Troubleshooting engine and house battery scheme (Beneteau)

[xjussix]

My problem is as follows. My boat, a Beneteau, has three battery switches: One negative isolator, one positive for the starter battery and one positive for the house battery/batteries. At the moment for any of the electrics to work both positives need to be turned on, meaning the three batteries act as one battery bank with no possibility to isolate the engine battery while we're at anchor for example. If I turn on the house battery switch and let the engine battery switch remain off, nothing happens.

Attached is a picture from the owner's manual which describes how it should be connected according to the manufacturer.

Given that I'm a newbie when it comes to boat electrics, where should I start looking? What are the possible reasons for this? Or have I simply not understood the way it's supposed to work?

[smac999]

something is not wired right if that is happening. confirm everything is tight and the wires match the drawing.

missing the black / blue wire between battery 1 and 2 would cause that issue. or a failed house switch.

[svHyLyte]

Originally Posted by xjussix

My problem is as follows. My boat, a Beneteau, has three battery switches: One negative isolator, one positive for the starter battery and one positive for the house battery/batteries. At the moment for any of the electrics to work both positives need to be turned on, meaning the three batteries act as one battery bank with no possibility to isolate the engine battery while we're at anchor for example. If I turn on the house battery switch and let the engine battery switch remain off, nothing happens.

Attached is a picture from the owner's manual which describes how it should be connected according to the manufacturer.

Given that I'm a newbie when it comes to boat electrics, where should I start looking? What are the possible reasons for this? Or have I simply not understood the way it's supposed to work?

Firstly, have you checked the house battery to see whether its charged? If so, with your engine battery and negative switches in the on position but the house battery turned off do you have power to your panel? If so, from your wiring diagram and description, I suspect the connection between your house battery (#2) and its switch has gone bad, or the switch, itself, is inoperable. To test the connections, with a multi-meter test to see if you have voltage between the battery side of the house battery switch and the engine side of the negative switch, when the negative switch is in the on position and the engine and house batteries are both in the off position. If so, the connections on the battery side of the house switch are good. Then turn the house switch to the on position and repeat the test to the engine side of the negative switch. If you have no voltage there, the switch has gone bad. Changing out the switch is a no brainer as is cleaning and remaking the connections from the house battery to the switch. Give it a go...

[xjussix]

Great tips, much appreciated! I'll see what I can do the next time I'm visiting the boat.

[bil56]

@xjussix :
on the scheme, consider
- switch 1 (left) is for the 2 house batteries both
- switch 2 (middle)is for the engine battery
- switch 3 (right) is for the negative (all batteries)

for safety, I prefer not to connect the engine battery with the house batteries (no 'orange' wire),
or possibly insert a switch on the 'orange' line, which will allow to momentarily couple all the batteries in case of weakness of the engine battery.

(I dont know if it's clear ...)

[Stu Jackson]

It's long, but try this:

https://forums.sailboatowners.com/in...eteau%20wiring

[Fernando Lopes]

The electric scheme proposed by Bénéteau is correct. It is based on a safe operation. One of the batteries - number 3 - must remain switched off by switch number 2 and always fully charged. The other 2 batteries - number 1 and number 2 - work in parallel, powering all on-board services, including the engine.
In case of total discharge of these batteries, the number 1 switch must be opened and the number 2 must be closed. This ensures that we always have the power to, at least, start the engine.
Unless the engine is equipped with 2 alternators, this operating scheme ensures that whenever the engine starts, it recharges the batteries in use.
In case of emergency use of battery 3, the alternator does not recharge batteries 1 and 2 unless there are 2 alternators on board. Some people make a momentanly parallel of the 3 batteries to switch the alternator to the 1 and 2 discharged batteries, but I do not advise this procedure because it prematurely ages the batteries.</SPAN>
</SPAN>

[hlev00]

I don't have any specific advice beyond what is already given, but there are three really good Beneteau groups on yahoo. The wiring you show looks very much like my 423. You may get some good advice there as some of these systems have changed much.

Be sure to have a different password and possibly user ID for Yahoo. They have had a few breaches over the years. I would plan defensively.

Harry

[smac999]

Originally Posted by bil56

@xjussix :
on the scheme, consider
- switch 1 (left) is for the 2 house batteries both
- switch 2 (middle)is for the engine battery
- switch 3 (right) is for the negative (all batteries)

for safety, I prefer not to connect the engine battery with the house batteries (no 'orange' wire),
or possibly insert a switch on the 'orange' line, which will allow to momentarily couple all the batteries in case of weakness of the engine battery.

(I dont know if it's clear ...)

the orange wire is their cheap and bad way to charge both banks from the engine. the better thing is to remove it and replace with an ACR. on the battery side of the switches.

but first he still needs to find the issue. with either switch on, you should be able to power the whole boat and start the engine.

I also often remove all the negs from the black switch and turn it into a parallel swtich. we do not switch grounds in north america.

[hzcruiser]

Good suggestions there; it could also be as simple as a wrong labeling of the three switches.
Have you tried all combinations of two of the three switches turned on? as in: 1-2, 1-3 and 2-3 only turned on?

