[dtbaker]

Originally Posted by Dave Koller

Since you took it out then I guess it was not that - BUT - I also thought that from your red line /arrow sketch over your picture... I tried to see where you had it hooked BUT it was hard to see - scribble a schematic... I could not get to http://localhost/EnviroKarma.org/ev/...heatduct11.htm

to see what pics you have !

I put in the link wrong at first... try this
http://www.envirokarma.org/ev/galler...3_heatcon1.htm
and several pix on either side of this one

- checked diode, it was in correctly neg->|pos and has differing resistance in one direction versus other, so is probably ok.
- I REMOVED the diode, and still blow fuse
- I bypassed heater contacter/fuses by hardwiring from main contactor to heater, and it worked.

[tomofreno]

- checked diode, it was in correctly neg->|pos and has differing resistance in one direction versus other, so is probably ok.
- I REMOVED the diode, and still blow fuse
- I bypassed heater contacter/fuses by hardwiring from main contactor to heater, and it worked.

If you bypassed the P&B relay and fuses and connected the core directly to the battery pack and it worked ok, and you estimated it's current draw at less than 15A in that case (if I recall correctly) it seems it has to be something in the relay wiring. How about if you just bypass the P&B and keep the fuses in the circuit? If this works, then do you have anything wired in parallel with the P&B that might be causing the problem? What resistance do you measure between the battery inputs of the P&B and between the pos/neg outputs of the P&B? Is the positive output on the terminal that connects to the positive input when the relay closes? If not, the diode on the output will short the battery terminals when the relay turns on.

Tom

[dtbaker]

Originally Posted by tomofreno

If you bypassed the P&B relay and fuses and connected the core directly to the battery pack and it worked ok, and you estimated it's current draw at less than 15A in that case (if I recall correctly) it seems it has to be something in the relay wiring. How about if you just bypass the P&B and keep the fuses in the circuit?

I guess I could try this just to see if indeed the draw is less than 20a thru the fuses with the P&B out of the picture.

Originally Posted by tomofreno

If this works, then do you have anything wired in parallel with the P&B that might be causing the problem?

no... the power feed to the P&B is fused, then to the P&B, then to the heater.

Originally Posted by tomofreno

What resistance do you measure between the battery inputs of the P&B and between the pos/neg outputs of the P&B? Is the positive output on the terminal that connects to the positive input when the relay closes? If not, the diode on the output will short the battery terminals when the relay turns on.
Tom

I removed the diode, and still am blowing the fuse...
I am not quite sure what you are asking here. I checked resistance from input side to output side for both pos and neg with the relay 'open' and 'closed'. Results were as expected.... I also checked across pos to neg for a short, but there wasn't. It is mind boggling, because there is not that much THERE to go wrong!

[tomofreno]

I removed the diode, and still am blowing the fuse...
I am not quite sure what you are asking here.

Duh, yeah, forgot that. If it works with the fuses in and the P&B out of the circuit, it has to be something with the relay. Again, Positive Batt is connecting to positive output contact to the heater right? If you have the diode on the output connected correctly, neg >| pos, and positive batt connects to neg output and vice versa, the diode will short the leads from the batt. My experience in troubleshooting is it is almost always some simple error like this.

Tom

[Dave Koller]

Remove the power leads to the contacts and remove heater leads - connect the ohm meter across the outputs of the DTDP and engage the coil - and see if there is some unknown direct short in the relay contacts if the pack voltage is shorted each time the relay closes - well, it is just another angle!

[Dave Koller]

(edited on my other machine !!)

I see you have a snubber circuit have you removed that also? I am not sure why it would do anything BUT you have tried everything..!


I am on my old machine (WIN 98) and it does not do edits well!

I think you have done what I asked above - so now back to square one...

Hmmmmm the fuses are for 200 volts right (slow blow? as the surge could take out a fast blow).

have you tried other loads? If they work the core has to have some quirk to it that causes the amp surge...

[Dave Koller]

The problem with A.D.D. is too many thoughts too fast ...

if the snubber circuit is causing a brief kick back on relay closure could that be the problem? Pop goes the fuse - or am I just hunting here

[dtbaker]

...after more testing and trying various configurations I am almost certain that the fault is in the heater core itself. I don't really know how these solid-state ceramic core work (especially at different voltages), so it is mind blowing to me that it seems to be 'partly working' in that it does get hot, but draws more amps than it is supposed to.

Can anyone explain the difference between the cores that are designed for different DC voltages? I looked around for replacements, and most of the EV places have different elements for different voltage ranges, and they are different prices, so I am assuming there is SOMETHING in there different?

Can I just go get a cheapo AC ceramic heater from Walmart and take the core out of it? They are way less expensive!

[TheSGC]

Originally Posted by dtbaker

...after more testing and trying various configurations I am almost certain that the fault is in the heater core itself. I don't really know how these solid-state ceramic core work (especially at different voltages), so it is mind blowing to me that it seems to be 'partly working' in that it does get hot, but draws more amps than it is supposed to.

Can anyone explain the difference between the cores that are designed for different DC voltages? I looked around for replacements, and most of the EV places have different elements for different voltage ranges, and they are different prices, so I am assuming there is SOMETHING in there different?

Can I just go get a cheapo AC ceramic heater from Walmart and take the core out of it? They are way less expensive!

What fuse are you using? Are you sure it's a DC fuse and not an AC fuse?

I am working on my ceramic heater from a cheapo $25 thing from Home Depot or Walmart, I don't remember which. I can't build mine into the car due to having problem with the AC system in the way, but instead I am going to make it a DC plug in heater I can rest on the dash or seat.

[dtbaker]

Originally Posted by TheSGC

What fuse are you using? Are you sure it's a DC fuse and not an AC fuse?

yes, i am sure.
20amp-250v dc rated