Rucksack battery advantages.

General Discussion about electric bicycles.
iperov   1 kW

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Rucksack battery advantages.

Post by iperov » Mar 30 2012 7:00am

Battery in rucksack:
+ bike lighter
+ arms do not tense up when moving bike
+ bike more maneuverable
+ no need install 2 bricks to bike
+ free space on rear rack
+ nobody can steal batteries

I plan add to my 20ah rucksack memory foam layer to reduce pressure.
Image
Sorry, bad english!

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johnrobholmes   1.21 GW

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Re: Rucksack battery advantages.

Post by johnrobholmes » Mar 30 2012 8:03am

Problems-

strain on back
strain on arms
if a fire occurs you are pretty much guaranteed to get burned.

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Re: Rucksack battery advantages.

Post by iperov » Mar 30 2012 8:29am

actually no strain on arms,
and due to memory foam, pressure distributed evenly

and this video, man flying over the mountains with battery in rucksack,
you cannot do this with heavy weight bike
Sorry, bad english!

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neptronix   100 GW

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Re: Rucksack battery advantages.

Post by neptronix » Mar 30 2012 8:40am

Disadvantages i can think of:

+ Extra weight in the wrong place. ( up high is the absolute worst )
+ The more range you want, the more weight you have to carry on your back. If you want a long range pack, it might break your back :lol:
+ You might not survive a lipo fire, in the ultra-rare chance that one occurs.
+ Battery weight will swing around and cause wobbly handling unless the pack is a really, really tight fit in the backpack and you have it strapped to you pretty tightly.

It really should be an option of last resort.
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Re: Rucksack battery advantages.

Post by kfong » Mar 30 2012 8:43am

The weight on your back throws you off balance during single track riding. In 90 deg weather or long rides it gets uncomfortable. Best setup is to have the packs centered on your bike in the triangle if possible.

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johnrobholmes   1.21 GW

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Re: Rucksack battery advantages.

Post by johnrobholmes » Mar 30 2012 8:54am

I have ridden with packs in backpacks, and my arms and back would disagree that there is no strain involved. I also hate the swinging effect of the bag, it is easier to control a unified mass with battery in bike.

Now maybe if I was still 18 years old and made of rubber I would agree more.

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Re: Rucksack battery advantages.

Post by johnrobholmes » Mar 30 2012 8:58am

And if you don't believe that extreme riding can be done with batteries in frame, look a little further

http://endless-sphere.com/forums/viewto ... 31&t=38061
https://www.phasorcycles.com/Photos___VIdeos.php


I can't find the vid offhand, but in one of them a fellow is dropping about 8 feet into a transition. Seems pretty capable to me!

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MadRhino   100 GW

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Re: Rucksack battery advantages.

Post by MadRhino » Mar 30 2012 9:02am

iperov wrote: and this video, man flying over the mountains with battery in rucksack,
you cannot do this with heavy weight bike
...
Don't be a dreamer, the weight that you carry in backpack is no less weight to ride. It is only placed elsewhere, and not the best place to let you have full use of your balance and agility.
Make it fool-proof, and I will make a better fool.
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dogman dan   100 GW

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Re: Rucksack battery advantages.

Post by dogman dan » Mar 30 2012 4:34pm

Fine for less than ten pounds perhaps. One thing about real talent, they make it look REAL easy. Skiing with a big pack is just as hard, but the Alta Utah ski patroll make it look like it's easy.

It doesn't mean it's easy for you. It's not that it can't be done, it's just not easy. On skis what other choice do you have to carry something? On a bike, you have a better choice.

Ever see cross country bicycle riders carrying a pack? Nope.

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knoxie   10 MW

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Re: Rucksack battery advantages.

Post by knoxie » Mar 30 2012 5:31pm

It depends what kind and what length of riding you want to do, I have done it many many times, short commutes with a light small pack perfectly OK, but heavier packs over rough ground and long distances is horrible and uncomfortable, you also have to factor in the fire risks too, lipo bags will buy you seconds whilst you stop and get the pack off your back, you would have to be super unlucky to have a fire but its possible, I would also recommend keep back pack batteries to 12S max! you have to start thinking about the potentials for shocks over that as the power cable will be swinging about around you, its your call at the end of the day, there is no rule.
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Re: Rucksack battery advantages.

