M/V Charging

[JMW]

I'm looking to upgrade the wiring on my boat (45 CC). When I run the genset, the battery charger is operational. I use the genset frequently when underway to power the A/C, should I disconnect the charger as the mains are also charging the batteries? In addition, does it make any difference it both MDE's charge the same battery? (Two alternators on one bank)

Thanks
Jim

 

[john monks]

Normally a charging circuit brings the battery voltage up to a predetermined level then stops charging. I personally would not worry about having two charging sources on the same battery but I think to myself, what if one of the charging circuits fails and overcharges the battery or what if the battery becomes disconnected and the voltage spikes on all the other electronics on the boat? Will it pop all the running lights and take out the radio? What about the ignition? I had a voltage regulator fail on a car I owned and I lost a lot of light bulbs when I disconnected the battery.

 

[JMW]

The regulator(s) are internal to the alternators. I've always connected them in parallel with AC charger, but am looking at a"best practices" scenario. While a good quality "smart" chargers, may adjust the charge accordingly, I don't know about an alternator. I doubt if the field even has PWM. I could make it "fool proof" by adding a relay powered by the ignition switch, but that is just one more thing to fail, and still won't solve the "two alternator" issue.

 

[john monks]

I certainly believe that two charging sources will work but I would be a little afraid of an alternator failing causing a bigger problem. Most automobile alternator regulators are analog devices. Is your battery essential for all your electronics? Can you start your boat with a dead battery? Do you have a separate battery? Just a little spooky.

 

[JMW]

Yes, that is one of the issues, I have a genset with a 30 amp charger. One of the questions is this is also operational when I'm underway using the genset. I frequently do this as I have an electric stove, and run the A/C. I'm splitting the battery banks, it will be seldom when I have both alternators on the same bank.
Guess it is time to contact Interstate or Heart.
Thanks

Jim

 

[JMW]

I e-mailed a major battery manufacturer with no response. I contacted a charger/inverter manufacturer and they responded.
Multiple charging points (alternator and GenSet set chargers) are not a problem at low load rates. If high currents are drawn, the lower rated charger may suffer damage or trip off line. As the wall charger is only 30 amps it will be the one that trips.