Backpack battery

M

Mathurin

100 kW
Joined
May 24, 2006
Messages
1,166
Location
Quebec
Since I took my bike apart to better put it back together, theese past few weeks I've been riding around with no kinda electric stuff on it, and I've come to really appreciate the difference it makes to have it light, feels like a bicycle! I can jump stairs, curbs, roadway dividers, normal bike shit like that. And having tested with carrying up to about 10 kgs on my back, there really isn't any comparaison to carrying same weight on the bike. It turns it into a slug. I can see how with only a front hub motor's weight on the bike I could still yank it around, since I got handlebars, so going up a small flight of stairs should remain very doable, obviously it's allready a lot harder to make the rear of the bike jump off the ground so any extra weight back there are a real no-no in my view.


Edit: Addressing Knoxie in this paragraph:
So I've come to the conclusion that on my back is the least hurtfull place to carry batterie's weight, and at term I'd like to maybe mount an NiMH or Li based pack up there. So my request to you is, I'd like to know more about how you did it, the batteries on your back thing, how you set it up maybe with better pics how it works and all. I mean, obviously you've used that system for a while now, so I'm guessing you've got the quirks pretty much worked out by now. Stuff like, are you using powerpoles, and exactly how do you route the wires, where do they connect on the bike, ect. Gooey details and backpack battery porn shots plz. (unless they're too prude)

I'm thinking this could work out rather nicely.
 
With a good hiking type back pack, well supported i bet it would be comfortable. I've considered this aproach many times over.

Using NIMH or NICAD one should allow for some kind of cooling, they get warm under mild use, hot under heavy load, stuck inside an insulated backpack might not be a great idea..

The lithium packs.. in the unlikely event of a vent, it would really suck.. but otherwise, light-weight and i'm told they remain fairly cool under even fair loads... i'd like to hear knoxies feedback on this as well...
 
Yeah the potential venting of Li and heat generation of NiMH have been sorta question marks for me, but NiCad is out of the question given the weight advantage of NiMH. I figure a backpack should be sufficiantly quick to ditch off if it starts spontaneously combusting. But when I see 3.4Kgs 36v 17Ah Kokam packs, it really makes me go "hmm"

So far, backpack seems to be the optimal battery-carrying solution. Once my lead'll be dead it's probably where I'll be going, lest I should somehow find better, they may start making batteries with anti-mass someday? So adding batteries makes an unpowered bike faster. Heh, you never know, but I doubt it's gonna happen.
 
very interesting subject - was talking to knoxie about this the other day.
The only concerns i had with my lithiums was the event of fire, if the batts are on the bike no problem it's bail time but on your back just below the back of your head is a worry (i plan to have mine in a the smallest rucksack possible standing upright).
I have the lipo's knoxie ran on the bmx with the bms.they seem very solid to me contained in i think ally housing and as far as i understand (limited) are'nt lithium polymer slightly safer than lithium ion?.
There is another issue we talked about - a good method needs inventing for the event of having to bail from the bike,we need something that will stay connected until it gets a fair pull then come apart regardless of angle of dismount - easy huh?
On the flip side in every way i can think of rucksack mounted batts is the best way for me as i simply don't want my bike to have a basket or rack at all.
Other plus points is how good the bike looks with only motor and controller to see,stealth is key for me to ride the woods.
I'm not sure about this one but i also think that my bike will handle far better if i only increase it's weight by 10lbs - i know that the 20lbs of lipo will be on my back but i can't see why the bike won't remain a better handling machin especially with pulling up the front and flicking it from side to side - leaning over 40lbs instead of 60 has to be easier no?
we'll see what knoxie sais as he has done this now for a while - im not sure if he's come up with anything in the way of connecting well - the bmx had the long cable from the controller if you remember but i want to have my "rip connection on the back of the seat if possible.
lets see what the man sais :)


D
 
are'nt lithium polymer slightly safer than lithium ion
Click to expand...

Other way around.

Lithium polymer is generally packaged in fragile foil pouches easily breached during an accident, has no venting mechanism (the pouch puffs putting pressure on other nearby cells and components), and has no PTC or PCB to help prevent thermal runaway. Li-ion is generally packaged in a much less fragile metal can, with a venting mechanism, and either a PTC or PCB inside each cell.

