# 12v 200amp relay wanted



## olley (May 1, 2005)

Hi I need a 12v 200amp relay with normally closed contacts, plenty about with normally open, but not closed. Anybody help; pretty please??  

Olley


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## gnscloz (Oct 4, 2008)

hi just bought 150 amp off these they have loads listed
http://www.willow.co.uk/HG4185.pdf


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## olley (May 1, 2005)

Hi gnscloz thanks for the link, best I have seen so far, I need them to pass enough current to start the RV, two in parallel might be ok.

Olley


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## gnscloz (Oct 4, 2008)

ring them up very helpfull good luck


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## andynkim (Apr 9, 2007)

Hi Olley
Have you thought of a starter solanoid like the ones fitted to old cars without pre engaged starters, Normally open I know but could you not use another smaller relay to keep the solanoid operated with perhaps a series resister to reduce the current though the solanoid coil and stop it burning out.

I don't really know what you are trying to do but also remember that the contact carrying current is much higher than the switching current.

Might be teaching grandma to suck eggs but a starter solanoid is an easy way to handle a large current.

Cheers Andy


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## olley (May 1, 2005)

Hi guys this is what I am trying to do.

It needs to be big enough to pass sufficient current to start the RV. Long story but my alternator is designed to produce 14.95volts It was designed that way by delco-remy to allow for the voltage drop when a solid-state isolator was used, unfortunately GM didn't fit one. 

Now on my 3rd set of batteries and enough's enough; I have fitted a 160amp split charge diode in the house batteries and they are now being charged at 14.15, the only way I can see of using it on the chassis battery is with a N/C relay, as soon as I turn the ignition on, the relay energises and disconects the direct connection to the charging sys, leaving the feed from the diode only, turn to start and the relay lose's its feed, and we have lift off. 

I did fit the diode directly after the alternator but its voltage sensing, so that was a waste of time.

Olley


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## Jean-Luc (Jul 21, 2005)

Hi Olley, You could use the N/C side of a change over relay, leaving the other terminal redundant. 
Willow Technologies make some seriously heavy weight stuff . I use the N/C side of one of their change over relays to make and break the connection between the habitation system and my leisure batteries as part of my B2B set-up.

Colin


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## olley (May 1, 2005)

Hi Colin, are they the ones gnscloz gave me a link for above? nothing I can see rated at 200amp, but two in parallel is a possibility if nothing else is available.

Olley


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## gnscloz (Oct 4, 2008)

hi, jean luc gave me the link a while back, he,s more clued up than me on electrics and gave me advice, helpful guy
mark


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## Jean-Luc (Jul 21, 2005)

olley said:


> Hi guys this is what I am trying to do.
> 
> It needs to be big enough to pass sufficient current to start the RV. Long story but my alternator is designed to produce 14.95volts It was designed that way by delco-remy to allow for the voltage drop when a solid-state isolator was used, unfortunately GM didn't fit one.
> 
> ...


 Not sure what you need to achieve. Do you want to isolate the 'house' batteries when starting and/or when running, or do you want to use them for starting and isolate then when running. Have you separate chassis batteries, if so where do they sit in the equation. If you would set out the whole process, step by step, you wish to achieve perhaps I could make a suggestion


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## olley (May 1, 2005)

Hi colin house batteries are fine, now being charged via the split charge diode, so its the chassis battery I need to sort.

I can't fit the split charge relay as normal, directly after the alternator, as the alternator has "Voltage sensing" so it just increases the voltage to compensate for the drop caused by the diode, the voltage sensing wire goes in to the PCM (Power train control Module) so I can't disconnect it.

I need to isolate the chassis battery from the alternator, but still allow it to start the engine, a NC relay would allow me to do this, energised only when the ignition is on.

Another idea occoured to me today, and that would be to use another diode to allow the battery to power the starter, but can you get diodes that big??

Any ideas??

Olley


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## Jean-Luc (Jul 21, 2005)

Hi Olley, sent you a pm

Colin


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