Sure Power splitter.. to split or not to split!

[Martin_J]

For something to do last night (as if I didn't have enough to do already) I was checking out the charging circuits on the Moody...

It has a one 12v engine battery and a bank of two (parallel connected identical 12v batteries) for domestic.

When I bought the boat I was told that the shorepower connected 3-stage charger would charge both engine and domestic. I was also told that the engine driven alternator would charge domestic only. This does appear to be the case and others I have talked to since have said that this is sometimes normal. It would mean that on a longer cruise when not connected to shorepower then engine battery would not get recharged - yikes!

Following the physical wiring last night I found that the alternator output is connected to the input (A) of a Sure Power 952 splitter. The outputs (numbered 1 and 2) are connected (1) to +ve on one domestic battery and the other (2) to the +ve on the other domestic battery. No wonder that only the domestics took the charge - both batteries being charged from the same place!!!

So - Do the experts think this is a case of mis-wiring... or is there any sound reason why the diode splitter outputs would be connected to two batteries that are in the same bank!!

I plan to move the second splitter output to the engine battery +ve unless I hear reasons for not doing this. Many thanks in advance.

PS - There is also an Adverc charge controller but I think this is irrelevant to the question.

 

[VicS]

Sounds like a cock up in the wiring, certainly is if the two domestic batteries are permanently in parallel.

I think you should move one of the splitter outputs to the starter battery.

You do not say exactly which Adverc cotraoller you have but the various instruction manuals can be found on their website.

Study the wiring diagram in the appropriate instructions. I think how it should be wired will then be quite clear. It is if I am looking at the right one!

 

[fireball]

Sounds strange!!
I assume the domestics are already in parallel - so the placing of both charge outputs on the same battery (not cell) is rather under utilising the splitter!!
FWIW I'd swap the 2nd one to the engine battery as well...

 

[dnickj]

Adverc

Just make sure the adverc does not charge the engine battery

 

[Martin_J]

Thanks VicS and Fireball.. Yes, I had checked the Adverc 'Split charging with blocking diode' diagram and it looks like the Adverc should just 'overlay' the existing connections. It doesn't change the fact that the splitter outputs should be split - one to the Engine and one to the Domestic batteries.

I'll let you know how it goes.. I plan to change it at the weekend when I have more time.

Fireball - Yes, the outputs do presently go to the +ve terminals on batteries in the same bank.

What is intriguing about the Adverc diagram is that a direct cable is shown from the splitter to the domestic batteries, yet to the Engine battery it is shown as going via an isolater (because it is connected at the starter motor end of the thick cable). Quite easy to do I guess and I would assume this way that the engine battery is only connected to the splitter when the engine isolating switch is closed. (Although the domestic remains connected!)

http://www.adverc.co.uk/batterymanagement/adverc-installation-instructions

Dnickj - The Adverc appears to be overlaid onto an existing setup. Whether the existing setup is correct or not - the addition of the Adverc does not actually change the original wiring. Also - charge does not come 'through' the Adverc. Perhaps you can clarify what you mean..

 

[VicS]

What is intriguing about the Adverc diagram is that a direct cable is shown from the splitter to the domestic batteries, yet to the Engine battery it is shown as going via an isolater (because it is connected at the starter motor end of the thick cable). Quite easy to do I guess and I would assume this way that the engine battery is only connected to the splitter when the engine isolating switch is closed. (Although the domestic remains connected!)

Somewhat inconsistent!
FWIW I am led to believe that RCD and BMEA codes of practice require isolators for both batteries that isolate all circuits except for those which need to be on all the time ( solar chargers, auto-bilge pumps memory circuits etc). That being the case then the isolator in the starter battery circuit is correct but there should be a similarly paced one in the domestic battery circuit.

 

[pappaecho]

I had a similar problem with my latest boat. To not charge the engine battery is pure madness.
I do not know if you have a 1,2 all, off master battery switch. When set on all, the alternator would charge all batteries anyway, which helps.. It also means you can start the engine with the domestic bank in emergency
You need to rewire in any event so that the splitter does exactly that and directs the charge to the battery bank that needs it most

 

[Martin_J]

VicS - You're right.. I thought the Adverc diagram was inconsistent in terms of that isolation switch as well.

As it happens I don't have a 1/both/2/off switch but I do have an Engine isolator switch and a Domestic isolator switch by the switch panel in the saloon.

Back to the Adverc diagram then - Agreeing with VicS on the inconsistency and the fact that there should be an isolation switch in each.. there is!...

Although - These isolation switches will be in the cables from the batteries to the load - i.e. either in the cable to the engine starter... or in the cable to the domestic switch panel. So - back to the diagram if I remove one of the splitter output cables from the domestic bank and connect it to the +ve starter contact then it will be exactly the same as the Adverc diagram. i.e. charge will go to the Engine battery but only when engine isolation switch is closed (i.e. on)... and the other will remain permanently connected to the domestic bank. (i.e. Inconsistency as per Adverc remains but at least the engine battery will charge from the alternator!)

 

[Martin_J]

Thank you...

VicS and Fireball.. thanks for your double check of the adverc diagram a few weeks back..

I did move the second splitter output to the engine battery - not as simple as just moving it from one battery bank to the other because the Adverc diagram showed it connecting to the starter motor +ve instead of to the battery +ve.

I am still intrigued by the blue and red Adverc monitoring wires. They monitor either end of a single big fat cable.. so must be very sensitive to differences... and the fact that the domestics remain connected to the splitter (because the main isolator is only in the output to domestic loads) but I guess this is normal. We don't usually have isolators between the alternator and the +ve of the battery.

All done now (exactly as per diagram) and alternator charges both banks. Thank you!