Add smaller 2nd Relay to Blueseas "Add a battery"?

[hostage]

It looks like they recommend a "switch" on the 16AWG that connects to ground from the add a battery SI-ACR relay for long term storage. I also heard about possible parasetic drain for this system. I am wondering if anyone has used a small relay, instead of a "switch". This way when the boat is turned on, it can close the relay on the circuit and allow both batteries to charge. Thoughts?

 

[dingbat]

It looks like they recommend a "switch" on the 16AWG that connects to ground from the add a battery SI-ACR relay for long term storage.

Not sure why you would break ground side when you could simply turn the battery switch off.

I also heard about possible parasetic drain for this system.

Not sure how you get parasitic drain with the battery switch turned off

I am wondering if anyone has used a small relay, instead of a "switch". This way when the boat is turned on, it can close the relay on the circuit and allow both batteries to charge. Thoughts?

Not sure what you’re trying to do.
The ACR automatically combines (charges) both batteries whenever a charge source (13+ Volts) is present on either battery

 

[hostage]

Not sure why you would break ground side when you could simply turn the battery switch off.

Not sure how you get parasitic drain with the battery switch turned off


Not sure what you’re trying to do.
The ACR automatically combines (charges) both batteries whenever a charge source (13+ Volts) is present on either battery

Looking at the instructions and diagram, I see the following:
OPTIONAL SWITCH FOR NO CURRENT DRAW WHEN IN STORAGE

source: https://d2pyqm2yd3fw2i.cloudfront.net/files/resources/instructions/990310020.pdf

My thoughts were the same, that when you set the battery switch to "off", it would isolate the batteries from any parastic draw. Though both batteries are still connected to the ACR. So seeing the optional switch for "when in storage", makes me wonder if this is why they are recommending a switch. Installing a switch on the ground return would stop the ACR from functioning removing the only potential for parasetic drain. If I used a small relay that closes the circuit, when the engine is on, then this could get around forgetting to manually turn on/off that second switch. Though I would love more clarity, so I might ask them.

 

[poconojoe]

The Blue Sea diagram shows two fuses, but I used circuit breakers and positioned them at the batteries.
I press the trip button on each one whenever the boat is not being used.

I trailer my boat, but if you dock your boat, make sure your automatic bilge pump has constant power at all times.

 

[dingbat]

My thoughts were the same, that when you set the battery switch to "off", it would isolate the batteries from any parastic draw. Though both batteries are still connected to the ACR. So seeing the optional switch for "when in storage", makes me wonder if this is why they are recommending a switch.

Physically connected or not, the ACR is simply a voltage actuated, normally open relay.
Batteries are not "connected" until a suitable charge current is applied to close it.

The only way I see this working is that you don't have a battery switch to break the positive connection or..... you have components hardwired to the positive battery terminal, in effect bypassing the battery switch. Switching ground would be your only option. Makes no sense otherwise

Installing a switch on the ground return would stop the ACR from functioning removing the only potential for parasetic drain.

I can tell you from experience it has no effect on the ACR operation.

10+ years now without the connection in question. System works as advertised

 

[poconojoe]

As others have stated, if you turn off the perko battery switch there should not be any parasitic draw unless something is directly connected to the battery.

All the ACR does is sense the voltage of the two batteries and if one is low, it will bridge them so both get charged.

I can't see the ACR creating any parasitic draw.
If you install the led indicator light for the ACR, it will only light up under certain conditions. It will stay lit for a short period after you shut down the engine, but it's a tiny led and doesn't draw much at all. It won't light up again until you start the engine.

 

[dingbat]

All the ACR does is sense the voltage of the two batteries and if one is low, it will bridge them so both get charged.

It’s even simpler than that….relay combines when the voltage is above 13.0 volts and opens when the voltage drops to 12.75 volt.

 

[sam am I]

The ACR if wired as per the Blue Sea, obviously then has its "A" and "B" inputs direct wired to each battery..........Shutting off the main battery switch(Perko or otherwise) doesn't open/break these direct to battery A and B input connections.

Internal to the ACR is ground referenced electronics (most likely op-amp comparitors) that connect to each of the batteries A and B inputs in order for the ACR to sense their voltages and then to be able to know when to open/close the main contactor relay.

This sensing electronics have a inherent current draw on the batteries.....Probably only in the order of *micro to probably just a few milliamps and can over a very long time span, draw the batteries down.........AND the ONLY way to break that path is to either.

1) Disconnect the two direct wired A and B battery connections( or pull fuses)
2) Break the ACR's ground path with a switch as the manu has suggested.

*I'm not sure of the exact value as I never measured it, Blue Sea knows or you could measure it by inserting a current meter in the ground path.

It looks like they recommend a "switch" on the 16AWG that connects to ground from the add a battery SI-ACR relay for long term storage. I also heard about possible parasetic drain for this system. I am wondering if anyone has used a small relay, instead of a "switch". This way when the boat is turned on, it can close the relay on the circuit and allow both batteries to charge. Thoughts?

@hostage .........Yes you can use a relay that gets powered when the main battery switch is set to "On"(Start of Acces). When energized, the relay's N.O. contact can be wired such that it grounds and energizes the ACR......This would work nicely if you want it more "automated" for storage as Blue Sea suggests can be done.

 

[poconojoe]

I mounted a tiny LED in my helm dashboard connected to the optional remote monitoring post of the ACR. This way I can see what mode the ACR is in.

I emailed Blue Sea asking for a copy of the sticker that's on the ACR. They sent me one, no problem and free. I stuck that sticker near the led so now I have a reference right in front of me as to which mode the ACR is in.