Battery in backpack vs. mounted to frame

General Discussion about electric bicycles.
Baron   100 W

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Battery in backpack vs. mounted to frame

Post by Baron » Mar 02 2016 6:34pm

Anyone use a backpack for their batteries instead of mounting them to your bike frame?

I've been toying with the idea of using a backpack since a lot of the bikes I would want to convert to electric don't really have a suitable space in the frame to mount a battery. See: freeride bikes and downhill bikes, for example.

Pros:
*less weight on the bike frame, more maneuverable?
*you can easily detach your battery and carry it with you. makes for easier storage and security
*backpack is useful for carrying other things too
*don't have to mount/unmount battery in the frame every time you ride.
*looks more stealthy with less batteries/wires/bags strapped to your bike

Cons:
*more weight on your shoulders and back. could get hot and sweaty in the summer
*backpack could be confused for a bomb?
*an e-bike frame offers better protection in a crash than a backpack

Your thoughts?

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Re: Battery in backpack vs. mounted to frame

Post by JumperJackFlash » Mar 02 2016 6:50pm

Battery pack in backpack catching on fire...

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Re: Battery in backpack vs. mounted to frame

Post by Gregory » Mar 02 2016 7:18pm

Wire umbilical between rider and bike that requires disconnecting/reconnecting every use....
Wire can get in the way when mounting/dismounting if you swing your leg over the seat....


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Re: Battery in backpack vs. mounted to frame

Post by Raged » Mar 02 2016 7:26pm

I've come off the bike twice and landed on my back hard after flipping over a car. I'd hate to think what an added battery fire would do.
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Chalo   100 GW

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Re: Battery in backpack vs. mounted to frame

Post by Chalo » Mar 02 2016 9:19pm

Raged wrote:I've come off the bike twice and landed on my back hard after flipping over a car.
You're definitely doing it wrong. Trust me, you can opt out of that stuff almost 100 percent of the time. You might have to wait until your hormones get under control and your brain finishes developing.

As for the OP, carryng anything substantial on your body when you could carry it on your bike instead is an incredibly chumpy thing to do. For me, a backpack is a tie with a shopping bag hung on the handlebars. (There are times for that, too.)
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Re: Battery in backpack vs. mounted to frame

Post by nutnspecial » Mar 02 2016 9:45pm

"You're definitely doing it wrong." Lol - you're funny.

"can opt out of that stuff almost 100 percent of the time" remembering back to the video evidence, I don't think I would have done any better. I'm doubful many would have, including you. Imo the only change in outcome would stem from higher visability encouraging the driver not to turn in front, a slower biking speed, or a superman dive with acrobatic roll upon impact with the car. 8)

I prefer as bike-like as possible, so that means a small pack. At that point I guess it'd be not horrible in a backpack @ ~11lbs but I feel it was well worth the time to work onto the bike in a location best retaining handling. Perhaps if I was a non-e bike pro I'd find best handling with the 10lbs on my back instead, but this seems much more natural and comfortable to me.

Even !0 lbs, a backpack, and a tether suck when you don't need or want them?

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Re: Battery in backpack vs. mounted to frame

Post by craneplaneguy » Mar 02 2016 9:49pm

I plan on occasional use of a backpack carried battery, when I go on "epic" rides, it will be in addition to my frame mounted one, each 11.5 AH/52 volt. That may change if I get the right rear rack or other way to carry more stuff on the bike, but for now the backpack scenario seems like a pretty easy way to extend the range. I plan (meaning, I have not done it yet) to replace the low battery with the fresh one, so no wiring from pack to bike required.

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Re: Battery in backpack vs. mounted to frame

Post by nutnspecial » Mar 02 2016 10:05pm

Great point, and there are of course full time backpackers also.
Foppel of 'dirty bikes' and most of that gang seem to opt for primaries in backpacks.

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Re: Battery in backpack vs. mounted to frame

Post by Leebolectric » Mar 02 2016 11:52pm

If I'm just cruising along, commuting or whatever...frame batery is cool, less weight on me.
...But if I'm riding agressively especially on a trail...the battery attached to my core jumps and corners much better.

Fears based on something that "could" happen but hasn't happened is just fear....
...none of the fearful posters has blown up a backpack...or knows someone who did either most likely. (apologies if I am mistaken)

As I understand, and I AM a newb with electronics...when 18650 batteries get a hard short...they will progressively get warmer till it catches fire.
From videos Ive watched, it looks like this warming takes several minutes....so if monitored after a crash...it's unlikely to just "blow up" on your back.

My plan...if I crash and bonk my backpack..I take it off and take a break...if it gets warm, i dont put it back on.

