Originally Posted by svlamorocha
I do understand how regulators work and I can find many affordable regulators that will do well what I need (regulate absorption voltage and protect the alternator with temperature sensing) and more or less well something I do not need (switch to float) because of the way I use the boat.
My post is about alternators because I know that the Yanmar
Hitachis have weaknesses (for cruising use) that no regulator
can fix (namely for a given charge current
they heat too much and do not withstand high temperature). The only reason I have not moved away from Hitachis so far is that I was not prepared to pay Balmarīs price
for a hot-rated 100A alternator with 3.15" saddle mount and connectors for external regulation.
Let's get back to the basics:
Here's why the Hitachi (NOT Yanmar) alternators don't work so well: (This has been posted a gazillion times all over the internet
by Maine Sail)
(by Maine Sail)
Some alternators though, such as those made by Hitachi and found on Yanmar
diesels, are dumber than a pound of beetle poop. Actually, to the alternator, they are pretty smart but to your batteries and the speed of charging
they are flat out stupid. Why?
Hitachi alts with dumb regulators, and some others, limit voltage but also reduce voltage
based on alternator temperature. This is a self protective feature installed in the internal dumb regulator
to prevent the alternator from cooking
itself. Remember voltage is the pressure that allows more current to flow. So, if we reduce the absorbtion voltage, then we also reduce the current the alternator is supplying.. The battery
simply will not accept the same current at 13.4V that it did at 14.4V and as a result the alternator will run cooler. What do you suppose this does to your batteries over time.......?
The problem is that when cold you will get 14.3V to 14.4V out of the Hitachi but as the alternator heats up the dumb regulator begins to reduce the CV/voltage limit based on the alternators internal temperature. It is not uncommon to find a Hitachi alternator at 13.4V when hot. This is REALLY, REALLY DUMB....
If you have a dumb regulator, and notice the voltage dropping, it is likely a temp compensated dumb regulator. Get rid of it or plan to buy new batteries more often.
If you have a temp compensated alternator or a Hitachi alternator on a Yanmar you really are in dire need of external regulation if deep cycling a larger battery bank.
This is from:
Musings Regarding External Regulation - SailboatOwners.com
and this, too:
Hitachi Alternator and Smart Regulator Instal Question
If you want 80A out of an 80A alternator, you're gonna have problems. Why? 'Cuz it'll overheat. Regardless of what your automobile alternator does in terms of voltage, its rating is far higher than the load that is placed upon it.
Not so with boat alternators. Newer battery technologies allow higher charging
amperages since battery acceptance is much higher.
For example, our wet cells of 390 ah at 50% SOC will only take about 60A, and I installed a 100A alternator. If I had AGMs or another new gen battery technology, that load would be MUCH, MUCH HIGHER at 50% SOC. My SYSTEM would not work, then.
I also use the Small Engine
Mode from our Balmar
MC-612 external regulator. I did not include battery or alternator temperature sensing. Here's why:
Alternator heat, Regulator Controls, Small Engine
Alternator heat, Regulator Controls, Small Engine Mode
Small Engine Mode - discussion with link to the picture of the toggle switch: Alternator heat, Regulator Controls, Small Engine Mode
I essentially do it manually. MOst good electricians recommend temp sensing.
That's why temperature regulation (better than the Hitachi internal) is always suggested for a good electrical
You can't just swap alternators without understanding the SYSTEM and how you want to or need to run it.
There are other alternator sources, like Leece Neville, best prices from ASE Supply Outlet Store
Call Bob there, but order online for the pricing.
Leece Neville used to make the alternators for Balmar, but not their newer Series 6, which Maine Sail says is a good piece of equipment
Good luck. There's a LOT more, but I can't type it all in one post or one day.
PS - If you type "Hitachi" in this forum's search engine, you can find and read the original thread that Maine Sail posted this info in. It's also the second link in the Hitachi story above.