How to make a battery box ?

[KirstinS]

I have a long and thin 36v 17.5ah pack of mj1 cells. It has kapton tape and heat shrink. It currently live in a 6 point velcro harness podsac tarp frame bag (with heavy duty foam placed at both end to protect cells from banging against frame)

This one

PODSACS Waterproof Frame Bag – Planet X Bikes

Waterproof frame bags from PODSACS that allow you to conveniently carry all your important items on any trip without upsetting the balance of your bike. Adventure-tough 7-point fixing system Stormproof 500D Tarpaulin fabric Waterproof external zip Retroreflective detailing 2.2L Capacity (small)...

www.podsacs.com

However , after 6 months or so the bag is breaking especially where the velcro straps meet the bag itself. I do a fair bit offroad and like to chuck myself and the bike about. So the stresses of weight pulling the bag down over time are the culprit.

I could just buy another but it is a slight pain to take on and off the bike to charge. And the next one will go for sure. It's a well made bit of kit, I just abuse it

So thinking of making some kind of frame box but have zero idea on how to do this or how to mount it

Anyone know of any good instructions or how to out there on this subject ?

Thanks as ever

 

[Nealh]

Probably grp is the way to K, though you need to make up a timber or styrofoam former to mould the grp on to. This means making it as a two piece enclosure with one side removable with plastic W buttons (I have plenty in black) a bit like the Swizzbee battery enclosure.
To prevent the grp sticking to a former cover it in cling film or grease proof paper etc.etc, though pro's use a Gel coat for a smooth int finish.
A grp one like the Podsac can be riv nutted to the frame if tightly made or attached with Velcro with slits in the grp structure.

My roofer friend has just recently replace my porch felt roof and he has done it all in fibreglass with pvc fascia, looks bloody amazing, you can finish the grp in whatever colour top coat you like.

vfr has made some nice battery enclosures once all his pics were viewable, I remember a Green one and a neat Red/White vey nice Rocky mountain one.

 

[Nealh]

You are being redirected...

1.Gel coat.
2. Matting,resin and hardner.
3. Top coat.

 

[cwah]

I have something similar with my bike and never had a problem. The solution is simple:
Use heavy duty strap instead of reliable on velcro:

Pardon our interruption...

Put few of them to secure it strongly against your frame and avoid wobble, then problem sorted.

My stolen bike uses few of these strap to secure the battery.

 

[Nealh]

Yep cam buckle would do the job, they are very versatile and they are cheap.
I use them to tie my bee hives down and use them for securing stuff on my ebike CF trailer.

 

[KirstinS]

Probably grp is the way to K, though you need to make up a timber or styrofoam former to mould the grp on to. This means making it as a two piece enclosure with one side removable with plastic W buttons (I have plenty in black) a bit like the Swizzbee battery enclosure.
To prevent the grp sticking to a former cover it in cling film or grease proof paper etc.etc, though pro's use a Gel coat for a smooth int finish.
A grp one like the Podsac can be riv nutted to the frame if tightly made or attached with Velcro with slits in the grp structure.

My roofer friend has just recently replace my porch felt roof and he has done it all in fibreglass with pvc fascia, looks bloody amazing, you can finish the grp in whatever colour top coat you like.

vfr has made some nice battery enclosures once all his pics were viewable, I remember a Green one and a neat Red/White vey nice Rocky mountain one.

Lots of info and there and abbreviations I don't understand. I'll get to grips and come back with questions!

 

[KirstinS]

I have something similar with my bike and never had a problem. The solution is simple:
Use heavy duty strap instead of reliable on velcro:

Pardon our interruption...

Put few of them to secure it strongly against your frame and avoid wobble, then problem sorted.

My stolen bike uses few of these strap to secure the battery.

Thanks cwah. I get this is a good quick and reliable fix. My bike is quite small and relatively clean looking and lightweight ( for an externally routed bbsxx conversions. )

I could just add such a strap to go under the bag and over the top tube. But it's another layer of hassle to remove for charging and another bit of bulk I'd rather avoid. No doubting it does the job mind

 

[anotherkiwi]

Is there a 3D printer in your life? You can print a box in PETG which has the same mechanical properties as ABS (or near so) and is easier to print than nylon or ABS which a lot of commercial cases are injection molded from.

