Battery Bank Charging

[randyp]

Need some advice. I have a dual-bank 20 amp Charles charger hooked up to my battery switch (1-2-both-off). Positive leads from charger go to Bat 1 and Bat 2 posts on the switch. Main lead off alternator goes to central post on the switch. (It's a 1977 F-26 with single Chry 318). For starting and underway I use Bat 1 (Group 27 starting battery in good shape). On hook I use Bat 2 (2 group 30s wired in parallel for 240 AH). At dock I plug in to shore power and, naturally battery charger now charges BOTH battery banks simultaneously since there are positive leads going to each battery switch post. Since this is a "dumb" charger it does NOT know that it's cooking my Bat 1 while pouring in the amps to the Bat 2 bank of 2 group 30s. So.....I was looking to add an auto charging relay (ACR). How do I wire in the Charger with the ACR? My head says wire charger lead (only 1) to the central post of the battery swiitch and wire the ACR directly to the each positive lead of the battery and the input to a lead off the central post (fusing each lead). Using this setup will I fry my alternator when I plug in at shore and turn on the charger? Of course I could spend the extra $$ on a smart charger but I still should use an ACR, right?

Thanks for any advice!

[prowlersfish]

I would get a smart charger and wire it to the batterys , I would use the battery switch to control the batterys and forget auto charging relay .but thats just the wayI would do it .