Our 2015 Vetus M4.35 has the stock 110A Alternator
without external sense or external controller. I have no idea who built the alternator
and there's no identification sticker on it.
It's connected to the 220Ah AGM
house bank with 2/0 cabling.
When i start the engine
and rev up a little bit, charge current
with batteries at about 50% goes up to about 80A. While that's good at first, current
directly starts to go down within few minutes, without the battery
bank hitting absorption voltage (14,1V with my alternator, which is quite low but that's probably not the problem here). About an hour of running, current has gone down to less than 30A, even if the battery
is still only hitting 13,5V. I've measured the voltage directly at the alt and got 13,65V.
I've read the article of maine
sail about alternators with internal temperature compensation before and so i measured the alternator temperature. It was at 107°C or 225F. Looks like the alternator cuts down charge current to protect itself.
While this is probably a good feature it also means that using an external charge controller won't help anything as the temperature is the problem and not the regulator
Does anyone have similar experiences? I know there is an older thread about alternator cooling
, but i'm hesitant to cut a hole in the engine
room and install a fan due to noise
. Our main energy source will be our solar
system so hopefully we won't need to use the alternator very often simply for charging
, but if we have to, i would like to have better performance than now.