Print Page | Close Window

Battery Power!

Printed From: Laser 28 International Class Association
Category: Laser 28 General
Forum Name: Sailing
Forum Description: Everything on sailing the boat
Printed Date: 28 May 2024 at 12:55pm
Software Version: Web Wiz Forums 11.03 -

Topic: Battery Power!
Posted By: fatjohnz
Subject: Battery Power!
Date Posted: 09 August 2011 at 12:33pm
I've noticed that my batteries are becoming depleted over time so I took some measurements.
(1) With a charged battery active, I read 13.5 volts across the terminals with the engine running. That's a good thing.
(2) When I switch to 1+2 and add a depleted battery to the loop, the voltage across the terminals of the good battery drops below 12 volts with the engine running.
So it seems to me that the alternator is not holding up its end of the bargain but I don't know what is typical for this 8hp buhk.
I appreciate your insight as to whether this is normal... maybe I should add a solar charger..., thx, js

Posted By: Cayuga
Date Posted: 15 August 2011 at 4:50pm
When you rev the engine up above idle does the voltage increase? I get about 14.2V at cruising speed and around 13.5 at idle. Is it possible that the depleted battery is so shot that it won't take a charge? It sounds like the good battery is trying to charge the depleted one.


Posted By: fatjohnz
Date Posted: 15 August 2011 at 10:10pm
thanks Andy, I did some reading and took some measurements and I think I need a solar charger to keep the batteries topped off. After our long distance outing, each battery took 48 hours on the home charger and its not realistic to think they will recharge on the iron genny. js

Posted By: Cayuga
Date Posted: 16 August 2011 at 12:25pm
Maybe, but we just got back from 9 days of cruising and battery power wasn't an issue. We did do a lot of motoring though.

Posted By: WarBird
Date Posted: 20 August 2011 at 12:06am
The alternator needs a certain minimum field voltage. Going 1+2 may take your battery bank below that threshold. Take your dead battery home and charge it. If it doesn't hold a charge it will : slow you down it is dead weight, kill your other battery, piss you off. Get a new one. With dissimilar batteries, you should keep them seperated, charge one, then the other while you motor. There is nothing you can do to make a battery last longer, there is plenty you can do to kill a battery prematurely. The power use should be such that you really only need one battery unless you do lots of overnighting. Leave the extra battery in the garage. The motor is easy to rope start anyway.

Posted By: fatjohnz
Date Posted: 20 August 2011 at 11:07am
Thanks WB. I took some amp measurements and each circuit uses between .25 to 1.7 amps with the stereo being the biggest consumer. Then I measured the voltage as I add circuits. The voltage at the battery drops as I add circuits until it looks marginal whether the alternator is keeping up.
The spec on the alternator says 210 watts at 12 volts which apparently converts to 17 amps if I'm doing the conversion correctly. This should be plenty of current even with all the circuits on.
So I guess my alternator is marginal...
That said, a solar charger would be a good addition to get the batteries fully charged between race days. If I know I have a 100% battery then the 2nd can stay ashore.
Just for yucks, if you get a chance, take a voltage reading with all your circuits on and the engine idling and see what voltage you have at the battery. thx, john

Posted By: WarBird
Date Posted: 20 August 2011 at 9:59pm
Sold the boat this spring, racing a B-32. At idle, your volts will be only a couple tenths higher than when everything and motor are off. At about 1/4-1/3 throttle your volts will go to about 13.7-14.1 if I remember right. This forum will correct me gently if I am wrong. Go to and make these checks. As stated in that thread, the regulator seems pretty solid and the alternator(gen) almost can't fail.

Posted By: WarBird
Date Posted: 20 August 2011 at 10:14pm
Maybe it is not the regulator. Did you check some of this? You have three wires (two?) coming from under the fly wheel. Are they at (I have found) 12-18 vac while you run? Those wires go right intothe regulator. The wireout should be 13-13.8(14.2)v depending on revs. Are your grounds all good? That regulator is a pretty simple affair and I have seen some well abused units working fine . Your battery-engine ground cable has been sitting under the floor board for 25 years, check it carefully. Make sure your start switch wires and contacts are clean. The engine will run with the key in the "off" position so check that "on" position wiring is good, that is what enrgizes your charging system. Stuff get put back in that compartment and could knock that harness arround. Some of the multi-pin conectors on the engine/harness get moved arround while cleaning or maintenance is performed. Some pins push out of the connector body a little and don't make contact. Try pushing them in individually, gently with a dental pick . Wire arround the connector if pins are broke or wire has sepperated from the pin. There is 25 years of stereo, vhf and instrument wiring through that area. Focus onthe charging stuff and make sure you do not have old wiring (+12vdc) laying arround getting wet or shorting to metal. Good Luck

