My first test with dewalt and 4110 fet upgrade

[The7]

I still have the original 10uf in mine, but the ramp up seems pretty instantaneous. Perhaps there's something else in the circuit that affects the ramp up speed. It seems like there's quite a bit of variation between individual controllers.
.

From the data:
the calculated "soft-start" time is typical 0.25s, but it could vary from 0.16s to 0.5s for different PWM chips using 10uF.

I would think 0.25s is a large LAG.

Would like to find is there any other ramp-up speed circuit?

The typical 0.25s is based on ramp voltage from 0 to 1.3V at pin 8 of KA3525.

If ramp voltage is 2.5 volt,
Then typical soft-start time = 0.49 sec ( from 0.31s to 0.98s)

 

[The7]

Did the 2.5s ramp time occur at no-load (with drive wheel off ground)?
Ramp up from what speed to what speed?

No, it's just my purely subjective assessment of the time it takes for the rush of power to build between about 0 and 5 mph. I could be mistaking normal, single-speed brushless motor operation for the current ramp. My 1500W brushed, single speed scooter feels about as quick between 0-5mph as my X5 ebike at 2800 watts -- and the voltage/speed of each is about the same (both go about 24mph at 48 volts), so the gearing is roughly the same. After 5mph, it's all ebike...

Wonder if you could do an simple experiment on your ebike 5304/20?
With the drive wheel off ground, give an quick FULL throttle and note
a) any delay time for the wheel start to rotate;
b) time for it to ramp up to no-load top speed: and
c) the battery current during ramp up.

 

[xyster]

Wonder if you could do an simple experiment on your ebike 5304/20?
With the drive wheel off ground, give an quick FULL throttle and note
a) any delay time for the wheel start to rotate;
b) time for it to ramp up to no-load top speed: and
c) the battery current during ramp up.

This bike is too heavy to lift and hold the rear end with one hand while twisting the throttle with the other -- which I can easily do with my Currie. I'd have to find or build something to prop-up and stabilize the rear of the bike. I'll look into it...

 

[The7]

Wonder if you could do an simple experiment on your ebike 5304/20?
With the drive wheel off ground, give an quick FULL throttle and note
a) any delay time for the wheel start to rotate;
b) time for it to ramp up to no-load top speed: and
c) the battery current during ramp up.

This bike is too heavy to lift and hold the rear end with one hand while twisting the throttle with the other -- which I can easily do with my Currie. I'd have to find or build something to prop-up and stabilize the rear of the bike. I'll look into it...

Your Curri uses brushed motor and not BLDC Ccrystalyte controller. So not relavent but you could compare it with 5304/20 if you like.

 

[xyster]

Your Curri uses brushed motor and not BLDC Ccrystalyte controller. So not relavent but you could compare it with 5304/20 if you like.

I know -- it was a statement regarding weight and the difficulty of doing the test, not a suggestion I should perform the test on the Currie instead.

 

[The7]

Did the 2.5s ramp time occur at no-load
Wonder if you could do an simple experiment on your ebike 5304/20?
With the drive wheel off ground, give an quick FULL throttle and note
a) any delay time for the wheel start to rotate;
b) time for it to ramp up to no-load top speed: and
c) the battery current during ramp up.

I did the test myself on AL1020 using 36V at no-load.

Two ways to apply FULL throttle quickly:
1) Twisting the throttle to FULL as fast as I could;
2) Press the brake, turn the FULL throttle. Release the brake and the throttle will be at FULL.

These two ways gave practically the same results .
1) There is a small LAG. Seems to be the order of 0.1s.
2) The speed ramped up to no-load top speed (45 km/h) at a short period. Seems to be the order of 0.5s.
3) An digital ammeter and an analog meter were used to read the battery current. During the ramp up, the ammeter never exceeded 4A. So the current limit (20A) was not reached for such no-load test.

Comment:
1) It seems the order of 0.1s LAG is not desiable.
From memory of motor-cycling in young age, there was no such LAG feeling.
Thinking of changing the 10uF to 1uF may reduce this LAG.
2) When the ebike was loaded (road test), the ebike reached its current-limit (20A) every time at FULL throttle. In such case, the ramp up time (order of several seconds) will be dictated by the current-limit, and the top-speed by the battery voltage.
3) Don't think that there is any other ramp up circuit other than the "soft-start" 10 uF capacitor.

Would like to hear what is your experience.

 

[The7]

Sorry for stealing Doc post on the "Soft-start" matter.

Would like continue it in "E-Bike Technical"

http://endless-sphere.com/forums/viewtopic.php?t=764&start=105

Thanks Doc!

 

[Doctorbass]

No problem!

 

[bobmcree]

Speaking of, I noticed Digikey has the IRFB4110s in stock again:
http://www.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=IRFB4110PBF-ND

Bet it doesn't stay that way very long.

digi-key is dependable; you can depend on them to have stuff if you will pay their high prices... i just got my 50 4110 fets for the awesome price of $2.50, so whoever reads this first JUMP ON IT!!!

i have posted before about my favorite fet vendor http://www.irtronix.com.

i have been buying the 4310s from them for 2.40 which is a good price, but i just got a call from my guy there who told me they have the irfb4110pbf for $2.50 !!!!! most places don't even have them or charge more than twice this price.

i think they have several hundred still in stock, so move fast

when i first looked at these parts i was a bit concerned that the increased gate capacitance would be a problem with dropping them in to our controllers, but several of you did it and told me there was not an issue, so i tried a batch, and the 35/40a controllers with the discrete transistor high side drive stage seem to handle them ok.

the 4110 has a typical rds-on of 4-5 milliohms vs 7-8 for the 4310. they might be a problem for the 20A controllers that drive directly from the 2101s driver, but there is another driver, the 2110 i think, that might drop in to these and work. i am going to try that on the 20a controller i have mounted inside one of the hi-koll motors.

they had another 250 in stock when i got mine an hour ago, so move fast, my friends.

 

[Doctorbass]

Thanks alot for the info Bob! :wink: