Solenoid Switch on the Battery Switch Panel, What Activates It?

[dkinzer]

I've been trying to understand how the battery switch panel works in my 2007 H41AC - I believe that Blue Sea Systems manufactured the panels for Hunter. This panel has two battery switches, both on/off, labeled Start and House. When I turn the Start battery switch to the Off position, the meter on the DC panel reads zero volts for the start battery as expected and the meter shows a reasonable voltage when the Start battery switch is set to On. However, the position of the House battery switch does not have a similar effect - I see no difference at all between the two positions (and, yes, the shore power was turned off so that the Xantrex inverter/charger was not supplying DC power). My conclusion is that the House battery switch is faulty (failed in the always on mode) but I need to disconnect some wires to test that theory.

This investigation has caused me to wonder about the source of the 12 V signal that energizes the solenoid switch that connects the start and house banks in parallel. The attached diagram depicts a 16 ga. yellow/red wire connected to one terminal and a 16 ga. yellow (battery negative, presumably) connected to the other. One possibility is that the activating signal is the alternator output. This would allow both the start and house banks to be charged by the alternator when it is producing power. Another possibility, perhaps less likely, is that it is activated by having the ignition switch on.

Does anyone know how the solenoid switch is wired on their boat?

 

[artboas]

The solenoid is activated by the key switch.
You might want to change this over to a Blue Seas ACR. In this way, the start battery will be charged whenever the battery charger is on.
It’s possible that your xantrex has an echo charge output, which already does this.
I don’t think your battery switch is defective

 

[dkinzer]

You might want to change this over to a Blue Seas ACR.

Yes, that is exactly what I'm considering. The Xantrex inverter/charger does have an "Echo Charge" output that is connected to the start battery so it gets charged when connected to shore power.

I sent a message to Blue Seas describing what I'm considering doing and the reply seems to indicate that I can simply swap out the solenoid switch for the SI-ACR. I expect to also hook up the "Start Isolation" signal to keep the banks isolated when cranking the engine.

 

[jssailem]

THis link may help...

Making Sense of Automatic Charging Relays - Marine How To

Making Sense of the ACR WARNING: ACR's are not for use with LiFePO4 Batteries! What is an ACR? An ACR is nothing more than a fully automatic, voltage triggered, BOTH/PARALLEL switch that closes when charging voltage is present and opens

marinehowto.com

 

[dkinzer]

Thanks, John. I had read through that earlier and noted #6 regarding where the alternator charge line should be attached. I asked Blue Sea about this specifically and they replied that it usually should be connected to the start battery but either the house or start battery connection would be OK. I haven't scoped out yet where the alternator output is connected on my boat but I won't be astonished to find that it is connected to the start battery.

 

[MFD]

Hi All, not the exact same use case to test but I happened to have the start battery out in preparation for some bilge cleaning. Also have been digging into some of the electrical systems this winter anyway both for inspection and also to clarify some of the details for myself.

Quick test I did a bit ago:

Setup:
1. Start battery removed.
2. No AC/Shorepower.
3. Primary DC Panel start battery set to 'off'
4. Waited about 10 minutes

Results:
1. Volt meter/house shows ~13.0
2. Volt meter/start shows ~12.4
3. The battery leads for the disconnected start battery off a Fluke multimeter show ~13.0

Thoughts:
- The echo charger is trying to do its job even with the start battery battery switch set to 'off'.
- This was with confirming the engine ignition switch is off.
- follow up adhoc test, yes, the engine starts without a start battery, and the starter was plenty peppy.
----- did not have the panel open or anybody around to listen for a 'click' on the relay/solenoid
- This test seems to be different than what @dkinzer tested?
- Unclear why the panel voltage vs. the actual start battery (not installed) voltages showed so different?

Follow up test:
- Cleared the start battery combiner charger/start breaker, left the start battery switch 'off' as it was.
- Start battery leads show ~zero voltage so echo charger probably still enabled but no power to the actual battery wires?

Hypotheses:
H1) either my combined 'charge/start' solenoid is stuck 'closed' or the wiring isn't exactly as shown.
H2) for now, make sure to turn off the actually battery breaker switch to clear voltage on the bank, above and beyond the regular 'off' switch.


A couple other notes...
A) I haven't opened up the main DC panel in many years, since I first bought the boat and looked inside once. I also believe it is a Blue Sea OEM (grew up in Bellingham and it sucked when the methhead burned down the factory just before COVID).
B) The upper distribution panels appear to be PanelTronics - Paneltronics: Electrical Panel Manufacturer ?

 

[obxjeff]

My guess is the start gauge is connected after the off switch to the starter not the battery side of the switch, so when off nothing is going to the starter thus 0v (unless disconnected, a starter will always have 12v but it isn't used until the starter solenoid/key triggers it to turn the starter motor)

My house battery disconnect switch goes between the charger and the batteries (each individual dc load is controlled by the fuse panel). the house gauge is also connected after the switch on the battery side and measures the present house voltage which will be the same whether the house switch is on or off assuming the charger is off. this is because the batteries have the same voltage and load no matter what the switch position.

To add to the complexity, the battery isolator(solenoid) is directly connected to the start battery bypassing any switch, this ensures the start battery is always being charged when input voltage is available. This isolator allows the dc to flow only towards the start battery and will open or disconnect (isolate) from the house batteries when there is a voltage difference (house in use and no charger/alternator). this way there is no discharge from the start to the house.

Why?
the start switch can check/show the start battery voltage (switch on) and potential connection of the motor starter to the house batteries (switch off). if there is a voltage when off it indicates that there is a connection to the house at the starter and the start battery will be discharged to any house load when the switch is on (bad).

the house switch shows the state of the dc charger, if the house batteries are used/low then there should be +12v with the charger and switch on and show the lower house voltage when the switch is off.

This is how my system works, and if yours is the same configuration then there is nothing wrong....