Domestic Battery not charging, Engine battery still is.

[Scotty D]

Hi all,

 

Apologies for the re-post, the last thread was hi-jacked by a some kind of cat fight over who was right and who was wrong. I'm just looking for some basic starter advice on the problem of my domestic battery not charging from the engine anymore, whilst my engine battery seems fine.

 

I was initially advised to take readings, and check battery connections...I've done this. Here are the subsequent details:

 

MULTIMETER READINGS

 

Engine battery (Eng off) 12.7V

Dom Batteries (Eng off) 11.99V

Engine Battery (Eng On) 12.57V immediate after start, then 12.67 15 mins after running.

Dom Batteries (Eng on) 11.99V immediate after start, and same 15 minutes later.

 

Equipment:

2 Dom batteries are Squadron energy marine & rec FLA 110 Ah deep cycle.

1 Engine battery

Sterling 4 step switch mode battery charger power pack (is this just for shore power?)

Steca 110 PR1010 Regulator for Photovoltaic systems (This is the solar panel controller you guessed at; the error message it was giving me was to tell me it's not going to do anything again until I get the batteries back above the "deep discharge ).

Kemo 2 Accumulator Charger (Connects engine battery to spare; but what does it do? Trickle charge I guess?).

 

I think the charging is done via a split charge diode? It has an alternator in point, a batt 1 out point and batt 2 out point. Batt 1 is engine battery, 2 is dom's.

There is also a solar panel with regulator panel which shows voltage etc too.

 

Readings across supposed split charge diode are Alt-Engine Batt (eng off) 1.32, Alt to Dom Batt, .61. This remains constant for dom battery with engine on and off but drops to 1.24 for alt-engine batt with engine on.

 

Does that give you any more clues?

 

I've looked at the connections and they look very clean and tight, I doubt this is the problem....would adding petroleum jelly make that big a difference if they are dry? IS checking by eye sufficient for clean connections?

 

Many questions, sorry, comes with steep learning cliff.

 

Warmest

 

Scotty

[MoominPapa]

Hi all,

 

Apologies for the re-post, the last thread was hi-jacked by a some kind of cat fight over who was right and who was wrong. I'm just looking for some basic starter advice on the problem of my domestic battery not charging from the engine anymore, whilst my engine battery seems fine.

 

I was initially advised to take readings, and check battery connections...I've done this. Here are the subsequent details:

 

MULTIMETER READINGS

 

Engine battery (Eng off) 12.7V

Dom Batteries (Eng off) 11.99V

Engine Battery (Eng On) 12.57V immediate after start, then 12.67 15 mins after running.

Dom Batteries (Eng on) 11.99V immediate after start, and same 15 minutes later.

 

I don't think either batttery is charging. The domestic batteries are lower that the engine one because they are more discharged. For either battery to be charging, there would need to be more an 13V at the terminals, unless it was very flat.

 

MP.

[Sir Nibble]

I don't think either batttery is charging. The domestic batteries are lower that the engine one because they are more discharged. For either battery to be charging, there would need to be more an 13V at the terminals, unless it was very flat.

 

MP.

Agreed, all earlier bets are off.

Scotty, I don't know what type of alternator you have, but I now suspect it. Please read the voltage from alt output terminal to -ve with engine on and off, and also from alternator D+ terminal to -ve also engine on and off, that's the warning light connection. Depending on the alternator type that may not be easy to find, if you can photograph the alternator or find a manufacturers type number I can identify it and be more specific. How is the warning light behaving? Does it come on with ignition and go off with engine running? Is there any slight glow with the lamp shadowed by your hand?

[Gibbo]

The alternator is producing no output. Or if it is, it isn't getting as far as the split charge diode.

 

Look at the voltage readings. All of them. The only way those voltages add up is if the alternator terminal on the split charge diode is lower than the battery voltage, not higher.

 

Gibbo

[Scotty D]

Thanks Gang,

 

Had me baffled for a while as after prodding around everything charged again, and then, it all stopped again yesterday....I suspected the black lead coming out the back of the alternator...had a look, and eh voila...charging again.

 

Turns out the red and black are secured together 6 inches away from the alternator, but with the red having a bit more length to the alternator and being a stiff cable, means it wants to be straight which pulls the shorter black's spade out of the connection....I've realigned them so they're equal length and slot equallt into the spades and hopefully that's solved it.

 

Brilliant. It's a nice feeling to have fixed my first problem.

 

Thanks for the advice, really appreciate it.

 

All the best

 

Scotty