Battery specs

[gotchiguy]

What specs would you consider appropriate for a single 3.4L engine outputting 140amps on charge, a large plotter and a few other misc instruments?

[Hightower]

I'd go to Specs savers and see what they say?

[Chris]

If you are going for a single battery then I woudl be looking at something along the 110AH size with at least 800 CCA (Cold Cranking Amps) Like the NUMAX here Batteries 4 Leisure. Caravan Batteries, Marine Batteries.

If you want to spend some serious money then an AGM battery woud be good but you would be spending about £350 the 110ah. They do last very well however and wont discharge over longer periods.

[captnjack]

petrol or diesel?
its not the running loads which count so much as a good minimum cranking amps for starting.

[Hightower]

I would have a look at your engine handbook. That'll state the required cranking amps and will in part dictate what size battery you should be fitting. Always go for as bigger ah as you can. Better to go to overcapacity and ha e a bit in hand.

I have twins in mine. One 85ah and a 110ah. Both with cca of 850 or there abouts.

[gotchiguy]

Hmmm...well we have just taken out a badly sulphated 100AH 700CCA trucking battery and were somewhat surprised at its lack of size.

The decision is whether to go for two 100ah batteries (to negate the need for a complex charge distributor) or one perhaps 130ah. Think we're leaning towards two for redundancy's sake because we are fitting a bilge pump too now

[bedajim]

Originally Posted by gotchiguy

Hmmm...well we have just taken out a badly sulphated 100AH 700CCA trucking battery and were somewhat surprised at its lack of size.

The decision is whether to go for two 100ah batteries (to negate the need for a complex charge distributor) or one perhaps 130ah. Think we're leaning towards two for redundancy's sake because we are fitting a bilge pump too now

Why not go for two 130s and an ACR+1 -2 or both isolater then you have a house and starter option
Get a set of leads made up so you can connect either one as a starter if your in trouble.

Sent from my phone in the bar

[Cookee]

Originally Posted by bedajim

Why not go for two 130s and an ACR+1 -2 or both isolater then you have a house and starter option
Get a set of leads made up so you can connect either one as a starter if your in trouble.

Sent from my phone in the bar

+1 or get a smart switch that charges the house battery and will link it all together with a switch in case of an emergency.

[Erin]

You really don't need high Ah batteries unless you are going to be running your electronics for extended periods of time without running your engine. By extended I mean 6 hours or more. What you need to aim for is a battery with a high cca which quite often results in a comparatively low Ah. Optima AGM are good something like 1000 cca but only 50 or so Ah. If you had a liveaboard with a fridge and cabin lights and the like then deep cycle batts are good, but just for engine starting and light loads then don't waste your (dad's) money on high Ah. IMHO twin batt setups on single engine boats with cruising trips like ours are overkill. If you're worried about unexpected batt failure then replace your single batt every 3 years as a precaution.

[gotchiguy]

So two 975cca/75ah Optimas would be good then? Only thing is that it suggests an alternator voltage of 13.8-15V, but ours outputs 55V..

[Hightower]

Originally Posted by gotchiguy

So two 975cca/75ah Optimas would be good then? Only thing is that it suggests an alternator voltage of 13.8-15V, but ours outputs 55V..

that'll explain you replacing all your electronics then.

[Pikey Dave]

Originally Posted by gotchiguy

So two 975cca/75ah Optimas would be good then? Only thing is that it suggests an alternator voltage of 13.8-15V, but ours outputs 55V..

Careful Olly, engage brain before triping

[chewy]

I'd sort your charging problems before replacing your batteries....

[gotchiguy]

Originally Posted by Hightower

that'll explain you replacing all your electronics then.

Originally Posted by Pikey Dave

Careful Olly, engage brain before triping

Originally Posted by chewy

I'd sort your charging problems before replacing your batteries....

Hmm....

Well the facts are as follows:

With the engine off the battery voltage is normal, 11.5-13.5ish. When the engine is switched on, even at idle then the voltage reading is always 55V. Now, I have absolutely no idea where the icommands are taking this reading from, it can't possibly be from the power supply they are receiving otherwise they would have blown up..

And certainly all the electronics only ever receive 12v because thanks to our myriad problems I have had to test them many times...

The wiring was done awfully when built but we are keen to get it right this time and do it properly. Should there be a voltage regulator between the engine an the battery then? Or am I missing something?

Battery taken out was a badly sulphated 700cca 100ah, condition not yet been tested

[Pikey Dave]

Originally Posted by chewy

I'd sort your charging problems before replacing your batteries....

In fairness to Gotchi, the Etec alternator does output 55v, this is used internally by the engine for the EMM& Ignition circuits. It's then chopped up , smoothed& regulated to 13.8v for external battery charging etc.

[chewy]

Originally Posted by Pikey Dave

In fairness to Gotchi, the Etec alternator does output 55v, this is used internally by the engine for the EMM& Ignition circuits. It's then chopped up , smoothed& regulated to 13.8v for external battery charging etc.

So is it the engine instruments that are reading 55v?

[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 and I think can tolerate abuse a bit more from bad charging. However, I doubt they'd be a problem for your Etec to handle.

[kwil]

So is it the engine instruments that are reading 55v?

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

[Pikey Dave]

Originally Posted by chewy

So is it the engine instruments that are reading 55v?

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.

[Pikey Dave]

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

Bugger, you beat me to it.