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  View original topic: does a Blue Sea SI-ACR Charging Relay drain starter battery?
jocoman Mon Apr 01, 2019 3:40 pm

If the ACR is simply wired I.E one Plus side to house battery and the other plus side to starter battery plus a ground does it contribute to parasitic drain on the starter battery? I measure 60K from either ACR post to ground. So if my math is correct it would have a constant drain of .2ma . If this is true then it would be only a very slight or negligible drain.
Does this make sense? Otherwise do I need a switch in there someplace?
txs

dobryan Mon Apr 01, 2019 4:01 pm

Why is 0.2ma an issue?

jocoman Mon Apr 01, 2019 4:05 pm

Not at all. I'm just wanting to understand this device . .2ma is peanuts if the way i am calculating is legit and would never cause a no start from the start battery.

Paulbeard Mon Apr 01, 2019 5:25 pm

I have a related question…maybe needs a thread but I'll see if anyone can answer it. I have a BlueSeas ACR and while it doesn't draw enough to worry about, it combines when I don't want it to. When I have my solar panel out and charging, the ACR will combine and lower the voltage going to the aux battery which I don't want. When it separates, the aux is lower (maybe .5V?) and then has to reclaim that. I want all the solar charge to go to the aux.

What I would perhaps like to do is prevent the ACR from combining unless the charge is coming from the alternator, ie, the motor is running. So I think I envision a relay and some way of sensing that current (the blue wire that turns off the ALT light?). Am I on on the right track? Talk to me like I am 5…

beach_creature Mon Apr 01, 2019 5:44 pm

You can add a relay for the ground wire of the ACR. I would tie it in to the run only, at the fridge relay.

Option two, a manual switch on the ground.

Option three, and don't know the long term of this, but add solar (+) fused to the ignition part of th ACR, shis should separate them when the ignition connector has power. Someone else should verify this.

Timwhy Tue Apr 02, 2019 3:35 am

Paulbeard wrote: I have a related question…maybe needs a thread but I'll see if anyone can answer it. I have a BlueSeas ACR and while it doesn't draw enough to worry about, it combines when I don't want it to. When I have my solar panel out and charging, the ACR will combine and lower the voltage going to the aux battery which I don't want. When it separates, the aux is lower (maybe .5V?) and then has to reclaim that. I want all the solar charge to go to the aux.

What I would perhaps like to do is prevent the ACR from combining unless the charge is coming from the alternator, ie, the motor is running. So I think I envision a relay and some way of sensing that current (the blue wire that turns off the ALT light?). Am I on on the right track? Talk to me like I am 5…

I added a switch to my ACR.


shagginwagon83 Tue Apr 02, 2019 5:19 am

Tim you could have installed a small switch on the small ground wire on the SI_ACR. On mine I have a relay but a switch would work too.

Also, Paul - the below is a solution to your SI_ACR. Basically the batteries will only combine when the engine is on.

That being said - I believe I just took the "automatic" part OUT of the automatic charging relay. I think a simple relay would do the job.


Paulbeard Tue Apr 02, 2019 6:05 am

shagginwagon83 wrote: Basically the batteries will only combine when the engine is on.

That being said - I believe I just took the "automatic" part OUT of the automatic charging relay. I think a simple relay would do the job.



That's pretty close to what I want. It still charges automatically, it just adds a way to ignore the solar charger. In high summer I wouldn't mind seeing both batteries topped up to 13.5V but it's early yet.

shagginwagon83 Tue Apr 02, 2019 6:14 am

Paulbeard wrote:

That's pretty close to what I want. It still charges automatically, it just adds a way to ignore the solar charger. In high summer I wouldn't mind seeing both batteries topped up to 13.5V but it's early yet.

The "Automatic" part of the SI_ACR can 'detect' when to bridge the batteries.

I think you could get away with telling a non-auto relay when to bridge (after the engine is on and the alternator 'excited'. I don't know what the cost is. One benefit of my setup is that after the SI_ACR is turned on, then it takes like 30 seconds to bridge - well after the engine is running.

But yes - I don't want my solar controller charging both batteries - only my aux. The only reason my starting battery would be dead is if the battery is bad/weak. I could jump myself with my aux.

Paulbeard Tue Apr 02, 2019 7:29 am

shagginwagon83 wrote:
I think you could get away with telling a non-auto relay when to bridge (after the engine is on and the alternator 'excited'. I don't know what the cost is. One benefit of my setup is that after the SI_ACR is turned on, then it takes like 30 seconds to bridge - well after the engine is running.



Yeah, the 30 seconds is how the ACR works…combines after seeing a steady source of 13.5V current for 30 seconds. So it's encouraging that the solar panel output can force it to combine this early in the year.

I need to better understand the signal the blue wire carries and how/if it can trigger a relay to do this.

shagginwagon83 Tue Apr 02, 2019 7:32 am

Paulbeard wrote:
I need to better understand the signal the blue wire carries and how/if it can trigger a relay to do this.

That's what I'm using - the blue wire found in the driver side battery box. That combined with a normal relay to control the ground. My wiring diagram above does what you need - ignore the 'key/ignition' part.

Paulbeard Tue Apr 02, 2019 7:36 am

shagginwagon83 wrote:

That's what I'm using - the blue wire found in the driver side battery box. That combined with a normal relay to control the ground. My wiring diagram above does what you need - ignore the 'key/ignition' part.

Gotcha. Thanks. I was misreading that…

Steve Arndt Tue Apr 02, 2019 8:54 am

Yes. The stand by current draw (parasitic draw) is in the blue sea data sheets. The reason I like this one is the much lower current draw:

https://www.ebay.com/itm/Victron-Cyrix-ct-12-24V-120A-Intelligent-Battery-Combiner/171934028788

shagginwagon83 Tue Apr 02, 2019 9:02 am

Yeah I would go with Victron if I had to do it again.

Paulbeard Tue Apr 02, 2019 5:59 pm

shagginwagon83 wrote: Yeah I would go with Victron if I had to do it again.

+1 on that. The one I chose was recommended by SolarBob but I would rather have the data over time that victron makes available.



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