Battery Mounting Hardware Tips for a Full Suspension DH

[ryan]

I'm preparing to build my first bike and would appreciate some tips on battery mounting.

Here is my bike (pre rear Crystalyte 5305 install):


The green boxes are where I'd like to place each of 2 Headway battery packs (36v20ah). I've tried a bunch of other places with my cardboard boxes, but those are really the only two that work for my bike. The rear battery is no problem Just a strong seat post rack. But the front is a bit of a challenge.

What I'd like to do is to "hang" the battery from the handlebar, with the weight of the battery controlled by the suspension forks. That way the weight is not directly pulling on the forks, but they can help stabilize. The head tube is set back a little bit so it won't take any thing.

The approximate size of each pack is 280x160x150mm (11x6.3x5.9in), weighing in at 7.5kg (17lb).

I'm going to look around the hardware store for a bit tonight for ideas, but is there anything you'd recommend? (other than a few roles of duct tape)

Hopefully the quick diagrams below of the proposed front battery placement show what I'm after. Care to brainstorm with me?

 

[ryan]

This isn't my bike, but the front fork is nearly identical:

 

[biohazardman]

Ouch! That is allot of weight and bulky size with a bike that is not to battery friendly. At 17lbs each the mounts need to be very strong to be durable enough to stay on the bike for any length of time. Makes it rough but many have been creative with their battery installs. You can look at the pics here to find some help with your mission. http://endless-sphere.com/forums/viewtopic.php?f=6&t=235 The lower you can keep your weight the better it will handle especially at low speeds when you need it. Abs plastic is easy to work with and not to heavy. I used it for my 2x8lb battery mounting as well as the controller and other goodies. Easy to put between boards heat, with a heat gun, and bend to be the right shape. Strong enough, I used the 3/16ths stuff, to drill and mount with brackets. Then the finished product just needs to be tucked away in the bags you made it to fit in for some stealth and protection from the elements. Some pics of what I did on this link. http://endless-sphere.com/forums/viewtopic.php?f=14&t=6586&start=15#p125502

Good luck with your build.

 

[Zoot Katz]

Good luck.
Battery packs always seem to be just a bit too large. . . and too heavy for unmodified seat post mounted racks.
A pack on the top tube between your knees and the other hung vertically under your saddle would be the ideal locations for the weight.
Knee and heel clearance would probably be the hard facts precluding this idealised set-up.

 

[johnrobholmes]

I heavily prefer my batteries around the top tube for proper weight bias. Headway's are pretty big beasts right?

 

[ryan]

Interesting Zoot. How do you recommend mounting the rear battery vertically?

Also, the Headways will be delivered in a hard plastic case. I'll still plan to stealth them a bit, but hopefully they're pretty sturdy as is.

 

[ryan]

JRH, I initially went for the top tube, but it was too wide for my legs to pedal and not enough clearance. I also thought I might be able to squeeze one on the down tube, but that was never going to fit.

 

[Zoot Katz]

Interesting Zoot. How do you recommend mounting the rear battery vertically?

Also, the Headways will be delivered in a hard plastic case. I'll still plan to stealth them a bit, but hopefully they're pretty sturdy as is.

Cable clamps, pipe strap, cutom molded resin adapter, chunked plastics, plywood, hose clamps, etc.

 

[patrickza]

How far are you planning on going, two 36v10ah packs in series would give you 768 watt hours. That's what I have and I do 30 miles on mine at low speed, 20 when I'm going fast. I also have a 5305.

You could always use the remaining cells for long distance packs and put them on a trailer or some type of pannier bag.

 

[dogman dan]

I did something very similar with a 24v 8 ah nicad pack. It worked but kinda sucked. Just made fast steering corrections take more strength. But what to do? When I had the bike too tail heavy, it was a wheeliemobile. Kinda fun, but sketchy to ride for much distance.

I took two sheets of aluminum from a recycled road sign and using wood blocks and screws, securely sqeezed the pack between them. One of the sheets had some strips of aluminum sheet attached to clamp the box to the handlebars and the stem. With a tripleclamp fork, you could clamp to the tubes easy.

But you won't be able to see the wheel on a rocky trail, and may have to use a lot of strength to flick the bars around on tricky terrain. On the street, none of that will matter that much.

I'm in the same boat, I have a 5304, I have a nice FS bike, but I can't figure out a way to mount 72v 10 ah that won't suck. With a123's or other small cells, and a bigger frame triangle, it can be done. But with big blocky headway packs, it will be tough. I'm thinking maybe just 48v, and put it on the rear rack.