Overcharge (usually too high a voltage) and breach of the pouch or can are the main user errors leading to either lipoly or li-ion "venting with flame". At rcgroups.com, members noted how so-called "Smart" chargers led to numerous fires after the smart charger miscounted the number of cells in series, or was set by the user to charge lithium as NiMH/Nicad.

Defective manufacture whereby metal dust contaminates the interior of the cell is the main non-user error leading to "venting with flame" and the reason for the lithium-ion recalls by Sony, et al.

Perhaps it's these high profile lithium-ion recalls that lends to the perception that lithium-ion is more dangerous than li-poly. As yet, there's not nearly so many large-capacity li-poly batteries in use worldwide, for fires to catch media attention and spur a lipoly recall. I read a story on another forum of a guy's lipoly powered ebike catching fire for no apparent reason while he was inside a restaurant with friends eating, and talking about how great the new lithium batteries are! Presumably, the incendiary event was caused by the same kind of metal-dust defect to haunt Sony's lithium-ion production.
 
If you could design a containment for the batteries that went in the backpack, it could have a nozzle to direct the flames to the rear.

That way, if the batteries decide to go exothermic on you, it will act like a rocket pack.

Got Nomex?
 
what would be the best way to house the lipo in the rucksack for safety?
i did see those,what looked like jiffy bags that contained the fire but they were only small batts not 20lbs worth :( what about a metal encasing?
you guys talking about venting and knowing these 2 lipos are going to be near my head is making me nervous lol.
come on knoxie stop blasting all over the shop on your lipo's and tell us what you think? ;)

D
 
Hi Guys

Watching the superbowl online!! ha ha how cool :) we have to pay to watch it here in the UK but i got a cheeky stream coming straight in to my xbox! ha ha.

Right I went out with the new blue battery today on the new bike 26 inch puma, mounted in my ruck sack, had a great ride as the weather was fine, did 30 miles on 10ah still loads left in the pack maybe 7ah or so.

The new bike with the 26 inch puma is great, its much more comfortable than my Trek and handles so much better, I think this has to do with the motor not hanging off the side of the bike and the batteries being on my back.

I really think now with Lipo there is no need to put them on the bike, they are so light to not be a problem. I use a decent medium size back pack that has a foam padded spine protector built in.

I sit the battery on a layer of folded bubble wrap, it doesn't get hot at all in the bag, the Lipo runs cool.

I did 30 miles with a 14lb battery on my back and it was a total pleasure!! i didn't want to come back but was trying to get back for the footy.

I don't think I really need to show any pics as it just as described,

As far as venting goes, it never enters my head if it did I wouldn't use them, I am careful and watch the battery loads as I use them, if the pack did start to go I think I would notice and get it off my back quickly enough.

I have seen pics of the very early point-1 packs that have split but not caught fire, we had this argument over on PA with Boca bike guy and he never came up with any pictures of the point-1 packs for all his naysaying.

Petrol is flammable and the odds of one of these packs venting with flame is as likely as the tank in my car or on my motorbike catching fire, lipo fire is still very rare, what's far more likely so start a fire is a poor connection, I worry about this a lot more, this is why i used greased andersons and change them for new ones every couple of months.

I have been using the Lipo packs for 6 months now with no problems what so ever, back mounting is fine in my opinion also the bike looks so much more normal (see the 26 inch post).

Its entirely up to you what you do, it pays to keep an eye on any battery technology, Lipo is less likely to catch far than Lion because the substrate is salt based and doesnt burn as easy as Lion.

Lithium is the future for e-power, oh and another thing if you lock your bike up you havent got 1000 bucks worth of batteries sat on it, they are with you...make sure you tuck the wire well in though as you may just alarm people!!

Cheers

Knoxie



:lol:
 
Watching the superbowl online!! ha ha how cool we have to pay to watch it here in the UK but i got a cheeky stream coming straight in to my xbox! ha ha.
Click to expand...

