Charging alarm question/help.

[NUTMEG]

Popped down to boat today. At high water I thought I would give the engine a run, to warm her up and clear a bit of mud from the drying pontoon.

Engine is a VP MD22, with 670 hours on the clock.

A few seconds after starting the charge alarm went off, but, curiously, the volt meter showed the usual 14v.

Switched of and restarted several times but the same thing, alarm sounded and gauge showed 14v.

For no reason, I tried switching the battery switch from BOTH to START (1) and the alarm stopped, Switched to HOUSE (2) and the alarm sounded, as it did if BOTH were selected.

So, switched to START (1), no alarm, 14v on the gauge, switched to either HOUSE (2) or BOTH, Alarm sounds but 14v still shows on gauge.

No problems prior to this. Does anyone have any idea where to look for faults? To be honest I don't have a clue where to start.

Any ideas most appreciated.

Thanks in advance.

 

[superheat6k]

What if any warning lamps were showing ?

Do you know the charge state of the batteries or the non run voltages from House and Start batteries ?

The alarm buzzer is sounded by Low Oil Pressure or high Water temperature, or the test button, not the alternator output, this only makes the Alt lamp light up if the charge field current from the alternator output reduces, indicating lack of charge.

An interesting one.

 

[NUTMEG]

Thanks for the reply.

The charging light comes on when the alarm sounds.

The batteries are all less than a couple of months old, one 100amp starter and two 120amp house. All three are att to a smart charger permanently which is on shore power all week when boat is in her pontoon.

When the alarm check button is pressed all the warning lights work and alarm sounds as you would expect..

 

[NUTMEG]

Bump.

This is getting worrying. No words of wisdom from the panel? Rats.

 

[oldvarnish]

Since you're sounding a bit desperate, I'll tell you what I would do.

If you're convinced there's enough oil pressure, then you can do no harm running the engine for a short while.

So, expose the back of the switch panel and remove all the contacts. Scrape them and put them back. Then find the oil pressure gauge, temp sensor and any others and do the same at that end. Make sure all the indicator bulbs are properly seated, and the contacts on the alternator.

Give the engine another spin.

You might be lucky.

 

[VicS]

Bump.

This is getting worrying. No words of wisdom from the panel? Rats.

The effects of switching different battery banks in/out of service would focus my attention on the battery circuits.

I would check , double check/ remake all connections to the batteries, the battery isolation, and section switches and the connections at the engine ends of the cables. Positive and negative.

The wiring diaGRm in the owners manual indicates an engine with an isolated DC system, ie does not use the engine block for the negative returns (except that the engine stop solenoid and the glowplugs do and require an earthing relay for their operation).

Dunno if this applies to your engine or not .... or quite what possible obscure faults it might be responsible for hiding.


Check also the alternator negative connection

Will the engine start equally well on the start battery alone, and the house bank alone as well as on both. if it does then probably all the above are OK

Do you have any fancy charging / alternator control system fitted, or any split charging such as diodes or VSR or is your charging distribution purely manual via the 1, 2, both switch.

BTW dont rely on a digital voltmeter for checking/testing. They will give a "normal" reading even through bad connections.

 

[NUTMEG]

Thanks Oldvarnish, yes, a bit desperate, or puzzled at least. Certainly not a pressure problem as pressure gauge sits at 60psi as usual, temp gauge normal AND B****Y volt meter reads normal (14v).

The problem is deffo linked to the batteries, as the charging alarm only goes off on BOTH or HOUSE, NOT ON START battery.

I am thinking along the lines of poor battery connection in the house bank, I wonder if this could trigger the 'not charging' alarm?
Trouble is all the batteries are new and shiny with clean posts/connections.

Steve

 

[superheat6k]

This strikes me as the module being defective.

The alarm does not normally sound if there is a charging fault - only high temperature or low oil pressure.

However, the diodes can easily fail, and I am wondering if your unit has somehow been spiked.

 

[NUTMEG]

Thanks VicS, the engine starts fine on any combination of batteries, as you would expect, all being new. No fancy charging or battery management gizmos, just the 1,2,both,off switch.

I will not be able to get down to the boat till next weekend, so have a week of cogitation and head scratching

 

[NUTMEG]

Superheat6k, if it is a diode/module type fault I am stuffed! When I last worked as an agricultural engineer tractors had only just got Q-cabs and power steering!!!

 

[nigelmercier]

When the house batteries are in circuit (2 or both) it appears that the charging voltage drops. To me this implies that the house batteries are very discharged, or are faulty. I don't see how a bad joint could cause this, but it depends on the way it is wired.

 

[VicS]

This strikes me as the module being defective.

The alarm does not normally sound if there is a charging fault - only high temperature or low oil pressure.

However, the diodes can easily fail, and I am wondering if your unit has somehow been spiked.

I was wondering about a fault in the "electronic module" but I dont see how switching between battery banks would affect its behaviour.


You are wrong, according to the owners manual ( http://pie.volvopenta.com/ViewFileF...=7736943&p=T403&d=Owners Publication&s=571493 ) page 9.3, about the audible alarm only sounding for high temperature or low oil pressure. It also sounds to warn of lack of charging.

