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Sterling Pro Split R - Not charging second bank


sirweste

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Hi all, hoping for some guidance and help on this one. 
 

I recently noticed that my voltage across the domestic battery bank (bank 2) wasn’t being charged when the engine was running. 
Engine battery, bank 1, is being charged and thus the alternator is putting out power. 
 

It seems that the Sterling Split charge job isn’t putting power to bank 2 for some reason. Starter battery is at 14.3v so I suspect it’s fully charged I..e I would have expected the Split job to have switched and begun charging bank 2. 
 

I’ve jumped the negative directly from bank 1 to 2 to rule out any earth faults. 
I’ve jumped the positives too, effectively missing out the Split job, and the alternator does then chuck out its max 35ish amps and charges both banks.

 

ive tried switching the Mastervolt Combi unit (it is wired directly to bank 2) off and it has not effect on symptoms. 
 

I’m lost!! Is the Split unit just buggered?

if needed I will sketch out the wiring diagram. 

 

cheers for any help / advice

A6D117B0-074B-4578-A50F-64ABE02BC82D.jpeg

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Probably buggered! But worth checking out the wiring, maybe there is a fuse of isolator switch between the Splitter and domestic battery? With the engine running, which LEDs are on?
I would check the voltage on the Batt2 terminal with the engine running, it should be the same as the starter battery, around 14.4v or so.

When you turn the ignition on, does voltage appear on the “pos ign feed”terminal?

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Yeah I’ve checked all of that sort of stuff. Measured volts (12.x) to bank 2 are all before the fuse / at the batt 2 terminal on the Split job

 

picture was taken with the engine running.

With engine off and genny running the charger, so bank 2 at 13/14V, it lights up the bottom 3 (as in picture) but the middle one (green) flashes. 
the bottom one (blue) is on despite ignition being switched off. 

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28 minutes ago, Tony Brooks said:

Throw the dam thing away and fit a correctly wired VSR. Easy to check, simple and low cost. Just make sure its over specified in relation to the alternator output.

Where will the spiders live then? No one ever thinks of the spiders. ??️?️

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1 hour ago, sirweste said:

It seems that the Sterling Split charge job isn’t putting power to bank 2 for some reason. Starter battery is at 14.3v so I suspect it’s fully charged I..e I would have expected the Split job to have switched and begun charging bank 2. 
 

 

I very much doubt any actual switching between banks is involved. You probably fell for the marketing hype over emphasising the natural way split bank charging works.

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Damn, more faff! Bloody floating houses!

i got this unit with the boat when I bought it. Though I would have fallen for the hype I’m sure. 

 

will get it ripped out at some point when it’s warmer! For now the genny does most of the charging and I can just jump the banks when I’m moving. 
 

cheers very much for the replies

 

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I've got one of these switching the charge between the start and BT batteries. Not sure if it's just over-hyped marketing spin but it's worked well for the past 15 years. Works either from the start/BT alternator or from my battery charger which has one output connected to the start battery.

 

 

image.png

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That's it a VSE. They can be got with either sensing from one battery or both (single or bi directional). The important thing is to ensure the main charging lead from the alternator  is connected to the bank most likely to be most discharged which is normally the domestic bank in the OP's case. Then the relay is used to connect that bank to the other bank, usually the engine battery.

 

By and large VSR vendors do not go on about charging a particular bank first because that is just what it will do in the sense battery is so discharged the charging voltage is lower than the relay's operating voltage. Then the charge will be apportioned between banks according to their degree of discharge.

 

With active (like the OP's) of passive diodes the charge will be apportioned between the banks according to their state of charge at all states of charge. Only an idiot would complicate things by designing one that charged one bank first. It simply is not necessary.

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14 minutes ago, Tony Brooks said:

  The important thing is to ensure the main charging lead from the alternator  is connected to the bank most likely to be most discharged which is normally the domestic bank in the OP's case. Then the relay is used to connect that bank to the other bank, usually the engine battery.

