Battery light on control panel.

[Timx]

Could anyone tell me what the red light coming on in the control panel means? It’s on the battery monitor control panel. My battery monitor Bmv tells me everything is charging fine, ie leisure batteries. Never noticed the red light come on before, what would it usually signify ?

Upside down for some reason, but you get the picture. Never lit up b4.

 

[ditchcrawler]

Is that on when the engine is running or prior to starting with the key switched on or with everything off

[Tony Brooks]

They/it are usually controlled from the alternator, but turned on by the ignition switch, so do you have a single or twin alternator engine? In the later case, the BVM would be looking at the domestic (larger) alternator, while the engine start alternator could have failed.

 

The normal operation is turn ignition on, light should illuminate, start engine and possible give it a rev and the light should go out ast he alternator starts to charge.

 

Things are not quite hat simple unless we know the alternator(s) make & model or photos to identify them.

 

It could also be a wiring fault but lets see what you actuall have.

 

 

[nicknorman]

Do you mean the small red light inside the Volta meter (it’s hard to see whether it’s on or not). If that one, it means the engine alternator is not charging, which is rather born out by the sub-14v showing on the meter.

 

Oil pressure looks very high for engine idling, does that gauge work?

[Timx]

1 hour ago, ditchcrawler said:

Is that on when the engine is running or prior to starting with the key switched on or with everything off

That’s when engine is running.

 

1 hour ago, Tony Brooks said:

They/it are usually controlled from the alternator, but turned on by the ignition switch, so do you have a single or twin alternator engine? In the later case, the BVM would be looking at the domestic (larger) alternator, while the engine start alternator could have failed.

 

The normal operation is turn ignition on, light should illuminate, start engine and possible give it a rev and the light should go out ast he alternator starts to charge.

 

Things are not quite hat simple unless we know the alternator(s) make & model or photos to identify them.

 

It could also be a wiring fault but lets see what you actuall have.

 

 

two alternators, have never seen the light come on before.i think they are 120 amp domestic and 90 amp start alternators, but will check and photo tomorrow. The light stays on throughout a cruise.

1 hour ago, nicknorman said:

Do you mean the small red light inside the Volta meter (it’s hard to see whether it’s on or not). If that one, it means the engine alternator is not charging, which is rather born out by the sub-14v showing on the meter.

 

Oil pressure looks very high for engine idling, does that gauge work?

Yes that light is on. The meter reading is always about there, also the oil pressure reading has been like that over ten years. I trust the victron battery meter which shows leisure’s are charged appropriately. Starter battery has worked fine last two days, only noticed light last night when running for charge.

Both showing 12.8v on internal engine battery monitor.

[nicknorman]

16 minutes ago, Timx said:

That’s when engine is running.

 

two alternators, have never seen the light come on before.i think they are 120 amp domestic and 90 amp start alternators, but will check and photo tomorrow. The light stays on throughout a cruise.

Yes that light is on. The meter reading is always about there, also the oil pressure reading has been like that over ten years. I trust the victron battery meter which shows leisure’s are charged appropriately. Starter battery has worked fine last two days, only noticed light last night when running for charge.

Presumably the engine has 2 alternators (as well as the travelpower) with one alternator being for the starter battery and one for the domestics. That light is for the starter alternator and if the starter battery isn’t charging then you will still get quite a few starts before it goes flat. The BMV712 has an input for the starter battery so you can measure its voltage. Did you wire it up  in which case what is the starter battery voltage?

 

Was the travelpower running at this time? One possibility is that the Travelpower is running the Combi charger which is pushing the starter battery voltage slightly above the starter alternator’s regulated voltage, and thus the field current has dropped to zero and thus the alternator warning light is on. Depends on whether it’s a 6 or 9 diode machine.

Edited October 30, 2024 by nicknorman

[Timx]

Just checked, engine hasn’t run for five hours, not hooked up by the way

 

 

2 minutes ago, nicknorman said:

Presumably the engine has 2 alternators (as well as the travelpower) with one alternator being for the starter battery and one for the domestics. That light is for the starter alternator and if the starter battery isn’t charging then you will still get quite a few starts before it goes flat. The BMV712 has an input for the starter battery so you can measure its voltage. Did you wire it up  in which case what is the starter battery voltage?

 

Was the travelpower running at this time? One possibility is that the Travelpower is running the Combi charger which is pushing the starter battery voltage slightly above the starter alternator’s regulated voltage, and thus the field current has dropped to zero and thus the alternator warning light is on. Depends on whether it’s a 6 or 9 diode machine.

The bmv does not wire into the starter battery, but my internal monitor is showing it at 12.8, thanks for looking but your last paragraph goes over my head.

But what people are saying is that light being on relates to the starter battery[unless a wiring fault]?

[Tony Brooks]

8 hours ago, Timx said:

But what people are saying is that light being on relates to the starter battery[unless a wiring fault]?

 

To be a bit more accurate (pedantic) the start alternator, that might be faulty, so far the battery is fine, and as you only need a few Ah to start a reasonable engine will remain so for some time.

 

The problem we have is that we don't know how your boat is equipped, only what is typical. If anyone has been modifying it or has extra equipment, then the reason the start battery is showing 12.8V and PERHAPS is till being charged are:

 

1. One of your alternators is a special thing called a Travelpower that links to a magic box to produce 230V AC. These often connect to the bat's 230V outlets plus a mains battery charger, so it is this that is charging both batteries.

 

2. Someone has linked both battery banks using an extra piece of equipment like a VSR or B2B charger in the hope they can use the engine alternator to help charge the domestic bank. If so, the domestic alternator could still charge the engine battery.

 

3. If you have solar then some controllers have two outputs or most can be persuaded to charge both banks in some way or another.

 

The chances are that the engine alternator is not producing output, so check the drive (fan) belt and there are at least two thin wires and one thick wire connected to it. There might be a third thin wire and a second thick wires.

 

 

 

[Timx]

Thank you for replies, I know now where to look, or at least get someone else where to look. If it’s starter battery then fine, it’s an aqualine, nothing has been modified apart from getting solar panels in. As I said the domestics are fine and starter battery fired engine first thing this morning. I was out in the country , no roads anywhere near. So have got near civilisation now and will go into a marina tomorrow and get them to look at it. Thanks again to every one.