Help! Battery Mounting Ideas

[Peter.Bridge]

So I have converted a Carrera intercity Disc 8 Folding Bike and handed it over to my mother in law , who seems very happy




It has an akm-75 front hub motor and a Yose Power seat tube battery that I have attached to the Front fixing point

So I was showing a photo of this to my son and he asked if I could build him one. He managed to get an identical, hardly used, Carrera Intercity Disc 8 (with steel forks).

I ordered another akm-75 front hub and I have ordered this bag battery (with waterproof cover) for the battery and controller

36V15AH Samsung INR21700-50E Li-ion Battery+Bag [36V15AH Samsung 21700+Bag] - $189.28 : Zen Cart!, The Art of E-commerce

Zen Cart! 36V15AH Samsung INR21700-50E Li-ion Battery+Bag [36V15AH Samsung 21700+Bag] - ★★★★★ SPECIFICATION: 36V15AH Samsung INR21700-50E Li-ion Battery+Bag 1-Capacity:36V15AH SamsungINR27100-50E 2-Cells in series:10S3P, total cells:30 pcs 3-BMS:20-40A 4.Bag Size:200*150*80mm 5-Discharge...

topbikekit.com

And I wanted to attach it to the mounting point



My idea was to get some sheet metal, glue it to the inside of the battery bag, and then drill a hole through the sheet metal / battery bag and attach with M6 screws. Any comments / alternative suggestions ?

 

[Raboa]

I had to buy the below as my frame bottle holder bolts were not in the middle of the down tube. They also do two and four slot versions. I then attached my battery holder to this and wrapped two velcro straps around the battery and down tube

Wolf Tooth Components B-RAD Mounting Base - 3 Slot | Sigma Sports

Shop the Wolf Tooth Components B-RAD Mounting Base - 3 Slot online at Sigma Sports. Receive FREE UK delivery on all orders over £60 and easy returns!

www.sigmasports.com

I collect scrap metal so I have bits of aluminium heatsinks about ( give me a rough size) if you want some let me know and I will send it to you.

 

[harrys]

I have a bag like that somewhere. Never really trusted it ti not rip with time,

I would get a L-shaped shelf bracket. Put a little floor on it. Put that in your bag and then bolt it to the bike. The floor will support the weight better. Might need some foam padding too,

 

[Raboa]

I have a hard drive top plate if that suits your purpose, they are steel or stainless steel

 

[Raboa]

This is 100mm wide and 280mm long, thin aluminium plate

 

[Cadence]

I had to buy the below as my frame bottle holder bolts were not in the middle of the down tube. They also do two and four slot versions. I then attached my battery holder to this and wrapped two velcro straps around the battery and down tube

Wolf Tooth Components B-RAD Mounting Base - 3 Slot | Sigma Sports

Shop the Wolf Tooth Components B-RAD Mounting Base - 3 Slot online at Sigma Sports. Receive FREE UK delivery on all orders over £60 and easy returns!

www.sigmasports.com

I collect scrap metal so I have bits of aluminium heatsinks about ( give me a rough size) if you want some let me know and I will send it to you.

A bit late now, but you could have saved some money and bought one of these:-

Pardon our interruption...

There are lots on ebay and aliexpress at around the same price. There are also two and four slot versions. I put one on the downtube of one of my bikes to fit a Hailong H1 battery and in conjunction with a couple of cheap toe-straps, it's held firm.

Pardon our interruption...

 

[Raboa]

I have have these but they are not the dimensions you are after, a bit small.

 

[AntonyC]

Nice looking bike. I'd do as you suggested using a rigid plastic plate, zip tie the cells+BMS pack to the plate inside the bag and then.... rub the inside of the bag with a damp sponge and squirt building foam all round the pack. That way you get thorough waterproofing without a shower cap, a little knock protection, a little less impact from sunlight or frost, a degree of theft dissuasion and a smartly plumped bag

Assuming VAT's invoiced after delivery the TBK battery at $189 works out at £245 doesn't it after shipping and VAT? Woosh is showing £229 which I think includes delivery for their seat-bag battery, which might work well for rear wheel conversions.

 

[chris_n]

I have a bag like that somewhere. Never really trusted it ti not rip with time,

I would get a L-shaped shelf bracket. Put a little floor on it. Put that in your bag and then bolt it to the bike. The floor will support the weight better. Might need some foam padding too,

Sort of seconding this as support under the battery will make a huge difference to the way the forces are absorbed but I wouldn't use a shelf bracket, I would fabricate something neater. I also would look to put the 'shelf' reasonably close to the bottom hole on your mounting point or some triangulation ribs to reduce the amount of leverage applied to that mount.
One thing that may need some attention (bearing in mind I can't see which bits actually move when you turn the steering) is whether the battery needs spacing forwards as per your original conversion to allow the steering to turn freely.

