I see. For now i'll use the kit and in the future if i want to upgrade i'll look at a new higher amp/volt battery and controller and take it from there. Seems about the only real option if you couldn't keep the same battery and just change the motor and controller and just loose the range.
Advice - New To E-Bikes
- Thread starter Scottyf
- Start date
Mate I'm in the same boat as you with understanding what does what, but I can say my 250W Tongxin averaged 17.8 over 177 (that's KmH of course 
) last week, so it's not as simple as just increasing the wattage.
More to the point, I cross the city every day and would be interested to try someone else's bike out for our mutual education. I also have a couple of spare controllers, another Tongxin and spare battery I would be happy to lend to see how they compare.
) last week, so it's not as simple as just increasing the wattage.More to the point, I cross the city every day and would be interested to try someone else's bike out for our mutual education. I also have a couple of spare controllers, another Tongxin and spare battery I would be happy to lend to see how they compare.
D
Deleted member 4366
Guest
The cheaper Lifepo batteries are rated at 1C continuous and 2C peak, which means 9A and 18A for this one. My 250w Bafang can draw 18 amps continuous up a steep hill, in which case it may well be damaging the battery. The 350w Bafang (with a suitable controller) will draw a lot more current than that - maybe 25A or more. It'll work for a while, but how long will your battery last, and I mean life-cycle, not charge-cycle?
Thanks, been doing some more reading on the matters and understand what you mean.
You can get it to do it but would limit life on the battery if not cause complete failure.
Been out on it today and tried getting round just on throttle mostly. Bar starting off and getting up to a decent speed. Still quite impressed with the baby motor and does make life getting round really simple. You definetly notice a difference once you turn it off. All in all been on it an hour on the single charge and it dropped to 80% battery life.
Still fun though and i'm sure i'll upgrade things in the future but for now i'm quite happy.
If i need more speed i guess i'll have to just over volt and get a higher mosfet controller.
You can get it to do it but would limit life on the battery if not cause complete failure.
Been out on it today and tried getting round just on throttle mostly. Bar starting off and getting up to a decent speed. Still quite impressed with the baby motor and does make life getting round really simple. You definetly notice a difference once you turn it off. All in all been on it an hour on the single charge and it dropped to 80% battery life.
Still fun though and i'm sure i'll upgrade things in the future but for now i'm quite happy.
If i need more speed i guess i'll have to just over volt and get a higher mosfet controller.
If you increase the battery Ah then it will be more happy at a higher discharge rate, IE: 10Ah rated 1C is OK for max 10amp discharge, change the battery to a 20Ah 1C then its OK for 20amp discharge....
The battery is 1C in both cases but the larger one will deliver more amps... The control is the gate keeper as to how much current is drawn from the battery so you choose the battery with an eye on what the controller is rated for... A 15amp rated controller (quite typical for 250W motors) will pull more or less 15amps from the battery therefore it makes sense, so as not to stress your battery too much to use a 20Ah battery if the one you are thinking of is rated 1C...if the battery is rated 2C then guess what? you could use a 10Ah one.
Pushing more current through the motor will increase torque up to a point but put more strain on the motor and if fitted with internal gearing put the gears under more stress. More heat will be produced in the motor and the controller will also be under more strain....there are limits and 15amp is a safe reliable one for Typical Bafang motors. Also current limiting in controllers can be imprecise, I've measured two different 15amp rated controllers and both pull 20~21amps from the battery, so keep this in mind when looking at batteries.
The battery is 1C in both cases but the larger one will deliver more amps... The control is the gate keeper as to how much current is drawn from the battery so you choose the battery with an eye on what the controller is rated for... A 15amp rated controller (quite typical for 250W motors) will pull more or less 15amps from the battery therefore it makes sense, so as not to stress your battery too much to use a 20Ah battery if the one you are thinking of is rated 1C...if the battery is rated 2C then guess what? you could use a 10Ah one.
Pushing more current through the motor will increase torque up to a point but put more strain on the motor and if fitted with internal gearing put the gears under more stress. More heat will be produced in the motor and the controller will also be under more strain....there are limits and 15amp is a safe reliable one for Typical Bafang motors. Also current limiting in controllers can be imprecise, I've measured two different 15amp rated controllers and both pull 20~21amps from the battery, so keep this in mind when looking at batteries.
