Sabvoton 72v 200 vs 96 120a

General Discussion about electric bicycles.
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Audisport09   10 W

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Sabvoton 72v 200 vs 96 120a

Post by Audisport09 » May 24 2021 3:24am

Hello, everyone. Summer is approaching and I feel like tinkering. Anyone know which one is more powerful? I was researching I read something about the 72v having better lower resistant fets? I have a QS205 3T with unlocked Sabvoton 72v 150a and an 18s battery. If I replace it with a 96v version and up the battery to 24s lipos, would I get better low down power or will it all be top end that I improve?

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MadRhino   100 GW

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Re: Sabvoton 72v 200 vs 96 120a

Post by MadRhino » May 24 2021 7:45am

Yep. You will have better top speed, at the cost of lesser acceleration from the start and lower efficiency at low speed. That is of course, if you set and pull the best power out of them both.
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Audisport09   10 W

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Re: Sabvoton 72v 200 vs 96 120a

Post by Audisport09 » May 24 2021 9:58am

Hello, thanks for the reply. So lower efficiency caused by fet resistance. I don’t know where I read something about that, this place a maze. Would the higher voltage not balance things out possibly.

Loss of acceleration is the biggest surprise. Could you kindly explain-or point me in the direction of why that might be?

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MadRhino   100 GW

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Re: Sabvoton 72v 200 vs 96 120a

Post by MadRhino » May 24 2021 10:32am

Nope. Lower efficiency at low speed because of the higher top speed caused by the higher voltage.

Lesser acceleration because of the lower power fed by the 96v controller.
Make it fool-proof, and I will make a better fool.

Audisport09   10 W

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Re: Sabvoton 72v 200 vs 96 120a

Post by Audisport09 » May 24 2021 12:52pm

Mind blown, tinker aborted. Thank you. Looks like I still have a lot of research to do.

I was running under the impression that higher voltage is always faster from start to finish.

So your saying higher voltage, lower current is better for high speed cruising and lower voltage, higher current better for lower speed acceleration? Correct?

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E-HP   100 MW

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Re: Sabvoton 72v 200 vs 96 120a

Post by E-HP » May 24 2021 2:15pm

Audisport09 wrote:
May 24 2021 3:24am
Hello, everyone. Summer is approaching and I feel like tinkering. Anyone know which one is more powerful? I was researching I read something about the 72v having better lower resistant fets? I have a QS205 3T with unlocked Sabvoton 72v 150a and an 18s battery. If I replace it with a 96v version and up the battery to 24s lipos, would I get better low down power or will it all be top end that I improve?
Assuming your figures are battery amps, what are the phase amp limit assumptions for the two cases?

Audisport09   10 W

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Re: Sabvoton 72v 200 vs 96 120a

Post by Audisport09 » May 24 2021 3:08pm

The unlocked 72v allows you to set 400 battery amps and 600 phase amps. I doubt it can even do those number but that is what I have set. The unlocked 96120 one should be able to do the same 600 phase amps not sure.

Lets forget unlocked, what I wanted to know was which is the more powerful controller for acceleration, not top speed, I don’t care about that.

72v Sab running 18s:
DC Current Limit: 200A
3). Max. Phase Current: 450A

Or

96v Sab running 24s:
DC Current Limit: 120A
Max. Phase Current: 300A  

The change of efficiency of the motor by adding volts is something I need to read into. I do tend to cruise under 20mph, and like to punch the throttle now and then.

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MadRhino   100 GW

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Re: Sabvoton 72v 200 vs 96 120a

Post by MadRhino » May 24 2021 4:02pm

Audisport09 wrote:
May 24 2021 12:52pm
Mind blown, tinker aborted. Thank you. Looks like I still have a lot of research to do.

I was running under the impression that higher voltage is always faster from start to finish.

So your saying higher voltage, lower current is better for high speed cruising and lower voltage, higher current better for lower speed acceleration? Correct?
Of course, the efficient zone does start later when the motor is fed higher voltage making faster top speed. For an example, a bike set to top at 30 mph is quite efficient at 10 mph because that is a third of its speed, while a bike that does 100 mph has very poor efficiency at 10 mph.

Acceleration is a matter of power. In the case of those 2 controllers, the 72v has lower resistance mosfets and can feed higher current. Fets that are rated higher voltage are generally higher resistance, thus rated lower current.

When the ‘higher voltage-lower current’ is matching in watts the ‘lower voltage-higher current’, like 100v 50A vs 50v 100A both making 5 kw, there is little acceleration difference but there is a notable difference at the beginning of the efficiency curve, thus the higher Amps will give better torque from the start.

That is why we don’t build a 100 mph bike when we plan to ride 50. It would make it less efficient.
Make it fool-proof, and I will make a better fool.

Audisport09   10 W

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Re: Sabvoton 72v 200 vs 96 120a

Post by Audisport09 » May 24 2021 7:02pm

MadRhino wrote:
May 24 2021 4:02pm
Audisport09 wrote:
May 24 2021 12:52pm
Mind blown, tinker aborted. Thank you. Looks like I still have a lot of research to do.

I was running under the impression that higher voltage is always faster from start to finish.

So your saying higher voltage, lower current is better for high speed cruising and lower voltage, higher current better for lower speed acceleration? Correct?
Of course, the efficient zone does start later when the motor is fed higher voltage making faster top speed. For an example, a bike set to top at 30 mph is quite efficient at 10 mph because that is a third of its speed, while a bike that does 100 mph has very poor efficiency at 10 mph.

Acceleration is a matter of power. In the case of those 2 controllers, the 72v has lower resistance mosfets and can feed higher current. Fets that are rated higher voltage are generally higher resistance, thus rated lower current.

When the ‘higher voltage-lower current’ is matching in watts the ‘lower voltage-higher current’, like 100v 50A vs 50v 100A both making 5 kw, there is little acceleration difference but there is a notable difference at the beginning of the efficiency curve, thus the higher Amps will give better torque from the start.

That is why we don’t build a 100 mph bike when we plan to ride 50. It would make it less efficient.

Wonderful, I love this site. Thank you for explaining things down to near my level of understanding. I think I got it now, I need an amp-monster controller for better acceleration. Very last question, I’m running 18s as it’s convenient 3 bricks of lipos. Would it be worth the trouble to add another 2s for 20s in terms of higher off the line toque or would this again shift efficiency and add top speed

75.6 x 150 = 11340 watts
84 x 150 = 12600 watts

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MadRhino   100 GW

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Re: Sabvoton 72v 200 vs 96 120a

Post by MadRhino » May 24 2021 8:05pm

This is more about the speed that you ride, than the acceleration that you want. You can feed much more than 150A with 18s lipo, when they are low resistance quality lipo of course. So you can have the acceleration without having to build a bike that is too fast for your need.
Make it fool-proof, and I will make a better fool.

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