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The sag will depend on the particular battery. Some lead-acid will sag less than some Li. Trying to get 10kW from a 60Ah 48V Li battery puts you into 5C or 6C discharge territory.

Invest in a voltmeter and ammeter so you know what you're getting now.

major
 

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Hi Brian_,

You seem to be missing something with the ME1602. It is a brushed PM DC motor and has a speed torque characteristic like the following example. The example is not the ME1602, just some unknown PMDC motor to show the shape as all PMDC motor speed torque curves look the same, just scaled differently.

**note: graph below is shown with a constant voltage (sometimes including a source resistance) applied to the motor.



From: https://www.bing.com/images/search?...608032770895513916&selectedIndex=0&ajaxhist=0

Unfortunately we don't have this type of performance curve for the ME1602 but the website gives us a few parameters to fill in. First is stated no load speed of 3360 at 48V. So the intersection of the of the pink RPM line with the Y axis is 3360. At 48V this is the maximum motor speed. At no load, meaning zero torque (on the X axis), the power output is zero and efficiency is zero, the red dashed and brown lines. The blue line intersects the Y axis at the no load current value.

You can see from shape of the speed torque line (linear) that peak power is midway between no load and stall. Speed will be half of the no load RPM. Large PMDC motors rarely operate at that point as they hit the controller current limit. The motor spec sheet rates it at 16kW, 48V for 1 minute which would be about 350A. His controller indicates 400A capability. Also noted on the motor specs is the use of double brushes providing 200A continuous or 9.6kW input. Looks as if the controller can handle that.

I think the ME1602 is far more motor than the Golden package. Although I am not a fan of PM brushed motors on heavy vehicle traction applications. IMHO, the few pounds to go to a wound field motor is worth it in the long run.

BTW, OP would do well to get an accurate vehicle load curve (speed vs torque at drive wheel). It would help tremendously in choosing the proper ratio.

Regards,

major

{edit}

Click on power curve to download set of speed torque curves for the ME0708 which I saw was basically the same as the ME1602.

http://www.thunderstruck-ev.com/motenergy-me0708.html
 

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In order to understand better my motor's performance I asked Golden Motor for their 72V and 96V graphs to compare with the 48V motor's graph and performance. If anyone can help in making sense of it I'd greatly appreciate it. The graph is really convoluted and doesn't make complete sense to me. My question being that provided I go to a higher voltage system (72 or 96) would a GM motor do the needful or I'd still look into getting a forklift motor for my needs?
Hi Kill,

It appears the graphs represent 3 different motors (or windings). Each designed to yield similar speed torque characteristics at respective voltages of 48, 72 & 96, nominal. I believe the motor package remains the same therefore the rated power likely is the same for all 3 models. Changing between the 3 models is unlikely to solve your problem.

major
 
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