safe to run lifepo4 pack inside airtight plastic?

[needWheels]

I am planning out my lifepo4 install for when it arrives and I am wondering if it's safe to put it inside a (nearly) airtight rubbermaid type of setup to keep it dry and possibly safer if a cell explodes or something (like when that solder got into someone's cell) They don't expand but do they need to vent heat into open air? How about the BMS ?

I am also wondering about some of the stories where some of you have accidentally shorted the pack with your voltmeter - if you experienced folks do it, I am kinda scared...

 

[dogman dan]

Depends on your climate. For me there is a lot more heat than wet. So my ping is wrapped in heatsinking aluminum and then carried in a ventilated steel toolbox. I did have to insulate it in the winter. My bms will start shutting down in warm weather if I carry the battery in an insulated rear bag I have on one bike. The plastic box could be set up to ventilate, with a louver of some kind to keep a sprinkle out. I carry a trash bag in case of an unexpected downpour.

 

[needWheels]

Darn I thought lifepo4 was less sensitive than that.
I'm too used to the ruggedness of SLA, I store stuff on top of them lol.

 

[dogman dan]

I think it's just the bms that needs some air, or other means to cool it. but the leads are so short, I haven't much choice about where to keep it. The battery will get warm discharging, but only to about body temp, which may be about 10 less than the ambient temp anyway. When I ride with the other bike, using the insulated bag, I just need to let a little breeze into it and then it's fine. Most of the boxed up batteries you can buy use some kind of metal, so I think that allows the bms to heatsink enough without ventilation. The bag I have trouble with is like a little ice chest. A plastic box may not insulate so much. Here in the desert, everything is running hotter than designed, so I overkilled it for the cooling of my battery.

 

[needWheels]

I wonder if I can make an open frame to hold the BMS and wrap it in goretex cut from an old jacket.

goretex claims water can't get in because the molecules are too large, but that air can travel through because it's smaller

the side of the pack will have 2 inches free on the side in my milkcrate basket so I am hoping to mount the bms on the side instead of on top where it will be more fragile

I guess I will have to wait and see. Got a tracking number, here's hoping everything works out...

 

[dogman dan]

You should be ok, as long as the bms can shed it's heat somehow. Its just when I put mine in an insulated bag that it is a problem for me. The plastic may be non insulating enough. If you start to have cut outs, pop the top off the box and see if the bms is very hot. If not, ride happily. I say try it, and see.

 

[monster]

does the BMS have an over-temperature shut down function?

 

[dogman dan]

Somebody, on another thread was saying that the bms high amp limit gets lower when it gets hot. I think it was on the high tech bike review thread, maybe Terry, but I'm too senile to remember for sure.

 

[EVnewbie]

I wonder if I can make an open frame to hold the BMS and wrap it in goretex cut from an old jacket.

goretex claims water can't get in because the molecules are too large, but that air can travel through because it's smaller

Love the Goretex idea! What a simple, yet briliant idea. I can use a flap of goretex over my aluminum battery box for water protection without cooking the packs. Thanks!

 

[Anonymous]

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[needWheels]

I think I am going to go with something like the idea that Dogman uses and try to find a toolbox that will fit it (and my basket)

I found this other good thread about battery boxes:
http://www.endless-sphere.com/forums/viewtopic.php?f=14&t=8659

 

[dogman dan]

It would be easy to just leave the hole for the wires open, and have a flap to keep rain out. On my toolboxes, one of the first things I do is put a drain hole in the bottom. When we do get rain, in the summer, If it catches you, you will get an inch in half an hour. I just have a trash bag with me in my messenger bag. I think eventually battery cases will start to come with a heatsink for the bms, at least in the high amp models.


We really still are in the frankenbattery stage here at this time. Pretty soon a duct tape battery will be as weird as a solid rubber tire, or a hand crank starter on a car.

Don't forget to have something between the metal toolbox and the battery tape. A guy with a vespa conversion had the battery rub on a metal part of the bike and it shorted the whole thing. My solution was the aluminum cookie sheet, that I cut and folded around the battery so it sits in a custom box with no sharp edges and absolutely perfect fit. That way the heatsink effect keeps my battery cooler, and the aluminum can protect it from a burr on the steel box. Then I use foam shims to snug it up so it doesn't rattle back there. A hole in the front for wires, and another in the back, and the box allows ventilation to the bms that sits on top of the whole thing.