 

[Raboa]

You could use a three point buckle to help support the bag. Put a webbing strap around the top and bottom of the frame head tube. Another piece of webbing would go around and under the bag, these pieces of webbing would be joined together.
You can also make an L bracket out of a piece of aluminium, outer cases for DVD, video players etc can be made out of aluminium. If you are handy you could fabricate one out of this metal and have to go at the back and under the bag. Another option is ask someone on here to 3d printer you a bracket and pay the costs

3 way point buckle - Google Search

 

[Peter.Bridge]

Thanks everyone very much.

So what I think I am going to do is get an L shaped sheet metal "bracket" and glue it to the inside of the bag with some zip ties running behind the bracket(so they will also get glued in place). I will then screw the bracket (and attached bag) to the front mounting point on the frame (it won't stop the handlebar turning). I will then sit the battery (2.2kg) on the bracket and secure with the zip ties. Add some foam around the battery , place the controller in the bag, and zip up the bag.

 

[saneagle]

Thanks everyone very much.

So what I think I am going to do is get an L shaped sheet metal "bracket" and glue it to the inside of the bag with some zip ties running behind the bracket(so they will also get glued in place). I will then screw the bracket (and attached bag) to the front mounting point on the frame (it won't stop the handlebar turning). I will then sit the battery (2.2kg) on the bracket and secure with the zip ties. Add some foam around the battery , place the controller in the bag, and zip up the bag.

You shouldn't use sheet aluminium unless it's very substantial, say at least 3mm thick otherwise it'll fail due to metal fatigue. Steel would be many times better, and you could go much thinner.

 

[StuartsProjects]

I did a similar conversion on a Brompton, I wanted the battery on the front bag block so the battery could stay in place when the bike was folded. The L shaped bracket takes most of the weigh, so the bag just needs to support the controller.

 

[Raboa]

The black heatsink in the picture is 60mm wide, 170mm long and 10mm deep, it has fins, the base plate is only a couple of mm thick.
I have two of these so you could make a l bracket out of these, I am unsure if you can knock out the bolt pins at each end

 

[Waspy]

Any comments?

I'm curious why you didn't get the same battery and use the same mounting solution that you used on your own Intercity Disc 8?

 

[Peter.Bridge]

I'm curious why you didn't get the same battery and use the same mounting solution that you used on your own Intercity Disc 8?

I think the Samsung 21700 -50E celled batteriy bag is very light for a 36v 15Ah capacity battery, 2.2kg, the equivalent seat post battery would be a bit heavier and I like the fact I can put the controller in the battery bag., the same as @StuartsProjects . The disadvantage is the battery is not easily removable

 

[Peter.Bridge]

The black heatsink in the picture is 60mm wide, 170mm long and 10mm deep, it has fins, the base plate is only a couple of mm thick.
I have two of these so you could make a l bracket out of these, I am unsure if you can knock out the bolt pins at each end

Thanks very much @Raboa for your kind offer, I have just got a (steel) bracket from B & Q - looks very similar to @StuartsProjects

 

[guerney]

You didn't say if you wanted good ideas or bad. Now that you have a sturdy steel L bracket, you could use it to make a heavy waterproof box with aluminium L bar, silicone sealant, nuts & bolts, aluminium sheet, hinge, and a clasp and/or lock for the door. Bad idea, don't do it.

 

[Peter.Bridge]

Off on a slight tangent - but when I was test riding the bike for my mother in law (who is a lot lighter than me), I was really subjectively impressed how powerful the tiny AKM-75 motor was, given that it has relatively lowly torque claims.

I tried comparing it on the Grin motor simulator to a couple of well known, heavier, hub motors, adjusting the wheel size to take account of the different maximum rpm speed. This is for 100kg rider + bike and 10% gradient, with 100 watts being provided by the rider, 36V 15 amps





A couple of reservations - 1) not sure what point it would overheat (not had any problems myself), 2) Obviously the BPM could go a higher current

The AKM-75 and the other "microhub" @Nealh 's Bafang G370 had very similar performance (there is also a 201 rpm version of the AKM-75 although not available on the simulator). I notice that the overheat time at constant 10% gradient would be around 7 minutes , that would require a 1.75 km constant 10% gradient - there's not many of those around !

 

[saneagle]

AKM motors have a higher internal reduction ratio, so will generally be more efficient at low rpm compared with others that have the same maximum rpm. If you want better hill-climbing, a motor with lower max rpm will always be better.