Re: [EVDL] Preventing Iota current draw (John O'Connor)
Hi John,
I have a similar setup to what Philip describes below, except using a key switch relay instead of a contactor. I added a small thermistor ($1.38 from Mouser) in the positive wire to the Iota take up some of the initial current draw. Without this thermistor, the relay was welding itself shut when I turned the key. My car has a 288V pack - you might not need the thermistor with a smaller pack, but for $1.38 it's not a big deal.
Good luck,
Richard
> My IOTA wiring went through several drafts before I finally decided on
> something (I think) I like. To prevent it from unnecessarily drawing
> current from the traction pack, the negative side of the IOTA input is
> wired to the switched-side of my negative-side contactor. This way it
> can only be powered from the traction pack when the key is in the
> "run" position. (The positive side is wired directly to the positive
> side of the traction pack.)
>
> Knowing that I also wanted to keep the accessory battery charged from
> external power, I have the IOTA's input switchable between AC (i.e.
> external power) or DC (traction pack). This relay defaults to the "AC
> input" position; it switches to the "DC" position only when the key is
> in the "run" position and AC power is not present. (There are also
> interlocks, of course, to prevent the Curtis's KSI relay and the
> negative-side contactor from switching on when AC power is present.)
>
> To doubly-ensure that the IOTA is isolated when the vehicle is just
> "sitting" (i.e. no AC power present and key not in "run"), I have an
> SW-60 contactor on the positive side of the IOTA's output, which only
> switches on with the key in "run" or with AC power present. (As Lee
> mentioned, there really shouldn't be any noticeable draw from the
> accessory battery back into the IOTA, but at least this way I can be
> really sure.
Richard Hamje
Portland, OR
[email protected]
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Hi John,
I have a similar setup to what Philip describes below, except using a key switch relay instead of a contactor. I added a small thermistor ($1.38 from Mouser) in the positive wire to the Iota take up some of the initial current draw. Without this thermistor, the relay was welding itself shut when I turned the key. My car has a 288V pack - you might not need the thermistor with a smaller pack, but for $1.38 it's not a big deal.
Good luck,
Richard
> My IOTA wiring went through several drafts before I finally decided on
> something (I think) I like. To prevent it from unnecessarily drawing
> current from the traction pack, the negative side of the IOTA input is
> wired to the switched-side of my negative-side contactor. This way it
> can only be powered from the traction pack when the key is in the
> "run" position. (The positive side is wired directly to the positive
> side of the traction pack.)
>
> Knowing that I also wanted to keep the accessory battery charged from
> external power, I have the IOTA's input switchable between AC (i.e.
> external power) or DC (traction pack). This relay defaults to the "AC
> input" position; it switches to the "DC" position only when the key is
> in the "run" position and AC power is not present. (There are also
> interlocks, of course, to prevent the Curtis's KSI relay and the
> negative-side contactor from switching on when AC power is present.)
>
> To doubly-ensure that the IOTA is isolated when the vehicle is just
> "sitting" (i.e. no AC power present and key not in "run"), I have an
> SW-60 contactor on the positive side of the IOTA's output, which only
> switches on with the key in "run" or with AC power present. (As Lee
> mentioned, there really shouldn't be any noticeable draw from the
> accessory battery back into the IOTA, but at least this way I can be
> really sure.
Richard Hamje
Portland, OR
[email protected]
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