I take my post racks, and support them with two tubes that complete a triangle between the rack midpoint, and the bottom of the seat post tube. You can't adjust the seat anymore, but the rack will now suppost 75 pounds. ( 30 pounds bouncing)

 

[kilowatt]

That rear seat post rack could support a set of panniers and both batteries; another idea for you and more hidden. Are you staying with a 36 volt parallel system @ 40 amps or series for 72 volt 20 amps? I split my cammy lifepo4 36 volt 20 amp into two halves and use panniers. I installed a bicycle trunk on the back rack that hosts my controller, BMS and wires. I have a rear hub motor and with the panniers hanging down and the wiring in black plastic wrap into the trunk, you can't tell its electric. This is my winter project. Good luck.

kilowatt

 

[ryan]

Thanks kilowatt. Unfortunately rear suspension pretty much disqualifies any thought of panniers. Typically seat post racks are rated for 20-25lbs. That's good for one battery.

If I had a hard tail I might do panniers, but that'd also mean I'd have room in the front triangle too.

 

[ryan]

How far are you planning on going, two 36v10ah packs in series would give you 768 watt hours. That's what I have and I do 30 miles on mine at low speed, 20 when I'm going fast. I also have a 5305.

I bought the batteries for distance. I'm hoping to get 40 miles out of a charge, not going too fast, but with some steep ascents along the way. This isn't for commuting. Just for fun.

 

[ryan]

I did something very similar with a 24v 8 ah nicad pack. It worked but kinda sucked. Just made fast steering corrections take more strength. But what to do? When I had the bike too tail heavy, it was a wheeliemobile. Kinda fun, but sketchy to ride for much distance.

That's my thought too. At the rear they're out of my way, but that's a whole lot of weight back there.

I took two sheets of aluminum from a recycled road sign and using wood blocks and screws, securely sqeezed the pack between them. One of the sheets had some strips of aluminum sheet attached to clamp the box to the handlebars and the stem. With a tripleclamp fork, you could clamp to the tubes easy.

Ooo, do you have a photo of that? Sounds sturdy. I need more time at the hardware store for brainstorming.

But you won't be able to see the wheel on a rocky trail, and may have to use a lot of strength to flick the bars around on tricky terrain. On the street, none of that will matter that much.

I'm not planning on anything tricky. Mostly roads and fire roads. No single track.

 

[nicobie]

These guys make racks for full suspension bikes, both front and back ones.

http://www.oldmanmountain.com/index.html

 

[ryan]

These guys make racks for full suspension bikes, both front and back ones.

http://www.oldmanmountain.com/index.html

Very cool. Looks like this can be built DIY style as well: (~$40-50 or much less if you find a used rack)
http://www.instructables.com/id/Bike_rack_for_full_suspension_mountain_bike/

Or the Axiom Odyssee Rear Suspension Rack: ($40)
http://www.amazon.com/exec/obidos/ASIN/B000C12BUY/svf-20

 

[dogman dan]

Sorry, never photo'd it and now it's off the bike, But the idea is simple, just some straps that attached to the top of the block, and wrapped around the handlebars on either side of the stem. Then a third piece of bent metal hose clamped to the stem down lower.

On my stiffened rear rack, I have a broomstick up the seatpost to strengthen it, and use a real stout axiom pannier seatpost rack. Then that is braced with two pieces of steel tube. As long as the frame doesn't crack..... I've carried 48v 8 ah nicad, 36v ping, three pints of water, tool kit, spare tube, pump, lock, all on 60 mile rides last summer on that rack. But the front hub helped it all balance. The frame would bend like a noodle though, I had to watch that.

 

[ryan]

So, Zoot, after visiting the hardware store and buying a few pieces to try on for size, I find out that there just isn't enough room for the rear battery to be placed vertically. I thought I had a great strategy planned but it just isn't going to work out.

Rear seat post still seams the best starting option. Though I'm impressed with some of the rear rack options with full suspension. I didn't know they existed.

I'm still working out the front pack.

 

[Mark_A_W]

I would just buy a decent dually with space in the triangle.

They do exist - I have both a Kona Dawg and a Giant DH Team which have ample space.

You are trying to turn a sow's ear into a silk purse - rear rack batteries SUCK.

They ruin the handling completely.

 

[docnjoj]

Definitely agree with Mark_A_W about rear rack placement of batteries. I have my fatpacks firmly attached to the middle of the trike underseat and when I placed my split Ping in panniers the handling really became poor. This on a trike made to carry heavy weight. If I can fix the Ping I will also remount it low and central. Those racers must know something.
otherDoc

 

[ryan]

Update: For this build I found front pannier packs that work with my suspension fork and put the packs in there. It looks a little backwards but it's really functional. Thanks for the advice about not doubling up on rear weight.

With the size of these 36v20a packs, I'm not sure anywhere else would've worked on this bike. If I wasn't doing so much hill climbing I'd consider buying a front hub and bringing the panniers to the rear.

Thanks for all your help.