That's a really interesting idea. Thanks! 2 x 4 awg is the same cross-sectional area as 1 x 1 awg (42.4 mm²) so I should be able to put 2 x 4 awg wire into a single 1 awg lug for my connections. I'm using a pair of SB350 andersons for an emergency disconnect; those lugs are sized for 1/0 awg but I was going to use a pair of 10 awg solid pieces as core to ensure a snug fit in those connectors; that would be even easier to do between two pieces of stranded 4 awg than introducing them into a single 1 awg. I might need to buy different heat shrink tubing but that's easy to check...
No conduit in my application, just grommets for any through-holes required to route, and anchored cable ties to hold them in place. If I route them not touching each other, that will keep them coolest. (Leaving the 4 awg in place would involve letting it sit in the box; I haven't started the conversion yet—need to keep using the ICE to vacuum up leaves until the trees are bare; then I'll have enough time to do the conversion as a novice... I had planned to re-purpose the 4 awg for welding purposes. But I can just buy more 4 awg instead.) On Sat, Nov 2, 2013 at 12:38 PM, Roland Wiench <[email protected]> wrote: > Hello Michael, > > Just leave the 4 gage in place and install another 4 gage in parallel with > the existing wire. We do this all the time in old and new installations. > Two 4 gages in parallel will run cooler than one 1 awg cable because of more > surface area. > > If you installing these wires in a conduit such as a water proof flexible > plastic or metal conduit, it is best that the conduit is 60 percent larger > than the wire to allow air flow. Do not seal the end of the conduits, unless > it is connected with seal tight box connectors to a ventilated enclosure. > > The current capacity of the wire should at least 1.25% larger than the > continuous current in the wire. Example: If you draw 100 amps continuous, > then a wire good for 125 amps should be used. > > Two 4 gage wires with a temperature rating of 75C is about 80 amps per wire > or 160 amps total for a standard insulation wire in conduit. Not in conduit > suspended in air for 100 feet is closer to 200 amps allowing for a 3 percent > voltage drop. > > Roland > ----- Original Message ----- > From: Michael K Johnson<mailto:[email protected]> > To: [email protected]<mailto:[email protected]> > Sent: Saturday, November 02, 2013 9:06 AM > Subject: [EVDL] Wire gauge for 48V lawn tractor/mower conversion: > sanitycheck > > > I'm new to the list. I expect this has been discussed before but I > haven't found the right search terms. I apologize if so and would > appreciate a pointer. > > I'm also entirely new to EV conversions. I've been scouring the net, > and have purchased most of the items to convert my lawn tractor to an > EV this winter. I'm using the ME1004 as a "drop-in" replacement for > the ICE in my existing hydrostatic-drive donor tractor, not doing > separate deck motors. I know several of the things I'll want to do to > reduce loss (belts, bearings, lube, new sharp blades, etc.) and I > understand the single motor/multi motor tradeoffs and already have the > ME1004... ☺ > > From what I've seen so far, ME1004 conversions on lawn tractors at 48V > consume 70-100 amps while actually mowing, and may momentarily consume > up to 200 amps while spinning up the mower deck. > > I misread something somewhere (I don't even remember where anymore) as > indicating that since I expect to have 20 feet or shorter, I could use > 4AWG fine-strand welding cable, so I bought some. Then I learned that > this might have been somewhat optimistic, so I'm expecting to chalk > that up in the "mistakes" column. I found the helpful articles at > engineeringtoolbox.com and a few references on resistance of copper > wire and am trying to calculate real voltage drop instead of following > rules of thumb. In particular, I'm looking at > > http://en.wikipedia.org/wiki/American_wire_gauge<http://en.wikipedia.org/wiki/American_wire_gauge> > and > > http://www.engineeringtoolbox.com/copper-wire-d_1429.html<http://www.engineeringtoolbox.com/copper-wire-d_1429.html> > which both > have similar numbers for ohms per thousand feet for copper wire. > > I intend to fuse the conversion no larger than 400 amps and possibly > at 200 amps using an ANL fuse. So I've been calculating voltage drop > over 20 feet (and also, pessimistically, at 30 feet in case it takes > more cable than I expect) at 100 amps, 200 amps, and 400 amps. > > My understanding is that I want to keep the voltage drop below 2%, so > with some room for error it seems like I want less than 0.9V drop in > normal operation, and not go much above it momentarily. > > I'd like a sanity-check on my math, as well as the wisdom of the list > on recommended wire gauge... > > For resistance per Kft, I am using: > 1/0 awg: 0.09827 > 1 awg: 0.1239 > 4 awg: 0.2485 > > (I see no point in buying smaller than 1 awg if I replace the 4awg I > bought, so I'm ignoring 2 awg in my calculations.) > > It looks to me like the voltage drop per 10 feet at 100 amps is the > same as ohms per Kft, since I divide by 100 to get the resistance of > 10 feet, then multiply by 100 amps to get the voltage drop, so it > cancels out. Multiplying by 2 should give me voltage drop at 20 feet > at 100 A (my expected normal operation) and by 8 should give my > voltage drop at 20 feet at 400A. > > Since 1/0 awg is more than twice as expensive as 1 awg as well as > harder to work, I'd prefer to use 1 awg. I calculate that 1 awg > (0.1239 Ohms/Kft) should drop about 1/4V at 100A at 20 feet (max > normal load) and about 1V at 400A at 20 feet (max momentary load). > > Am I missing anything? > > Thanks much! > _______________________________________________ > UNSUBSCRIBE: > http://www.evdl.org/help/index.html#usub<http://www.evdl.org/help/index.html#usub> > > http://lists.evdl.org/listinfo.cgi/ev-evdl.org<http://lists.evdl.org/listinfo.cgi/ev-evdl.org> > For EV drag racing discussion, please use NEDRA > (http://groups.yahoo.com/group/NEDRA<http://groups.yahoo.com/group/NEDRA>) > > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: > <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20131102/9df4410d/attachment.htm> > _______________________________________________ > UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub > http://lists.evdl.org/listinfo.cgi/ev-evdl.org > For EV drag racing discussion, please use NEDRA > (http://groups.yahoo.com/group/NEDRA) > _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
