Battery location pros & cons

ldc

Pedelecer
Jun 2, 2020
58
4
So it appears my bike, is too small to fit a battery within the frame and it appears other than buying a new bigger bike or a ready-made ebike, that I need to mount the battery on a rear rack or the seat post, I am just looking for the pros and cons of mounting a battery in such a place
 

01wellsd

Pedelecer
Apr 30, 2020
110
94
34
Bristol
People say that having the battery and the motor on and above the rear wheel can make the bike feel rear heavy.
I've never felt this on mine though. I have a rear hub motor and pannier mounted battery.
 
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ldc

Pedelecer
Jun 2, 2020
58
4
People say that having the battery and the motor on and above the rear wheel can make the bike feel rear heavy.
I've never felt this on mine though. I have a rear hub motor and pannier mounted battery.
thanks i am actually going to get a front wheel hub, what battery do you have on the rear, did it come with pannier or did you buy it seperate?
 

01wellsd

Pedelecer
Apr 30, 2020
110
94
34
Bristol
thanks i am actually going to get a front wheel hub, what battery do you have on the rear, did it come with pannier or did you buy it seperate?
I didn't build the bike myself, its a Whisper 705se. The front hub and rear battery should even out your weight distribution a fair bit. The picture attached is how mine is set up, there are kits that incorporate a battery and pannier.

35998
 

Scorpio

Esteemed Pedelecer
Apr 13, 2020
376
165
Portugal Algarve (temporary)
I have a rear hub with 36v/12ah downtube battery fitted to the rear rack. With rider the weight is split 30kg/90kg (30kg/120kg with some shopping in the panniers). Center of gravity is a lot further back than normal so I lift the bike by the seat post, otherwise its not noticeable.
 
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Nealh

Esteemed Pedelecer
Aug 7, 2014
20,981
8,565
61
West Sx RH
My Boardman hybrid mx/cx 700c day out bike is rear hub Aikema 128c has a downtube battery and a 91 cell rear rack/topbag battery , handling is only compromised if tackling gnarly slow tight twisty wooded sections. Other wise handling is good in the woods, open trials and on the Downs off piste.

My 700c commute/town bike has a Bafang cst with down tube battery, handling with panniers full of shopping is a different game and can be awful if it is weighty.

For a rack battery to cause handling to be really bad is has to be badly mounted or mahoosive. For rear rack the rack needs to be as far forward and as low over the wheel as possible.
 
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egroover

Esteemed Pedelecer
Aug 12, 2016
1,050
635
57
UK
I prefer the weight to be as central and as low as possible, like my Boardman MX Comp conversion here. When I put a spare battery in the rack bag, it changes the handling especially on slow awkward turns off-road

36010
 
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ldc

Pedelecer
Jun 2, 2020
58
4
I prefer the weight to be as central and as low as possible, like my Boardman MX Comp conversion here. When I put a spare battery in the rack bag, it changes the handling especially on slow awkward turns off-road

View attachment 36010
id love to have the battery in that location but my bike is just too small, wheres you get that controller case ?
 

Nealh

Esteemed Pedelecer
Aug 7, 2014
20,981
8,565
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West Sx RH
egroover doesn't have a controller case, the controller is integrated in to the mid drive. The top bar case is a cheapy that can be had on ebay.


 

Nealh

Esteemed Pedelecer
Aug 7, 2014
20,981
8,565
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West Sx RH
That there is the front derailleur clamp for your gears.

The integrated all in one PAS are problematic and need about 10mm clearance between crank and BB shell.
 

ldc

Pedelecer
Jun 2, 2020
58
4
That there is the front derailleur clamp for your gears.

The integrated all in one PAS are problematic and need about 10mm clearance between crank and BB shell.
what sensor do you recommend then, please? what's the difference other than size and cost between s12s and s09p

s12s https://bmsbattery.com/home/1024-s12s-500watts-torque-simulation-sine-wave-controller.html
so9p https://bmsbattery.com/home/1009-s09p-500watts-torque-simulation-square-wave-controller.html
 

Nealh

Esteemed Pedelecer
Aug 7, 2014
20,981
8,565
61
West Sx RH
I use 10 pole magnet disc with sensor/BB retaing ring behind the chain ring on all my builds.
This type of design with my external bearing BB.

Or use this type for square taper.