Originally Posted by gamayun
Recently installed a bank of 4, 6-v Lifeline AGMs (GPL-4CT) and and 1, 12-V starter battery (GPL-2400T). Given what I've been reading about charging them correctly (whether at the dock
or on alternator), I'm having concerns that the ProMariner (ProTech 1220i) that came with the boat, might not be up to snuff. It has been set for AGM1 type battery and 1 hour absorption. Now I am reading about smart battery combiners, and how some smart battery chargers are not really that smart, and temperature compensation during charging, and how much AGMs love fast C rates, and the Peurkert constant, and on and on till my head
has started spinning. Also read Practical Sailors' article on the problems with sulfation when these batteries discharge. My plan is to upgrade the alternator (it's currently 50 amp), add solar panels
by the end of this year, and do more off the grid sailing in another year or two. Right now, I keep the power cord mostly hooked up and the voltage seems to float around 13.3. This was a big cost investment and I'd like to get started on the right foot to get the most life out of them. If anyone has already gone through this thinking process and would care to share their thoughts on this, it would be greatly appreciated. If I'm overthinking it, I can take that criticism, too
I can only give you my experience. I'm sure there are a variety of smart (alternator) regulators. I have "Next Step" from "Ample Power" for over 12 years. I think they are still based in Seattle
. It required a heavy cable from the alternator and as I was busy with work I got a sparky to install it. It's mounted on a board inside a quarter berth adjacent to the alternator side of the engine
and above 2 of the batteries which being AGM
can be installed under the berths on each side.
There are several connections including battery temperature and voltage sensing.
At the same time I replaced the stock 55 amp alternator with a secondhand 80 amp originally on a larger Yanmar
. It required some simple internal work to operate with an external regulator
Once it was all installed and operating correctly, the first thing I noticed was belt slip and a heavy load on the 20 hp Yanmar
after the house batteries had been used at anchor
overnight also running a small Engle electric
fridge. Then there was belt wear and constant readjusting. The alternator got very hot. Too hot to leave my hand on it.
I fixed all that by having an engineer
make a machined double pulley for the alternator for two belts. He also grafted a matching second pulley on the engine
pulley which I easily removed to save his travel. I had the alternator pulleys made 10 mm larger diameter than original to increase the belt wrap and decrease the load on the motor
and the revs of the alternator. That doesn't seem to have noticeably affected the charge rate. Part of the alternator overheating
was from belt slip and part from working hard for the first hour. The oversize double pulley overcame both those problems. The original single
alternator pulley was 2 bits of pressed steel
which gave little contact area.
I understand that some competition motor
vehicles use a larger pulley on the alternator to reduce the power absorbed by the alternator. From memory 746 watts = 1HP and 80 amps X 14 volts = 1120 watts. That's 1, 1/2 horsepower. The little Yanmar 20HP is really only 13HP or less at the prop. So with the alternator at full charge there is 10 / 15 % power loss. It's not a problem any more with the larger pulley and the charge is fine.
Then I installed a reasonably large plastic fan from an electronics
supply shop. That blows onto the alternator from the front of the engine box and is wired to the back of the "ignition" switch accessories terminal with its own cable, and spade fuse near the switch. It operates all the time the motor is running and has given no problems.
I also have a hard wired Pro Tech mains charger for use at the dock but seldom use that now as solar is all I need. The Pro Tech is very good and you will be familiar with that.
After all that, the system works fine and my AGM house batteries must be 13 years old by now. With LED lights
(now) and still with the electric
fridge the batteries last fine overnight at anchor
. My AGM start battery only lasted 11 years.
A weak start battery is risking over cranking and water
in the exhaust
I'm sure any good make of smart regulator would have required that extra work as the idea is to make the alternator work hard for an hour then step down the charge to avoid overcharging. It doesn't kick in until 10 or 20 seconds after starting, to avoid load and hard starting.
Oh, one other thing. My wind
gauge not far from the regulator cable goes permanently 90* the wrong direction with the motor running and needs resetting for when I sail. I recently read a learned article written by a professor from the University of Oregon
about marine electrical interference
. One of the many things he explained was the effect of high current in smart regulator cables
affecting instruments. One day I will wrap the cables
from the alternator in wire braid and earth each end to see if that prevents the interference
I hope I haven't put you off smart regulators because after all that, I think it was worthwhile. I have 2 Optima yellow top batteries for house, and one blue Optima for start. I also have a completely isolated smaller AGM with its own solar supplying the instruments. I cooked 3 chart plotters motoring long distance using the Autohelm
both originally on the same house circuit. They were replaced free although out of warranty. An Autohelm
will generate spikes both + and - which can't be filtered out. I eventually realised that. Hope it all helps you. G.O.