2 buy or not 2 buy, which is the question

[THX1138]

i have a Currie 24vdc 650 watt motor that is rated at 36 amps which i am running at 36vdc with a 40 amp 1000 watt controller " I'm not too woried about motor issues since i have 5 more of these motors on hand " None the less I'm ok with the 23- 26 mph it will do but with the three sla 12v 12ah batteries I'm running out of power in about 7/8 of a mile, Which really SUCKS
Should I purchase a 40 ah lifepo pack or put a 30 amp controller and buy a 30ah " " or?
Then there is the matter of my being " at best " less than zero familiar with these type of Kaa - Boom batteries
Then on the bright side I see that most of the places I can purchase these things at, they come with their chargers included

 

[deardancer3]

Depends on your goals... Speed, acceleration, range, miles/amphr (doubtful).

Tell us more.

d

You are probably getting less than 6ah out of your SLA's before hitting LVC, running at 3C, the 12AH rating is at 1/20c.
you are discharging a little higher than 1/20c.

 

[vanilla ice]

If job #1 is range get a 15 to 20 amp controller..

 

[StudEbiker]

Should I purchase a 40 ah lifepo pack or put a 30 amp controller and buy a 30ah " " or?
Then there is the matter of my being " at best " less than zero familiar with these type of Kaa - Boom batteries

LiFePo batteries are not kaboom batteries. They are extremely safe. I think you are confusing them with LiPo.

 

[THX1138]

i would be more than happy with 20 mph even if it took a city block to reach that speed, but this running out of power completely in less than a mile is for the birds...What am i doing wrong?
If i were to, lets say put a 20amp controller on the thing what wattage should it be and what will that do? To say i am confused by all this motor size in watts, amps drawn by motor. Controller watts and amps , battery amp hrs and then gearing.
Confusing me, hell that’s an understatement of astronomical proportions
These electric bikes are involving, big - big time....DDDAAAAAMMMMM
20mph 5miles or so, really am i asking to much???
Honestly, the thing came with a 24vdc 450 watt geared motor. noisy as hell...it did 14mph
I put a 1200 watt 48 vdc motor on it. the motors are like10" long so i had to run a countershaft to bring the chain back center with the rear sprocket. It was a mess but it worked ok i suppose if one didnt mind batteries strapped on the seat, under the rear fender etc, it looked like hell. No hell must look better. Then i tried a 36vdc 500 watt motor, that sucked. Then i tried one of those 900 watt 24vdc motors. It drained two batteries in a about a 1/4 mile. Now im running the 650 watt 24vdc motor, as stated at 36vdc with a 40amp 1000 watt controller
So after about a million hours of work doing gearing changes, countershaft designs, motor changes, controller changes .Then also how much money i have invested in all this stuff... O Boy look at me, i can do 23 mph for less than a mile
So straight out and being as honest as I can possibly be, I tell you all that I am resigned to the fact that I have absolutely no clue whatsoever what I am doing.
Can someone please just tell me what to get, whatever it is I dont care anymore, I’ll buy it.

As it stands the thing / creature!!! Has a 15 tooth sprocket on the motor, and 80 tooth sprocket on the rear wheel. the tire size is 20 inches the motor is a currie 650 watt rated at a 36 amp draw. Whatever that means.

 

[deardancer3]

You are doing wide open throttle acceleration on fixed gear ratio motors on the inefficient part of the motor curve, drawing much more current from batteries that they are rated for with no power limiting device up to top speed.

Get a power meter and monitor what the power draw is; under these conditions the motors can draw peak over twice their long term rating.

Or get a very good meter and control the power draw.

Moderate your acceleration and watch the power needs decrease.

Drop your top speed and watch the power needs decrease.

Use variable ratio chain drive and stay on the efficient paret of the motor curve

Get batteries designed for your current draw.

Learn to read motor curves and what they mean.


The more of these you do, the happier you will be.

(I can run at 20mph with moderate pedaling for 20 miles, with a 360w motor and 20ah of 24v batteries, I take maybe 1/4 mile to get up to 20mp, and I use my gears.)