Make it make sense please.

[Elias lector]

I have a 30amp controller that will take 36-72v.
I decided the top speed was a bit much with 72v so I put one of my 48v batteries which is more than capable of dumping 300 amps let alone 30. I can't seem to wrap my head around how this thing is so dead from a stop now. Maybe I'm just missing something here but I figured 30amps is 30amps, the higher voltage just means a higher top speed.
In my mind I see it as I have X amount of available amps so from a stop it should release the same amount no matter the voltage. Am I wrong in my assumption??

 

[offGridDownUnder]

If I have a pipe that can deliver 100 gallons per minute, and I close the valve, I'm not going to see 100 gallons per minute. I'm going to see zero (if there are no leaks).

If i open the valve a hair, I also won't see 100 gallons per minute. I'll see less than that.

The rest of the set up (at the time in that configuration) doesn't permit 100 gallons per minute, even if it might be capable of it in other configurations.

Does this analogy help?

 

[lnanek]

30A x 48V = 1,440 Watts. 30A x 72V = 2,160 Watts. If the two produced the same work you'd be pumping out 720 Watts of heat down there to waste the difference, which is almost a toaster.

 

[Elias lector]

If I have a pipe that can deliver 100 gallons per minute, and I close the valve, I'm not going to see 100 gallons per minute. I'm going to see zero (if there are no leaks).

If i open the valve a hair, I also won't see 100 gallons per minute. I'll see less than that.

The rest of the set up (at the time in that configuration) doesn't permit 100 gallons per minute, even if it might be capable of it in other configurations.

Does this analogy help?

Actually yes thank you. I was looking/ thinking of it exactly like a valve.....kinda lol

 

[Elias lector]

30A x 48V = 1,440 Watts. 30A x 72V = 2,160 Watts. If the two produced the same work you'd be pumping out 720 Watts of heat down there to waste the difference, which is almost a toaster.

OK, I have a slightly better understanding but it's a 1500 watt controller. Am I again wrong in thinking that it's 1500w max no matter what.?? I'm sorry to obviously be ignorant with this. But I thought I had a basic understanding. Amps=torque. Volts=speed. I know it's a little more complicated than that but I thought this was the "bottom line" so to speak.
Thank you for helping clear this up for me

 

[orcasprout]

as I have X amount of available amps so from a stop it should release the same amount

Uh, perhaps you controller is "releasing" 30A but, from a stop, the motor "spends" a lot of energy to get you going. A motor is more efficient at speed so perhaps you're working through what "release the same amount" means.

I'll admit I'm a little confused by what you are asking for?

Perhaps it's more "off the line power"? Amps are current and Volts are pressure. As I understand it, the motor draws the most current when stopped or from a stop. On a subway car I can feel 5 or so gear shifts between 0 and 3mph. It requires a lot of work (hope I using that term correctly) to get it going from a stop. A motor spinning fast is "efficient" at applying a "push"

I'm still forming my analogies but I believe one needs a TON of amps to get going (from a stop) and high voltage to go fast (at speed)

As Leffix says, your gonna get 1440 Watts at nominal voltage.

 

[orcasprout]

Leffix

Whoops, sorry. I meant Inanek

 

[offGridDownUnder]

Actually yes thank you. I was looking/ thinking of it exactly like a valve.....kinda lol

Ok, from that start.

My analogy was gallons per minute. Notice that is a rate, not a quantity (of something). The 'per minute' part.

Amperes are also a rate. It is the count of how many units of electric charge (plus or minus) that flow past a chosen point in a chosen time:
Ampere: Introduction

Read on down to this part:

In November 2018, however, the redefinition of the ampere ― along with three other SI base units: the kilogram (mass), kelvin (temperature) and mole (amount of substance) ― was approved. Starting on May 20, 2019, the ampere is based on a fundamental physical constant: the elementary charge (e), which is the amount of electric charge in a single electron (negative) or proton (positive).

Now think of a lazy slow wide river, and a raging but narrower torrent. There are some ways you can think of electricity as water, and some ways that does not work. The 'raging' bit suggests speed, but forget that and instead think of the force. The lazy river and the torrent might flow the same quantity of water past a point in the same time, but one does this with much more force.

Voltage is electrical force. It's how hard the electricity is pushing. The same count of electric charges is flowing in the same time period, but the low voltage flow doesn't pack as much energy as the high voltage flow. Same amps though. Just not the same energy. (And by the way, power is the rate of energy delivery - some unit(s) of energy per some unit(s) of time.)

Be careful with this - we are near the places that the water analogy breaks down and doesn't work. But it may help to distinguish some of the basics.

 

[Elias lector]

Thanks to everyone for your responses. I just had it in my head that off the line/from a stop the volts shouldn't have as much as an influence as long as I was still using the same amount of amps. But with my 72v battery it would lift the front tire about 3 inches but with the 48v battery it's like I have an anchor tied to the bike. So I will be going back to 72v.

 

[Chalo]

Power to the ground = volts * amps * gross efficiency. Change any one of the factors and you will have different power output.

 

[hilllzofvalp]

I wish I lived in anytown

 

[Elias lector]

I wish I lived in anytown

It's not that great of a place really. But Atleast the cops don't bother me when I'm passing cars on the highway on one of my real emotos ?? I guess none of them have pedals. This whole debacle was on my kids bike that I do jump on from time to time