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Hi Scottyf
You bought a Nice low powered kit it works Enjoy it
If you want to go faster and mote Grunt on hills you need 48 volt with 10 C rating battery's these will be 12 AH or 16AH with 80 amp continuous BMS Plus you need high power controller with 18 mosfets Tuned to handle 80 amps then a heavy duty direct drive motor
so 16 AH battery 16 cells LiFepo4 3.2 volts per cell 16 X 3.2 =51.2 volts
51.2 X 80 AMPS = 4096 watts out off the BMS motors 85 % Efficient
4096 into 85 % 3481 Watts Aprox Divide by 750 watts = HP 4.65 WOW Cost aprox £ 2500
Frank
You bought a Nice low powered kit it works Enjoy it
If you want to go faster and mote Grunt on hills you need 48 volt with 10 C rating battery's these will be 12 AH or 16AH with 80 amp continuous BMS Plus you need high power controller with 18 mosfets Tuned to handle 80 amps then a heavy duty direct drive motor
so 16 AH battery 16 cells LiFepo4 3.2 volts per cell 16 X 3.2 =51.2 volts
51.2 X 80 AMPS = 4096 watts out off the BMS motors 85 % Efficient
4096 into 85 % 3481 Watts Aprox Divide by 750 watts = HP 4.65 WOW Cost aprox £ 2500
Frank
Excellent. Thank you all for your posts. I know you probably have to go through this kind of thing on a weekly basis. But you have no idea how helpful these posts are to me.
It also will not fall on deaf ears as i will use this information to create another ebike in the future.
Personally i love the kit an although it has its limitations i really will use it as a stepping stone.
I.ve learnt alot thanks to you guys and don't feel so daunted when i go on a site like bms battery and understand what the parts do. What they can be joined and their functions.
Really is great as reading beginner guides didn't tell me the full storey.
It also will not fall on deaf ears as i will use this information to create another ebike in the future.
Personally i love the kit an although it has its limitations i really will use it as a stepping stone.
I.ve learnt alot thanks to you guys and don't feel so daunted when i go on a site like bms battery and understand what the parts do. What they can be joined and their functions.
Really is great as reading beginner guides didn't tell me the full storey.
Sorry to revive an older thread.
Has anyone took one of these batteries apart on a sunlova kit (Same batterys BMSbatteries supply) an just added a few more panasonic cells and then changed the bms to creat a 48v battery at all?
Just playing with the idea of saving money and making it into a battery with 48v with a slightly higher capacity.
If its a no go I'm sure i can wsell the current battery and change it for a 48v 12ah and controller to boot.
Just a thought...
Has anyone took one of these batteries apart on a sunlova kit (Same batterys BMSbatteries supply) an just added a few more panasonic cells and then changed the bms to creat a 48v battery at all?
Just playing with the idea of saving money and making it into a battery with 48v with a slightly higher capacity.
If its a no go I'm sure i can wsell the current battery and change it for a 48v 12ah and controller to boot.
Just a thought...
D
Deleted member 4366
Guest
Nice idea but not really feasible. You'd need a 48v BMS as well. Plus, there isn't enough room in the case to get another 3 cells in there.
D
Deleted member 4366
Guest
An interesting idea and I don't see why that shouldn't work - but I'm no expert. You'd need to charge them seperately to be safe. If you want to use a SLA battery to try it out, you shouldn't discharge it too much otherwise they don't last very long. I would guess that you'd go faster and climb better, but you can't go as far because you'd need to stop after you'd used about 5aH. Best would be to try it and let us know what happens. I've heard that some 36v controllers can run at 48v without mods. It would be interesting to use a relay to switch the extra battery in and out of the circuit as a temparary power booster rather than have it running all the time. You could also wire 12v lights and other accessories to it.
Is it safe to wire in two different battery types though?
SLA would be easy could just buy 4x12v batteries of the same AH. However you'd get all the problems of having an SLA. The weight, the discharge the limited life cycle etc etc.
However as cheap as they are and if i can mix the two types it might be worth a go. I would imagine I would need another controller as I can't see the standard controller being able to cope with the added voltage.
SLA would be easy could just buy 4x12v batteries of the same AH. However you'd get all the problems of having an SLA. The weight, the discharge the limited life cycle etc etc.
However as cheap as they are and if i can mix the two types it might be worth a go. I would imagine I would need another controller as I can't see the standard controller being able to cope with the added voltage.
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