Help me understand relays/solenoids

[PlayItForwrd]

I mentioned in another thread that I need to replace the charging solenoid/relay in our new-to-us Allegro bus:


It was suggested by Cruzer that I replace it with this bad boy:


Here's where I need help---

This is my what my existing relay looks like, notice it has 2 battery cable lugs and ONE 12v input lug. After a little research I've found this is a "coil grounded to case" relay..


This is the same relay, but with TWO 12v input(?) lugs, this is an "isolated coil" relay:


The 200 amp bad boy relay is available ONLY in the isolated coil version. So I have a simple question: Do I have to run a jumper from the 2nd 12v input lug to ground for the relay to work? (and if so, it shouldn't matter which lugs I use for + and - should it?)

[Marty too]

Playitforwards: You got this one right. If it were me-----if the relay is mounted on a metal base-----I would run a short jumper from one contact around the corner to under a mounting bolt/lug or what ever. That would be your ground. The rest would be straight forwards from the orgional.

Quote:

"The 200 amp bad boy relay is available ONLY in the isolated coil version. So I have a simple question: Do I have to run a jumper from the 2nd 12v input lug to ground for the relay to work? (and if so, it shouldn't matter which lugs I use for + and - should it?)"

Marty

[PlayItForwrd]

Thanks Marty!

[wa8yxm]

Quote:

Originally Posted by PlayItForwrd The 200 amp bad boy relay is available ONLY in the isolated coil version. So I have a simple question: Do I have to run a jumper from the 2nd 12v input lug to ground for the relay to work? (and if so, it shouldn't matter which lugs I use for + and - should it?)

Yes, just run a jumper from one of the two small terminals to one of the mounting bolts... The other small terminal gets the control wire. (the existing small terminal wire)

I've worked with both kinds and had to run a jumper more than once.

[DAN L]

Quote:

Originally Posted by wa8yxm Yes, just run a jumper from one of the two small terminals to one of the mounting bolts... The other small terminal gets the control wire. (the existing small terminal wire) I've worked with both kinds and had to run a jumper more than once.

what size wire should this jumper be?

[Cruzer]

Same size as the input wire. It's probably a 16 gauge wire, which is capable of handling up to 10 amps. That's more than what the solenoid coil wil ever use. It never hurst to go larger though, even though it's not needed.

On the newer Bus there is a ground lug buss bar at the top of the compartment where all of the ground wires go to. If you have one of these I'd run the wire right up there and insert it into one of the ground lug screws.

If you don't have a buss bar handly then be sure to use start lock washers when you attach the ring terminal on the end of the wire to the bolt that will br your ground point. That'll help bit into the terminal and make a good connection. Also be sure that the bolt your are connecting to is a good ground source, not something that's attached to an insulated surface. I'd rather run a longer wire to get a good ground than a short wire to a questionable ground.

[PlayItForwrd]

Thanks guys! --and there IS a ground bus bar on my panel--



--I'll be sure to use it!

[hamguy]

Quote:

Originally Posted by Marty too Playitforwards: You got this one right. If it were me-----if the relay is mounted on a metal base-----I would run a short jumper from one contact around the corner to under a mounting bolt/lug or what ever. That would be your ground. The rest would be straight forwards from the orgional. Marty

In my 30+ years dinking with RVs, I have found that nothing about them is "straight forwards."

BTW, I learn something worthwhile from this forum every day. Thanks folks!

[Theberrys]

Playit

It looks like you already have a ground to the existing relay.
Here is a picture of your relay with labels.

You will probably need to observe polarity on the ground and control wires. It should be shown on the body of the new relay.

Dick

[PlayItForwrd]

Got the new relay installed--

And--- Didn't get the bad boy, I wimped out...

... was online checking out the Mouser website, the bad boy was just under $50, the original style (but with the extra terminal) was $16.67, 3 for 1... And buying the OE style meant no new installation worries, just remove the old, put in the new. Took about 5 minutes:





BTW, there was no markings on the terminals, so I just attached the ground to the top, the 12v input to the bottom (where it was on the original)...

Works like a charm!

[Theberrys]

PlayIt

Looks factory.

Good Job

Dick