Charging Problem for the hard of understanding.

[oldgit]

Thanks Paul.
Off down the boat again this morning, the wife is convinced there is another "she" in my life, which is true in a way.
This time going make sure it is only the alternators putting volts into the system.

The problem is simply that on any decent run ( 7-8 hours from the Mudway to Teddington )the leisure batteries do not appear to be getting charged from the alternators.
As for charging the domestics during a couple of hours a day on tickover while on the Thames, no chance .

 

[Alex_Blackwood]

Because the upper brown wire goes to the Stb alternator, there is no connection to the port alternator. For the port alternator to charge both batteries you would need a second diode.

I may be being a bit paranoid here but that wiring on the diode splitter looks suspicious. I would have assumed, perhaps incorrectly that the RED was the alternator and the Two BROWNS were the batteries. I know the indications are as Paul says, but, Is it worth double checking to confirm where the wires actually go. Just doesn't look right

 

[PaulRainbow]

I may be being a bit paranoid here but that wiring on the diode splitter looks suspicious. I would have assumed, perhaps incorrectly that the RED was the alternator and the Two BROWNS were the batteries. Is it worth double checking to confirm where the wires actually go. Just doesn't look right

The top terminal is definitely the alternator in and the voltage readings with the Stb engine running indicate that it's wired correctly to the alternator. The other two terminals are outputs and the voltages suggest they are connected to the batteries, but there is a significant voltage drop.

I wouldn't get hung up on the wire colours, there shouldn't really be any browns there at all. They may have used red and brown to differentiate the two batteries, but who knows.

That aside, the tests in post #16 will confirm which goes to where.

 

[PaulRainbow]

Thanks Paul.
Off down the boat again this morning, the wife is convinced there is another "she" in my life, which is true in a way.
This time going make sure it is only the alternators putting volts into the system.

The problem is simply that on any decent run ( 7-8 hours from the Mudway to Teddington )the leisure batteries do not appear to be getting charged from the alternators.
As for charging the domestics during a couple of hours a day on tickover while on the Thames, no chance .

Can you also confirm, from post #6 "How are the batteries connected, both engines start from engine batteries, or one from engine battery and the other from the domestics, or what ?"

 

[oldgit]

The latest numbers all taken at 0 degrees centigrade.
Both engines start from the 2 x starter batteries . No start when + terminals removed from both battery posts.

 

[PaulRainbow]

Both alternators appear to be charging OK
The voltage drop from the diode is about what i'd expect, so it looks like that's OK too.

The top brown wire is from the alternator
The middle brown wire is to the engine batteries
The red wire is to the domestic batteries

I don't see anything wrong with the engine batteries voltages, would be better without the diode, but they are also being charged from the port alternator.

The domestic batteries are 50% flat. With a voltage of 12.86, with the diode bypassed, they will never charge much (if at all) past that. The fact that they read 14+ volts on shore power, or when in parallel with the port batteries suggest the batteries are capable of taking a charge.

It's looking like the connection between the diode and the domestic battery is suspect. Can you run a temporary wire from the alternator terminal of the diode to the domestic batteries ? If the engine batteries are close enough to the domestics, you might be able to use the engine battery wire from the diode, just disconnect the domestic wire from the diode and the batteries, then connect the wire from the engine batteries to the domestics.

 

[B27]

It would be useful to know the current going into each battery.
The voltage of a battery can be misleading if you don't know the current.

Also a battery with no current in or out can give a misleading voltage for quite a while after being charged or discharged at all.

How does the generator charge both batteries? Is it an alternator on the genny engine or a charger from the 230V?
Maybe it only charges one battery the 14.5 on the leisure battery could be spurious, stored surface charge from charging it with the shore power? Maybe that's what the 'diode' is for, or maybe the generator has a VSR or similar?

Do we assume the 'shore power' is a dual-output charger?

I'd be re-checking the voltages in the first post, wondering if the starter batteries were still recovering from starting engines when the readings were taken.

It might be useful to measure the voltages across the diode splitter, that will indicate where current is flowing.

Watching for voltages changing over a few minutes can help, as can seeing how they are affected by adding a load like a headlamp bulb.

 

[Alex_Blackwood]

It would be useful to know the current going into each battery.
The voltage of a battery can be misleading if you don't know the current.

Also a battery with no current in or out can give a misleading voltage for quite a while after being charged or discharged at all.

How does the generator charge both batteries? Is it an alternator on the genny engine or a charger from the 230V?
Maybe it only charges one battery the 14.5 on the leisure battery could be spurious, stored surface charge from charging it with the shore power? Maybe that's what the 'diode' is for, or maybe the generator has a VSR or similar?

Do we assume the 'shore power' is a dual-output charger?

I'd be re-checking the voltages in the first post, wondering if the starter batteries were still recovering from starting engines when the readings were taken.

It might be useful to measure the voltages across the diode splitter, that will indicate where current is flowing.

Watching for voltages changing over a few minutes can help, as can seeing how they are affected by adding a load like a headlamp bulb.

Try reading the post before letting your belly rumble!

 

[Refueler]

The alternators are 80A not 50A and both putting about 14.50 V.
Found the Diode thingy (stop me if am getting to technical ) and got the following readings.
View attachment 185657
Why does the splitter appear to be working with one engine but not the other.
Confused of Medway.

I have one of those still fitted to my S25 ... mines from Stirling ... I disconnected it as it had too much of a voltage drop - needed alternator to be cheated or fit a booster.

 

[PaulRainbow]

It would be useful to know the current going into each battery.
The voltage of a battery can be misleading if you don't know the current.

Also a battery with no current in or out can give a misleading voltage for quite a while after being charged or discharged at all.

Seriously ?

How does the generator charge both batteries? Is it an alternator on the genny engine or a charger from the 230V?

It's powering the mains charger, as i said previously and supported by readings given in post #1

Maybe it only charges one battery the 14.5 on the leisure battery could be spurious, stored surface charge from charging it with the shore power?

I'm speechless on this one

Maybe that's what the 'diode' is for, or maybe the generator has a VSR or similar?

I have explained in detail what the diode is for and how it's connected and that's supported by the readings in posts #11 and #25

Do we assume the 'shore power' is a dual-output charger?

Of course it is, otherwise how do you account for the readings in post #1, with the Emg switch off ?

I'd be re-checking the voltages in the first post, wondering if the starter batteries were still recovering from starting engines when the readings were taken.

did you notice #25 ?

It might be useful to measure the voltages across the diode splitter, that will indicate where current is flowing.

Again, have you seen #11 and #25 ?

Have you read any of the previous posts at all ?

It's really useful to read the thread before proffering advice, especially poor advice.