Re: [EVDL] wiring questions
If you see a short small wire connection that is on a appliance that is
about a No. 10 wire which is good for 30 amps at about 30 feet, but may be
good for a very short length with 50 amps to it, as in a stove, this is call
DESIGN LENGTH that was calculated by the manufacture.
Now in a battery connection link of about 6 inches long, you might get by
with a No. 10 wire on 50 battery amps using only one link between only two
batteries. But let say you 100 cells, as I did at one time, this makes the
total link lengths = 100 x 6 = 600 inches or 50 feet long for the links
only.
You have to take the total length of the links, the feeder lengths and
connections as the length of you conductor. In my first EV, this would be
about 100 feet loop.
So you should use the same size wire through out the circuit if uses the
same fuse. It is allow to tap off a smaller wire off a larger wire, but the
smaller wire must be fuse for that rating or fuse the entire circuit for the
smallest wire and/device rating.
Anytime we run a 20 amp receptacles circuit over a 50 foot run from the
circuit breaker to the first receptacle, we will use a No. AWG 10 wire to
the first receptacle then use a No. 12 AWG to the rest.
You see in this example, the No. 12 wire to a 20 amp device has a maximum
overload interrupter of 20 amps, even though you have a 30 amp wire in the
circuit.
Roland
----- Original Message -----
From: "Phil Marino" <
[email protected]>
To: <
[email protected]>
Sent: Monday, August 06, 2007 10:31 PM
Subject: Re: [EVDL] wiring questions
>
>
>
> >From: "FRED JEANETTE MERTENS" <
[email protected]>
> >Reply-To: Electric Vehicle Discussion List <
[email protected]>
> >To: "Electric Vehicle Discussion List" <
[email protected]>
> >Subject: Re: [EVDL] wiring questions
> >Date: Mon, 6 Aug 2007 22:49:03 -0500
> >
> >as an electrician I have replaced too many "short " pieces of wire that
> >should have been ok because of >short length etc . but they still burned
> >the insulation off and shorted out . also I have changed many >parallel
> >wires because one was a few inches shorter ! than the other and the
> >effect is the same >burned off insulation and shorted wire . your
> >probably
> >will cause problems . it is very bad advice to tell >some trusting soul
> >yes go ahead till be ok when in fact you know there is a honest chance
> >that there >will be a short .
>
> Fred -
>
> A "short" is when two conductors that are supposed to be electrically
> separated come into contact.
>
> Battery interconnects are single conductors. I don't see what they can
> "short out" to, especially if they are only three inches long.
>
> Most people don't insulate the battery terminals themselves, and, that
> doesn't cause "shorts".
>
> The worst thing that can happen is that the insulation will burn. Even
> that
> is unlikely, because a three inch piece of copper wire can't get much
> hotter
> than the battery terminals it's connected to. The terminals would act as
> heat sinks.
>
> I did mention the possibility of burnt insulation, and I didn't say "go
> ahead and do it". I said it would "probably be OK"
>
> And it more than probably would be OK.
>
> Phil
>
> don't cost nothing to the advisor but the poor guy who trusted some one
> who had no risk and was will to gamble with his project and pocket book
> takes the full loss .
> > ----- Original Message -----
> > From: Phil Marino<mailto:
[email protected]>
> > To:
[email protected]<mailto:
[email protected]>
> > Sent: Monday, August 06, 2007 3:37 PM
> > Subject: Re: [EVDL] wiring questions
> >
> >
> > Fred
> >
> > What you say about Mike's idea about using a small piece of 2AWG wire
> > between batteries is true, but it's also true about any piece of wire.
> >
> > Any wire is a resistor in the circuit, and any wire will limit the
> >current
> > that you can draw without voltage loss. ( and limit it to zero amps;
> >since
> > any current in any wire causes a voltage loss).
> >
> > Using 3 inch lengths of 2AWG wire as battery interconnects is probably
> >fine.
> > It depends on the max battery current.
> >
> > A 3 inch piece of 2AWG will have 0.000050 ohms ( that's 50
> > micro-ohms).
> >If
> > you put 400 amps through it, the voltage drop across it will be 0.020
> >volts
> > ( or, 20 mv). Not too bad. The energy lost ( and converted to heat
> >within
> > the wire) will be about 8 watts. Also, not too bad. This piece of
> > wire
> > will be physically much larger than a typical 10 watt resistor, so I'm
> >sure
> > it could dissipate that much heat without the copper melting. Whether
> >the
> > insulation chars would depend on how long you drew that much current,
> >how
> > effective the battery terminals were as heat sinks, and the particular
> > insulation.
> >
> > So, it would probably be OK.
> >
> > Phil
> >
> >
> > >From: "FRED JEANETTE MERTENS"
> ><
[email protected]<mailto:
[email protected]>>
> > >Reply-To: Electric Vehicle Discussion List
> ><
[email protected]<mailto:
[email protected]>>
> > >To: "Electric Vehicle Discussion List"
> ><
[email protected]<mailto:
[email protected]>>
> > >Subject: Re: [EVDL] wiring questions
> > >Date: Mon, 6 Aug 2007 08:28:22 -0500
> > >
> > >DO NOT USE THE SMALLER WIRE it will become a resistor in the
> > circuit
> > >and it will limit the current that you can draw without voltage loss
> > > ----- Original Message -----
> > > From: mike
> > golub<mailto:
[email protected]<mailto:
[email protected]>>
> > > To: Electric Vehicle Discussion
> >List<mailto:
[email protected]<mailto:
[email protected]>>
> > > Sent: Monday, August 06, 2007 5:05 AM
> > > Subject: [EVDL] wiring questions
> > >
> > >
> > > Is OK to connect the contactor like an albright 80
> > > directly to a curtis 1205?
> > >
> > > I was thinking I could bolt the contactor directly to
> > > B+ without any cable.
> > >
> > > Also, is it necessary for my high voltage cable to be
> > > the same size?
> > >
> > > If I have a short run between batteries, can I use a
> > > smaller gauge for that.
> > >
> > > For example I wire everything with 1/0, but I'll use a
> > > 3" piece of 2AWG between two batteries.
> > >
> > > Thanks,
> > >
> > > Mike
> > >
> > >
> > >
> > >
> >
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