XT90s connectors are nice and solid, rarely have one disconnect if my leash is properly sized.
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Re: Battery in backpack vs. mounted to frame

Post by paracidium » Mar 03 2016 12:30am

I've ridden with batteries in my backpack for years, much prefer it this way. Means I can quickly lock up my bike and take my batteries with me. Also keeps my not so road legal setup looking stealthy. This is my most recent backpack which is heavily padded to protect my LiPo. http://www.amazon.co.uk/Wenger-600630-B ... B01260JAHK

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Re: Battery in backpack vs. mounted to frame

Post by Baron » Mar 03 2016 12:32am

I didn't mean for this to devolve into an argument. Just wondering if the idea was viable.

I ride 50/50 dirt and road, there's a nice freeride bike on pinkbike I've been eyeing. 6" suspension front and rear, but it comes at a cost..no way to mount the battery in the triangle. And I've tried rackmounted batteries before, they aren't very fun.

I think I could pull off the backpack idea. I'm thinking a nice strong coiled thether and maybe a well-padded box inside the backpack for my batteries. They're hardcase lipos, so they should probably be okay in a crash if protected well enough.

I take my batteries off my bike every ride so it should make that process a whole lot easier too.

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Re: Battery in backpack vs. mounted to frame

Post by LockH » Mar 03 2016 1:19am

Can backpack be hooked to bike frame itself? Rather than on riders back? Just thinking of weight, where generally weight as low down as possible = "better".
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Re: Battery in backpack vs. mounted to frame

Post by nutnspecial » Mar 03 2016 3:02am

Lipo is far more reconfigurable. I'm a fan of various 'sew on' hook/loop products (ebay) in conjunction with top tube pannier style bags (amazon) for a minimalist non-triangle frame pack (40 cells in mine).

But if you wish to remove when not in use or to charge, this obviously isn't as handy as a backpack. Among others, Leebo weighed in and you could ask him specifics on backpacks, and I've mentioned 'foppel' whom you could search out for tips on backpacks too. Also negatives have been mentioned. I would go for the coil tether too, and I think foppel noted in his build what he used for that.

One thing I'm confused of is 'devolve into argument'. I didn't notice any negative argument aspects?
http://www.merriam-webster.com/dictionary/argument
https://en.wikipedia.org/wiki/Argument_(disambiguation)
https://en.wikipedia.org/wiki/Argument
A negative connotative definition is included, but only secondarily afaict and described as 'angry'. I find the assumption 'argument' falls into this category mostly or all the time as a stumbling block in the language. Imo a bane and total newspeak https://en.wikipedia.org/wiki/Newspeak for it to be included as a possible direct definition at all, when adding an adjective does the same without propogating confusion and detracting from the purest definition. Same with many words actually, dam weasel words.


In this case, I assume by 'devolve' that you convey negative meaning to 'argument', but I see not only any drawn out disagreement or argumentation, I see no anger?

In the purest sense, any statement for backpack or frame mount (or anything) is an argument when any reasons or information is included to back statement. Further discussion(and argument) would only be natural in nearly any venue (cept in church . . .or with kids 2 parents . . .or when 'wifey' is 'not having it'), though I'd def expect at least some in a 'VS' thread?

Hmmm, thinking this through... if you meant more like devolving into off topic argument. . . . oops I may have just done that? Sorry?

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Re: Battery in backpack vs. mounted to frame

Post by greg_p » Mar 03 2016 5:24am

I've been using motorbike for some times now (20y), and what I can say is I don't want to wear anything on my back. If you fall, anything but a back protection will make any injury worse and think about spinal ones...
Of course you don't fall, actually you can't really imagine it unless you get older than 25 (for males), that's physiological... But anyway from times to times, shit happens.

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Re: Battery in backpack vs. mounted to frame

Post by dogman dan » Mar 03 2016 7:45am

Just to sweaty in my climate for year round backpack use. I can't believe those water pack guys, I'd rather carry water in my stomach, well before that ride.

But anyway, it all depends on the size and shape of the battery in the pack. a 15 pound 8x8x8 square, no thanks. But a 2" x 6" x 12", that weighs 8 pounds, that would work. I just described a 48v 10 ah rc lipo pack. But the flip side is, an 8 pound lipo pack carries pretty well on a handle bar mounted bag or box too.

My fast dirt bike can carry 10 ah on the front bag, and the other 10 ah on a rear rack. Yeah, not ideal, but I don't sweat. And 8 pounds on the rack doesn't make me crash in the dirt. Put 20 pounds back there, it will flip you off in the corners over and over and over.


Re the hitting cars. I hit a car one time, in 1977, entirely my fault. since then, I have never allowed a car to touch me. Chalo is right, cars don't hit you, you let them hit you. If you can't stop overdriving your bike or motorcycle, you need to leave the street for your life. I took it to the dirt for 20 years, I was not safe to be on a street motorcycle till I matured. I never completely stopped crashing, but I had a chance for survival in the dirt.

