48v20ah frame bag?

[Haste]

one of those duct tape vpower packs..was thinking a soft lunchbox with it moved as much forward and up as possible...? they make anything I can use?

[amberwolf]

I would put it in a hard case where it can't flex around or get banged up. If it is like mine, it's a bunch of cylindrical cells badly spotwelded together with nickel strips, and held together with hotglue and ducttape. It's not particularly stiff, so it's too easy for those spotwelds to break, disconnecting cells from the groups they're part of. They may not be fully disconnected, and sometimes hooked up and sometiems not, but the effect is that cells become abused and undercharged and overdischarged, over time, if the welds get broken.


If you do put it in a frame bag, i recommend a hard stiff case around it first, then into the bag.


Also keep in mind it's pretty dang heavy and fairly bulky, and if they still use the same BMS it's very large (bigger than both my hands palm to palm including fingers but not thumbs).


I have seen some of those cheap padded "insulated" lunchboxes that mine would fit in if i ripped out the padding/insulation, and cut the dividers between sections, but the BMS would not fit in there with it, and the bags I've seen are not very tough, would probably rip apart at the seams with that kind of weight.

[dogman]

48v 20 ah is just heavy enough to blow the seams on many of the soft lunchboxes. Some of the more stout offerings are more like 12 pack coolers, and tend to be too big.

I'd say the starting point would be to build a sturdy wood or metal shelf on the frame to support that weight, then figure out the bag. The bag is not supporting the weight that way so much.

For me, once you have a shelf on the frame, the logical step is to use 1/8" plate aluminum to make sides for the battery box. I like hard shells on my batteries. One reason I like the 36v 20 and 48v 15 ah size is they fit perfect in antique metal toolboxes.

If you do go the bag route, I highly recomend coroplast real estate or political sign material for crash protection. More abrasion resistant than foam. I've also made protective inner boxes out of cookie sheets and the top from a large storage tote. Even inside the metal box, I still have an inner liner that fits perfect on the batteries to completely eliminate chafing or dings on the cells.

Protect your battery well. Mine have been through some wild crashes, leaving the bike when racks broke, etc with no physical harm to any of my batteries. Nothing is funnier to me than the guy who says, " I've made sure nothing can happen" It happens anyway eventually.

[Haste]

2 peices of styrofoam, and just duct tape it in the triangle...should this work temp? I cant find anything other than those ubolts at home depot to use...hmm

[TonyReynolds]

I have a 48V 11.5Ah triangle pack in a frame bag and it fairly fills my frame triangle. I don't know what chemistry you're using, but mine is A123 cylindrical cells, and there isn't enough room for 8.5Ah worth of additional cells... That said, I truly enjoy having the batteries low and central to my CG.

[TonyReynolds]

2 peices of styrofoam, and just duct tape it in the triangle...should this work temp? I cant find anything other than those ubolts at home depot to use...hmm

Better than styrofoam would be Ethafoam: http://www.qualityfoam.com/ethafoam-faq.asp



Styrofoam is a beaded product, unless you search out extruded Styrofoam used as sheet insulation. Ethafoam is tougher, can be easily cut, is low static and is impervious to water. It's used a lot for absorption blocks in electronics shipping packaging. Ethafoam doesn't dent or break. It must be cut. It comes in many different densities, but a lightweight density, in about 3/8" to 1/2" thickness would work great for what you need.