A/C battery chargers working while 5.7 mercs are running?

[Chiefshack]

I just bought a 1989 3207 Aft Cabin. It has twin 5.7 MIE Mercruisers and a 6.5 Kolan Gen Set. I found out today the battery charger is "hard wired" to the the A/C panel circuit. My question is can the charger be used while the engines are running without damaging the engine batteries, alternators (original) or the charger itself? As is stands right now, if I am on shore power or the genset the charger is on always whether the engines are running or not!!
Thank you in advance,
Chief Shack
USN (Ret)

[Midnightsun]

Not an issue. The is common within the boating industry. All chargers sense if they need to charge, one or both will charge the bank as required. In my case I have a couple of solar panels hooked up so there may be as many as 3 sources charging at the same time.

[Chiefshack]

Thank you Hans, now knowing that I am going to install a "Smart" 20 Amp 3 bank charger. So my new starter, house, and genset batteries can be kept healthy

[Viper]

If you spend a couple of days at a time at anchor, you may want to consider something bigger than 20 amp charger so you can maximize the charge for the length of time you run the generator away from the dock. The only way to charge faster with a small charger is to run the engines instead, however that will take much more fuel. If you simply go from port to port and spend most of your time at the dock, then a 20 amp charger is fine. I only install 20 amp chargers on small runabouts now and even then boating habits and power usage have to be taken into consideration.

You can operate your charger while the engines are running however the engines should charge the batteries on their own through the alternators. No need to have the charger working if the engines are running.