For fast on and off a few nylon webbing belts and cam buckles would do the trick.

 

[vfr400]

3mm plywood sheet is very easy. Cut the shapes and glue into a box. You have to make sure that any fixings on the inside can't dig into the battery. You can hold it to the frame with U-brackets made out of aluminium or stainless strip.

Start with the strip that will be adjacent to the frame. Make the brackets and drill the holes to match, then see how it fits on the frame. when you're happy, epoxy the screws in so that the threads stick out. Dismantle it, lay your battery on it and build the rest of the box around it, leaving a hole for the main leads. Mount your charge socket and switch into a side before gluing the side on. When all sides are glued, sand down the edges a bit, then seal it with sanding sealer, prime it and spray it with auto aerosol paint. You have to destroy the case if you ever need to service it, but hopefully, that will never be required. it's much more complicated to make a nice box that allows the battery to be removable.

Here's one I'm making for a 40 cell battery to fit between the downtube and low crossbar of one of those ladies bikes with a drop-down crossbar like two downtubes.

 

[KirstinS]

Thanks very much all.

I think the ply approach seems more within my comfort zone for a first build !

But I do like the grp idea too

Hmmm. Need to start measuring and costing out

Great info though

 

[Parsons]

Make a wooden frame and some side panels

 

[Weldinpatt]

Thanks very much all.

I think the ply approach seems more within my comfort zone for a first build !

But I do like the grp idea too

Hmmm. Need to start measuring and costing out

Great info though

Yes great stuff exactly what I was thinking . As long as it keeps nice and dry rely on previously learnt skills at least you know the result will be what you want. I
Was wondering cover the assembled battery cover it in expanded foam file/ rasp to my shape seal it then encase in fiber glass resin like a kayak mild with wires coming out terminated in XT90 or 60 s.

 

[Parsons]

Send use a pic mate just use wood and ally for the side that will so the job

 

[guerney]

3mm plywood seems too flimsy? I finally bought a pop riveter and rivets the other day, with a view to making a battery box to secure to the rear rack, using 3mm and 5mm aluminium sheet. I might add a dayglow yellow and reflective shark fin...

 

[Parsons]

What frame you putting it into mate

 

[Parsons]

Bike battery box biuld

 

[guerney]

Bike battery box biuld

Very nice job indeed! What sheet material did you use?

I'm going with aluminium for a tough waterproof case to go over my battery, adding a hinged lid and lock, keeping the battery easy to remove when briefly popping into shops. It'll have a rack on top, for cargo.

 

[matthewslack]

3mm plywood seems too flimsy? I finally bought a pop riveter and rivets the other day, with a view to making a battery box to secure to the rear rack, using 3mm and 5mm aluminium sheet. I might add a dayglow yellow and reflective shark fin...

Blimey - aluminium boats are thinner than that! 1.6mm ought to be plenty strong enough - as long as it is a suitable alloy, not soft floppy pure Al. Careful with the conductivity!

 

[guerney]

Blimey - aluminium boats are thinner than that! 1.6mm ought to be plenty strong enough - as long as it is a suitable alloy, not soft floppy pure Al. Careful with the conductivity!

Yes, 3mm is a bit overkill for the sides, the 5mm is for the base - I've got some 2mm kicking around too... I frequently have had to carry heavy loads last summer, and the rack on top of the box needs to be adequately supported (I have some box section aluminium tube, to constuct a frame for the battery box & rack - I'll pop rivet sheet to that). I might find that the whole construction is heavy... but I have a 19.2ah battery which has more than enough capacity for rolling around a bike with a heavy box, home grown veg and shopping for many miles. Plywood needs care, and will eventually rot regardless. I bought a 2m X 2m X 6mm rubber mat for my work area the other week, I might cut some of that off to use under the battery, for vibration reduction. 2X6mm layers might do the trick.

That's a very good point about conductivity!

 

[Parsons]

1.2mm steel sheet was looking at plastic bsides but hi powder-coated mine at work
I got my 52v battery and controller and charger into the box