Charging issue - alternator / split charge question

[Adamf5023]

Hi I have a SO 37 and have just experienced a charging issue but only with the domestic batteries. The boat must have a split charging system. The engine battery is fine and the alternator is good and providing a charge. I have four isolator switches fitted to the boat. These all work as expected.
1) Domestic only positive switch
2) Negative switch (for both domestic & engine -ve )
3) Engine only positive switch
4) Shunt switch that connect the engine +ve and house +ve (batteries) (in the event that the engine battery is low or fails).
Both 100A domestic batteries were replaced last year and are in good condition. The house batteries are no longer being charged unless I turn on the shunt isolator which allows the alternator to directly charge the house batteries. This was never needed in the past. With the shunt disconnected (normal operation) I am only showing nominal battery voltage 12.7v for the house batteries). With the shunt connected I have 14.4v at both the domestic and engine batteries. The engine noise also changes indicating that the alternator is charging the house batteries.
I have looked for a split charge relay or diode pack but cannot find one. There is a relay installed in the engine bay but this is for the ventilation / fan system. I checked this and it is operating fine. It looks as though there could have been another relay fitted in the engine compartment and this is actually shown in the wiring diagram.
I suspect that this may have been removed when the engine was replaced. As I mentioned earlier I have a Volvo D130 engine which was replaced about a year before I bought the boat. I have not had any issues with the charging system until recently.
Does anyone know how the alternator is wired in or how split charging works if you only have the alternator fitted and no relay or external diode pack?
Any other suggestions on what else to check please?

 

[greeny]

i would keep looking for the split charge unit either relay or more likely a diode block I would think. If there really is no charge splitter of some sort I'd be surprised. Otherwise you're maybe looking at broken charging wires or blown fuse in the house charge circuit maybe. I take it that your wiring diagram doesn't show the charging circuits or it's not clear?

Just had a look at the standard wiring diagram for the SO37. It shows a charging relay (item 69) on drawing. Not clear but looks as though it's maybe in the engine bay next to the ventilation relay. Is it possible the relay has become dislodged and fallen under the engine so you can't see it?
You did mention an empty relay socket in the engine bay.

 

[PaulRainbow]

Jeanneau typically fit split charge diodes, Goggle will show you what they look like. Generally fitted not far from the batteries. Follow the heavy red wire from the alternator, if it goes to the starter you will likely have a VSR, if you have a diode it will go the that. My money is on a diode and it's failed on the diode that charges the domestic bank. Easy check would be to swap the two cables on the alternator that go to the batteries.

Rather than replace it with another diode, i'd fit a Victron ArgoFET. Bit more money but vastly less voltage drop.

 

[Tucepi]

Hi I have a SO 37 and have just experienced a charging issue but only with the domestic batteries. The boat must have a split charging system. The engine battery is fine and the alternator is good and providing a charge. I have four isolator switches fitted to the boat. These all work as expected.
1) Domestic only positive switch
2) Negative switch (for both domestic & engine -ve )
3) Engine only positive switch
4) Shunt switch that connect the engine +ve and house +ve (batteries) (in the event that the engine battery is low or fails).
Both 100A domestic batteries were replaced last year and are in good condition. The house batteries are no longer being charged unless I turn on the shunt isolator which allows the alternator to directly charge the house batteries. This was never needed in the past. With the shunt disconnected (normal operation) I am only showing nominal battery voltage 12.7v for the house batteries). With the shunt connected I have 14.4v at both the domestic and engine batteries. The engine noise also changes indicating that the alternator is charging the house batteries.
I have looked for a split charge relay or diode pack but cannot find one. There is a relay installed in the engine bay but this is for the ventilation / fan system. I checked this and it is operating fine. It looks as though there could have been another relay fitted in the engine compartment and this is actually shown in the wiring diagram.
I suspect that this may have been removed when the engine was replaced. As I mentioned earlier I have a Volvo D130 engine which was replaced about a year before I bought the boat. I have not had any issues with the charging system until recently.
Does anyone know how the alternator is wired in or how split charging works if you only have the alternator fitted and no relay or external diode pack?
Any other suggestions on what else to check please?

 

[Tucepi]

Can you follow the alternator output leads and see if one goes to a large diode pack. There should then be cables coming from that to each battery bank. Diode pack is easy enough to test if you have a multimeter.

