Battery Pack on a downhill bike

[espresso]

Hi. First build for me.
I'm looking at putting a BBHD onto a downhill bike, but the frame is very tight and small.
Would it be possible to put the battery on the underside of the bottom tube?

[mtm408]

Sure, I’ve seen several ebikes that have batteries mounted that way. Just make sure to use extra attachment straps to keep it secure.

[ykick]

Straps yes. And check that full fork compression doesn't drive the wheel into the battery pack.

[JPLabs]

I second ykick's advice, and wanted to mention a bit more. Really do check for contact at full compression. Not, just, 'I bounced on it and it didn't hit'. You most certainly want it to also not hit when you go over a surprise drop and land hard, etc. Contact = crash.

Depending upon the fork, there are various methods to limit compression, like rubber blocks, or raising the oil level, etc, if needed.

If it's an air fork, just let the air out to check.

[espresso]

Hi mtm.
Thanks.
I have never seen a battery fitted like that, or even a photo of one!

[mtm408]

Here is a photo of one. Look at post #12.

https://electricbike.com/forum/forum/builds/ebike-building-directions/39186-risun-motors-mustang-bbshd-full-suspension-boost-ebike-build-starting-from-a-frame

It's not the optimal way to mount a battery, but it can be done. Some people prefer to use a backpack and a cord rather than a permanently mounted battery.

[mtm408]

There are some here on the forum if you look around.

[Zippy]

That is the very reason I specifically bought a full suspension bike with a fairly big triangle so I could mount a battery inside it but if you compress your forks you'll likely see you won't bottom out on the battery. Like others said above take adequate measures to make sure the battery is not going to move around. You might be able to figure out something with hose clamps around the down tube secured to the battery cradle and a couple scuba knife straps for some extra protection too.

[max_volt]

Where there is a will, there is a way

[xcnick]

So far, so good. Used velcros to get it secure. The Uzzi had a bottle bracket so there were screws, but it had to put on upside down. Someday I will get to putting it rightside up with some new riv nuts.

https://electricbike.com/forum/forum/builds/ebike-building-directions/40947-intense-uzzi-with-bbshd

[xcnick]

Down hill bikes with slack geometry have more room under the down tube, but EVERY bicycle has room under the down tube. God bless the Fusion idea to fit most triangles, but some bikes don't have triangles and under the down tube gets the weight lower. If I had to make only one battery it would be under the down tube.



What is wrong is duct tape or velcro becomes a structural component. Maybe hose clamps or someone smarter than me can come up with something. My quick design has flat spots for velcros. I can't think of a bike it would not fit. Pictured is 5p, but take off two rows from the bottom and it is 4p. 4p with 30Q cells and 50amp BMS would be ideal.



If you make it, I will buy it. (Field of Dreams vague reference.)

[Zippy]

I'm sure you know about Duallock Velcro Nick, that stuff holds so well it's scary. Tried using some on a few effects pedals on my guitar pedalboard, had to stop because it's so hard to remove them once they're on there, had to use screwdrivers to pry them off to move around. Might be good for mounting batteries in difficult spots.

[xcnick]

First I heard of Dual Lock. Cool, thanks. But I still wonder if velcro is just as ghetto duct tape.