36v vs 48v for climbing?

[Prescott]

Hi all mates. Im Prescott, new in this forum.

My question is simple, i belive ...

500w 36v vs 750w 48v o even same wattages different voltage, wich gonna climb better? Read somewhere low voltage needs lower rpm but then is the torque, power, pedaling cadence etc

Well, thats all by now
Thanks

 

[Dewey]

The answer is the 48V system, play around with the Grin Tech motor simulator, it doesn't have the bafang bbs mid-drives but you can select a bafang G01 hub motor, try different power configurations.

 

[Prescott]

Thanks Dewey.

However, the voltage can be lowered to 38v right?

 

[Dewey]

the voltage can be lowered to 38v right?

On the Bafang G01 hub motor I think Grin Tech sells an external controller that can be set to either voltage, presumably through a usb programming cable and software but check with Grin Tech.

On the Bafang BBS mid drives you make your choice at the time of purchase as the controller is built in and works on one voltage: BBS01 = 36v, BBS02=48v or 36v, BBSHD=48v but you can use a 52v battery. You can change the other settings with a usb programming cable and software but not the voltage. The rated voltage will be stamped on the casing. When tuning the controller you can change the current amp setting and this will determine the peak power using the formula amps x voltage= Peak power in watts, so on a 48v battery you could set current to 15 amps to get 720w peak power, on a 36v system you could set current to 14 amps to get 504w peak power. But in real life no one is going to check your settings unless you accidentally hurt someone so you may wish to tune the controller for hill climbing, I have a BBS01a with the upgraded 3077 mosfets controller and it’s happy with current at 18 amps, but I got a burning smell when I tried raising the current to 20 amps so 18 amps it is which is 648w peak power and it climbs hills adequately - the BBS02 would be a better purchase because the stator is slightly wider.

 

[Prescott]

https://electricbike.com/forum/foru...bbshd-standard-programmed-low-voltage-cut-off

Cut off voltage?

 

[Dewey]

https://electricbike.com/forum/foru...bbshd-standard-programmed-low-voltage-cut-off

Cut off voltage?

Yeah that’s the BBSHD which I don’t own and haven’t programmed but Luna can tell you what else you can do. For the BBS01 & BBS02 read Karl Gesslein’s post about programming it has screen shots showing the settings you can change. https://electricbike-blog.com/2015/...rying-your-controller-and-losing-your-sanity/

 

[Prescott]

Dewey before i go into the links ... the lower voltage = lower rpm is true? Take in mind im not in good shape to hold high cadences

 

[Dewey]

Dewey before i go into the links ... the lower voltage = lower rpm is true? Take in mind im not in good shape to hold high cadences

The BBS01 is happy at 80rpm, BBS02 goes up to 110rpm, don’t know about BBSHD. This is a function of how the system was set up by Bafang, I don’t think voltage makes a difference

 

[tomjasz]

Any BBSxx will be a good hill climber in the right gearing. The only difference will be speed.

 

[harryS]

Prescott, you aren't going to run a 48V BBS02 at 38 volts using the 48V battery, The battery's own cutoff circuit in its BMS will kick in around 40 volts and at that point it's 90% used up, so even if there were no LVC, there would be no kick in the battery.

And if it's a 36V BBS02 with a 36V battery, about 40% of the capacity of that battery is gone at 38V. You've also used up a lot of the battery's grunt, unless it's a big AH unit.

You want to climb, shift down and let the gears multiply the torque, and help with your feet too. I suggest getting the higher voltage unit too.

 

[tomjasz]

I don't quite agree that higher voltage is needed but agree that buying the highest Ah is always advisable. I have a couple of old 36V 350W BBS01's. Great climbers, just slow, but their new batteries will be at least 20Ah.

 

[Jelester]

Prescott, you aren't going to run a 48V BBS02 at 38 volts using the 48V battery, The battery's own cutoff circuit in its BMS will kick in around 40 volts and at that point it's 90% used up, so even if there were no LVC, there would be no kick in the battery.

And if it's a 36V BBS02 with a 36V battery, about 40% of the capacity of that battery is gone at 38V. You've also used up a lot of the battery's grunt, unless it's a big AH unit.

You want to climb, shift down and let the gears multiply the torque, and help with your feet too. I suggest getting the higher voltage unit too.

I HAVE 36 VOLT 13 AH battery 500 watt hub, What would be the result of a 48 volt battery and controller in range?

 

[harryS]

Jelester, we need the AH on the second battery for your answer, Range is proportional to watt-hours. You find that by multiplying AH x volts. Your first battery is 36V x13 Ah= 468 watt-hour. Suppose you bought a puny little 48V 10Ah battery, which is 480 AH, almost the same. If you rode the same speed with that battery, it would have about the same range. If you rode the bike using the higher speeds available, then you burn the watt-hours faster and a 48V 10AH battery might have less range.

In real life though, if you found a 48V 13AH battery ( 624 watt-hr), that would be 33% added range.

 

[Jelester]

Jelester, we need the AH on the second battery for your answer, Range is proportional to watt-hours. You find that by multiplying AH x volts. Your first battery is 36V x13 Ah= 468 watt-hour. Suppose you bought a puny little 48V 10Ah battery, which is 480 AH, almost the same. If you rode the same speed with that battery, it would have about the same range. If you rode the bike using the higher speeds available, then you burn the watt-hours faster and a 48V 10AH battery might have less range.

In real life though, if you found a 48V 13AH battery ( 624 watt-hr), that would be 33% added range.

It is just getting winter and I will get to ride very little so I will try and find a 36 Volt 17AH Dolphin case. That should solve my problems. I am looking at one from Dillinger now. If I went the 48 Volt route it would have to be real high AH.