How to make a rack for battery

[Deleted member 4366]

I decided to tidy up my GNG kit bike. It had a heavy 10aH battery and nowhere for the controller. I wanted to swapp the battery for a 200aH Ping LiFePO4.
Here's where I started - a bit of a mess:

I copied the technique we used on Saneagle's Kraken. You can make a nice installation for a few pounds. I prefer it to a ready-made rack because you can get the battery lower and further forward - and, of course, it's cheaper. The bag isn't ideal because it's a bit too tall. I'll look out for another one maybe, but this one only cost £1 from a boot sale. In addition to the bag, you need a packet of 30mm M5 coach bolts (£1 from boot sale), a length of aluminium tube ( a few quid from Wickes) and a bit of aluminium to cut and bend into brackets. If you're lucky enough to have holes in the side of your frame, you don't need brackets, and finally, a piece of 3mm plywood cut to the same size as the inside base of the bag.

You cut the tube to length, bash the ends flat and drill holes to bolt it together. Here's the kit:

You pre-assemble the tubes and brackets, then cut the plywood to the right size/shape and bolt it to the tubes. Mark it out accurately otherwise it'll come out crooked. When your happy with it, unbollt the plywood, put it inside the bag and poke a hot soldering iron through the bolt holes, then bolt it back onto the tubes.
Here it is assembled:

 

[Deleted member 4366]

Here's the inside:

..and finally on the bike:

Next is to convert from crappy rim brakes to hydraulic discs:

 

[Scimitar]

Nice neat job. The sidestand looks much more substantial than the cheap POS I had - any idea where it came from ?

 

[Deleted member 4366]

It came off my old Sunlova bike. I've seen them on Ebay sometimes. There's some similar ones on there now, but I don't see exactly this one.

 

[hech]

all due respect here d8veh but dont think your going to sneak that 200ah ping into that wee bag there!

 

[Scimitar]

It came off my old Sunlova bike. I've seen them on Ebay sometimes. There's some similar ones on there now, but I don't see exactly this one.

Cheers, I'll have a look now I know what it was fitted to - some sort of starting point.

 

[Deleted member 4366]

all due respect here d8veh but dont think your going to sneak that 200ah ping into that wee bag there!

Bloody keyboard keeps giving double characters, as in swapp as well.

 

[cwah]

Nice one dave! Really like the way you manage to create clean part out of nothing!!!

Why do you need the iron on the bolt holes? Is it to make holes on the bag?

 

[Deleted member 4366]

Nice one dave! Really like the way you manage to create clean part out of nothing!!!

Why do you need the iron on the bolt holes? Is it to make holes on the bag?

Yes, and it seals the edges to stop the hole from tearing further.

 

[cwah]

Thanks dave. What do you use to seal the holes? I usually use tape but it doesn't work very well

 

[Deleted member 4366]

Thanks dave. What do you use to seal the holes? I usually use tape but it doesn't work very well

I never worry about the holes. Rain doesn't get as far as any electronics. Most of it is in your rain-shadow when riding. My philosophy is to make sure that any water that gets in can get out easily, but to be honest, I've never seen any water inside despite having holes where the wires come in.

 

[Deleted member 4366]

My friend Saneagle wanted a new electric bike because he sold his old one to finance his motorhome. i had a spare 48v code 10 Bafang BPM and my old Claude butler bike hanging round, so we set about converting it. The problem is the ull suspension that makes fitting a normal rack tricky, and a seatpost rack puts a heavy battery too high and far back, so I decided to do something similar to the above.

here's the bike's rear suspension set-up:



I needed a front fixing point so I made this bracket out of scrap steel strip:



The rest of the rack is as per the one above with aluminium tue from Wickes. I figured from the last one that it's best to fit the vertical struts about 60% of the way back:





The plywood is inside the bag. The bolts go through to hold it in place:



Finished bike. Just needs a bit of final tidying tomorrow:

 

[pdarnett]

Nice neat job there, the bag looks like my old one which was an IKEA BRANA CD bag!

 

[patpatbut]

How do you stop the battery moving around the bag?

Pat

 

[Deleted member 4366]

How do you stop the battery moving around the bag?

Pat

The bag's a football boot bag that you can get from any sports shop for about £6, or £1 from car boot sales.

To stop the battery moving, you can pack it tightly with foam, strap it round or through the plywood with velcro or large cable-ties. If you use cable ties on a pouch-cell battery, you need to re-inforce the upper corners to stop the cable-ties digging in. A small plate of aluminium bent into a right-angle does it.

Here's another one that shows how a nice tight fit works:

 

[Arbol]

Nice work, d8veh.

If one added a couple of 6s 5000mAh lipos and a controller on top of the plywood, and one put another piece of plywood on top of it all in order to hide the lipos and the controller, do you think that visually people would realize there is something inside the bag? Or the bag would seem empty?

I ask this because with your big battery, it is clear there is "something". But maybe with smaller batteries, it could look like empty.

 

[cwah]

Can I do that on my dahon jetstream for a bike seat?

 

[jackhandy]

Why not? As long as your passenger's ok with having their reproductive bits in intimate proximity to something that is classed as hazardous & has been known to ignite when abused

 

[Deleted member 4366]

You can apply several levels of security. I put a cable-tie through the zip. This stops light fingers looking in the bag. If a thief were to open the bag, he wouldn't know what that stuff is. Everything is joined by wires, so he might bbe scared of getting a shock. If you cable-tie the battery in or even make some metal straps, it'll make it difficult to get the battery out.

If you park in the same spot every day, a thief might figure out what you've got and target it, in which case there's not much you can do to protect it other than a silent alarm as long as you're not too far away.

i've bbeen using ags for the battery for three years now. I park at the supermarket, council offices, pubs, etc, and not had a problem so far. I think thieves would try and nick the whole bike rather than your battery. There's very few people know what it is and how it works at the moment, but that will change in the future.

 

[neptune]

There is also the chance that some thief looking inside the bag, and seeing batteries and wires might assume it is a bomb. You might come back to the bike just in time to see it being disposed of in a
"Controlled Explosion". I am being half serious here.