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  #21  
Old 02-11-2019, 08:26 PM
GalinHdz's Avatar
GalinHdz GalinHdz is offline
 
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If you disconnect the diode and everything works, then the diode was installed backwards. Unless as Mike S stated:

Quote:
Originally Posted by Mike S View Post
Or, maybe the battery is hooked up backwards??
FWIW: To check a diode:
1 - Set your Ohm meter to a low resistance setting
2 - Check the resistance
3 - Reverse the diode (IOW change the polarity) and check the resistance again
4 - You Ohm meter should indicate a low resistance with the test probes one way and a high resistance with the test probes reversed.

Here is a short video on how to do it

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Last edited by GalinHdz : 02-11-2019 at 08:36 PM.
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  #22  
Old 02-11-2019, 09:26 PM
rv7charlie rv7charlie is offline
 
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Just so you don't feel all alone, the same failure in his -8 a couple of weeks ago.

If the diode is burned, that's almost certainly the cause of your problems. If it was installed backward, it would likely cause the wire to fail as soon as the master is flipped on. If it was installed correctly, but failed shorted, you'd get the same result when it failed. If it fails shorted, it will eventually burn itself open if something else in the circuit doesn't fail open first.

You can check the contactor coil with a cheap volt/ohm/amp meter set to amps on the 10A range. Holding current will be around 1-2 amps for a master contactor.

Charlie

edit: In the master contactor control circuit, it's unlikely that you could make a wiring mistake to let the smoke out of the control wire. If it shorts to ground, it'll just cause the master contactor to pull in; same as the switch.

Last edited by rv7charlie : 02-11-2019 at 09:30 PM.
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  #23  
Old 02-11-2019, 10:07 PM
lr172 lr172 is offline
 
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Quote:
Originally Posted by JonJay View Post
Not sure it is common practice for the Master Contactor. It is for the Starter Contactor, at least per Vans instructions.
All relays, especially those with relatively large current draws, should have diode protection for the switches they are connected to. The starter relay is the same as the master contactor, except the contactor internally bridges the Batt connection to one side of the coil and it constant not intermittent duty rated.

I would be surprised this is not one of Van's recommendations. That said, the keyed switch is much more fragile, electrically, and therefore more deservant if your only willing to install one.

Larry
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Last edited by lr172 : 02-11-2019 at 10:10 PM.
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  #24  
Old 02-12-2019, 01:07 AM
rv8ch rv8ch is offline
 
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Default use a zener

You can buy kits here:

https://www.periheliondesign.com/suppressors.htm

(Updated to remove bad information flagged to me by Charlie)
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Last edited by rv8ch : 02-12-2019 at 09:33 AM. Reason: removed wrong information
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  #25  
Old 02-12-2019, 05:46 AM
RV7ForMe RV7ForMe is offline
 
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Default THANK ALLL OF YOU!

Alright guys,

This forum and you guys are truly amazing! Learned quite a bit about how it all works. Thanks for clearing up my questions.

I will get to testing with the multimeter. Order a couple diodes and see about.
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  #26  
Old 02-12-2019, 08:08 AM
rv7charlie rv7charlie is offline
 
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Hi Mickey,

Just a heads-up about zeners. To avoid someone coming to grief in the future after reading this, zeners very definitely *must* be installed in the correct orientation.
https://www.elprocus.com/how-does-a-...age-regulator/
The product you linked is actually a *pair* of zeners, wired nose to nose. If you click on Perihilion's pdf link, it will show the device's schematic. While there are places where they really are needed, and they will work fine in this application, they are kinda like using a Cessna 206 for a solo 10 minute local flight. The only surge that's of any concern at a relay coil is the field collapse when powered off, and it only moves in one direction. So, a simple 1A to 3A diode is more than adequate.


Charlie
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  #27  
Old 02-12-2019, 09:35 AM
rv8ch rv8ch is offline
 
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Default Updated

Quote:
Originally Posted by rv7charlie View Post
Hi Mickey,

Just a heads-up about zeners. To avoid someone coming to grief in the future after reading this, zeners very definitely *must* be installed in the correct orientation.
https://www.elprocus.com/how-does-a-...age-regulator/
The product you linked is actually a *pair* of zeners, wired nose to nose. If you click on Perihilion's pdf link, it will show the device's schematic. While there are places where they really are needed, and they will work fine in this application, they are kinda like using a Cessna 206 for a solo 10 minute local flight. The only surge that's of any concern at a relay coil is the field collapse when powered off, and it only moves in one direction. So, a simple 1A to 3A diode is more than adequate.


Charlie
Thanks Charlie - I didn't know this! I really appreciate you flagging it to me. I have been using Eric's Zener kits, but didn't realize that they were a pair. I corrected my post.
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