Blue Sea ACR Vs. MinnKota On Board Alternator.

[Cabin2010]

So last year I installed a dual battery set up with the Blue Sea SI-ACR to tour 195. This "combines" batteries during charging to maintain both batteries at full charge.

The 195's magneto puts out 360 W @ 6000 RPM, or about 30 amps. The problem i've found is, if one of the batteries is at a low state, the charging system cant handle it and it ends up throwing a CEL for a low charge state. And inevitably both batteries suffer.

I'm looking to eliminate the "Combining" aspect of charging both batteries.

MinnKota's MK-1-DC Alternator "Isolates" the batteries, when the starting battery reaches full charge (13.6V) it then diverts all the charging to the secondary battery.

The MK-1 requires a 12AMP min (Remaining after all on board systems are running, ie: radios ect) to operate.

While this charger was designed for trolling batteries, I'm not seeing any reason it cant be used to maintain a house battery as well. (Our trolling motor is a standalone Lithium & Solar setup)

Thoughts from the crowd?

 

[Beachbummer]

Your ACR has a ground wire. Connect a switch in line to the wire, so you can disconnect the ground at will. It will not bridge the batteries while the ground is not connected to the ACR.


If I understood correctly, this will achieve what you want.

 

[Cabin2010]

I actually do have it set up that way now, the prob is i need to keep the house battery charge constant. Our down riggers run from that battery as does our sonar ect, this puts a big consistent drain on it.

 

[FSH 210 Sport]

What size is your house battery and its type?
What do the down riggers pull amperage wise.?

Your stator output is 25A. 360 / 14.4=25

The CEL you mentioned, what is it exactly? The reason I ask is because when I was researching down riggers, the minnkota electric ones manual stated to have a stand alone battery as they could put noise on into the system. Is this not coming in when you are trolling? What’s the system voltage when this is happening ? Is the charging system not able to handle it, or is the CEL just a low voltage warning ? Does the voltage recover after you have been idling for a while?

Im wondering what the output of your stator is at idle that it can’t handle the down riggers.

If you put the dc to dc charger in, it will still pull the same power off your starting battery as it just connects to the start battery right? The only isolating it will do is disconnect itself when the voltage drops to 12.7? I’m pretty sure the blue sea system operates the same way.

 

[Cabin2010]

The Cel is low voltage only and does shut off once the cycle detects nominal voltages.

Stator outputs are constant regardless of RPM.

Down riggers have a max draw of 30 amps ea, which isn't an issue with the group 24 battery as their draws are not continuous.

The Minn Kota system systems differs from the BlueSea in that the BlueSea will combine the batteries during charging, thus the stator is work to charge both at once. The Minn Kota system disconnects charging from the starter battery once it reaches 13.6 V and then diverts all charging power to the 2nd battery, thus regardless of which battery is charging the system is only charging one at a time.

 

[FSH 210 Sport]

Okay, the CEL alarm sounds logical. At what voltage / when does this come on? How long does it take for the CEL to clear at idle? Aka what voltage is the alarm clear voltage?

Your stator sounds phenomenal, all other stators that I have dealt with in my life have a lower output at lower rpms than at rated rpm. Impressive.

Your understanding of how the Minnkota alternator charger is at odds with what Minnkota states:

https://minnkota-help.johnsonoutdoors.com/hc/en-us/articles/4413541136663-Using-the-Alternator-Charger

The Minnkota alternator charger does not isolate the start battery and force all charging amps to the house battery, the start battery is a necessary component of the MinnKota system and is the source for the MinnKota charger.






In short, the Minnkota alternator charger has a permissive, the purple wire that is connected to an ignition hot, once that permissive is met, when the start battery reaches 13.6 volts the MinnKota alternator charger will takes its feed from the start battery that it is connected to and push 10A’s to your house battery and will do so until the house battery you are charging reaches 14.4 volts. At this time the start battery will still be charging as its voltage has not come up to 14.4 volts, so that draw down that you saw with the blue sea VSR system will still be there. If your start battery voltage drops below 13.6 volts while the ignition is on, then the minnkota charger will stop charging and wait for the start battery voltage to recover to 13.6 volts before it starts charging. If there is a problem with your start battery, and when the MinnKota charger starts charging it may very well drop back below the 13.6 volts and charging will stop.. this could result in an on and off cycling.

The main difference is that when you turn off the engine with the blue sea system the VSR will not open until the combined batteries voltage reaches 12.75 volts, whereas the MinnKota charger will drop off immediately once the ignition hot is gone to the purple wire.

m-Series Automatic Charging Relay - 12/24V DC 65A - Blue Sea Systems

Automatically combines batteries during charging, isolates batteries when discharging or at rest.

www.bluesea.com

To save yourself a bunch of money, time and effort, simply use the “storage“ set up and switch the ground on your dash. Wait until the start battery voltage has come up to say 14 volts before turning on the VSR. I did essentially the same thing with my boat as I have a LiFePO4 house battery and I wait until the agm start battery voltage climbs above the house battery before supply power to the DVSR via dash mounted rocker switch.

Did you hook up the SI / start isolation wire when you installed the blue sea system?



It sounds like there may be something wrong with your start battery, is it new / good condition? Connections all good? On a charger when not in use? The start battery should require very little if any charging after starting your engine. With as powerful of a stator that you have the voltage should not dip enough to cause a CEL alarm. I’d also check all the connections coming from the stator etc.. for tightness and corrosion.

I’m not trying to crumb on your idea, just trying to save you frustration and money.

 

[FSH 210 Sport]

@Cabin2010 Any updates?