What are the advantages of running at 48v

[fishingpaul]

I am thinking of running my torq 2 at 48v with lead acid batteries,is it likely to make much difference to the hill climbing ability or would it be more on top speed only, would using four batteries help reduce the amount of stress put on the batteries.

 

[flecc]

The eZee controller has an upper voltage limit of 44 volts, plus or minus a half volt. Fed from 48 volts (circa 52 volts when freshly charged) from SLA batteries would cause it to cut out with a 7 flash diagnostic signal on the controller LED.
.

 

[fishingpaul]

The eZee controller has an upper voltage limit of 44 volts, plus or minus a half volt. Fed from 48 volts (circa 52 volts when freshly charged) from SLA batteries would cause it to cut out with a 7 flash diagnostic signal on the controller LED.
.

I am now using an ecrazyman 36v controller which ecrazyman advised cuts out at 56v,my main worry is damaging the rather thin ezee hall sensors or the ezee phase wires the controller hall sensors and phase wires are thicker guage wire.

 

[HarryB]

I am now using an ecrazyman 36v controller which ecrazyman advised cuts out at 56v,my main worry is damaging the rather thin ezee hall sensors or the ezee phase wires the controller hall sensors and phase wires are thicker guage wire.

I don't think that it sends 48v down the hall sensor wires so you are ok on that one. I have a feeling that this has been done before so maybe a search might help.

PS it was on a sprint rather than a torq so a different motor - see here:http://www.pedelecs.co.uk/forum/electric-bicycles/1664-modded-sprint.html?highlight=sprint

 

[flecc]

Thanks Paul, I'd forgotten you were using that other controller. Although aaannndddyyy's Sprint has a very different motor from the one on the Torq 2 with the SB motor, it will be ok on the higher voltage and it's been done before on the SBs. I don't know about the current Torq 2 motor which eZee claim is their own, but I'd be very surprised if it wasn't capable of accepting 48 volts since that's well within normal safety margins. After all, the SLAs peak only a bit above their nominal voltage at around 52 volts, while the standard lithium 37 volts batteries peak at around 44 volts when fresh off the charger, so the difference then is a maximum of about 8 volts.
.

 

[Tiberius]

Hi Paul,

It depends which motor you have. I wouldn't do it with the early Torq 1 Bafang motor, but the later ones should be ok.

The danger is at low speed and full throttle - eg climbing steep hills. That's when the battery/controller will put the most current into the phase windings, and that means the most heating inside the motor.

If you have a controller that limits the motor current (very few do), then you don't have a problem. But for most systems, it is this heating effect at low speeds that is the limiting factor when over-volting.

Other things being equal, the heat generated varies as the square of the voltage.

Nick

 

[fishingpaul]

Thanks for the replies,i have just finished the wiring connections off properly and i am hopefull of a test ride on friday, the motor is now spinning at an amazing to me 51mph with the wheel off the ground, this is with the old 36v ezee lithium battery attached just for for testing purposes previously it ran at 24mph derestricted with wheel off the ground, this battery is no good for on the road use any more though, i think i will try it on lead acids at 36v and then try adding a fourth 12v battery in a temporary position before making up or purchasing a new battery case, unless it makes a significant difference to climbing which is already quite good i will stay at 36v.

 

[john]

Watch the gears

I think a chap on ES had to change the gears for steel ones when he did this with a BF motor as he stripped the nylon ones with the extra torque produced.

 

[Mussels]

The danger is at low speed and full throttle - eg climbing steep hills. That's when the battery/controller will put the most current into the phase windings, and that means the most heating inside the motor.

If you have a controller that limits the motor current (very few do), then you don't have a problem. But for most systems, it is this heating effect at low speeds that is the limiting factor when over-volting.

Other things being equal, the heat generated varies as the square of the voltage.

Nick

How much overheating is likely, just enough to make you concerned or are we talking blazing saddles?

 

[emissions-free]

I'd say just enough to make you concerned rather than blazing saddle

I've over voltaged a very small 36V geared hub motor to 48V Lifepo4 which in actual is well over 50V and it did noticeably heat the motor but my feeling is that if it's used with a little mechanical sympathy it should be ok. As was already mentioned avoid very low speeds at full throttle up a steep hil, not just giving it full throttle off the line and not using full throttle all of the time. If your commute isn't too long or particularly tough I think it'll be fine, but at the end of the day you take your chances

My experience with over voltage on the motor I used was that the power seemed to drop off a little after some use. I feel it's the windings getting rather hot and the resistance increasing, therefore reducing current flow and power generated.

If I'm not mistaken over voltage from 36 to 48V should give you a 36V 250W motor that becomes a 48V, 250*1.33^2 = 444W, I think...