Maximum amperage of alternator

Jun 15, 2012
717
BAVARIA C57 Greenport, NY
I presently have a house battery bank of 3, 8D Deka Gel batteries. The Amp hour is listed as 225 each. What is the Maximum amperage of an alternator with external regulation and temperature sensors that I can upgrade to? I thought 165 amps would be good.
 
May 20, 2016
3,015
Catalina 36 MK1 94 Everett, WA
What engine and size and type of belt?? For 165 you probably want dual 1/2 or serpentine
 
Feb 6, 1998
11,759
Canadian Sailcraft 36T Casco Bay, ME
I presently have a house battery bank of 3, 8D Deka Gel batteries. The Amp hour is listed as 225 each. What is the Maximum amperage of an alternator with external regulation and temperature sensors that I can upgrade to? I thought 165 amps would be good.
There really is no limit other than to say that you will be limited by the belt you are using and the type of alternator you choose. Large frame or J180 type alternators are considered extreme duty and can run for hours on end at or near full output but they require fully custom mounts (eg: local machine shop) and can get expensive to install. Small frame alternators can output their rating but will not do so for long periods unless they are gutted and running externally rectified.

I do have access to a kit that fits a J180 large frame 200A or 250A extreme duty alt to a 4JH4 engine.


If you expect anywhere near 165A from a 165A small frame alternator, don't get your hopes up.

An alternator in the .3C range would be a good choice for GEL but this is 200A, when the alternator is hot, which really means a 230A-250A alternator be installed... A 165A alternator, such as a Balmar AT-165, set to run at 120A to 130A, using Balmar's belt load manager, would give you an effective charge rate of .18C to .19C..