how many amps should the parallelising battery banks relay be?

vas

vas

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hello and happy festive season!

sitting idle is not something I can do, so working on the layout of a e/r el. box with various fuses and relays.

One of the things I want to fit in there is the relay that will help me parallelise the two banks effectively helping me start the engines if the engine bank has failed for some reason.
I've bought a 24V 100A relay for another job which is now surplus and was thinking of using it. It's of similar size to the one that p/o (or even factory) has fitted many moons ago but brand new so I'd rather use it instead of the other one. Plan is to toggle the switch, start the stbrd engine first (that's charging the engine bank) and then it's alternator should help in starting the port engine.
That's the one I have, the tech specs on that page confused me a lot tbh!
http://www.albrightinternational.com/products/sw80/

cheers

V.
 
thanks,

sorry should have givem some more details it seems.

the parallel switch on the dash is a push button so will only work for as long as you want to have the starter running. Once the engine fires up, you shouldn't really need it.
I do have a victron 24V/60A charger with separate circuits for the service and engine banks and I also have 600W solars which charge the service bank via an MPPT 100/30 controller, so I'm covered as far as charging is concerned.
Wont be using a split charge relay in this setup, don't need it.

So effectively this relay (which is similar size to the typical starter motor relays) is only going to be used for 10-15sec (and I'm exaggerating here as engines start on the first crank) once in a blue moon. TBH, if the system fails, I can easily go down to the e/r and use a massive jumper cable with clips I have there as an emergency, so not the end of the world, but rather have something that it's fit for purpose.

Wonder what relays other mobos have in such setups!

cheers

V
 
robrennie said:
Hi,
Might be a better solution to use a starter motor solenoid to parallel the batteries for starting; https://www.ebay.co.uk/itm/STARTER-...997105&hash=item27e51e4608:g:GxAAAMXQVT9S8iVE

And a split charge relay to give you a correct charging strategy.

Benefit is that you will never leave the switch in the wrong position and risk charging only the 'spare' battery.
Click to expand...

arent starter solenoids (coil as well as contacts) meant to be in series with the starter? If they should be wired that way then you will seriously over volt the coil if used as you suggest.
 
vas said:
thanks,

sorry should have givem some more details it seems.

the parallel switch on the dash is a push button so will only work for as long as you want to have the starter running. Once the engine fires up, you shouldn't really need it.
I do have a victron 24V/60A charger with separate circuits for the service and engine banks and I also have 600W solars which charge the service bank via an MPPT 100/30 controller, so I'm covered as far as charging is concerned.
Wont be using a split charge relay in this setup, don't need it.

So effectively this relay (which is similar size to the typical starter motor relays) is only going to be used for 10-15sec (and I'm exaggerating here as engines start on the first crank) once in a blue moon. TBH, if the system fails, I can easily go down to the e/r and use a massive jumper cable with clips I have there as an emergency, so not the end of the world, but rather have something that it's fit for purpose.

Wonder what relays other mobos have in such setups!

cheers

V
Click to expand...

You can still weld contacts shut in 15 seconds.
 
You can for sure wire the solenoid to put the batteries in Parallel.

My current boat, a Beneteau and two previous boats, a Fairline and Sealine, both used a solenoid not a relay.

Solenoids do not arc in the way that Relays can, simply wire the momentary button you have on the dash to the positive connection on the solenoid and it will work a charm.

As you have the charging very nicely sorted, this would all work fine.
 
thanks guys,

you confuse me though, what's the difference between a solenoid and a relay?
I guess both have a low voltage coil which triggers and moves a core to close contact, no?
I mean, such a relay has a coil to activate and close the high current circuit, no?

could you point me to what you have, or what you suggest?
Do you consider the one I linked to as a solenoid activated relay?

sorry many Qs but I'm slightly lost!

cheers

V.
 
Sorry, I didn't see your link.

Just looked it it.

It looks like a contractor (heavy duty relay) and also states that it is designed to be anti-weld.

So looks like a perfectly good fit for starting an engine.

Not sure what the price would be for it, so if it is cheaper (or you already have one) would seem OK.
 
Vas, your solution with the relay that you have should work,
BA has just a big manual battery parallel swich in the ER,
The Karnic has a victron Cyrix, works semi automatic.

HNY
 
vas said:
thanks guys,

you confuse me though, what's the difference between a solenoid and a relay?
I guess both have a low voltage coil which triggers and moves a core to close contact, no?
I mean, such a relay has a coil to activate and close the high current circuit, no?

could you point me to what you have, or what you suggest?
Do you consider the one I linked to as a solenoid activated relay?

sorry many Qs but I'm slightly lost!

cheers

V.
Click to expand...

Boring technical definition:
A solenoid is a coil and something that is moved by energising the coil.
A relay is a solenoid combined with a switch so that the switch is operated by energising the coil.
 
robrennie said:
Sorry, I didn't see your link.

Just looked it it.

It looks like a contractor (heavy duty relay) and also states that it is designed to be anti-weld.

So looks like a perfectly good fit for starting an engine.

Not sure what the price would be for it, so if it is cheaper (or you already have one) would seem OK.
Click to expand...

thanks, I do have one sitting on my desk, so I'll use it!

BartW said:
Vas, your solution with the relay that you have should work,
BA has just a big manual battery parallel swich in the ER,
The Karnic has a victron Cyrix, works semi automatic.

HNY
Click to expand...

HNY 2Y Bart :D

yes, actually it's more of a 'project' to give use to one of the redundant switches on the el.panel and less of a mission critical piece of equipment. If it fails, I just go down there are rewire (or bridge) the engines to the service batteries and be done with!

Dougal Tolan said:
Boring technical definition:
A solenoid is a coil and something that is moved by energising the coil.
A relay is a solenoid combined with a switch so that the switch is operated by energising the coil.
Click to expand...

thanks!
that's close to my understanding as well.

I'll post next week some pics in the main rebuilt thread of the layout and setup of this new el.panel

cheers

V.
 
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