Do they exist!!

[Low]

Hi there, took several posters advice and bough my self a second hand cyclocicty 1000wat 48volter... AWESOME

Before buying i was toying with diy on my old bike and managed to buy 200 tested 2nd hand 18650s.. All tested at 1700mah, id like to build an extra battery with them to pit on a cycle rack, iv got a solder and a glue gun but really am not that clever with the actual application... Then, i saw this..

 

[Low]

My question is... Is there such a thing as a pre wired case that is a "just add batteries" affair, would be awesome if there was a box that when full gave me 20ah at 48 volts, could just balance my batteries and wack them in!

Do they exist ?

 

[craiggor]

My question is... Is there such a thing as a pre wired case that is a "just add batteries" affair, would be awesome if there was a box that when full gave me 20ah at 48 volts, could just balance my batteries and wack them in!

Do they exist ?

Try searching endless sphere for solderless battery,for all the homemade ones.I suppose no one makes them to sell because putting one battery in the wrong way and you will have a fire on your hands.

 

[Low]

Yep thats what i figured.... I think with the right protection and balance chargability they woukd prob sell well.. Figured the amount of home builds on line prob means they dont exist

Cmon china sort it out

 

[Deleted member 4366]

To use your cells you need a spot-welder. You can get them from Aliexpress/Ebay for about £100. You also need the nickel strip to join them.

Unless your cells are tabbed, soldering can damage them because you need a lot of heat to join anything to them.

1700mah cells won't fit in many of the cases. The one you showed is a 52 cell case, so you'd only get 13S4P, which would be 6.8Ah and maximum current of 20 amps if you're lucky. For your motor/controller, you'd need at least 13S6P to get a useful battery from those cells.

Modern cells are double the capacity and three times the current of your present ones. Weight is the most important characteristic for an electric bicycle, so there's a lot of advantage to buy a ready-made modern battery and swallowing the cost. The 52v 6.6Ah Mighty Mini battery from Luna only weighs 3 pounds.

 

[Low]

Thank for the help all... I know the sells are naff but i got 200 of them to burn,
Even a cheeky 6ah would help, wont spot weld as dont want to pay the 100 pounds, will solder and see of i get away with it, gallon of flux on standby

Going to go 13 across and 9 high, bout 18ah [i think], bear in mind i personally resemble a bone wrapped in clingfilm re body weight

 

[Deleted member 4366]

Do the 9 highs first so that you have 13 separate blocks. Leave a small gap between 4 and 5 so that you can solder a central joining wire. That way, you can use thinner wire to join the 9, since you only have half the current running each way to the central point. Maybe 16g stranded wire. That means less heat. Then run 12g wire down the middle to join them in series. Leave a slight extension on the parallel wireson one end so that you can attach the sense wires forthe BMS.

YOU NEED TO BE VERY TIDY AND CAREFUL TO AVOID BIG SPARKS. You'll be surprised to see how easy it is to short things out when you're building a pack.

 

[Low]

Great advice, i will do that, thankyou

 

[Deleted member 4366]

One more thing. When you build your 9P strings, wrap some gaffa tape or something similar around them. Just leave the places where you need to solder further exposed. That will prevent a lot of shorting out during the build.

 

[Low]

Thanks deva much appreciated, time to hit utube a learn gow to balance batterys on the cheap

 

[Low]

Thanks deva much appreciated, time to hit utube a learn gow to balance batterys on the cheap

Perhaps learn some spelling while I'm there!

 

[Gringo]

Back in the day, building ni-cad & NiMh packs for RC cars and I'd use the biggest iron I had (110w). Hard and fast to minimise heat transfer

If you use a low power iron you'll have it on the cells for very long time before the solder flows and that will damage the internals

 

[soundwave]

what you need is some thick ass nails and a 1000w soldering iron

 

[Gringo]

what you need is some thick ass nails and a 1000w soldering iron

That guys iron is 300w not a 1000w, beats me by 50w. My biggest is only 250w (the big black one at the top

 

[Low]

Im rocking 100 watts of ebay cheapness... Doubt if it will even last the job!!

 

[soundwave]

had them for years and still working tho the gas one has been in bits a few times and loose gas unless if left up right.