Post by sn0wchyld » Mar 30 2012 7:39pm

johnrobholmes wrote:And if you don't believe that extreme riding can be done with batteries in frame, look a little further

http://endless-sphere.com/forums/viewto ... 31&t=38061
https://www.phasorcycles.com/Photos___VIdeos.php


I can't find the vid offhand, but in one of them a fellow is dropping about 8 feet into a transition. Seems pretty capable to me!
great to see that guy finally getting into production!

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Re: Rucksack battery advantages.

Post by cwah » Mar 31 2012 4:30am

Which backpack would you use?

I'm thinking about getting a cheap backpack such as this one:
http://www.ebay.co.uk/itm/Shugon-Tokyo- ... 791wt_1163

But after I would need to drill a hole to allow the electric cable to go outside. And I'll also need something to protect the hole created.

Any idea where I could find that?
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Re: Rucksack battery advantages.

Post by Scottyf » Mar 31 2012 6:47am

Cwah I just used my old reebok back pack I've had since I was 14, the bags about 13 years old.
I poked a few holed in it to run cables from the battery packs in the main area. To the controller which is in one of the pockets.
This then runs quite thick gauge cables and powerpoles to the bike.

I've stuck all the wires in a smaller think inner tube to water proof the cables.
It already houses the wires to a cut off if I come of the bike that kills the batteries and controller. Also the wires to hard wore my lights using deans connectors.
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cwah   10 GW

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Re: Rucksack battery advantages.

Post by cwah » Mar 31 2012 6:51am

Thanks Scottyf.

I was thinking about getting some rubber ring to protect the holes created in the bag:
http://www.ebay.co.uk/itm/Washing-Machi ... 500wt_1180

What inner tube did you use to waterproof the cables? Is it something such as a heatshrink? And how did you houses the wires to a cut off?
Help me find my stolen electric brompton: http://bit.ly/1a0vbBC and Bosch Sinus B3 http://bit.ly/1eV0WQz

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Re: Rucksack battery advantages.

Post by Scottyf » Mar 31 2012 7:03am

I just used an old inner tube that I punctured and repaired. I have quite a few lying about and so thought I'd use it. Before that I just used insulation electrical tape to create a loom.

The cut off is just a shorter valve that if pulled disconnects first before the main cable gets pulled. Most power poles tend to disconnect anyway. Never had an issue with battery pack patterns even with falls and the UK weather.

I thought the balance and weight was better than on the bike. Especially from moving the bike around.
Probably not the best as Described above for trail riding but as I mostly do road it's been better than keeping the batteries on the bike.
It also means I can disconnect the batteries when I park up and not worry about someone fiddling as the main elective are with me. Also means people are less likely to steal it in densely populated areas.
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cwah   10 GW

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Re: Rucksack battery advantages.

Post by cwah » Mar 31 2012 7:14am

Thanks Scottyf, you're an inspiration :)

Have you ever thought of getting the batteries in the rear rack? Because 5kg batteries are quite heavy and during summer it makes you sweat.

I'm thinking about having a backpack with a quick release from the rear rack. So I can always carry the batteries with me without having to carry them when I'm cycling.
Help me find my stolen electric brompton: http://bit.ly/1a0vbBC and Bosch Sinus B3 http://bit.ly/1eV0WQz

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Re: Rucksack battery advantages.

Post by Scottyf » Mar 31 2012 7:19am

Jerry uses a similar method to what you after.
I wanted the bike to still stay like a bike on the odd occasion I don't use the electric side of the bike.
This is why I kept the battery and controller off the bike.

I didn't like the rear rack as it up set the balance of the bike.
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Scottyf   100 W

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Re: Rucksack battery advantages.

Post by Scottyf » Mar 31 2012 7:27am

Heres some pictures I took just.

