What batteries are my two volt meters measuring?

[philipm]

I have two battery volt meters visible on the cockpit dashboard. I recall the salesman saying one was for the starboard engine battery and one for the port engine battery. Fine.

However I notice when I use the bow thruster that one of the volt meters gets depleted temporarily. I would have thought that the bow thruster would run off the domestic batteries? If true, that means one of these volt meters is for the domestic batteries, not the engines. It would make sense to know what condition the domestic batteries are in after all.

Any view on whether the salesman was right or wrong?

 

[Rocksteadee]

I have two battery volt meters visible on the cockpit dashboard. I recall the salesman saying one was for the starboard engine battery and one for the port engine battery. Fine.

However I notice when I use the bow thruster that one of the volt meters gets depleted temporarily. I would have thought that the bow thruster would run off the domestic batteries? If true, that means one of these volt meters is for the domestic batteries, not the engines. It would make sense to know what condition the domestic batteries are in after all.

Any view on whether the salesman was right or wrong?

Either, each meter is for port and starboard bank or each meter for start and domestic banks, depending on your wiring.

feasibly the bow thruster is from the start bank, on the grounds that you would probably not be using bow thruster without the engines running.

 

[oldgit]

Either, each meter is for port and starboard bank or each meter for start and domestic banks, depending on your wiring.

feasibly the bow thruster is from the start bank, on the grounds that you would probably not be using bow thruster without the engines running.

The only thing normally connected to the start batteries will be a starter motor. ?
Everything else usually is powered from domestics.
On modern craft the bow thruster frequently has its own remote battery.
Two meters normally measure either the domestic or starter battery alone.
Some boats only have one battery condition meter which can be switched between both banks
Some boats do have a method of using all batteries at once to get boat started, usually because the battery used to start engines is not holding sufficient charge. ie its knackered.

 

[Momac]

Any view on whether the salesman was right or wrong?

If you could say what make and model of boat you have it may help if the owner of a similar boat is reading this.
My boat has a dedicated battery for the bow thruster and anchor winch.
Others may use the domestic bank but a starter type battery is better suited to a bow thruster.

 

[philipm]

Thanks all. Seems like I'd need to be an electrician to establish which meter measures which batteries.

I have 4 batteries in total - two which sit together and I'm sure are for domestic use (because one failed a while ago and I had no lights etc) and two separate batteries, one of which sits in the engine bay and the other sits close to the above domestic batteries.

Boat is a 2010 Jeanneau Leader 9.

 

[simonfraser]

if the voltage drops when you run the thurster that is likely a battery which supplies the thurster

you could employ and electrician, or get a voltmeter, and sort out yourself what is going on, start a seperate thread for this, plenty of help out on this forum

 

[Beamishken]

Sounds like the thruster is run from one of the start batteries. Your dash instruments should read engine batteries and reading will indicate if alternators are charging or not (keeping an eye on the volt guages is a good way of knowing if you have lost a fan belt & possibly avoiding an overheat)
Potentially nothing wrong with the system its just a different way of doing things. If you dont like it no doubt you could change it to your prefered system but in my opinion if it aint broke don't fix it.

 

[halcyon]

if the voltage drops when you run the thurster that is likely a battery which supplies the thurster

you could employ and electrician, or get a voltmeter, and sort out yourself what is going on, start a seperate thread for this, plenty of help out on this forum

Or turn off all batteries,( isolators ) turn one on and see what works, cabin lights engine start, what does a voltmeter do, turn off and repeat for next battery, and so. Would have thought bow thruster on a engine battery would be likely as they would be with the engine running.

Brian

 

[John100156]

Thanks all. Seems like I'd need to be an electrician to establish which meter measures which batteries.

I have 4 batteries in total - two which sit together and I'm sure are for domestic use (because one failed a while ago and I had no lights etc) and two separate batteries, one of which sits in the engine bay and the other sits close to the above domestic batteries.

Boat is a 2010 Jeanneau Leader 9.

Just isolate or disconnect for a few seconds and you will know which is which.

 

[philipm]

Thanks all, the isolation strategy seems the most straightforward. I will look into it.

Seems odd to me that a meter showing domestic battery voltage is not included as standard - it may be in this case, we shall see.

 

[Rocksteadee]

Thanks all, the isolation strategy seems the most straightforward. I will look into it.

Seems odd to me that a meter showing domestic battery voltage is not included as standard - it may be in this case, we shall see.

It may well be. Without knowing how it is wired it is difficult to say.
Are these 2 independent gauges? Are there other volt gauges on any engine panel

 

[bluetooth]

Thanks all. Seems like I'd need to be an electrician to establish which meter measures which batteries.

I have 4 batteries in total - two which sit together and I'm sure are for domestic use (because one failed a while ago and I had no lights etc) and two separate batteries, one of which sits in the engine bay and the other sits close to the above domestic batteries.

Boat is a 2010 Jeanneau Leader 9.

What does the manual say ?
Being 2010 boat this should be detailed enough to explain setup and wiring; unless its all in french !

 

[Beamishken]

If there is a guage for the domestic battery then it should be next to the domestic panel its unlikely to be on the dash with the engine guages

 

[Chris_d]

Strictly speaking the two meters on the dash are not reading battery voltages but the alternator outputs of the respective engines. The actual battery voltages will be the other side of various splitter diodes or relays, solid state charge regulators etc.... There are some setups where both alternators are combined to charge separate battery banks.
As others have said unless there is a wiring diagram the best option is to follow the various cables yourself armed with a multimeter.

 

[rafiki_]

On my boat, one V meter is for the engine batts, the other for domestic services. The bowthruster should run off either the engines batteries or it’s own. Sounds like you have 1 bank of starter batteries and 1 of domestic. Should be easy enough to tell the difference.

 

[John100156]

Yep - on my old F43, my engine battery bank was dedicated to the port engine, with a changeover switch if needed, my service batteries connected to all services and my STB engine, but also was stowed in proximity to my stern thruster so that was connected too, I had a separate battery for my bow thruster - fortunately the charger had three outputs and the set-up worked very well.

 

[philipm]

On my boat, one V meter is for the engine batts, the other for domestic services. The bowthruster should run off either the engines batteries or it’s own. Sounds like you have 1 bank of starter batteries and 1 of domestic. Should be easy enough to tell the difference.

I have a voltmeter on the left side of the instrument panel and another voltmeter on the right. The one on the right dips slightly whilst the bowthruster is being operated. Seems like the easiest thing will be for me to disconnect the various batteries in turn and see how the two voltmeters react.

 

[rafiki_]

Why disconnect? Just take the batteries off charge, and monitor as you switch stuff on. Engines, fridge etc.

 

[halcyon]

I have a voltmeter on the left side of the instrument panel and another voltmeter on the right. The one on the right dips slightly whilst the bowthruster is being operated. Seems like the easiest thing will be for me to disconnect the various batteries in turn and see how the two voltmeters react.

See #8

Brian