That's great! But if our football players were real men like Rugby players, they wouldn't need all that goofy padding. :)

Lipo is less likely to catch far than Lion because the substrate is salt based and doesnt burn as easy as Lion.
Click to expand...

Can you substantiate this claim, knoxie? My read is the exact opposite. Li-ion is encased in solid metal cans, whereas lipo lives in a fragile, easily punctured pouch. Li-ion cells are protected by PTCs or PCBs, Lipo cells are not. Puffed lipos put pressure on neighbors, potentially causing shorts.


http://www.batteryuniversity.com/partone-9.htm
The pouch cell is exclusively used for lithium-based chemistries. Manufacturing cost is still higher than conventional systems and its reliability has not been fully proven. In addition, the energy density and load current are slightly lower. The cycle life is not well documented but remains less than that of other packaging systems.
 
A critical issue with the pouch cell is the swelling that occurs when gas is generated during charging or discharging. Allowance must be made for some expansion, even though battery manufacturers insist that the cells do not generate gas if correctly charged. It is best not to stack pouch cells, but lay them side-by-side.
Click to expand...

http://www.batteryuniversity.com/partone-5.htm
The commercial cells use a separator/ electrolyte membrane prepared from the same traditional porous polyethylene or polypropylene separator filled with a polymer, which gels upon filling with the liquid electrolyte. Thus the commercial lithium-ion polymer cells are very similar in chemistry and materials to their liquid electrolyte counter parts.
Click to expand...

http://www.rcgroups.com/forums/showthread.php?t=209187

"Lipo Fire Incidents by Cause

Posts that have referenced a lipo cell catching fire have been categorized as to failure cause. This list most certainly does not contain all the incidents and a statistical analysis would be meaningless. It does however show that the warnings presented for lipo cells are not just legaleeze but warnings that should be heeded to prevent possible personal harm and/or property damage.

These first two posts will be updated as data is collected.
Information was gathered from the posts referenced. Please PM me if you see any discrepencies. The listing does not include any of the many 'ballooning only' reports.

FIRE DURING CHARGING:
Operator Error-
9s pack catches fire while being charged at 10s setting. (9)
2s pack catches fire being charged as 3s (10)
2s pack catches fire when charged at 3s setting (13)
2s pack catches fire in plane while charging at 3s setting. (22)
3s pack charged at 4s voltage ignites (27)
2s pack catches fire charged at 3s (30)
2s pack ignites when charged at 10.2V (31)
Overcharged battery (34)
2s pack charged at 11.1V catches fire. (36)
2s pack charged at 3s setting (40)
2s pack charges at 11.1V burns – (44)
2s charged at 11.2V goes off in garage – (47)
2s charged at 3s voltage ignites in garage – (49)
2s charged at 3s ignites in workshop – (52)
Another count problem – Heli burns (57)
Cell count error caused fire – (61, 62)
Pack charged on NiCd setting - (66)
Run Down pack catches fire during charge – (71)
LiPo Burns during charge on 109 charger after mode mis-set (82)
Charging slightly swelled pack causes fire (86)
Li-Ion cells catch fire from charger setting error (88)
Cell catches fire during attempt to repeak - (91)
Charging puffed cell causes it to ignite – (93)
Lipo burns during attempt to restore overdischarged cell with CC/CV PS (94)
Pack ignites during charging – smoke corrodes shed and contents (98)
Possible damaged pack burns like rocket in can – (100)
Attempt to recharge dead lipo causes plane fire (103)
Charging probably fully charged 3s pack with Astro 109 result in pack ignition. (104)
2s charged as 3s ignites in safe (109)
Restart of charger resulted in wrong charge mode – (113)
Wrong charger settings burns 2 packs – (112)
LiPo burns in modelers hand after charging - (115)
Charging slightly puffed cell causes fire, plane burns (117)
Using NiCd setting causes LiPo fire. Owner forgot to switch over to LiPo setting during charge cycle (118)
Charger set on 4 cells with 3 cell pack (126)
Garage fire during charging (127)
Modeler reports 2 lipo fires from wrong cell count (129)
Lipo charged on NiCd setting ignites (130)
Auto cell count charger fire – (131)
5s2p4000 packs ignites on first charge (133)
Overvoltage charge ignition – (135)
Lipo ignites during charge causing house fire – possible charger setting error. (139).
Too high charge rate burns battery (142)