Image
Image
Image

Not the most technical but it works. Batteries go in the main part and then I carry clothes for work etc. Batteries are foam padded though. Probably no where near as fire resistant as it could be. But for the last year its been ok.
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Re: Rucksack battery advantages.

Post by kfong » Mar 31 2012 7:41am

If you take a torch to a thin screwdriver tip. You will be able to burn an exit hole than won't frail.

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Re: Rucksack battery advantages.

Post by cwah » Mar 31 2012 8:14am

Nice job Scottyf. I may steal your idea with the inner tube. Seems quite clean. :)

Kfong, you're right, maybe I can just cut some heatshrink and stick it to the exit hole.
Help me find my stolen electric brompton: http://bit.ly/1a0vbBC and Bosch Sinus B3 http://bit.ly/1eV0WQz

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Re: Rucksack battery advantages.

Post by GMUseless » Mar 31 2012 10:43am

I routinely carry over 20lbs in a backpack on my 36 mile round trip commute. And often 15 when snowboarding or riding downhill. It's completely do-able and comfortable with the right pack. Your Reebock book bag is not included.

The right pack means all of the weight is transferred to your hips, not your shoulders. You must have a padded hip belt and sternum strap. My shoulder straps are usually quite loose. Keep the hip and chest straps tight, and you'll barely notice the load while being completely mobile and active.

I'm a fan of Gregory packs, and I use their winter backcountry ski packs while biking: waterproof, hydration, and load balanced for movement.

Also, I'm always amazed at how guys 40+ lbs overweight complain that adding 15 lbs above the bikes center of mass will ruin the handling. How does your gut not ruin it? Because you carry that weight on your hips as well.

By the way, a pound of fat is over 4 kw-hrs of energy. Now that's a big pack. Too bad the C-rate is so low. :P

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Re: Rucksack battery advantages.

Post by d8veh » Mar 31 2012 11:21am

I tried a battery in a rucksack. It's OK up to about half an hour and 3kg. After that, it becomes uncomfortable (for me). The other problem I had was that it was difficult to get the length of wire right. I either had a great loop hanging down or I couldn't twist enough to make the connection. It would be easier if you could coil the wire like a guitar lead.

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Re: Rucksack battery advantages.

Post by Scottyf » Mar 31 2012 11:41am

I think it can be done with those coil wires like daahub kits use. Keeping the controller on the bike and just wiring the battery (2 wires) from the battery pack to the bike.

I know my bag isn't the right sort but it was avaliablemand easy and I wasn't bothered about it. I always make sure it's strapped on tightly. But using a bag that does offer support round the waist. Still I've not had an issue. Maybe when I'm 60 it might be an issue. But I also don't carry to many batteries.

There are better ways of doing it though.
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Re: Rucksack battery advantages.

Post by Phoebus » Mar 31 2012 12:36pm

I use this pack, and wouldn't use anything else:

Image

With the additional heavy duty waist straps ($40), almost all of the weight is transfered to your hips. It's quite comfortable.

The pack with all accoutrements weighs 5.0lb. My LiFe 500wh weight 11.4lbs, with padding. The battery doesn't move at all inside the pack, and the pack doesn't move at all on my back. It also provides excellent protection in falls, in my experience at least. My pack is very scratched up from numerous falls, with no damage to my battery either. Obviously LiPo is a bad idea for many reasons.

I've also used my 18.9lb 700wh LiFe battery. They weight is obviously much more noticeable, but surprisingly not very bad. Up to 30lb, when properly loaded in a proper backpack, is very do-able.

ALL of my riding is off road, technical trails.

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johnrobholmes   1.21 GW

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Re: Rucksack battery advantages.

Post by johnrobholmes » Mar 31 2012 1:25pm

Ok, now I can see a backpack that could properly carry weight on my back and make it feasible! What pack is that?



My question is how much easier it would be to bunnyhop the bike with weight on the hips VS weight on the bike. Moto Trials bikers can still get up massive objects, so there is obviously technique AND rig setup involved. I know that I can lift lighter bikes higher however, so there is an argument to be made that weight on the back will make the bike more maneuverable.

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