Battery for Tongsheng 36v motor

[peteryou]

I have 2 Bosch 35v 500w batteries can these be used with a tongsheng motor? I can't see if the BMS will be affected.
Thanks
Peter

 

[soundwave]

no there can bus locked to only work with a bosch controller

 

[peteryou]

no there can bus locked to only work with a bosch controller

Thanks that's what I thought. Just hoped there might be a work around.

 

[soundwave]

you could rip out the bms and replace it but those batts are expensive so might be better to sell them and get 1 big batt custom made.

there £633 new and not many about last time i looked

 

[peteryou]

Yes I'm e-biking a tandem so will most likely go down the custom route.

 

[soundwave]

eBike Batteries

ebikebatteries.co.uk

they can custom make any size batt you want and use copper to connect the cells and has a 30k spot welder

 

[Bonzo Banana]

Torque sensor based mid-drive motors typically have the widest current range they use. When climbing a hill with the motor providing maximum torque which could be in the range of 80-100Nm they use a huge amount of current somewhere between 600-800W for so called legal motors and often above that for mid-drive motors rated above 250W. You need a very good high capacity battery pack. You can't cheap out with a mid-drive motor unless you can restrict the wattage somehow but then why buy a mid-drive if you are doing that? Surely the joy of a mid-drive is the super high torque output.

 

[Bikes4two]

Oh dear, another scaremongering ebike fire pic!

250w rated (as in continuous power) are perfectly able to develop peak powers well in excess of 250w as has been said but this is perfectly normal and legal so to do.

Let's say there's a peak power of 800W (not likely BTW, but worst case and all that!) and the battery is nominally 36v - that gives a current 800/36 = 22 Amps which in lithium ebike battery terms is no great shake and certainly not huge.

For my own TSDZ2 (36v 250w) I use a 10Ah bottle battery which has a 20Amp fuse at the discharge port and whilst I rarely do so, I have ocassionally ridden at max assist just for the fun of it and the fuse has not blown.

 

[Nealh]

If you can get good money for the bosh batteries then sell them , if not simply rip out the bms and use a generic bms .

 

[Bikes4two]

Re-using the Bosch batteries might well turn out to be the best option, providing you're OK with replacing a BMS and any other work needed in terms of battery cables, connectors and so forth (not a straight forward task for those unfamiliar with that sort of work).

I don't know what money you might get for Bosch batteries? It might be a lot less than the cost of alternative batteries for the tsdz2 build.

 

[soundwave]

problem is those batts are held together with 4 clips each side and is a pita to get it removed without braking them.

also the new smart batts wont work with the older motors even tho they will fit but how much there worth depends how many charge cycles they have had.

a bosch dealer can give you a print out but they will want paying for it.

 

[Bonzo Banana]

Oh dear, another scaremongering ebike fire pic!

250w rated (as in continuous power) are perfectly able to develop peak powers well in excess of 250w as has been said but this is perfectly normal and legal so to do.

Let's say there's a peak power of 800W (not likely BTW, but worst case and all that!) and the battery is nominally 36v - that gives a current 800/36 = 22 Amps which in lithium ebike battery terms is no great shake and certainly not huge.

For my own TSDZ2 (36v 250w) I use a 10Ah bottle battery which has a 20Amp fuse at the discharge port and whilst I rarely do so, I have ocassionally ridden at max assist just for the fun of it and the fuse has not blown.

You haven't actually mentioned anything about the battery pack. A 20A fuse won't typically blow at 20A they normally have a tolerance above. The whole point is how much stress you are putting each individual cell under when the discharge rate is close to their maximum repeatedly. You design in over-capacity so the cells get an easier life and less chance of failing and leading to a fire which will engulf the whole battery pack. 20A at 36V is 720W. I've got a 48V 13Ah battery pack that allows for 25A sustained output and 30A momentary peak and should be safe but smaller battery packs may only provide 15A sustained output and perhaps 20A momentary peak which would be completely unsafe for that application. It would be fine for a hub motor controller that only peaks around 11A and is sustained at about 7-8A. Also bear in mind many battery packs over-state specification a little bit.