Alternator Upgrade - Balmar - What is this?

[NickBee]

Hi,

I have a Dufour Gibsea 43 - 2000. I will upgrade the alternator for a 100A Balmar with a ARS-5 Voltage Regulator. This boat originally comes with a Battery Isolator to divide the House and Starter battery. Close to the Isolator (DIVI-CHARGE), there is a kind of ''shunt'' that I think is connected to the existing Regulator with a blue and black wire. It also seems like the power from the alternator is connected to this device before going into the Isolator... (see photo attached).

Is this is a kind of ''power monitoring'' from my old alternator? Can I remove this completely and install my new ARS5?

(my boat is on the dry, winterized and I don't have access to it.. I base my supposition on pictures.)

Thanks for your Help!

[PirateGuy]

Looks like a high side shunt to me. Maybe someone wanted to monitor the alternator output

[RaymondR]

Originally Posted by PirateGuy

Looks like a high side shunt to me. Maybe someone wanted to monitor the alternator output

That would be my guess also. If so somewhere on it will probably be a notation something like "50 A 50 mV" which means that 50 amps of current through it there will be a 50 miii volt voltage drop across it.

Quiet handy to have a current meter on the alternator output. You can infer a lot about battery condition from how they respond to charging current.

[Adelie]

Shunt for measuring current it looks like.

[Stephenmac]

It may be to provide power to the alternator. I believe the instructions for the Balmar external alternator requires that the power wire be on the battery bank side of the isolator if one is part of the DC system.

[j.g.evans]

Keep the shunt. If there is not an amperage meter then you can use a multimeter on a temporary basis. My shunt produces 100 mv for 100 A and thus no scaling is necessary. I have a small 200 mv DVM that I bought for less than $10 to monitor current.
Issues with the Balmar: I have a 100 A Balmar and found it would break belts. Balmar sent me a larger sheave which cured the problem. I observe that my charging current is much less than 100 A. The current is high initially and then drops to about 10 A charging 200 AH of battery. I don't think the batteries want to accept more. This makes me question why I replaced the 40 A charge that came with the motor.

[waterman46]

Originally Posted by j.g.evans

Keep the shunt. If there is not an amperage meter then you can use a multimeter on a temporary basis. My shunt produces 100 mv for 100 A and thus no scaling is necessary. I have a small 200 mv DVM that I bought for less than $10 to monitor current.
Issues with the Balmar: I have a 100 A Balmar and found it would break belts. Balmar sent me a larger sheave which cured the problem. I observe that my charging current is much less than 100 A. The current is high initially and then drops to about 10 A charging 200 AH of battery. I don't think the batteries want to accept more. This makes me question why I replaced the 40 A charge that came with the motor.

It's always good to have a higher output available if you need it. If you were using 12V to do other jobs, like run reefer, watermaker, whatever, while running the engine, then you will be happy to have the higher output available.

[cottonsail]

Keep in mind that a single V belt can barely pull a 100 amp Balmar. Had to adjust my V belt about every 10 hours. Constant black power. Belt alignment was checked by me (former FAA A&P mechanic) and 2 other very qualified techs.

[Stu Jackson]

Originally Posted by j.g.evans

>>>>>>>
>>>>>>>>>>>>>>


I observe that my charging current is much less than 100 A. The current is high initially and then drops to about 10 A charging 200 AH of battery. I don't think the batteries want to accept more. This makes me question why I replaced the 40 A charge that came with the motor.

You did the right thing with the larger alternator. Your belt issue could have been not using amp manager or small engine mode if you have an external regulator.

And perhaps you are missing the point: would you rather have a 40A alternator that is working at 100% and heating up, or would you rather have a 100A one that is running cool and comfortable, given the exact same load.


And, of course the amperage drops like that - it's basic battery charging 101.

[RaymondR]

Originally Posted by j.g.evans

Keep the shunt. If there is not an amperage meter then you can use a multimeter on a temporary basis. My shunt produces 100 mv for 100 A and thus no scaling is necessary. I have a small 200 mv DVM that I bought for less than $10 to monitor current.
Issues with the Balmar: I have a 100 A Balmar and found it would break belts. Balmar sent me a larger sheave which cured the problem. I observe that my charging current is much less than 100 A. The current is high initially and then drops to about 10 A charging 200 AH of battery. I don't think the batteries want to accept more. This makes me question why I replaced the 40 A charge that came with the motor.

The larger sheave reduced the load on the belt however in doing so it also reduced the RPM of the alternator and the fan cooling.

Probably not a problem when only recharging a single cranking battery but you will notice a difference when you charge a large bank of discharged house batteries. Since Balmars generally have temperature control it won't hurt the alternator only reduce it's charging capacity. A better solution may have been bigger belt size or double belts.

[IBlake]

I was having the same problem with the belt wearing out with black dust. I have AGM batteries which accept a heavier charge taxing the alternator. I converted to a serpentine belt with the pully only a little larger then the old one. The serpentine pully fits over the current pully. I moved from 50A to Balmar 120A with their regulator. The larger alternator should last a long time not having to run very hard. New belt works fine, don't need to adjust.

[hzcruiser]

Originally Posted by IBlake

I was having the same problem with the belt wearing out with black dust. I have AGM batteries which accept a heavier charge taxing the alternator. I converted to a serpentine belt with the pully only a little larger then the old one. The serpentine pully fits over the current pully. I moved from 50A to Balmar 120A with their regulator. The larger alternator should last a long time not having to run very hard. New belt works fine, don't need to adjust.

Do you have a link for such an upgrade? I'm thinking of upgrading my stock alternator as well (on a Perkins 4.236). Do you need an extra idler pulley to install a serpentine belt?
My understanding of serpentine is that the belt covers more of the radius of each pulley to avoid slipping, which would require an additional pulley.
Maybe I got that wrong?

[hzcruiser]

Originally Posted by NickBee

Hi,

[...]

Is this is a kind of ''power monitoring'' from my old alternator? Can I remove this completely and install my new ARS5?

The voltage between the two wires tell the regulator how much current is flowing. Your new alternator does need a regulator as well, so the shunt would still be needed. Check the manual for the new gear.
A bigger alternator is also very useful if you upgrade your batteries to LFPs, since they can accept higher currents all the way until full and don't need absorption, hence reducing engine run time.

[hzcruiser]

Hmm, just read the ARS5 manual: it's purely voltage driven, so you won't need the shunt for this, but I would leave it there anywhere as you can add a smart device that tells you how many Ah went into the batteries.

[walbee]

Originally Posted by NickBee

Hi,

I have a Dufour Gibsea 43 - 2000. I will upgrade the alternator for a 100A Balmar with a ARS-5 Voltage Regulator. This boat originally comes with a Battery Isolator to divide the House and Starter battery. Close to the Isolator (DIVI-CHARGE), there is a kind of ''shunt'' that I think is connected to the existing Regulator with a blue and black wire. It also seems like the power from the alternator is connected to this device before going into the Isolator... (see photo attached).

Is this is a kind of ''power monitoring'' from my old alternator? Can I remove this completely and install my new ARS5?

(my boat is on the dry, winterized and I don't have access to it.. I base my supposition on pictures.)

Thanks for your Help!

I have a couple of these on my vessel. The boat is new to me so I have not had time to fully investigate. I believe they are used by the Ammeters, of which the port side is not functional. Upon further investigation, I found one of the shunts was either burned through or rusted out, can’t really tell. See attached pics.