How difficult is it to integrate a GMAC (rear) or Grin All Axle Hub motor (front) into a factory 250W Mid drive bike?

Joined
May 19, 2012
Messages
611
Would be nice to have regenerative braking combined with the efficiency of a factory mid drive bike. I like the factory mid drive bikes because they place the pedals equidistant from each other as well as being narrow in Q factor.

IMO 250W factory mid drive + 500W regenerative braking equipped hub motor >> 750W factory mid drive for my purposes.

One reason I would like the regenerative braking is because it would reduce brake pad wear.
 
Consider that both of these motors will add some continuous drag. So you'll want there to be a good reason to have that extra power. You'll probably also need a much more powerful battery to supply both.. two controllers.. and two throttles also.

For me? i wouldn't really do it because the power would not combine so well. I'd find myself not using the mid drive very quickly, unless i had to scale a mountain.
 
neptronix said:
For me? i wouldn't really do it because the power would not combine so well. I'd find myself not using the mid drive very quickly, unless i had to scale a mountain.

Was planning heavy weight and steep hills
.....so the 250W mid drive will find use keeping the hub out of the inefficient speed range.

Something else to consider will be recapturing the energy which would be considerable....
but I have read even a good BMS can only handle 7 amps for Regen. 7 amps is not very much...and with a single battery I would be missing out on a lot of energy I could be recapturing I think.
 
FOC controllers should help

I think I will take the same approach, but because my use case requires 3-5 times the power

The mid gearing is great for low end torque, the hub motor for backup / reliability, use for ticking along at speed, low amps needed.
 
Anyone have any ideas on how many batteries I would need to optimize Regen when going down steep hills?

Which hub Gmac or Grin All axle can take the most power for Regen? I am assuming it is over 1000 watts for each hub motor provided enough amps on the BMSes are present?
 
john61ct said:
I think I will take the same approach, but because my use case requires 3-5 times the power.

If I could I would optimize for 2000 to 3000 watts Regen....even though I am only targeting a bit less than 750 watts (total) for electric propulsion.

Heavy weight going down steep hills (even at moderate speed) needs a lot of braking force.
 
And batteries need to be depleted.

Better maybe to use those 1000+W ceramic or aluminum braking resistors instead

I guess that's why they're called that...
 
Does anyone how much charge current the Grin ligo batteries can handle?

I couldn't find the spec for this.

Higher number of grin ligo vs. a lower number of some other battery for optimized Regen?
 
Sticking to a 1C rate, each pack can absorb around 100W aka 4A @24V

Ah capacity increases by paralleling so ten packs is 40A

double that for 48V of course
 
I found out the ligo+ batteries use Samsung 30q cells which are 3000 mAh and 1.33 C rate for max charge.

However, the ligo+ batteries are designed to be under 100 wh, so are these 10s1p batteries are being charged to lower volts?

And if they are being charged to lower volts how would translate in charge cycles at 1.33 C and 1 C?
 
Capacity is not a fixed number, varies greatly depending on the current rate.

So maybe that 2.7Ah is measured at the rated max 10A

Acceptance or rejection of any given pack will be at the discretion of the agents present at that time.

And they might only allow a few of them, total count was left undefined.
 
john61ct said:
ebike4healthandfitness said:
I found out the ligo+ batteries use Samsung 30q cells
Link please?

https://ebikes.ca/36v-ligo-plus-battery.html (scroll down to specifications and then click on it.)

Information on 30q here as well:

https://ebikes.ca/product-info/grin-products/ligo-batteries.html (scroll down to internal specs)
 
Heavy weight and steep hills, does require more power than your 2 suggested motors are capable of together.
 
Back
Top