On-board Battery Charger with Generator and Engines Running

[Midnightsun]

don't switch while the engines are running unless you are sure that the wiring is so that the alternator is always connected to some battery bank.

This is one of the reasons you cannot use your alternator connected to a LifePo4 (Lithium) battery since the BMS will disconnect abruptly when fully charged or some some other abnormal parameter may occur which will also cause a disconnect. In other words, same as removing the battery from a running alternator. Poof goes the alternator.

[bud37]

Just to add.... Your boats operating manual does explain the main switch operation but just to remind...... even with the make before break switches ( which are labelled if I remember right as such ), you still need to remember NOT to cycle the switch thru the OFF position with any engines running or else there is risk of damage..

[km1125]

Another issue with using a common battery source for both engines is that it's harder to tell if ONE of the engines is having a problem with its charging circuit until BOTH have a problem. I like the installations that have a dedicated battery for each engine, with an "emergency start" contactor between them for low/dead battery issues.

This way when you look at the voltage for each engine, you're seeing the charging voltage when it's running, and the dedicated battery voltage when it's not, rather than just seeing the combined voltage.

[bud37]

To add.....I do know for instance that, Mercruisers for one, ecu operated engine package install instructions clearly state that a separate battery is required for each engine due to needing a stable voltage. Now whether the boat makers have stuck to this is open for discussion but I can say that the ones around 2001 are that way and can be read thru the dash volt meters.....but you have to know how to manipulate things, again this creates another unfortunate user problem.

[Viper]

QR_BBPOST ...even with the make before break switches, you still need to remember NOT to cycle the switch thru the OFF position with any engines running....

That is correct. Most new switches now have the OFF position at one end rather than in the middle like some used to, you would pass through the OFF position when switching between banks. From what I recall, newer switches will say something like "Stop engines before switching to OFF"

[Viper]

QR_BBPOST....I like the installations that have a dedicated battery for each engine, with an "emergency start" contactor between them for low/dead battery issues.....

This is what I've been preaching for years. A solenoid, some wiring, and a switch at the helm is all you need. Simple, inexpensive, and no parasitic monitoring draws. You just have to ensure that the switch (rocker, toggle, pushbutton, etc.) for the helm is a "momentary" type that releases when you let go so the banks return to an isolated state. Nothing to forget!

[bud37]

QR_BBPOST This is what I've been preaching for years. A solenoid, some wiring, and a switch at the helm is all you need. Simple, inexpensive, and no parasitic monitoring draws.

Trojan boats had that exact thing as an option in their models as far back as the 70's......

[Viper]

It goes further back than that with Trojan bud, I had a '60's Trojan woodie with that option, it was awesome. Never had to worry about maintaining a selector switch, and the paralleling option at the helm came in handy a few times.