Lithium Battery OK in a Backpack??

[doubledipsoon]

I'm buying a spare 52v 14.25AH spare lithium- can I put it in a zipped up packpack while it's hooked up and running a BBSHD? Don't they need to be "ventilated"? or am I making too big a deal about it.

 

[amberwolf]

existing experiences and commentary; not every post is relevant but many are.
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[flat tire]

No they don't need to be ventilated unless you chose a battery poorly suited for your setup and it gets hot.

The backpack is a bad place for a battery cuz you are always moving around on the bike and it's annoying. You will be much better off mounting it to the bike. There is ALWAYS a place to mount your battery, so get your creative juices flowing and you will be pleased you did so. If you bought a second battery and intend to carry it on rides for when the first battery attached to the bike quits, that's just dumb and you messed up your planning. One battery is always better.

 

[serious_sam]

You will be much better off mounting it to the bike.

I totally agree with flat tire here.

FWIW, I've been running a 7kg (20S5P) backpack battery for a bit over 1000km of on-road transport and off-road fun. My frame doesn't have room to fit a pack easily, so I went with the backpack battery as a trial to see if it was practical for my purposes.

The bottom line is, it's do-able, but it's also a PITA. There are pros, but mostly it's cons. Short term, or if it's just now and then for added range, it's fine. But as a long term solution, it kinda sucks.

I'm glad I did it. It got me on the bike quicker. I've learned from the process. But now I'll be putting more effort into getting the cells onto the frame. Somehow.

 

[BVH]

Lithium Ion is certainly not as volatile as Lipo, but I would never wear a Lithium Ion battery of that size and energy capacity because of the chance of Fire. You'd very likely suffer burns of some extent before you could extricate it from yourself. I backpacked a 52V/12Ah LiFeP04 pack on one trip and ended up with significant back and wrist problems for a few weeks.

 

[doubledipsoon]

Yeah, I hear your anti-battery-in-a-backpack sentiment loud and clear- I already got my creative juices flowing and put it the rear of the seat area, semi-vertically, a perfect fit. I cut off the rack from a seat post pannier, attached a piece of 1/4" aluminum plate as a base, attached it to the mount pipe with pipe mounts, and strapped the battery against the back of the seat, but not enough to get in the way of my you know what. Now I've got 27AH @52v- should get me around 22 "strong miles" with my outragious BBSHD- perfect for my 20 mile round trip from my oasis in Aromas to Hollister and/or Gilroy for all my junk food!

 

[serious_sam]

I already got my creative juices flowing and put it the rear of the seat area, semi-vertically, a perfect fit.

Good choice. Hope it works out.

 

[serious_sam]

Lithium Ion is certainly not as volatile as Lipo, but I would never wear a Lithium Ion battery of that size and energy capacity because of the chance of Fire. You'd very likely suffer burns of some extent before you could extricate it from yourself.

I hear you. The safety concerns should be considered.

There is a risk, but IMO there are a few things that can be put into perspective:
- Taking a backpack off isn't like getting out of a car with a 5 point harness and roll cage. You literally just fling it off your back.
- The real likelyhood of a healthy battery just suddenly bursting into flames is basically nil.
- Consider taking safety precautions like physically durable enclosures, over-current/short-circuit/thermal cut-off protection.

Compare the risk of a backpack battery fire to other risks being taken whilst riding a bike. For example, riding a bike in traffic. Backpack fire is pretty much my last concern.

 

[BVH]

With my two 51.2V/12Ah LiFeP04 paralleled packs, I can get from 30 miles using only electric and not sparing any throttle and up to about 75 miles if pedaling hard so you should have plenty of capacity for heavy throttle and your 22 mile trips. I have my Phaserunner capped at 1700 Watts for use on my 1500 Watt rated motor.

 

[Dak77]

You will be much better off mounting it to the bike.

I totally agree with flat tire here.

FWIW, I've been running a 7kg (20S5P) backpack battery for a bit over 1000km of on-road transport and off-road fun. My frame doesn't have room to fit a pack easily, so I went with the backpack battery as a trial to see if it was practical for my purposes.

The bottom line is, it's do-able, but it's also a PITA. There are pros, but mostly it's cons. Short term, or if it's just now and then for added range, it's fine. But as a long term solution, it kinda sucks.

I'm glad I did it. It got me on the bike quicker. I've learned from the process. But now I'll be putting more effort into getting the cells onto the frame. Somehow.
07.JPG

I love the enclosure you made. That's pretty clean looking.

 

[serious_sam]

Thanks. It was my solution to cover things like toughness, balance/shape, and heat emission. As far as carrying a weight around on my back, it's been pretty good.

 

[Hillhater]

I have bikes with battey packs in various places. In frame , rear carrier, front fork mounted, in triangle , and backpack.
My favorite by far is the backpack... ( 5 kg lipo Multistar ) on a 1kW mid drive.
The bike is super stealthy, and together with the non attached battery when parked, makes it much less attractive to thieves ( a real consideration in city’s. )
Its also much lighter for lifting up steps , or loading onto racks etc, and that is all before you consider the handling when you are riding..especially offroad. . Riding a bike offroad with a pack on a rear rack is a joke !
The lighter bike is much nicer to ride in the rough.
A fire in a backpack may destroy the pack, but you could still ride home,...whilst a fire in a frame mounted pack, will take the whole bike with it. ! ..and you are walking home.