Battery selector

[citygent111]

Hi all

Picked up the 'new to us' boat this weekend.

When we got home I obviously wanted to play with it, and run the engine. It has a Mercruiser 4.3 mpi. I put the battery selector to 1 but it wouldn't start, so I had to set the selector to BOTH and it started just fine.

My guess is that the No. 1 battery is on its way out so I'm going to replace it, but my question is, how do I know which battery is No. 1?!

I'm not sure if the selector is a 1-2-both-off type, I think it was just 1-both-off ( it's raining hard right now so I'm not going out to check! )

Looking forward, what's the best way to keep the batteries in good charge, given the boat will spend its time in a storage yard?

TIA

 

[Stemar]

I'd start tracing wires to work out what's what. At least starter cables are big enough to be fairly straightforward to follow.

As for keeping batteries charged, a yottie solution would be a solar panel with a two battery charge controller. This has the advantage that it'll still work when you're at anchor somewhere, prolonging the time before you have to start the engine to charge up again. As someone who likes to be independent of shore power, I'd fit as much as I conveniently can.

The alternative is a smart charger that's permanently plugged in to shore power when you're alongside. The initial cost of the solar system will be higher, but it's free juice for the next 20 years or more. A good charger probably won't be as much to fit as solar, but you'll be paying marina prices for leccy for ever more. Cheap chargers left on indefinitely are a good way to wreck your batteries.

 

[RupertW]

You shouldn’t ever need to charge the starter battery except from the alternator provided it’s always isolated when the engine is off, and assuming your engine usually starts easily.

Then just concentrate on keeping your domestic bank charged every day. Solar is best if you are often off grid. We probably had 2 or 3 marina nights a month in our last few months cruising and even then we often didn’t plug in as solar and inverter did the job.

 

[VicS]

Hi all
Picked up the 'new to us' boat this weekend.
When we got home I obviously wanted to play with it, and run the engine. It has a Mercruiser 4.3 mpi. I put the battery selector to 1 but it wouldn't start, so I had to set the selector to BOTH and it started just fine.
My guess is that the No. 1 battery is on its way out so I'm going to replace it, but my question is, how do I know which battery is No. 1?!

I think I would disconnect each of the batteries in turn and discover which tallies with which switch position

I'm not sure if the selector is a 1-2-both-off type, I think it was just 1-both-off ( it's raining hard right now so I'm not going out to check! )
Looking forward, what's the best way to keep the batteries in good charge, given the boat will spend its time in a storage yard?
TIA

A 1-both-off switch would be very unusual. Maybe they exist but I dont know where Id go to find one! If its is a 3 position switch it is more likely to be a 1-2-off switch, with no both position. Maybe you will find that its is the common 4 position 1-both-2-off switch.
Post a good picture of the front of the switch

A solar system may be the best way to keep the batteries fully charged. Provided you arrive back at the dock with both batteries fully charged from the engine it need not be very large but you do need to sus out how your system works.

 

[citygent111]

Ok, rain stopped and home from football....

Here's the switch, with the split charger device below, and hopefully a photo of the batteries...

I agree I think I need to disconnect both and see which works when!

 

[citygent111]

Just been doing some research, this is it - they come as a set.

Still doesn't help me know which is which!!

While the boats at home this week, if I were to use a mains powered battery charger (the type with crocodile clips or whatever), would it matter which battery I connected them to?
I am HOPELESS with electric stuff, so apologies if these are really obvious questions!!

 

[Tranona]

This is what you have. bluesea.com/products/7650003/Add-A-Battery_Kit_-_120A_%5BBoxed%5D The batteries are independent banks so one battery is dedicated to the engine. Trace the cables to the engine to determine which one. Sounds like it is dead. When you combine you are using the house one to start the engine. Read the marketing bumf and the installation instructions and it will become clear.

Edit. Typed as you posted. Trace the red cable from the starter motor back to th switch and then use the wiring diagram to trace back to the battery. A car type charger is OK but will be slow. You will soon see which one is dead when you attach the charger.

The second battery should be wired to your domestic distribution board for lights, instruments etc. Usually an engine start battery stays charged because as soon as the engine starts it will be recharged and then nothing else draws on it. so common to just have a means of keeping the domestic battery charged when not using the boat.

 

[VicS]

Just to add a couple of points to what is said in the Blue Sea video and to what Tranona has said

Your "Dual Circuit Plus" switch parallels the batteries when in the "combine" position. This will allow you to use both batteries together to start the engine if your engine battery is failing or is too deeply discharged to do so on its own. Dont leave the switch in this position though or you run the risk of running both batteries down.

