Battery specs

[Erin]

Originally Posted by kwil

No VSr's, relays or diodes.

Keith

So how does that work then? Mosfets?

[gotchiguy]

Originally Posted by kwil

Sort of, he has icommand guages that can be configured to read allsorts of data and Gotchi has his set to read the alternator voltage, which as Pickey says in an Etec is 55v. What he needs to do is tab through the gauge setup to find Battery Voltage this will then show the normal battery charging voltage.

Hmm. I must say I am pretty sure that we had this problem in the beginning because it was set to alt voltage and so the reading was 0 with the engine off but we changed it to battery voltage to get a reading..but perhaps not.

Originally Posted by kwil

Gotchi if you really want to make use of the Etec battery charging features you can fit the Auxillary charging lead and charge 2 battery banks independantly. No VSr's, relays or diodes.

Yes, this is exactly what Pikey dave has suggested to me before and I think the way that I want to go, however I have three questions about it:
1. Can the two batteries be of different sizes
2. Would it be possible to wire them together in such a way as that one could do house and the other starting but they could be linked together/swapped just by turning a switch?
3. How easy is it to retrofit

Originally Posted by Erin

Do you know that your batteries were actually sulphated? If so, they could possibly have been saved (or part rejuvenated). Sulphation and its causes are complicated, but lack of use and bad charging can cause it. AGM batteries are more robust than SFL lead acids.

Yes I took it out myself and it was horrendous. Remember there was only one undersized truck battery coming out.

Originally Posted by Pikey Dave

I think what is happening is the i-commands are set to read "alternator" voltage which is 55v, this is a NMEA2000 sentence from the EMM, not a true voltage reading as such. Change this to "Battery" & it should read sensible numbers. If all else fails stick a voltmeter across the battery terminal on the solenoid & earth.

I have stuck a voltmeter across and the voltage coming out has only ever been around 12/13

[captnjack]

Originally Posted by gotchiguy

I have stuck a voltmeter across and the voltage coming out has only ever been around 12/13

Alternator voltage should be about 13.7V fully charged. About 14.4V when charging.

Perhaps the reason the existing battery failed is due to flawed or inadequate charging?

[Pikey Dave]

Originally Posted by gotchiguy

Yes, this is exactly what Pikey dave has suggested to me before and I think the way that I want to go, however I have three questions about it:
1. Can the two batteries be of different sizes Yes
2. Would it be possible to wire them together in such a way as that one could do house and the other starting but they could be linked together/swapped just by turning a switch? Yes, all you need is an isolator switch between the 2 +ves
3. How easy is it to retrofit Very, it's a plug in wiring harness


I have stuck a voltmeter across and the voltage coming out has only ever been around 12/13 Was that at tickover or +2000rpm?

No problem

[Pikey Dave]

Originally Posted by Erin

So how does that work then? Mosfets?

It's all done by the EMM, the aforementioned 55v output from the alternator is normally paralleled into 1x 50A charging supply, the harness splits it into 2x25A supplies. The main engine battery is connected as normal to the starter leads, the auxilliary is connected to the Aux battery charging harness, just like a battery charger. If you fit a heavy link between the +ves with an isolator switch inline, you have to option of linking both batteries if something goes wrong. The -ves would be linked as a matter of course.

[BogMonster]

Originally Posted by Hightower

that'll explain you replacing all your electronics then.

Boom

[bedajim]

Originally Posted by kwil

Sort of, he has icommand guages that can be configured to read allsorts of data and Gotchi has his set to read the alternator voltage, which as Pickey says in an Etec is 55v. What he needs to do is tab through the gauge setup to find Battery Voltage this will then show the normal battery charging voltage.
Gotchi if you really want to make use of the Etec battery charging features you can fit the Auxillary charging lead and charge 2 battery banks independantly. No VSr's, relays or diodes.

Keith

So does this mean changing the wiring harness from the engine or adding more cables to the existing one through the under deck trunking ?

[Pikey Dave]

Originally Posted by bedajim

So does this mean changing the wiring harness from the engine or adding more cables to the existing one through the under deck trunking ?

He'll need to run the auxiliary charging leads to wherever his aux battery is, presumably under the console. The aux charging harness plug into the main harness under the engine cowl.

[kwil]

Attached are a couple of pages from the Etec installation manual showing the battery istallation options.

Keith

[kwil]

Wish I could type - spelt Pikey wrong in an earlier post and now spelt installation wrong.

Keith

[Pikey Dave]

Originally Posted by kwil

Wish I could type - spelt Pikey wrong in an earlier post

Keith

I noticed that, but didn't say anything. That would be just being pickey

[gotchiguy]

Originally Posted by kwil

Attached are a couple of pages from the Etec installation manual showing the battery istallation options.

Keith

Ok thanks very much for that. (no4 for us I think..) How would the house electronics fit into this then? That set up sorts starting, but which positive do we take for the plotter etc?

[bedajim]

Originally Posted by gotchiguy

Ok thanks very much for that. (no4 for us I think..) How would the house electronics fit into this then? That set up sorts starting, but which positive do we take for the plotter etc?

Can you do a sketch of what you've got ?

Wiring wise

[Pikey Dave]

Originally Posted by gotchiguy

Ok thanks very much for that. (no4 for us I think..) How would the house electronics fit into this then? That set up sorts starting, but which positive do we take for the plotter etc?

Assuming you use setup 4, you would feed your electronics from battery "aux2" In normal operation, the engine would start from "primary" & electronics would run from Secondary. I wouldn't bother with the battery changeover switch, they can cause problems. I would fit a battery isolator switch between the positives of both batteries. This would normally be in the Open position.

[kwil]

Ok thanks very much for that. (no4 for us I think..) How would the house electronics fit into this then? That set up sorts starting, but which positive do we take for the plotter etc?

As Pikey says.

Keith

[gotchiguy]

Originally Posted by bedajim

Can you do a sketch of what you've got ?

Wiring wise

There is nothing there, just lots of holes..


I've attached a proposed wiring diagram. The electronics are less of an issue really, save that when I do v2 I'll put the switch box next to the fuse box

The only NMEA0183 is going to be the existing AIS

[Cookee]

Originally Posted by gotchiguy

I've attached a proposed wiring diagram. The electronics are less of an issue really, save that when I do v2 I'll put the switch box next to the fuse box

The only NMEA0183 is going to be the existing AIS

To be fair I am easily confused but are you switching the negatives? If so why?

[jezza2011]

Dont switch on the Negatives.
means that the devices are "live" all the time as it were.
can lead to all sorts of odd things happening.

whats the 50Amp fuse feed from the house battery to the engine for?

[gotchiguy]

Thought there would be a couple of questions about switching the negatives. As we are starting afresh there is no specific reason to go either way really, I know it is convention to switch the positives however I figured and read eslewhere that it makes no difference to switch the negatives, plus where the switches and things will be it would be easier to switch the negatives.

If it is an important issue then it wouldn't be hard to switch the positives I suppose.

The 50 AMP line is part of the auxiliary charging circuit and copied straight from the diagram in one of the links above.

[jezza2011]

arr so you do have a aux charge out. ok makes sense now.
main batt charged form motor and 2nd charged from aux charge. cool

best practice would be to switch the +. safest