Undetermined Cause While Charging
Fire damages garage while charging pack. (7)
1500 3s pack catches fire during 1A , 11.1V initial charge. (1)
2 cell pack ignites while being charged with 2 cell charger. (11)
Car burns when pack being charged in car catches fire. (24)
2s2p pack catches fire in helicopter – possible that charger misread # of cells. (25)
2s pack ignites while on charger set for 2s. (28)
$30,000 damage to house when pack ignites during charging. (no details) (43)
3s pack burns in garage – (35)
3s pack burns at correct settings- (41)
3s pack burns at correct charger settings – (46)
3s 8000mah pack catches fire after 15min – correct settings – (53)
Helicopter and pack burns after 15min charge – (54)
Automatic cell count charger – pack catches fire (55)
Automatic cell count charger – pack catches fire (56)
Lipo rockets across room (58)
Automatic cell count charger – Lipos burn in garage (59)
Battery ignites in car seat during charging (63)
Damaged battery ignites during charge (67)
Pack balloons during charge, burns while under water (68)
11s3p pack burns during charging at correct parameters (70)
Another charging fire – (72)
Helicopter burns when LiPo ignites during charge (73)
Undetermined cause to LiPo fire during charge – (74)
Chopper burns from charging LiPo fire (76)
House fire (81)
3s Pack Ignites burning front of car during charge at correct settings. (83)
Helicopter in garage burns while charging (106)
Well used Lipo ignites under correct charging parameters (107)
SUV Vehicle burns (114)
Garage burns during charging – (119) Extensive pictures
2 fiires in 2 weeks (120)
Charging battery in plane fire with 109 – posts 97&99 (121)
Charging 3000mah with Triton catches fire in garage- (122)
Pack in plane ignites while being charged under hood of truck (123)
Fire in Basement – (136)
Lipo catches fire during charging and continues to burn in salt water (138)
Lipo charging in Helicopter ignites burning carpet, drapes and Heli (141)



FIRE FROM PACK DAMAGE:
Cell poked with exacto knife catches fire- (2)
Dog bites pack, pack catches fire (4)
Lexus burns after pack from crashed plane put in car. (8)
Ballooned pack ignites when punctured. (20)
Repaired pack catches fire when connected to plane. (29)
Pack catches fire after plane crashes. (37)
Pack cut while shrink wrapping (39)
Pack punctured during crash burns. (64)
Plane crashes, pack removed and 10 minutes later burns (65)
Battery pack at 1V ignites while charging (71)
Puffed pack ignites during charging – (77)
Puffed Pack smokes when punctured (79)
Nicked pack catches fire (87)
Plane crashes, battery catches fire (89)
Damaged pack catches fire – (90)
Dog chews pack, chars pillow and smokes house - (95)
Battery compartment screw penetrates pack causing loss of plane (102)
Pack balloons dring mischarge, ignites when punchured (108)
Pack ignites 20 min after Heli crash – (111)\
Nicked pack “explodes in modelers handâ€￾ (116)
Intentionally punctured LiPo burns (124)
Dented Heli pack burns i min after disconnecting- (137)
Poked Lipo burst into flame (140)


BATTERY SHORTED FIRES:
Shorted pack catches fire (26)
Pack burns after shorting (15)
Possible Short (38)
Shorted when moved on table – (42)
Pack Shorted putting connector on and burns – (45)
Shorted pack burns hole in BMW seat – (48)
Crash causes 3s pack to short and burn – (50)
Pack ignites sometime after connector shorted for a short time (85)
Lipo Shorted for 4 sec. 3 min later it burns (143)


CAUSE UNDETERMINED:
Multi cell pack catches fire in flight (5)
Possible over discharge (33)
Lipo pack catches fire in car (60)
2s pack starts house fire (84)
In flight F3A fire reported (92)
New pack partially burns sitting on desk (96)
Pack ignites with no known cause (97)
Pack ignites after soldering wires on (101)
Pack catches fire in pick up truck (105)
In Air ignition – (125)
Pack ignites in pocket (132)
Pack ignites in car at 3AM (134)

OTHER
2s pack connected in series with 3s pack ignites in fireball (78)
Lipo burns garage (99)
Packs used in parallel catch fire in flight (110)
Too high current draw causes fire (128)"
Click to expand...
 