The ACR ( we normally call then VSRs ) will operate to change both batteries which ever one is actually connected to the charger. That answers your last question.

 

[citygent111]

Cheers VicS

That's pretty much the conclusion I came to last night after watching 4 or 5 more YouTube videos about the installation process.

Still bugging me which is the engine battery though!!

 

[Refueler]

Surely just diconnect one +ve terminal on one of the batterys ... have switch on BOTH - then try start engine. If it still starts then the battery still connected is the '#2' or your 'domestic' good battery. If it does not start - then one connected is the failing Engine battery #1

 

[citygent111]

Makes sense, thanks! As I say, I am clueless when it comes to electrics

 

[PaulRainbow]

Surely just diconnect one +ve terminal on one of the batterys ... have switch on BOTH - then try start engine. If it still starts then the battery still connected is the '#2' or your 'domestic' good battery. If it does not start - then one connected is the failing Engine battery #1

Don't need to do that. Just disconnect one positive cable and if the engine circuit is dead that's the engine battery, if the domestic circuit goes dead the other one is the engine battery.

 

[citygent111]

I think I just need to get my spanners out and dive in!!

 

[Stemar]

Just be careful where you put them. A mate dropped a spanner across the terminals of his car battery. It welded itself into place and wrecked the battery. The spanner wasn't too pretty either!

 

[Refueler]

Don't need to do that. Just disconnect one positive cable and if the engine circuit is dead that's the engine battery, if the domestic circuit goes dead the other one is the engine battery.

OK - accepted - but OP hasn't said that battery is totally dead ... I would suspect that its still 'alive' but not sufficient to spin the starter. If as you assume battery is really dead as a dodo - I agree. But pressing the start button if power appears to be there will load it and show if its not good enough ..

Yet again another example of - its Refueler - so lets have a go ...

 

[Refueler]

Just be careful where you put them. A mate dropped a spanner across the terminals of his car battery. It welded itself into place and wrecked the battery. The spanner wasn't too pretty either!

Guy who taught me to drive - blew his wedding ring asunder and permanently disfigured the hand working on his car battery ...

 

[Sandy]

I think I just need to get my spanners out and dive in!!

Aways worth wrapping your spanners in electrical tape.

 

[PaulRainbow]

OK - accepted - but OP hasn't said that battery is totally dead ... I would suspect that its still 'alive' but not sufficient to spin the starter. If as you assume battery is really dead as a dodo - I agree. But pressing the start button if power appears to be there will load it and show if its not good enough ..

[/QUOTE]
Think you have it the wrong way around. The OP said that the battery seems to be failing. But it doesn't matter if it's fully charged, half flat or fully flat. If one cable is removed the circuit that the battery supplied will be dead and the other won't be.

Yet again another example of - its Refueler - so lets have a go ...

No, yet another example of you not being able to accept a different answer to your own.

 

[Refueler]

Think you have it the wrong way around. The OP said that the battery seems to be failing. But it doesn't matter if it's fully charged, half flat or fully flat. If one cable is removed the circuit that the battery supplied will be dead and the other won't be.


No, yet another example of you not being able to accept a different answer to your own.

Forum rules prevent me replying in the manner it deserves.

I was just pointing out that the battery may be able to supply less demanding items .. to quote "The OP said that the battery seems to be failing" ... ... but not able to start engine. Judging by his post - he understood its failing because it would not start engine ... he has not said in any form that it did not power less demanding items. I do not have a crystal ball as you seerm to have .....
Or have you never experienced such 'failing battery' ?? If not - then I invite you to my abode and I will demonstrate just for you.

 

[PaulRainbow]

Think you have it the wrong way around. The OP said that the battery seems to be failing. But it doesn't matter if it's fully charged, half flat or fully flat. If one cable is removed the circuit that the battery supplied will be dead and the other won't be.


No, yet another example of you not being able to accept a different answer to your own.

Forum rules prevent me replying in the manner it deserves.

I was just pointing out that the battery may be able to supply less demanding items ... but not able to start engine. Or have you never experienced such ?? If not - then I invite you to my abode and I will demonstrate just for you.

Still don't get the point, do you ?

If one battery is disconnected, that circuit is dead, no matter the battery state of charge.

The other circuit will still have power.

The circuit that still has power is NOT the one you disconnected.

It aint rocket science, well, not for everyone except you.