 

[NUTMEG]

Just thinking here. If there was corrosion, or general filth, on the battery connectors, is it possible that there would or could be enough resistance to trigger the no charge alarm?

When we were in Brightlingsea last weekend the Webasto would not fire up on the house bank (low voltage error message). I had to briefly start the engine to start the Webasto. Once fired up I turned off the engine and the heater run all night happily on the house bank.

The two 120amp batts are new and left hooked up to a D-Tec smart charger between trips. The Chargers green lights are on showing fully charged banks.

I can not believe the house batts are dead otherwise they would not have run a Webasto all night. But what if there is resistance at a terminal/battery post? Is this possible. Mould it trigger the alarm?

 

[nigelmercier]

... according to the owners manual ... the audible alarm ... also sounds to warn of lack of charging.

Quite so.

 

[Tintin]

Just thinking here. If there was corrosion, or general filth, on the battery connectors, is it possible that there would or could be enough resistance to trigger the no charge alarm?

When we were in Brightlingsea last weekend the Webasto would not fire up on the house bank (low voltage error message). I had to briefly start the engine to start the Webasto. Once fired up I turned off the engine and the heater run all night happily on the house bank.

The two 120amp batts are new and left hooked up to a D-Tec smart charger between trips. The Chargers green lights are on showing fully charged banks.

I can not believe the house batts are dead otherwise they would not have run a Webasto all night. But what if there is resistance at a terminal/battery post? Is this possible. Mould it trigger the alarm?

Check thru the whole -ve path from the house bank to the common point for all systems- often faults hide away.

 

[superheat6k]

When you resolve your fault if you could be so kind as to let us know what the issue is I would appreciate it.

The modules I am familiar with do not sound the alarm for alternator fault. I assume you must a later version. The link kindly provided by Vics doesn't work on my ipad - only shows the front page.

Assuming the module is working then something is causing the charge voltage provided via the internal charge diodes within the alternator to fall, causing the charge excitation current to be provided by the module. This suggests a massive draw on the alternator draining its output voltage and causing the internal excitation current to collapse. Possibly a knackered house battery, or even defective main charge diode/s within the alternator. Is there any possibility you have run the engine with the alternator disconnected, causing the diodes on the main bridge rectifier assembly to blow. A near to fully charged starter battery may not show this problem, as it could charge OK from just two diodes on the bridge rectifier assembly within the alternator, but the higher demand of the house battery means the alternator cannot cope.

Hopefully the pointers here will help you resolve the problem.

 

[Billjratt]

What does the voltmeter read before the engine is started, in all 4 positions of the battery switch?
Can you trace the cabling to make sure the meter is wired sensibly - positive to the load (wiper) side of the battery switch, negative to the common bus in the distribution board (fuse panel).And as mentioned already, make sure the common negative circuit is wired correctly and functional.
As far as I can surmise, the 'ign' lamp will light when there is a voltage across it EITHER WAY but the alarm should only sound when the alternator D terminal (or the oil or temp switches) goes down to 0V and the battery is able to feed the plus side, so that doesn't fit in with a faulty battery dragging the voltage down. (you could get a lamp on but not the alarm (assuming it is fed by diodes in an OR Gate configuration.)
Is the lamp as bright in the fault condition as it was before the engine was started? If you don't trip over the fault while looking at the above, you will need a multimeter to check the voltages on either side of the ign lamp relative to negative to see which is not near 14V. Then trace and fix or report back here.
Best of luck

 

[NUTMEG]

The dashboard panel is a VP Deluxe version with all the bells and whistles on it. The voltmeter only reads whilst the engine is running, at least I have never noticed it reading anything with the engine off. I have not yet put a multimeter on the batteries yet, first job on Sunday I hope.

The wireing has not been altered or fiddled with and everything worked fine until now so I do not think incorrect wiring is the issue.

The red charge warning light is just as bright with or without the engine running iirc.

Thanks for your input,

Steve

 

[NUTMEG]

I always wonder what happened next when threads drop off of the bottom of the list and the OP never comes back to explain if it worked, they sorted it out, or whatever.

So, to close this thread, I went back to the boat today, removed, cleaned and refitted all the battery post clamps and started the engine. No charging warning buzzer. I had a hunch that a bit of corrosion on a post/clamp might give a resistance and this resistance might set the alarm off. No scientific knowledge or anything, just a hunch. It seems to have worked. I tried restarting several times and no problems. I hope that's the end of it.

Thanks for your help chaps.

Steve

 

[VicS]

I always wonder what happened next when threads drop off of the bottom of the list and the OP never comes back to explain if it worked, they sorted it out, or whatever.

So, to close this thread, I went back to the boat today, removed, cleaned and refitted all the battery post clamps and started the engine. No charging warning buzzer. I had a hunch that a bit of corrosion on a post/clamp might give a resistance and this resistance might set the alarm off. No scientific knowledge or anything, just a hunch. It seems to have worked. I tried restarting several times and no problems. I hope that's the end of it.

Thanks for your help chaps.

Steve

Thanks for the feed back.

Hopefully now cured although a bit of a mystery why the alarm sounded when both batteries were selected but not when just the starter battery was selected.

I think Id be wondering if both were actually connected or if only the house battery is connected when the switch is in the both position......... perhaps worth checking that out as a possibility ?????