 

[Adamf5023]

Hi all - thanks for your replies. I think you are all right and that there must be a split charge circuit somewhere. I can see where a relay was fitted (next to the ventilation relay) and yes it is shown on the wiring diagram but it is definitely not there now and I cannot see any wiring that support it being installed. I think that this and the relay was removed or replaced when the new engine was fitted. Good advise about tracing the charge wires from the alternator. I will do that and I will also check the isolator switches to see what is connected and therefor charging the engine battery and also what is missing or faulty for the domestic circuit. I am pretty sure it is something simple and so back to basics.

 

[QBhoy]

Hi.
If it helps, a good split charge system will charge the bank of batteries which most require it firstly then go to a float on both banks. Might just be that it’s doing what it’s meant to.
Failing that, you can usually fool the system by swapping over the tiny feedback wires on the relay under the cover. Then have a look at the voltage. If nothing else make sure they are connected. You can test the operation by doing this too. You’ll hear the relay clicking. Just remember it’s live.

 

[PaulRainbow]

Hi.
If it helps, a good split charge system will charge the bank of batteries which most require it firstly then go to a float on both banks. Might just be that it’s doing what it’s meant to.
Failing that, you can usually fool the system by swapping over the tiny feedback wires on the relay under the cover. Then have a look at the voltage. If nothing else make sure they are connected. You can test the operation by doing this too. You’ll hear the relay clicking. Just remember it’s live.

The relay will close as soon as it senses a charging current that exceeds it's set point. Despite the blurb that the manufacturers spout.

 

[William_H]

Hi.
If it helps, a good split charge system will charge the bank of batteries which most require it firstly then go to a float on both banks. Might just be that it’s doing what it’s meant to.
Failing that, you can usually fool the system by swapping over the tiny feedback wires on the relay under the cover. Then have a look at the voltage.

Yes this concept of magically charging first the battery that needs the charge is just salesman's hype. A VSR will operate to connect 2 systems when the charge voltage reaches a selected voltage. Usually around the 13v mark. This means that the voltage of the first battery (which is also the charge voltage at the time the charge voltage being pulled down to the battery voltage) must rise to this preset point. The second battery system is then connected. This connection will usually pull the charge voltage down as the new battery comes up. (this disconnect voltage point will be lower so it stays connected). (hysteresis). Once paralleled the voltage will be the same for alternator and both batteries however the most discharged battery will naturally take more current. This same thing happens with diode feed.
So while the sales blurb will claim it charges as a priority the discharged battery what else would you expect. ol'will

 

[Adamf5023]

Thanks everyone for your suggestions. I am going to trace the main charge lead from the alternator to verify where it goes to and then from there if there is any additional wiring to a diode pack or split charge relay / fuse etc. The system used to work OK and I know that the charge is not floating as the house batteries were discharged. I am sure it must be something simple. I will drop a note back with what I find. Again - I appreciate your comments and help.

 

[spindreams]

Hi, rather than open a new thread as my question is quite similar I thought to add here.

I have a Bav 42 Cruiser fitted as stock with a Waytek 1202 multi battery isolator, I have determined trough tests that the isolator is faulty and rather than replace like with like I would switch to an intelligent DC to DC charge controller as my two battery banks are of differing types (AGM and Wet) but I am having trouble finding exactly what I need. Any suggestions?

I am in europe so something I can get here would be good..

 

[PaulRainbow]

Hi, rather than open a new thread as my question is quite similar I thought to add here.

I have a Bav 42 Cruiser fitted as stock with a Waytek 1202 multi battery isolator, I have determined trough tests that the isolator is faulty and rather than replace like with like I would switch to an intelligent DC to DC charge controller as my two battery banks are of differing types (AGM and Wet) but I am having trouble finding exactly what I need. Any suggestions?

I am in europe so something I can get here would be good..

The Waytek is a diode pack, a better product would be a Vicron ArgoFET.

Charging profiles for AGM and lead acid are very similar, your alternator regulator will be designed for lead acid, AGM can be charged at slightly higher voltages. Hard to see a real benefit in changing to anything other than the Victron product, this will be better than the diode pack as it suffers less voltage drop.

If you insist on changing, then take a look at a battery to battery charger, such as those made by Sterling. If fitting such a device you will also need to look at any other charging devices onboard, such as shore power, solar etc

 

[VicS]

Hi, rather than open a new thread as my question is quite similar I thought to add here.

I have a Bav 42 Cruiser fitted as stock with a Waytek 1202 multi battery isolator, I have determined trough tests that the isolator is faulty and rather than replace like with like I would switch to an intelligent DC to DC charge controller as my two battery banks are of differing types (AGM and Wet) but I am having trouble finding exactly what I need. Any suggestions?

I am in europe so something I can get here would be good..

