I punched a "pimple" that sticks out far enough to make good contact with the positive end of the battery. I filed each pimple flat to give a better area of contact.

On the negative end of the battery, to put "spring tension" on the battery, I wrapped a piece of thick, rigid plastic foam (kindly provided by Schwinn in the box my Meridian came packed in) in several layers of aluminum foil. Pushing the battery into place compresses the foam and makes a very tight contact. Each parallel row of cells is held down by an aluminum strap over a piece of foam plastic.

Fully loaded with terminals for balance leads. A mirror-image pack will go on the opposite wall of the cargo box.

 

[George S.]

That's a great experimental build. I know of three solderless systems, Vruzend, BatteryBlok, and NESE. I think you can use thermal type cameras, infrared, to see where the weak points are. If it gets hot, there is resistance. Test at different amp draws. If you can build on a microcontroller (Raspberry Pi?) this might work. One of those little laser type thermometers might work.

 

[Gary Shannon]

That's a great experimental build. I know of three solderless systems, Vruzend, BatteryBlok, and NESE. I think you can use thermal type cameras, infrared, to see where the weak points are. If it gets hot, there is resistance. Test at different amp draws. If you can build on a microcontroller (Raspberry Pi?) this might work. One of those little laser type thermometers might work.

UPDATE:

This design didn't work out very well. The batteries tend to work loose and the connections get more flaky as time goes on. For what I spent on various "money-saving" battery experiments I could have bought a battery spot welder to begin with. Lesson learned. Ordering a spot welder.

 

[indianajo]

Thanks for the negative datapoint. A good thing about forums is learning what not to do.

 

[Dan de Angeli]

Hi Gary:

I am trying to upgrade my Yuba Mundo with a bigger battery pack. May I ask where you get your batteries and what size you recomend? Currently I have 18650s (50 total) generating 36v. 10 ah. I would like to double that.

thanks

Dan

 

[Gary Shannon]

Hi,

I got them off eBay from a vendor called durnergy. For what it's worth, the next time I need batteries I'm going to buy a ready-made battery pack and skip all the hassle of building my own. It was an interesting experience, but I found it stressful and time-consuming.

 

[St Michael]

Nice build, nice post. I too am doing an experimental battery pack build with

Cheap 18650 Li Mn batteries, Ya I bought some cheap 18650 Li Mn batteries on E-bay. Lot of 100 high drain 35 Amp 2500 mah for $60, Just as experiment to build a battery pack and to try out my Sunkko 709A spot welder, How could I go wrong? LOL, oh well, while waiting for the batteries I found a site selling them for half the allready super low price I paid for them, Ya a lot of 100 for $32 at (Link Removed - No Longer Exists). That's 32 cents a piece ,( darn, how bad are these batteries) I'm sure I can use these cell's in something, but my as for my 48V 13S 6P battery pack build , well we will see ;-) I will post my test results when when I get these so called 2500 mah 35 amp high drain batteries in.

 

[tomjasz]

Unfortunately those low output budget batteries can be an accident waiting to happen, an$ at tha5 price are likely nowhere near the rated mAh

 

[tomjasz]

Please do update. Free shipping of 100 hazmat rated batteries has my head spinning. Legal packagin* and shipp8ng costs are higher! How well is your 709 working? Do you have Micah Tolls battery building book?

Nice build, nice post. I too am doing an experimental battery pack build withView attachment 19090
Cheap 18650 Li Mn batteries, Ya I bought some cheap 18650 Li Mn batteries on E-bay. Lot of 100 high drain 35 Amp 2500 mah for $60, Just as experiment to build a battery pack and to try out my Sunkko 709A spot welder, How could I go wrong? LOL, oh well, while waiting for the batteries I found a site selling them for half the allready super low price I paid for them, Ya a lot of 100 for $32 at (Link Removed - No Longer Exists). That's 32 cents a piece ,( darn, how bad are these batteries) I'm sure I can use these cell's in something, but my as for my 48V 13S 6P battery pack build , well we will see ;-) I will post my test results when when I get these so called 2500 mah 35 amp high drain batteries in.