 

Many are not wired that way, the reason being they say  " the starter battery charges first." Cobblers, they charge simultaneously as the same voltage is applied to both.

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29 minutes ago, Alan de Enfield said:

 

So it doesn't matter which way it is wired ?

I would say so as there is a lot more energy (I hope that's the right word) to go into the domestic bank and very little to go to the starter, so it makes more sense in my opinion to feed direct to the domestic where a large current will be flowing for a long time compared to the starter with a small current for a short time going through the relay.

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29 minutes ago, ditchcrawler said:

I would say so as there is a lot more energy (I hope that's the right word) to go into the domestic bank and very little to go to the starter, so it makes more sense in my opinion to feed direct to the domestic where a large current will be flowing for a long time compared to the starter with a small current for a short time going through the relay.

Yes I think that is quite reasonable. But putting the other side of the argument, if the alternator is connected to the engine battery and the relay fails, you notice because the lights etc go dim and the battery monitor (if you have one) shows flat batteries. If it is connected to the domestic battery and the relay fails, you don’t really notice until the engine won’t start and then you are scuppered (well, until you find those jump leads, anyway).

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1 hour ago, Alan de Enfield said:

 

So it doesn't matter which way it is wired ?

 

Yes it does because of what Brian said. The object is to wire it so minimal current passes through the contacts. If the alternator goes to the engine battery as the engine battery spends most of its time fully charged you would get full alternator output plus a bit more from the engine battery through the contacts. Its because all to often for ease of wiring and the fact the instructions are written for vehicle work that split charge relays fail and some say they are unreliable.

 

Don't fully understand Nicks point because on a half decently wired boat you would have a voltmeter to monitor both batteries. That can be two voltmeter or one voltmeter with a change over switch.

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8 minutes ago, Tony Brooks said:

 

Yes it does because of what Brian said. The object is to wire it so minimal current passes through the contacts. If the alternator goes to the engine battery as the engine battery spends most of its time fully charged you would get full alternator output plus a bit more from the engine battery through the contacts. Its because all to often for ease of wiring and the fact the instructions are written for vehicle work that split charge relays fail and some say they are unreliable.

 

Don't fully understand Nicks point because on a half decently wired boat you would have a voltmeter to monitor both batteries. That can be two voltmeter or one voltmeter with a change over switch.

But so many boats have no domestic battery monitoring at all. The Beta fancy C spec panel has a voltmeter, but it only shows engine battery voltage.

Edited by nicknorman
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Just now, nicknorman said:

But so many boats have no domestic battery monitoring at all.

 

I agree but wiring charging to the engine battery has been shown over the years to hasted relay failure. For the cost of that Sterling device I think you could get ammeter and voltmeters monitoring both banks plus the relay.

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1 minute ago, Tony Brooks said:

 

I agree but wiring charging to the engine battery has been shown over the years to hasted relay failure. For the cost of that Sterling device I think you could get ammeter and voltmeters monitoring both banks plus the relay.

Overall I agree with you, I was just putting the counter-argument forward in the interests of balance.

  • Greenie 1
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Good points. I was coming at this from the perspective of my van and it's leisure battery - which is seldom used compared to the starter. But you're right it should be wired to feed the big current direct to the domestic bank.

Yes I've a Smartgauge (which seems to be getting less accurate with time, but still sufficient as a rough guess) on the domestics and the needle gauge on the start.

 

TBH I'm having to jump the starter off the domestics as it's never been great to crank (starter motor at fault I believe - even after a couple of rebuilds) and in the cold weather the single starter battery wont get the old lump firing. SO I may as well flip the connections and have the domestic Bank 2 wired to the working Bank 1 terminal. I can just put the start battery on charge from time to time. I rarely run the engine these days. Probably start it once a month just for fun, the alt puts out such a measly charge it's makes no sense to run a 2.5 litre dirty as out diesel when I've a wee modern genny attached to a 100A charger (which has 240v bypass so when it's running it feeds the ring-main and I can charge up the laptops, hoover, run the breadmaker etc

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