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Re: Battery in backpack vs. mounted to frame

Post by brumbrum » Mar 03 2016 12:05pm

To the op. If you have money to spend, you can get yourself a 'boblbee' hard case motorcycle/skiing backpack. They are crash tested, although not fire proof. You can pick them up on ebay in good used condition.
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Re: Battery in backpack vs. mounted to frame

Post by WoodlandHills » Mar 03 2016 1:24pm

What about broken ribs and crushed vertebrae from landing on the battery pack in a crash? Fire, after the crash, when you are lying there unable to feel your toes is just adding insult to injury.

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Re: Battery in backpack vs. mounted to frame

Post by The fingers » Mar 03 2016 2:11pm

For a lot of my pedaling only years, I carried a heavy backpack full of books while riding, so I could study for school while at work. The sweat on hot days completely soaked me, but I has younger then. I had to put all the books in plastic bags and the backpack itself had salt lines all over it. You really don't want to let water cause a short on your back causing Kentucky Fried Plumber's crack. :shock: Or with lots of asbestos padding added one might not think about it so much. :lol:
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Re: Battery in backpack vs. mounted to frame

Post by friendly1uk » Mar 03 2016 2:58pm

I have to use a backpack a lot of the time. The freedom felt when I don't have to is akin to that of a flying dream. I love the summer months when I can go out in just a t-shirt and get that free feeling. Building a bike that couldn't do that really makes no sense to me.
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Battery in backpack vs. mounted to frame

Post by Grizzl-E » Mar 03 2016 3:40pm

Depends on you. I weight almost 200 lbs and am 6'2", I bike, snowboard, ski and hike with 15-25 lbs on my back all the time. And I carry a 40lb tool bag around as a service mechanic. I don't even notice 15lb well packed in a good backpack. Others do.

On road I prefer it on the bike. Off road I like it better on my back. But I live in Canada and only bike with downhill gear on anyway so I just deal with the couple months of hot days. It's really not a big deal to convert either way unless your custom welding a pack.
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Re: Battery in backpack vs. mounted to frame

Post by Raged » Mar 04 2016 4:35am

Backpack technology has advanced leaps and bounds over the last 10 years... I personally use backpacks which sport a mechanism similar to the deuter aircomfort system ( http://www.deuter.com/DE/en/back-systems-865.html ). It's a hiking backpack which lifts the weight off your shoulders and on to your hips. It also leaves a gap between the pack and your back so you dont sweat like a mofo.

Image

Mine's a chinese knockoff (AUD$25-30) that serves as a day pack and also carries a 3L hydration bladder (hiker). As the weight is held up by your hips/ass, it feels extremely light and as wind can flow on your back, its not as hot either.

In regards to doing it wrong if you're flipping over your bike... I'll just repost my vid that "shit happens".



1. I landed *HARD* on my back after flipping over the car. Hard enough to rip the shoulder straps of my North Face backpack out.
2. The backpack provided cushioning as I bounced off the ground. I landed back first and luckily had work clothes in it (shirt/pants/shoes).
3. I was in shock for a while... I dont know how long, but people ran over/neighbours on the street came and helped.. Telling randoms to rip off backpack in case of fire is bad.

If you get a motorbike structural backpack then yeah, go for it, but I dont recommend a standard backpack.
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Re: Battery in backpack vs. mounted to frame

Post by dogman dan » Mar 04 2016 6:07am

I do agree, you'd want a good backpack.

In a crash, yes, you don't want an 8x8x8 cube on your back. You want a flat battery for sure. Mostly, you'll land on your side or your face anyway. Unless it's a skateboard.

I just don't get carrying the water pack, when everybody who lives in the desert knows if you are thirsty, you just drank at least an hour too late. While they are getting thirsty, and sucking on the pack, I'm stopping to piss.

Learned that from how the Israeli army hydrates. Drink early and big, carry that water in your belly.

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Re: Battery in backpack vs. mounted to frame

Post by rider95 » Mar 04 2016 11:35am

Never put any thing hard or anything that has a edge or point in a backpack you have to understand you will crash with it sometime , only soft items no tools ,screwdrivers,no cans,

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Re: Battery in backpack vs. mounted to frame

Post by Paladin » Mar 12 2016 1:46am

I started using a backpack for the stealth aspect... so the bike looks more like a bike.

I prefer the pack now. Heavy padding. Over a year with it, 8lbs lipo. I just ride under 10 miles in the dirt, so it works for me.

Bigger heavy AH batteries for longer rides or on road, I think I would want on the bike in the frame.

Positives:
If your bike gets stolen you still have the batteries.
Makes the bike lighter more nimble.
Can carry tools.

I crashed a couple weeks ago, over the bars, stuffed the throttle into the back of my calf muscle.
Came unplugged, which I think is kinda neat in an accident. No run-away throttle action.

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Re: Battery in backpack vs. mounted to frame

Post by Ykick » Mar 12 2016 10:44am

For range extension I carry batteries in backpack but not tethered. I just swap packs when the bike pack’s empty.

For certain applications (aggressive off road) tethering power from a backpack might make sense but I don’t have need for something like that.

I seem to remember numerous threads about this over the years? ‘guess ES needed another one...
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