Balmar ARS-5 fuse issues

[Diverrob]

Good day hive mind!

I have a question I’m hoping someone may be able to help me with. I am running a ARS-5 external regulator combined with a Balmar 150A alternator. This weekend we were out for a couple nights and I had to replace the 10A in-line fuse three times. Obviously there is something going on where too much amperage is getting to the fuse (I believe this is during flash up).

Here is what has happened over the past few weeks…

Alternator needed repair due to a faulty internal terminal block. Had this done at the local shop and everything seemed to work well after.

I moved the red positive and black negative from the back of the alternator to the house battery posts. This was to get a more accurate voltage reading from the house bank and ensure better charging performance. This was done after reading the article https://marinehowto.com/alternators-voltage-sensing/

I don’t see how this could be the culprit but if anyone knows I would appreciate the help. When the system is running normal there is about 3.5A going through the red positive. Hopefully someone can point out my mistake and send me in the right direction. Thanks

Rob

 

[Diverrob]

Ok so went down to the boat today to do a bit of troubleshooting. Checked the regulator for a short and it checked out ok. Then checked the harness and bam! Found a short in the power supply. I tried to find out where it was and could not find it. Both ends are connected directly to the + and - battery post directly to the regulator. I removed the + off of the battery post, checked for the short and it’s gone. Connected it back to the battery and checked, no short. Flashed the boat 4-5 times and everything works fine. It’s a real mystery to me at this point, I will probably replace both lines as well as the inline fuse holder just to be sure.

 

[Diverrob]

Sooo as things are on boats nothing is as simple as you first think. We headed out today for a quick overnight and wouldn’t you know it but the fuse went again. Did a bit more troubleshooting and found that it goes whenever I use my bow/stern thrusters. I’m still a bit confused but this is what I think “may” be happening. I have my alternator feeding a battery isolator from there the power can go to the house bank and the thruster bank. With the regulator power/sensing line connected to the house bank there is a false impression given to the regulator that the alternator is not providing enough power to the house when using the thrusters. This is because of the huge draw from the thruster bank which diverts all power from the alternator to that bank. The regulator then asked the alt to give more power (increase power to the field coil wire) which increases the power going through the fuse until it blows. Once I moved the power/sensing wire back to the alternator the regulator sees that the alternator is working and does not freak out.

Not sure if that makes sense but after going back to the original setup everything works well so I’m going to just leave it that way. If anyone knows how to get an independent voltage sensing wire to a Balmar ARS-5 let me know, thanks

Rob

 

[CharlieJ]

Rob
I am making the assumption that the system worked before the alternator repair. If so, then I think that you have to investigate what the shop did inside the alternator. My thought process is that the ARS-5 can produce a max of about 6A of field current to the blue wire. That 6A is provided by the red wire in the Ford plug. Doesn't matter what the electrical load on the battery is, full field is 6A. So blowing a 10A fuse indicates that something else is wrong.

 

[Diverrob]

Thanks for that info, I was not aware of the max 6A production through the field coil. I did go back to the repair shop and ask what exactly they had done to ensure it was not something on their end. They said all they did was replace the terminal blocks inside the alternator and there was no way for that to cause excessive draw on the power to the regulator. What may not have been clear in my original post was that I moved the red and black power/ground from the back of the alternator to the battery post on my house bank at the same time the alternator was returned from repair. This made me think it was the alternator and not the wire but it looks like that was the wrong direction to go.

What I’m now thinking is that some how based on the setup inside the regulator by moving the power line to the house battery I was able to bypass the battery isolator. Then when I use the thrusters there is a path to pull from the house bank which blows the fuse. I will know more today when I pull anchor and head back to the dock. Batteries are low and will want lots of power from the alt and I will play with the thrusters at the same time to see if I can blow the fuse again.

Thanks for the input I love getting help from the group and it really shows the value of this forum. ?