*** Lithium ion polymer batteries, or more commonly lithium polymer batteries (Abbreviated Li-Poly or LiPo) are rechargeable batteries which have technologically evolved from lithium ion batteries. Ultimately, the lithium salt electrolyte is not held in an organic solvent like in the proven lithium ion design, but in a solid polymer composite such as polyacrylonitrile. There are many advantages of this design over the classic lithium ion design, including the fact that the solid polymer electrolyte is not flammable (unlike the organic solvent that the Li-Ion cell uses). Lithium ion polymer batteries started appearing in consumer electronics around 1996. ***

Thats the first hit from the wiki page about them, I never said they weren't encased in foil? I know they are basically in pouches, the point-1 packs are then held in an aluminium box as a unit.

A lot of the Lipo fires that have been reported have not been accidents but intentional and started by people to get high hit counts on youtube, sure there are some genuine ones of course, there are risks but then there are risks with everything, if you are sensible and you keep an eye on things Lipo makes a very fine power source, I for one am sold on it, If people worry about them, make them so you can easily remove them and store them outside your house, its far too cold to bother doing that!! (no fire jokes please) :lol:

Knoxie
 
Mark at team hybrid has boxes of em in his front room lol - he doesn't seem too worried about them.
Knoxie do you think i sould keep mine outdoors? i have a bin cupboard that is all brick and nothing in it and i planned to charge them in there?at the moment their just sitting in my office about 6 feet from the radiator lol.
Mark said i didn't have to worry too much about charging i could just leave the chargers connected (within reason) and they wouldn't overcharge?
If anyone needs to worry about venting it has to be Steve Head - he has his mounted just below the "family jewels" :)
what do you think about a little extra safety within the rucksack ie. a metal plate covering back and top ? i think i will want to have mine held secure anyway so they dont bash each other whilst im riding so maybe design something that would protect my noggin from venting and hold them well?
do lithiums perform better warm or cold?
damn it wished i'd of paid more attention at school i might actually have learnt something :)


D
 
From those fire reports, it sounds like you could scatter them on the ground and use them as mini-land mines.

And you can take them on an airplane with you, but not a bottle of water.
 
(3) 12v 12ah SLA batteries in a backpack with chest and belly straps, 14Kgs:

7584f249.jpg


90cecfff.jpg


dc360e34.jpg


cc79cc8e.jpg
 
SLA's on your back?!
From your pic I can see a hernia forming already :)
 
Hey he's a real man carrying lead on his back, no fancy light weight stuff here.

Joe
 
The Powerpoles work amazingly well so far, connecting & disconnecting them gives a feeling in the fingers, like it reeks of quality. In reality I made this pack because the batteries had been sitting on my desk for over a month since I ripped everything ebike apart, of course they had received a full charge at the time, but it's good practice to occasionally charge lead batteries to keep them fresh. Also in the unlikely event I should fall off the bike, I trust the Powerpoles'll disconnect instead of ripping out something like the angled computer plug thing would have surely done.

Edit: they were down to ~39v, from ~42v for a full charge.


3a93b3a3.jpg
 
xyster said:
Can you substantiate this claim, knoxie? My read is the exact opposite. Li-ion is encased in solid metal cans, whereas lipo lives in a fragile, easily punctured pouch. Li-ion cells are protected by PTCs or PCBs, Lipo cells are not. Puffed lipos put pressure on neighbors, potentially causing shorts.
Click to expand...

With about 3 years of experience using/messing/charging/discharging lithium polymer packs, your read pretty much matches mine. Whatever the substrate is made from, they seem to have similar limitations compared to lithium ion 18650 cells - except that the enclosure is more fragile. They can combust when overcharged, discharged at extreme rates (shorted), punctured, or overheated and they also suffer from shorter life by discharging below ~3V.

