rsn48
Guru
- Joined
- Feb 18, 2019
- Messages
- 2,019
- Location
- Canada
- Vessel Name
- Capricorn
- Vessel Make
- Mariner 30 - Sedan Cruiser 1969
I am just going to do a copy and paste from a conversation I had elsewhere. I will comment after the copy below:
"Grant October 12, 2019 at 11:45 am
Rick – you might want to reconsider holding off on that alternator upgrade – your Mercruiser 70A unit is internally regulated at a fixed 14.4V – and your $2,000 worth of new Fireflys are not going to like that long-term. They have specific float voltage requirements of 13.4-13.5V, and other criteria – see manual. They’re a great battery, but I wouldn’t make the investment until I had all my charging sources sorted out to deliver the appropriate charge profile they recommend…
So I did go into the Merc manual. My first mistake is the alternator is 72 amps hot and 65 amps cold. But so far I have found nothing about voltage being fixed at 14.4V.
I assume the above gentleman has done his homework and what he says is true. Is there anything that can be done in the above scenario so as not to cook the batteries. By the way, I am not considering an alternator upgrade currently as it will affect my Merc warranty and confirmed in a phone call to them in Wisconsin.
"Grant October 12, 2019 at 11:45 am
Rick – you might want to reconsider holding off on that alternator upgrade – your Mercruiser 70A unit is internally regulated at a fixed 14.4V – and your $2,000 worth of new Fireflys are not going to like that long-term. They have specific float voltage requirements of 13.4-13.5V, and other criteria – see manual. They’re a great battery, but I wouldn’t make the investment until I had all my charging sources sorted out to deliver the appropriate charge profile they recommend…
So I did go into the Merc manual. My first mistake is the alternator is 72 amps hot and 65 amps cold. But so far I have found nothing about voltage being fixed at 14.4V.
I assume the above gentleman has done his homework and what he says is true. Is there anything that can be done in the above scenario so as not to cook the batteries. By the way, I am not considering an alternator upgrade currently as it will affect my Merc warranty and confirmed in a phone call to them in Wisconsin.