The battery is built.... Now for

[Low]

Hi all, massive thanks for all the help iv had, have just finished building my 11p13s battery, going to bag and mount on a rear cycle rack.

I have a 1000watt cyclotricity stealth bike and am just interested in how you guys would combine the original bottle frame battery and my new homemade battery pack, the picture below is of the connection point the bottle battery that came with the bike goes into... Is there any reason i cant take that to pieces and solder my new battery out wires under the pins.. Would the batterys fight each other, could this be done?


Alternativly could i cut into the below wire and splice the two batteries up



Massive thanks again to everyone

Low

 

[Low]

Just wondered also if the two Bms would get confused.. This is my battery

 

[anotherkiwi]

No you can't use both at once, only identical batteries can be put in parallel. Different batteries with the same Amp rating can be put in series to increase voltage.

 

[Andy Bluenoes]

Interested to see how this develops as I have the stealth, and would love to have a bigger battery.
Was it a big job, and how much did it cost to build the battery?

 

[craiggor]

Nice work,did you build your own spot welder ?

 

[Low]

The whole job has cost about 250 pounds so far... Not really all that cost effective, i tried to solder copper first, made a real mess of it, then i tried using a car battery to spot weld, that was equally unpleasant so i bit the bullet and bought the cheapest suncco welder i could.. Hense the 250 outlay, welder was 100 pounds, could easilly have bought a smallish battery for 250 but have really enjoyed the learning experience and i think im pushing 20ish mahs from my borg cube.

Cost wise.. 150 tested ex laptop cells 83quid, imax 25quid, and of course the spot welder at 100quid plus a few minor expences, got all the gear now tho and this defo wont be my last build, going to run her until the motor fails then buy a magicpie and spend real money on massive mah cells brand new.

So its an either or with my pack and the standard bike bottle battery, as always thanks for the info

Ps
Anyone in norfolk.. U are welcome to borrow the spot welder any time.

 

[Low]

Duh.... Anotherkiwi, im so dumb, now u say it its obvious hence arranging the paralel runs in the pack i bought to have the same mah... Spent hours lining em up and adding em up, how quickly i forgot!!

 

[Low]

Actually there is one more thing... The outer two rows dont have series links, i have 6 in total, figure the bars can carry 5amps each do you think iv got enough series conections?

 

[Low]

Decided im going to chop into the lower wire at a conector with a switch so i can toggle between batteries... Anyone recomend a decent switchy connecter type item?

 

[Deleted member 4366]

The welding looks good and I think it's Ok with the strips you have. In fact I think it looks wheelie nice!

You can connect both batteries in parallel as long as they're very close voltage when you connect. You must disconnect them for charging.

Make a simple "Y" connector between the battery receiver and controller, so that you can connect either or both batteries. Don't bother with a switch. Just connect in or out whichever battery/s you want. bear in mind that the unconnected connector will be live, so you might want to use a blanking plug when not in use.

 

[Low]

d8veh, thanks! I will do exactly that... The bottle battery actually has an on off switch, that may help my problem of leaving the terminal live

 

[Low]

Ordered...

 

[Deleted member 4366]

Those connector are pretty good.

The switch on bottle batteries only switches off the BMS. I'm not sure whether that's enough to isolate them. Probably better not to rely on it.

 

[anotherkiwi]

d8veh I am sure I read somewhere that both batteries had to have the same number of cell groups and that the Ah of the smallest one was the one that would be doubled? Is that only aplicable to LiPo?

 

[awol]

A great looking project. I bet you've learnt loads whilst building it and although you think it did not end up cost effective, you now have the equipment for future battery builds which will then work out a lot cheaper.
This is a project I am plannig on doing too later this year or next year hopefully.
I would be interested in knowing the aH of your borg cube and the weight too as I bet you could build one with the same power about 1/2 the size and weight with the new Samsung or Panasonic cells.

 

[Deleted member 4366]

d8veh I am sure I read somewhere that both batteries had to have the same number of cell groups and that the Ah of the smallest one was the one that would be doubled? Is that only aplicable to LiPo?

No, that's not true. the only thing that matters is the voltage. current can only flow between them when there's a voltage difference. I've run a12s LiFepO4 in parallel with a 10S Li-ion for 6 months with no detrimental effects, and that was charging only through one of them, though in theory, that can give balance problems, which can cause consequences.

 

[Low]

A great looking project. I bet you've learnt loads whilst building it and although you think it did not end up cost effective, you now have the equipment for future battery builds which will then work out a lot cheaper.
This is a project I am plannig on doing too later this year or next year hopefully.
I would be interested in knowing the aH of your borg cube and the weight too as I bet you could build one with the same power about 1/2 the size and weight with the new Samsung or Panasonic cells.

Yes awol, have learnt lots and actualky quite enjoyed it, charged and discharged i got just over 15Ah which for 143 cells is rubbish! Defo couod get that with

 

[Low]

Yes awol, have learnt lots and actualky quite enjoyed it, charged and discharged i got just over 15Ah which for 143 cells is rubbish! Defo could get that with Far less cells and weight, suspect these 2nd hand cells are well past it but as you say, well worth it all for learning power alone.. Next build is going to be 200 pounds worth of the best cells i can get

Make a nice lightweight monster, just hope the extra run time a bigger battery wont burn the motor out

 

[awol]

Next build is going to be 200 pounds worth of the best cells i can get

Jimmy at Insat is highly regarded on this forum and will sell the best genuine cells, he could also advise you on the best ones for your application if you call first.
http://www.bga-reworking.co.uk/e-bike-batteries.html

 

[Low]

thanks il bear that in mind.. Its amp hours im interested in over discharge power, see how long this battery lasts me tho, need a bike rack and bag either way so size and weight arnt thr end of the world to me, plus im a lightweight myself so already have a head start... Certainly would be good to have the same power for the whole journey as i feel for the first mile.

Can anyone tell me what N- stands for on a BMS, google has failed me