 

[St Michael]

Nice build, nice post. I too am doing an experimental battery pack build withView attachment 19090
Cheap 18650 Li Mn batteries, Ya I bought some cheap 18650 Li Mn batteries on E-bay. Lot of 100 high drain 35 Amp 2500 mah for $60, Just as experiment to build a battery pack and to try out my Sunkko 709A spot welder, How could I go wrong? LOL, oh well, while waiting for the batteries I found a site selling them for half the allready super low price I paid for them, Ya a lot of 100 for $32 at (Link Removed - No Longer Exists). That's 32 cents a piece ,( darn, how bad are these batteries) I'm sure I can use these cell's in something, but my as for my 48V 13S 6P battery pack build , well we will see ;-) I will post my test results when when I get these so called 2500 mah 35 amp high drain batteries in.

Nice build, nice post. I too am doing an experimental battery pack build withView attachment 19090
Cheap 18650 Li Mn batteries, Ya I bought some cheap 18650 Li Mn batteries on E-bay. Lot of 100 high drain 35 Amp 2500 mah for $60, Just as experiment to build a battery pack and to try out my Sunkko 709A spot welder, How could I go wrong? LOL, oh well, while waiting for the batteries I found a site selling them for half the allready super low price I paid for them, Ya a lot of 100 for $32 at (Link Removed - No Longer Exists). That's 32 cents a piece ,( darn, how bad are these batteries) I'm sure I can use these cell's in something, but my as for my 48V 13S 6P battery pack build , well we will see ;-) I will post my test results when when I get these so called 2500 mah 35 amp high drain batteries in.

Ok the batteries came in final price $32 for 100 batteries, that's $0.32 a battery. Are they worth thirty two cents each ..... NO, They all worked , they all charged to 4.2 vdc but the highest capacity of all the batteries tested was 455 mAh not the listed 2500 mAh

 

[St Michael]

Unfortunately those low output budget batteries can be an accident waiting to happen, an$ at tha5 price are likely nowhere near the rated mAh

Ok the batteries came in final price $32 for 100 batteries, that's $0.32 a battery. Are they worth thirty two cents each ..... NO, They all worked , they all charged to 4.2 vdc but the highest capacity of all the batteries tested was 455 mAh not the listed 2500 mAh , The 709 works great but should be plugged into a 110 vac 20 amp circuit, with a 15 amp circuit, sometimes the circuit breaker flips.

 

[tomjasz]

Oh well, you have a lifetime supply of marginal flashlight batteries and best of all batteries to practice welding on. I'd build a couple of small packs with them for practice! I use some nickel coated steel ribbon, I got ripped off, to practice on salvage cells.

 

[indianajo]

What do you do, weld nickel tabs on the batteries, then weld the tabs together? Saw nickel tabs on e-bay. Don't you have to have argon or CO2 to make the welds good? I've got a Hobart 250 mig welder, I need to build a 200 ms pulse switch/transistor to make it a spot welder.
I've got a 15 AH 48v scooter battery I got a refund on because the last stack (of 11) connected shook loose in the eleventh mile. 6 volts instantly, 0 with a load. Supposedly Sanyo 18650 cells, we'll see. I disassembled down to the protection board, no obvious prolems with solder joints there. I have the heat shrink tube 800 mm to re-enclose it already.
I got the replacement 15 AH 48 v battery from a sun-ebike.com warehouser (LA) on e-bay. Lasted 60 miles already. With two 58 v batteries in series, I might be able to power my sawz-all and cut up trees and limbs 1000' from the electrical cord. Been using a 10 gauge 700' extension cord but it won't reach the boundaries of my summer camp. Radio Flyer power wagon, anybody?

 

[tomjasz]

What do you do, weld nickel tabs on the batteries, then weld the tabs together? Saw nickel tabs on e-bay.

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