That said, I have never personally see a lithium polymer cell burn - and I have seen them take a lot of abuse. I have personally punctured cells - to see what would happen - nothing happening... pretty anticlimatic. I have accidently overcharged one pack (set to 9.6V NiMh instead of 11.1V lithium polymer - it puffed, and I felt faint when I realized what I'd done hours later. And I have puffed a bunch of cells from overheating/excessive discharge rates. I have read reports from people that I trust of various issues - someone punctured a cell and then had it go up spontaneously, and lots of reports of people having large fires in their garages. And I have absolutely no doubts that I could cause one of my packs to combust if I tried.

The main advantage that lithium polymer packs give is very high discharge rates (especially compared to lithium ion cells). I have seem lithium polymer packs that are rated to 40C (80A from a 2Ah cell!). The key disadvantages (compared to 18650's) to my mind, are higher cost, and a more fragile enclosure.

But I have played and read and researched enough on lithium polymers that I don't think I could say that they are safer than lithium ion. Both require battery management systems, both require a certain level of caution (to my mind) - particularly in homebrew systems.
 
Wow, this thing is great!

There's truly no comparison with having the batteries strapped onto the bike, I can actually jump onto curbs and such, no slowing down to like 3 km/h. Rough terrain is alright, except the bike is heavy obviously so it tends to sink into deep snow. Also it's hella slower uphill carrying this weight compared to none, takes a lot more impulsion to keep up with cars between stoplights... I guess you don't really notice such weight difference with a motor. I find myself more likely to keep me going onwards if the front wheel gets sucked into a soft patch suddenly, didn't manage to fall that way but I did fail to hop a 2 foot snowbank and I sorta slowly stalled midway and fell backwards in slow motion. That was interesting. The pack actually follows my body pretty well, it's just that I'm not used to being an 85kg fatso yet. The pack is easier to put on then the old one was to strap onto the rack, especially since I can do it in the warmth. Based on my experience carrying laptops and stuff, it's important to properly adjust a backpack so it doesn't rub around, because it makes one's back all moist and the skin tender, this one was no different, but the contents is snugged in with the side straps so it won't move around, and I took a few mins to adjust the various body straps so it fits me very well. I went riding with it and kept it on for a few hours, although it wasn't especially pleasant, it's not uncomfortable... I can see that if I borrowed it to someone who's not made like me for a quick spin, they may decide it's uncomfortable if they don't bother to adjust it first.


Front view of bag, upper pocket holds the charger with room to spare.
9152b309.jpg



Bike de merde as it stands today
d16eeddc.jpg


3d8b0a96.jpg
 
(3) 12v 12ah SLA batteries in a backpack with chest and belly straps, 14Kgs:
Click to expand...

I just realized I have almost exactly 14kg of lithium on my bike (300 cells X 46 grams = 13.8kg). And I have a backpack. Hmmmm.....but if I needed extra straps to secure it like you're using, I'm not sure I could shed the pack fast enough should it catch fire :cry:
Also not sure they'd all fit in there.
 
http://en.wikipedia.org/wiki/Body_mass_index
I'm 1.8m, 70Kgs. This makes my BMI ~21.5
w/battery pack: BMI ~26, overweight.


Motor is on my desk, sir.
 
Motor is on my desk, sir.
Click to expand...

Talk about a mobile office!
Talk about taking your work with you on the road!
How did you hook up the motor to those little carpet slider wheels?
How's the aerodynamics?
Have you gotten to race any of those noisy, smelly, ICE-powered desks yet?
 

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Mathurin said:
The pack actually follows my body pretty well, it's just that I'm not used to being an 85kg fatso yet. The pack is easier to put on then the old one was to strap onto the rack, especially since I can do it in the warmth.
Click to expand...

I was commenting on this idea in the "weight distribution" thread. Since bicycles are designed to handle stresses coming from the handlebars, pedals and seat from the rider it would seem that at high speed the "backpack battery" would produce less bizarre behavior than mounting the weight onto the frame. It's not an "ideal solution", but short of actually redesigning the frame for these new loads it would allow you to go faster with less to worry about (as far as the strange new loads, but not the higher speeds) on the bike.
 
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