Suggest better ideas for mounting battery on my dually ebike

[jgregs]

So to my surprise the battery for my Bafang 8FUN kit actually (just) fits within the frame of my dual suspension MTB. This was a relief, because I really didn't want to have to sit it on a panier rack out over the back wheel.
At present I just have it strapped in place with a luggage strap. Any suggestions for a better way to mount it? I was going to drill a few holes in the underside of the top tube of the frame, and insert those little threaded doo-dads so I could slide the battery in and out of it's cradle as was intended, but because it is such a tight fit there would be no room to actually slide it into the cradle once it was on the frame

 

[Lurkin]

So to my surprise the battery for my Bafang 8FUN kit actually (just) fits within the frame of my dual suspension MTB. This was a relief, because I really didn't want to have to sit it on a panier rack out over the back wheel.
At present I just have it strapped in place with a luggage strap. Any suggestions for a better way to mount it? I was going to drill a few holes in the underside of the top tube of the frame, and insert those little threaded doo-dads so I could slide the battery in and out of it's cradle as was intended, but because it is such a tight fit there would be no room to actually slide it into the cradle once it was on the frame



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I have been commuting with one of these for the past ~6,000 kms. They are actually very, very good to use, but putting more time into setting them up and mounting them well pays off alot in the long run.

Couple of options:-
Leave it where it is:-
Advantages - it fits
Disadvantages - if you are relying on a strap and it fails, you lose your battery. You can drill and add bidon (water cage) mounts, but it could comprimise the structural integrity of your frame.

Underside of downtube
Advantages - won't hit it with your knees
Disadvantages - better to have the weight as close to you are particularly as speed increases.
Same as above with bidon cage mounts

Inside the triangle, where its designed to be
Advantages: easy installation
Disadvantges: looks like it would foul on the suspension

Alternative
Consider adding large hose clamps that go around your frame (protect frame with inner tubes). Cut strap, drill holes in aluminium end of the mount and either side of the cut sections of the clamp, attach.
the other end has plastic clips that you can run the clamp through, no need to cut and drill.

Advantages:
allows for attachment without reliance on bidon mounts
real sturdy
if you come off and hit it from side on it will move rather than break. I made the mistake of using the bidon mounts as well (mines mounted in the triangle) which stopped its ability to shift under force. Consequently, the top plastic mounts have broken. Will be looking to strengthen this going forward and do away with relying on bidon mounts altogether.

The key thing here is that if it can move under force, its less likely to break in a minor accident. Bidon cage mounts do not allow this.

Disadvantages
hose clamps look kinda nasty compared to the neat installation achieved with water cage mounts

 

[jgregs]

Thanks Lurkin for the detailed response!!

I think I'm going to go with your alternative suggestion.

Just one thing I wanted to clarify - you said " Cut strap", and "drill holes....either side of the cut section of the clamp"

...I'm not sure what you mean by this. What strap am I cutting? The hose clamp?

 

[Lurkin]

The base has no fittings or clips for the hose clamp to go through (unlike the plastic part at the top of the battery mount).

You have to have a means to attach the aluminium base to the hose clamp, which in turn attaches both to the frame.

If you cut the hose clamp in half, you will be able to drill holes on either side of the aluminium base, and either end of the strap. Each drilled strap end bolts to the aluminium base with the screw fitting in the middle. Make sure you use inner tubes between the clamp and the frame. the purposes is twofold - protect the frame and stop it slipping.

Once you get the hose clamp and hold it to the base it will be more obvious (this explanation is sticky). Hardware stores typically have different grades, I bought the stronger version.

 

[Samd]

Careful with the 36v version of this pack. CNEbikes seldom pack enough foam inside the unit to stop the cells bearing down on the internal fuse holder and the main power outlet. They tend to break internally at this junction after a bit of abuse. If you're using one on a dually I'd recommend cracking it open and adding double sided tape to the blue shrinkwrapped battery of cells inside to stop it sliding back and forth.

 

[Lurkin]

Should probably mention you need to open the base mount up to do the drilling. Again, this is to check there is no controller within the base as some suppliers do this as well, ensure you don't drill through anything extra.

 

[jgregs]

Picked up some hose clamps today..will have crack at it over christmas with a bit of luck. Thanks Lurkin and Sam!

 

[D-lo]

I got mine to fit, and it looks like you have enough room to mount it where the water bottle goes. That is the best place for the battery if you can get it there.