The interconnect wiring will see the same current as the wiring between the pack and the chair... So in theory ought to be the same size as first approximation... However the interconnects are generally much shorter, so in theory lower resistance allowing for smaller wire - but I suspect the calculation (which I haven't done) wouldn't show a significant difference because the none of the wiring in a chair is what most would consider to be very long...
If you look at what comes on factory chairs, I've mostly seen AWG 10, sometimes AWG 8. Aside from a couple of Invacare chairs I saw mentioned here a few years back (and my Invacare H-frame project chairs used AWG 10) I haven't seen many reports of chairs having overheated wiring issues, so they seem to get away with it.... Their wiring is all poly insulation from what I've seen.
In addition to BM, the other 'extreme use' case I've seen is power soccer, and we had a member a few years back that was coach for the Team USA power soccer team that won the world championship that year (we'd like to think our advice helped...
) His opinion based on experience wiring soccer chairs was that AWG 8 was more than adequate for normal use, and OK for most soccer chairs, but that AWG 6 was marginally better at the highest level.... (and overkill for everyone else)
Since the most common SB-50 / PP-75 pin is sized for AWG 6, it is a bit easier to use, and the cost difference is trivial, I see no harm in overkill....
Also as far as I'm concerned, in general having a wire get noticeably warm is a BAD thing, as it means you are wasting power on heating the wire instead of doing actually useful work (not to mention reducing the amount of power reaching the work...) Better to use heavier wire if possible / practical....
I used welding cable - heavy poly insulation, and my feeling is that if it can stand up to the abuse that cables get in a welding shop, it is going to be fine on a chair where it's generally tucked away inside the frame....
I actually don't like silicone insulation for MOST applications as it is a bit more fragile and easily damaged than poly. I only like silicone in cases where the heat tolerance is needed because the wiring size is limited...
ex-Gooserider
swalker wrote:expresso wrote:Would you say using 8 AWG wire for the interconnects is OK
Based on my research, I decided that 10 mm2 is the right size for interconnects between cells. I think I have seen BM recommend 10 mm2 as well, but he can confirm or deny.
Per wikipedia, 8 AWG is 8.37 mm2 and 6 AWG is 13.3 mm2. I really wanted 7 AWG, which is 10.5 mm2.
Unfortunately, 7 AWG wire and connectors are not readily available in the US. So, I settled on using 6 AWG.
I could not find tinned, copper 6 AWG wire with silicone insulation, so settled on some with PVC insulation.
Life would be easier if I lived in a country that used metric, like most of the rest of the world.
Steve