Charging diagnostic challenge

[kalanka]

I have recently replaced a switch panel on a Sadler 34, 1988. This went smoothly but on my first outing after the replacement I noticed that I have lost charging – first indicator being the tachometer not functioning. Engine is Volvo Penta 2003. There is no change to battery voltage when the engine is running. House battery bank is 3 x Deka DC27

To connect the battery meter on the new panel it was necessary to input a positive connection to tap voltage from each battery bank . I tried to do this by accessing the rear of the battery rotary 1/2/all/off switch but in the end took the feeds from two heavy red leads in the engine compartment. These new connections are running at 3 o clock here:



I assumed that I had disturbed a connection that was now preventing charging, especially the thin wire at the back of the alternator, but all connections seem sound and jiggling has no effect. Battery connections are clean and sound. House battery bank and starter battery currently showing 10.4/ 10.5 V

There is a Sterling battery management system fitted which I have never really understood. I recall it was necessary to install a new field connection (I think) to the alternator on installation of the Sterling to allow high output when charging. There was also a relay that had to be fired up to get the system to boot.

With engine running this is the display - the top Green is flashing



Here is what I believe to be the relay




I am baffled by the diagnosis of the problem and all too aware of my limitations in this area. I would be very grateful if anybody could give me some steer. I can do electrics but am generally baffled by electronics...

I suppose that a broken connection remains a possibility but other possibilities that occur to me include:


A coincidental failure of the alternator


The voltage tap has somehow messed up the power management system


Damage to a charging diode or the relay


Fault in the rotary battery selection switch



Any suggestions?



Thanks

 

[Baddox]

If I understand your problem, you have fitted a new panel with a battery meter but the meter is reading 10.5V and the tacho no longer works.

Do you have a multimeter that you could use to check the battery readings at the battery terminals? Do they match the 10.5V measured by the panel’s meter?

You mentioned your first outing which suggests you have been able to use the boat which in turn suggests that the engine could be started and instruments work. Both of these are unlikely with batteries reading 10.5V.

 

[William_H]

I think with tacho not working and alternator not charging, you have a failure of the excitation of the alternator. This is where current from the battery feeds directly to alternator field. (the rotating part fed by brushes and slip rings) to provide a start up for the alternator. Once some current is generated the alternator provides it's own filed current which is in turn controlled by the regulator to ensure voltage out is correct regardless of load. Now in an old fashioned sytem this start up current is provided via the "ignition" or alternator lamp on panel. It glows when current is being provided going out when current is not flowing being superceded by alternator's own supply. However you have a sterling smart regulator about which I know little.
However a common failure of alternators is in the slip rings and brushes that feed the filed current to the rotor. Usually accessed at the opposite end to the pulley 2 screws remove a plate with brushes attached. Slip ring can be cleaned and ensure brushes have plenty of pressure and length. (sorry all generally speaking with knowing alternator type. ol'will

 

[VicS]

I have recently replaced a switch panel on a Sadler 34, 1988. This went smoothly but on my first outing after the replacement I noticed that I have lost charging – first indicator being the tachometer not functioning. Engine is Volvo Penta 2003. There is no change to battery voltage when the engine is running. House battery bank is 3 x Deka DC27

To connect the battery meter on the new panel it was necessary to input a positive connection to tap voltage from each battery bank . I tried to do this by accessing the rear of the battery rotary 1/2/all/off switch but in the end took the feeds from two heavy red leads in the engine compartment.
>
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Any suggestions?
Thanks

Does your new panel have LEDs instead of filament bulbs for the warning light?

If so that may be the cause of your problem because an LED does not pass enough current for the initial excitation of the alternator.

Whether or not this is the explanation depends on the alternator ( some have a separate excitation feed from the ignition switch), on the engine installation ( some have an excitation resistor to provide a direct feed) and maybe ( I don't know) on the Sterling regulator. What engine do you have and what make is the alternator?

If this is the explanation a feed from the ignition switch to the alternator warning light terminal via a 33 ohm, 5 watt resistor should fix it.

William's suggestion regarding the brushes and sliprings may be correct but perhaps not if the ignition warning light glows continuously from "switch on" and throughout engine running ?

Apart from the problem non charging problem
Those two thin wires for the voltage readings should be fused to protect them
and
A voltage reading of 10.4/ 10.5 would indicate a dead flat battery ... You'd certainly not be able to start the engine if true.

 

[kalanka]

Grateful for your suggestions so far. My post was in error. The battery level of charge is actually 12.5 - an important difference. Sorry! Engine runs and there is limited charging from solar panel in the Scottish sun. Engine monitoring instruments (oil, temp, etc are not working.

VicS - thanks for the comments on including a fuse - a simple in line one?

 

[kalanka]

When the new battery bank and battery regulator were installed I recall the engineer installing something to deal with the excitation - could this be the relay shown in one of my pics? - a little square cube with connections. Is it worth replacing that? Thanks