Torque

[Andy1865]

Does anybody know what the torque is of a 500watt cyclotricty kit that will be running off a 36volt battery and the controller is 30amp so i believe. Thank you.

 

[Benjahmin]

Hot of the charger, at 30 amps, that's going to give you 1512 watts, not allowing for inefficiecy's. Torque then depends on motor gearing and, when figure is quoted, it's never stated where it's measured. i.e. at the wheel or the motor axle, thereby mostly meaningless.
As is the 500w rating of the motor. This figure is merely the continuous rating and nothing to do with it's actual power.
Better make sure you've got a well impressive battery !

 

[Andy1865]

All i know its a 250/500watt kit that im having fitted and that the company is useing my orginal 36v samsung battery that i have now.

 

[Nealh]

Torque should be greater as by sounds of it you are upgrading to higher spec controller, the torque will be mostly the same whether 250 or 500w.
Though I doubt your 36v battery will be grateful for having to supply 30a discharge If asked to, you don't say what the battery or cell product is used except for Samsung and they make a lot of cells. For EV use Samsung only really make a couple of very good 18650 cells for ebikes. Most batteries use 4 or 5 cells in parallel and the majority of these aren't up to supplying a 30a peak load without issues, only the 25R & 30Q are capable in 4 or 5p config.

 

[Andy1865]

Its a freego hawk with a samsung 36v and 15.6Ah battery. My current controller is nominal 7a and limit 15a. The one the company is putting in is rated 15a and max 30a. The kit is 250/500 cyclotricity. Thats all i know Nealh

 

[Nealh]

At a guess 15.6ah suggests they may be Samsung 26F 60cells (10s 6p configuration) most likely they will struggle when drawing high amps on hills or in a higher assist level (3 or more), so you may experience cut outs as the cells struggle to deliver the power asked and voltage will sag collapse under high load (26F are mediocre very low power cells).

If the above happens then voltage will recover once the load has been reduced and may be all right on flatter terrain if you use a lower assist level.
You may find you will need a battery with much better cells in side, if this is the case use a Jimmy for a recell using 15/20a cells.
Your current battery is optimised for use with the 15a max controller so expect performance and range to be worse, battery life will suffer.

 

[Andy1865]

Thank you for your input. Not putting you on the spot but in your opinon you wouldnt have this upgrade done then? Could you direct me to the website that sells them Jimmy batteries. Thanks.

 

[Benjahmin]

A 30A max controller is asking a lot from any battery. Make sure Jimmy knows the controller specs.
https://bga-reworking.co.uk/contact/

 

[Andy1865]

Have you heard of Cyclotricity and their 250/500w kits. The Electric Bike Factory in Stoke on Trent said the 36v is enough for the kit, but im open to other suggestions. My orginal controller says on it Nominal 7A and Limit 15A and is a 250w. They say the battery is ok for Rated Current 15A and Max Current 30A on a 250/500w. Im a complete novice on these things so im hopeing you can explain things to me in laymans terms please. Thanks

 

[Benjahmin]

A battery is made up of individual cells, mostly 18650 cells. The 36v is made up (normally) of 10 cells in series. They are approx 3.6v each, so giving the 36v (though this will be 41/42v hot off the charger). Each cell has a rated current that it is capable of delivering without voltage sag. So, if the cells used have a current capacity of 5A, one string of 10 cells will deliver 5A. To get 30A you would need 6 strings in parallel. So this would be a 10s6p battery. Now, in practice, in order not to get voltage sag during prolonged high draw events (climbing hills) it's best to have a battery that is rated at twice your controller maximum current (or at least 1.5 times). So, in your case, this would be a battery capable of delivering 60A. With 5A cells this would be a 10s10 or 11p battery. That's a big battery.
The reason you don't want voltage sag can be seen in part of Ohms law:
P=IV That's Power = Current X Voltage. So if the voltage drops so does the power available. Really not useful when your legs a burning half way up a stiff climb. If the sag is really bad then the voltage will go below the low voltage cutoff (LVC) of the battery management system and the power will cut off entirely. When voltage recovers (once load is removed) then the system can be restarted. However this stresses the battery and if done repeatedly, will shorten battery life.
So what your installers are saying re voltage is true. But they are not asking or telling you that your batteries ability to deliver the current may not be sufficient.
It will work, but for how long and at what range?
As Neal said, your current battery will probably have been configured to supply the needs of your existing controller. It may well not be very satisfactory with the new system.
I have no experience with Cyclotricity kits but a 30A controller sounds very high to me.
Hope that helps.

 

[Andy1865]

Thank you very very much for that and for taking the time to explain it all to me

 

[Andy1865]

So its best to keep it to 250w uphill and swop to 500w on the flat to feel the wind in my hair lol.

 

[wheeliepete]

So its best to keep it to 250w uphill and swop to 500w on the flat to feel the wind in my hair lol.

Not really, the point of having higher amps is for better torque for climbing hills. On the flat you won't notice a lot of difference between 250/500w because there is no load. If you want speed, you need more volts.

 

[Andy1865]

So you mean a 48v battery, can i do something called overvolt i hear but wouldnt know how to do it. My current battery slots behind the seat post on my freego hawk. What make of battery would you recommend to slot in the same place Pete

 

[Nealh]

Andy to over volt means using a battery of higher voltage then your 36v so convention says 48v is better, it will give 33% more speed and torque over the 36v set up.
A 30amp controller is too much for a 36V system and not necessary on a 48v system unless you have the very best cells inside the battery and that means 15 or 20 amp rated cells and will output some 1500w from the controller.

Try your bike with the upgraded controller and original battery and see what we are talking about it may be ok on the flat (though range will be limited), then try it on a good incline and see what happens eventually the voltage sag will cause the batteries bms to cut out as it will not be able to deliver the loading asked.
You then need to have Jimmy to replace the cells in your battery with either Samsung 30Q or LG HG2, if feeling really flush then go for Sony VTC6.
As mentioned you must let him know that your controller is 30a rated.

 

[Andy1865]

Does anybody know where in the U.K i can buy a 48volt battery like the one that goes behind/beneath the seat like on the freego hawk crossbar, because im being told that my current battery may not be up to the job of supply enough ummf to the new upgrade of the cyclotricity 250/500w kit. Thank you for looking

 

[Nealh]

Does anybody know where in the U.K i can buy a 48volt battery like the one that goes behind/beneath the seat like on the freego hawk crossbar, because im being told that my current battery may not be up to the job of supply enough ummf to the new upgrade of the cyclotricity 250/500w kit. Thank you for looking

Andy you are not listening !!!
Any after market battery is highly unlikely to be up to the task of coping very well with your new 30a controller especially one like yours if you can buy one, the cells inside will not be all that great and will still be mediocre ones I have no doubt.
Your best solution is to have a chat with Jimmy @BGA/Ebikebatteries , you will need a more bespoke battery for your controller.