Ranger 21EC Engine Bank ACR Charging Issue Troubleshooting

[harley]

I have a 2010 21 EC that I recently purchased and have run for a few days and noticed that I am not getting Engine bank charging from alternator. The following are the symptoms. I do not have the factory wiring diagram for the two bank system with SI-ACR and have not changed how that is setup except for one or two things which I will describe:

1. I have a single starting battery and a single house bank battery. No bow thruster or ac batteries. Both batteries are new Interstate AGM batteries.
2. I have the Blue Sea 7610 120 Amp SI-ACR wired as the boat came to me used.
3. I recently installed a new battery charger that has two bank charging and I connected the two bank charging wires to the two separate batteries directly (ACR wiring diagram shows charger only going to "House" bank and using ACR to combine when house charged, but this is not how the old charger was setup and not how the charger install manual battery said to do it).
4. When on battery charger, both batteries charge properly and test with meter at 14.6 volts at battery and on instrument readouts: garmin nav and engine panel.
5. When on alternator only the house battery gets charge, tested at 14.6 volts. Remains that way after three hours of engine operation. Starter battery stays around 12.5-12.6 while engine is running. Alternator is obviously working as evidenced by the 14.6 volt reading on house bank.
6. The batteries are not combining even after many hours of engine operation and the house bank is getting good charge but starter battery does not receive additional charging and the ACR is obviously not combining the banks.
7. I checked and the A and B posts do run to the separate battery banks.

Any ideas? How to test the ACR? Anyone have a diagram or suggestions?

I appreciate the help,

Harley
Ranger 21EC Runcible on Shaw Island, Wa

 

[ohioan55]

You may have the charging relay wired backwards. One post goes to the primary charge battery and the other post goes to the battery to be charged. Mine is setup to charge the start battery first, and the charge relays (I have 2) connect to the house battery and the AC battery bank. On my boat, the A terminal goes to the primary charge battery (start battery) and the B terminal goes to the battery to be charged. Blue Sea does make more than one model of charging relay, so it's best to check your model on their website. They have instructions on how each model is wired.
https://www.bluesea.com/

 

[ohioan55]

Step 2: Testing. After you have verified the wiring is correct. Connect a volt meter to the battery to be charged. Note the voltage. Start the engine and then check the volt meter again. If the voltage has increased, the the relay picked up and allowed the second battery to be charged. Note - the charging relay will only pick up if it senses that the second battery has dropped below a set voltage and needs to be charged. Hope this helps, and feel free to ask more questions.

 

[harley]

Step 2: Testing. After you have verified the wiring is correct. Connect a volt meter to the battery to be charged. Note the voltage. Start the engine and then check the volt meter again. If the voltage has increased, the the relay picked up and allowed the second battery to be charged. Note - the charging relay will only pick up if it senses that the second battery has dropped below a set voltage and needs to be charged. Hope this helps, and feel free to ask more questions.

I did this test as described and one battery was being charged that was connected to the "A" post of the ACR and tested at 14.6 volts. The "B" post battery was reading 12.6 volts. Maybe 12.6 is still above a level that would require charging?
Do we know what the level is that the ACR would determine is a battery in need?

Thank you for the help.

 

[Wee Venture]

You mentioned that the “A” and “B” posts are connected to the the two batteries (it really doesn’t matter which battery is connected to which post) but you didn’t mention whether the ground wire is connected. Check to make sure that a ground wire (probably #16 or so yellow or black) is connected to the correct ground connector (the one labeled “ground,” not “start isolation” or “LED”). The ACR will not work without the ground.

In most installations the alternator output goes directly to the engine battery. It appears that yours is going to the house bank. That would make me want to further check the cabling. The designated engine battery negative terminal should have a cable (yellow or black) connected to the engine ground. The positive terminal should have a red cable also going to the engine. I am not familiar with the specific 21EC wiring but in most cases it will go to the stud on the solenoid/starting motor. The alternator output will in most cases connect to this same stud. Therefore, the engine battery starts the engine and then the alternator brings the voltage up to feed a charge back into that same battery.

When the ACR senses the higher voltage from the alternator output (>13.0V for 2 minutes) the relay will close, sending the charging current to the other bank as well. The ACR doesn’t care whether the charging voltage is applied to the house on one side or the engine on the other, it will still close. But if the alternator is charging the “house” battery, that makes me wonder if that battery is actually the one that is starting your engine. Could you maybe have the two batteries mixed up?

Here is a link to a good explanation of how the ACRs work:
https://www.bluesea.com/support/article ... _Explained

John

 

[harley]

You mentioned that the “A” and “B” posts are connected to the the two batteries (it really doesn’t matter which battery is connected to which post) but you didn’t mention whether the ground wire is connected. Check to make sure that a ground wire (probably #16 or so yellow or black) is connected to the correct ground connector (the one labeled “ground,” not “start isolation” or “LED”). The ACR will not work without the ground.

In most installations the alternator output goes directly to the engine battery. It appears that yours is going to the house bank. That would make me want to further check the cabling. The designated engine battery negative terminal should have a cable (yellow or black) connected to the engine ground. The positive terminal should have a red cable also going to the engine. I am not familiar with the specific 21EC wiring but in most cases it will go to the stud on the solenoid/starting motor. The alternator output will in most cases connect to this same stud. Therefore, the engine battery starts the engine and then the alternator brings the voltage up to feed a charge back into that same battery.

When the ACR senses the higher voltage from the alternator output (>13.0V for 2 minutes) the relay will close, sending the charging current to the other bank as well. The ACR doesn’t care whether the charging voltage is applied to the house on one side or the engine on the other, it will still close. But if the alternator is charging the “house” battery, that makes me wonder if that battery is actually the one that is starting your engine. Could you maybe have the two batteries mixed up?

Here is a link to a good explanation of how the ACRs work:
https://www.bluesea.com/support/article ... _Explained

John

John, I will go out to the boat today and trace everything. There is a positive bus bar where most the positive (red) cables go before heading to the batteries and the ACR. I have not removed the plastic cover to the positive bar, so I am not sure which connections are made in there. There was a black wire connected to the negative terminal of the ACR and it was fused. I will check that fuse and connection to ground. I do know that the "combined" light on the ACR was not on when the one battery was fully receiving alternator charge of 14.6 according to the multimeter for more than 2 minutes. The cables are labeled to the batteries as house and starting when I got the boat and have not changed their position.
Anyway...full schematic to come.....it may be a prose version as I am not that accomplished at doing a graphical version.

 

[Wee Venture]

The positive terminal should have a red cable also going to the engine. I am not familiar with the specific 21EC wiring but in most cases it will go to the stud on the solenoid/starting motor. The alternator output will in most cases connect to this same stud. Therefore, the engine battery starts the engine and then the alternator brings the voltage up to feed a charge back into that same battery.

I neglected to include the battery switch. So both engine and house batteries will first go to the switch(es), enabling you to turn them off or parallel them. From there, the engine battery positive cable should go to the engine as I described. (The negative terminals of both batteries should be grounded to the same bus, or at least to each other, however.)

John

 

[harley]

Well its the simplest things...thank you for the note to check the ground wire. Sure enough, when I reconnected the new batteries, I left off the small ground to the ACR. It is now attached and batteries are combining properly.
Had a great run around the San Juan Islands today.

Love tugnuts!

Harley