[Fernando Lopes]

For safety reasons, we must have on board a permanently charged battery, able of starting the engine and / or allowing emergency communications via VHF. In your case it is the battery number 3 that ensures this function. And to be able to stay permanently charged, the switch number 2 must be open.
But let's go back.
When the vessel is in the marina, connected to the pontoon, the energy passes through a small electrical board with the following outputs:</SPAN>
- Alternating current supply to the vessel;
- Possible supply of the hot water boiler;
- And ... power the battery charger.

The battery charger has the following characteristics:
- 1 input 110-240 V AC
- 2 DC galvanically isolated outputs, each one permanently connected to a battery pack, regardless of whether the switches are open or closed and are operated in accordance with the principle of the communicating vessels, ie they preferentially charge the most discharged battery pack and then also the two groups of batteries to which they are connected. In your case, one of the outputs is connected to the batteries 1 and 2 that are in parallel and the other one to the battery 3.</SPAN>
When the engine is running, it has coupled an alternator, which only charges the battery pack where the engine is running (1). In normal operation, all on-board services must be connected to the battery pack where the engine is switched on, stopped or running. Under no circumstances should the engine be disconnected from the batteries when it is in operation, under serious risk of malfunction.
In normal operation, the on-board services including the motor must be connected to the batteries 1 and 2 in parallel. The battery 3 must remain in standby (switch 1 closed and 2 open).</SPAN>
IMPORTANT REMARKS
A permanently standby battery have the risk of aging without being detected. It is therefore a good rule to periodically start the engine on it.
Never do parallel batteries in different charge states. Circulating currents that appear can permanently destroy the batteries. Therefore, if it is necessary to switch the motor from battery group 1 + 2 to battery 3, first open switch 1 and then close switch 2. The reverse is also true. Any of these operations can not be done with the engine running, for the reasons I pointed above.
If for any reason I do not know, you want to parallel the 3 batteries, the only time this can be done is when the charger is connected to the pontoon and it is guaranteed that the 2 groups of batteries are also charged.
Good navigations, in safety.

(1) It is possible to charge the 2 groups of batteries with a single alternator using a special device. Personally I do not recommend it as this is a possible additional cause of malfunctions and it is necessary to adjust the voltage regulation of the alternator to a higher value.</SPAN>
</SPAN>

[hzcruiser]

Originally Posted by Fernando Lopes

Never do parallel batteries in different charge states. Circulating currents that appear can permanently destroy the batteries.

Fernando,

did you quote some of these "rules" from a manufacturer's manual?

In particular the statement above would be new to me. I have connected batteries with different SOC hundreds of times without damaging them. All that happens is you get a rather small current from one to the other.

[hzcruiser]

Originally Posted by Fernando Lopes

The electric scheme proposed by Bénéteau is correct. It is based on a safe operation. One of the batteries - number 3 - must remain switched off by switch number 2 and always fully charged.

I'm sorry but in that diagram above there is no switch to turn off batt 3, it is always in parallel to batt 2.

Batt 1 seems to be the starter battery, 2 and 3 are house.

[Fernando Lopes]

Originally Posted by hzcruiser

Fernando,

did you quote some of these "rules" from a manufacturer's manual?

In particular the statement above would be new to me. I have connected batteries with different SOC hundreds of times without damaging them. All that happens is you get a rather small current from one to the other.

Parallel batteries in different states of charge
Let us assume that in the Bénéteau scheme the 2 batteries of the services working in parallel are exhausted and have a voltage of 10.5V and the standby battery was fully charged at 13.2V.</SPAN>
In the moment of the parallel there are to the terminals of the switch a difference voltage of 13.2-10.5 = 2.7V
The internal resistance of an acid battery is extremely low, in order of 3 mΩ. For the 2 batteries in parallel we have 1.5 mΩ. The total resistance of the circuit at the moment of the parallel is: 3 + 1.5 = 4.5 mΩ which will give a circulating current of 2.7/0.0045 = 600 Amperes, a sufficiently high value to cause plate heating, gas emission and mechanical deformation irreversible of the alveoli where the lead is conditioned.
Is this clear? I am enclosing documentation on this subject.
</SPAN>

[hzcruiser]

Originally Posted by Fernando Lopes

The total resistance of the circuit at the moment of the parallel is: 3 + 1.5 = 4.5 mΩ which will give a circulating current of 2.7/0.0045 = 600 Amperes, a sufficiently high value to cause plate heating, gas emission and mechanical deformation irreversible of the alveoli where the lead is conditioned.
Is this clear? I am enclosing documentation on this subject.

Thanks for the quick response, Fernando!

I'd like to say I don't doubt your math, I just never noticed a high current (as in even a little spark or increased temp of the contacts) in such a case, so have you, as in, first hand?
As a side note: the internal resistances would be in series to each other to complete the circuit, even though the batts are hooked up in parallel (as seen by the load).

I'd ask other forum members whether they can share their experience but it might high jack the thread or at least drift it away from the original question. So feel free to PM me instead.

No offense, mate, just in (my) reality, I have cable and contact resistances in series and my charged batt wouldn't be able to deliver anything near 600A.