Tortuga's Lie wrote:
I am getting ready to do this upgrade. I have the W40 and bought the Balmar 7 series/80 amp with an external regulator (Defender had them on sale in the fall). Anyway, on the original Motorolla alternator, there are a lot of common grounds on a terminal that feed the instruments and oil pressure switch/alarm. I am assuming that I would re-connect these to ground but as Berwick stated, the red power coming off of the alternator goes to the amp meter. This is wrapped in a bundle, so I guess I would abandon this wire/ meter and monitor the external regulator for output? The new positive output wire should then go to the solenoid? If I abandon the power feed to the old amp meter, am I in danger of deleting a power source to anything else in the instrument panel?
PLEASE DO NOT USE THE FACTORY AMMETER!!!!!
I know you were not intending that but wanted to at least make that point so it can be seen...
These circuits are flat out dangerous with the factory alt and burn your boat down dangerous with a high output alt. they are also the main culprit in early battery death due to horrible voltage drop and chronic undercharging.
Rx=
1- Replace the Ammeter with a simple DC volt meter. Usually the alt output was a red and orange or red & white wire to/from the ammeter. Keep one of them for the volt meter and clearly mark and abandon the other.
2- Run the alt output to:
Starter Post - The alt current then picks up the large gauge battery wire back to the banks. DO NOT pass the battery switch through the OFF position when the engine is running. This is not "ideal" for many reasons but the #1 reason is improper voltage sensing. With the alt run though the batt switch the best you can do is sense the "C" post of the battery switch but this can still result in poor voltage sensing..
Direct to House Bank - with proper overcurrent protection within 7" of the house bank. OCP should be a bare minimum of 20-25% larger than the alts max rated output with 50% larger being much better as it will minimize voltage drop across the fuse..
Also wise to install a "service disconnect switch" for the direct wired alt to discontinue 12V at the alt terminal when working on the engine.
With the alt run direct to the house bank you can also properly sense the house bank + terminal.
If you want to see current I would suggest installing a battery monitor like the Victron BMV-600 which has a proper 500A rated shunt....
Westerbeke stopped this foolish and dangerous wiring many moons ago yet there are plenty of these high resistance, voltage dropping systems out there. Truly scary stuff...
With the Balmar the best performance will be in running positive and negative wires direct to the house bank. Size these wires as large as possible because even a 3% voltage drop at 14.4V results in just 14.0V at the battery bank and can lead to horrible charging performance.
Proper wiring minimizes voltage drop and allows the regulator to performs its duties and not have to over compensate for inadequate wiring.
I do not suggest grounding the alt to the engine block even though the 7 series is a case ground alt (not ideal but works). If you want the best performance run a dedicated new negative wire, same size as the positive, to the house bank or the house bank neg busbar. If you had a clamp meter you would see that 90+% of the current will take this new wire over the engine block path. Ultimately an isolated ground alt would be the best but the 7 series was never built that way, that I can recall.
jvoelxen wrote:
3. Voltage regulator Connection: I have a Balmer AR-5 regulator. If I recall, the installation instructions tell you to attach the voltage sensing wire to the alternator output. I chose to connect mine to the common terminal of my battery switch. I did this because I knew there was about a 1 ohm voltage drop, at high charging currents, between the alternator and the battery so I wanted the alternator voltage output to be controlled by the lower voltage at the battery. Not sure it had any effect, but made me feel better.
If this is the closest you can get the and alt output can be "switched" this is the best you can do..
The better method, performance wise, is to run the alt to the house bank and sense voltage at the house bank + terminal.
Voltage sensing can ONLY sense directly at a bank if that is where the alt B+ is physically wired to. Voltage sensing at the bank is the only way you get the best performance short of massive wires..
I have seen many owners cook batteries by improper sense wiring. Follow me here:
Alt goes through battery switch
Installer puts v-sense on house bank / #1
Owner selects start/aux bank #2 and fires up motor
Regulator see's no change in voltage at the house bank and continues to full field the alt driving the voltage of the start bank to exceed 17V+!!!!
Start banks survives this for a few hours then says enough already............