Will a Sterling "alternator to battery charger" do what you want? They will deliver enhanced charging of domestic battery, programmable for a whole range of battery types , and bog standard charging of the engine start battery

https://sterling-power.com/collecti...cts/alternator-to-battery-chargers-up-to-130a

 

[spindreams]

Will a Sterling "alternator to battery charger" do what you want? They will deliver enhanced charging of domestic battery, programmable for a whole range of battery types , and bog standard charging of the engine start battery

https://sterling-power.com/collecti...cts/alternator-to-battery-chargers-up-to-130a

Yeah that looks like it would do it but boy the price.......

 

[spindreams]

The Waytek is a diode pack, a better product would be a Vicron ArgoFET.

Charging profiles for AGM and lead acid are very similar, your alternator regulator will be designed for lead acid, AGM can be charged at slightly higher voltages. Hard to see a real benefit in changing to anything other than the Victron product, this will be better than the diode pack as it suffers less voltage drop.

If you insist on changing, then take a look at a battery to battery charger, such as those made by Sterling. If fitting such a device you will also need to look at any other charging devices onboard, such as shore power, solar etc

I had looked at the Vicron ArgoFET but as I had the two different battery types I thought best to go intelligent, i don't know how much damage charging AGMs at SLA voltages will do if any?

 

[PaulRainbow]

Will a Sterling "alternator to battery charger" do what you want? They will deliver enhanced charging of domestic battery, programmable for a whole range of battery types , and bog standard charging of the engine start battery

https://sterling-power.com/collecti...cts/alternator-to-battery-chargers-up-to-130a

I don't think this is suitable here Vic. It would allow the domestic batteries to be charged at a higher voltage than the engine battery, but only via the alternator. The mains charger will still be likely to charge at the same voltage for all batteries, as would a solar or wind controller. A battery to battery charger allows the domestics to be charged at the higher voltage, from all charging sources.

Personally, i don't see the small fraction of a volt difference in charging profiles to be worth the expense. It might make more sense to fit an engine battery that can be topped up and charge at the higher AGM voltage, or to fit an AGM starter battery.

 

[PaulRainbow]

I had looked at the Vicron ArgoFET but as I had the two different battery types I thought best to go intelligent, i don't know how much damage charging AGMs at SLA voltages will do if any?

No damage, might take a tiny bit longer to charge than it would at the higher voltage. Why not just fit an AGM engine battery ? Your mains charger and solar controller (if you have one) can them be set to the higher voltage. The alternator will of course still be charging at lead acid voltages. I doubt you'll notice a difference by fitting a "smart" charger, the difference between your old diode and the new Victron one would be several times greater, in your favour.

 

[spindreams]

No damage, might take a tiny bit longer to charge than it would at the higher voltage. Why not just fit an AGM engine battery ? Your mains charger and solar controller (if you have one) can them be set to the higher voltage. The alternator will of course still be charging at lead acid voltages. I doubt you'll notice a difference by fitting a "smart" charger, the difference between your old diode and the new Victron one would be several times greater, in your favour.

I think you might be right, would you go for the 100 or 200 amp version, current one is 130 amp so I was assuming to go with the 200 amp?

 

[PaulRainbow]

I think you might be right, would you go for the 100 or 200 amp version, current one is 130 amp so I was assuming to go with the 200 amp?

Whichever one is rated for your alternator max output. I'd suspect the 100 amp one, but check to be sure.

 

[halcyon]

Yes this concept of magically charging first the battery that needs the charge is just salesman's hype. A VSR will operate to connect 2 systems when the charge voltage reaches a selected voltage. Usually around the 13v mark.
So while the sales blurb will claim it charges as a priority the discharged battery what else would you expect. ol'will

Just for the record, this applies to the early 80's when you had Dynostart or 20 amp alternators fitted to diesels that were not good at starting. So heavy start current draw was not uncommon and charging the engine battery up to around 50/60%, or alternator regulation voltage, first was desirable. Having a small charge current meant a slow increase in battery voltage, not like modern high output units, giving the initial delay. Next 13 volt is the drop out voltage ( 12.9 preferably ), the relay is engaged at 13.55 volt, allowing for 13.6 volt regulators, higher to-day with modern alternators. The system worked on the engine battery being charged to 13.6V, engage service bank at lower level so voltage falls, say 13.25V, this is to low to charge engine battery, and to high to allow discharge, so all charge goes to service bank till it's voltage reaches engine battery level. Current VSR's can work on monitoring both volts and amps to control charge distribution to upto 4 battery banks.

The other consideration between VSR's and solid state splitter's is any failure in the split charge system will not effect charge to engine battery with a VSR, relays are bi-directional so allow or engine starting via VSR.

Brian