I've pasted my input there but check that thread briefly. You have 3-5 circuits, the largest being 1.7 amps. all things being equal, you have some connection/grounding issues. Swear to GOD this is a true story. For 1/2 a season I climbed behind the head and pull started the motor every race, day sail etc. because it only clicked and i was afraid of the repair cost.(It is hot and sweaty back there sometimes but I got good at 1-2 pull starting). The battery posts were snug but not tight. tightening the posts made everything was good but it was August at that point!!!! True story, I thought the connections were good, they were not.

Posted By: WarBird
Date Posted: 20 August 2011 at 10:45pm
My thoughts are all on charging one battery that is not dead! I was skepticle of 109(rapscallion) that had max13.9-14.0 out put. Loaned him a newer battery and he sailed a solo 130 mi race running auto pilot on battery for 4 hours befoore charging for one hour while still running auto pilot(tillerpilot). he had no problems with juice for30 some hours! That motor is crude, and rough, and stoneage but it seems to work and charge through about anything.

Posted By: fatjohnz
Date Posted: 01 July 2013 at 8:21pm
I've been re-reading posts about charging cause my battery died (again) after an 8hr + 8hr road trip. Do I read your comment correct that you are supposed to leave the key in the 'on' position for charging? I was told, after she starts, to put the key back to the neutral position. thx, js

Posted By: bal149
Date Posted: 01 July 2013 at 10:31pm
key in off position, that is straight up and down, turns off the electrics- motor will run anyway as the injection  is mechanical however will not charge. You should turn 2 clicks clockwise to engage the starter then move back one click under power, two clicks to shut off and then back to middle position once it shuts down

Posted By: fatjohnz
Date Posted: 02 July 2013 at 6:31pm
Making sure that the key was in the run position did not help deliver any extra voltage to the batteries. I checked the SA link that WB posted and they said their problem was the ignition switch. Not sure how they determined that.
The wiring diagram in the shop manual is a little hard to read. But tomorrow I'll check the wires from under the fly to see if they are delivering 12-18vac to the regulator. Looks like the bottom tab of the regulator is the battery feed.
And then what... its hard to see where the regulator activation lines are coming from but I'll try to trace them back.

Posted By: fatjohnz
Date Posted: 04 July 2013 at 7:26am
Hi, I disconnected and check the 3 wires coming from the engine top (alternator) and find 12.5 vac on each yellow-to-red leg, (25 vac yellow-to-yellow).
What I found is a green line coming off the regulator going to the amp light which is 9v. The other side of the amp light is connected to 12v so the amp light is glowing due to the voltage diff.
I conclude that if the regulator was working correctly , that 'sense' line should have 12v on it.

Posted By: Winner
Date Posted: 07 July 2013 at 8:54pm
Somewhat related but I've been having trouble starting the engine this year. Last year (my first year with the boat) it always fired up no problem.  Now, it needs to turn over for a good 5-10 seconds and a few times I've needed to select both batteries.  Once the engine is warm (i.e. after a sail when heading back to the dock) the engine always fires up right away.

I did voltage checks across the battery terminals and found:

engine off: 12.2/12.9
engine at idle: 14.6/14.3
1/2 throttle: 14.6/14.3

A quick check of the wiring and I really don't see any corrosion or anything but I'm completely unfamiliar with the electrical system on this boat...

These voltage values seem normal based on what I've read above but I'm kind of stumped here.  Do I need new batteries or is something else the problem and if so, what's the best way to find out?

Thanks in advance for the help.

Eclipse #240
Thunder Bay, ON

Posted By: Mike V
Date Posted: 07 July 2013 at 10:15pm
Hi Chris
I would have the batteries tested. One bad battery can affect the other if the switch is on all. Your local garage will load test them for you. They will also affect charging voltage. Your charging voltage looks ok. It would be nice to know how many amps it is charging at. Also check the engine ground. Many techs overlook the ground side of the circuit. Ask the tech that load tests your battery and let me know the results. What is the voltage while cranking? A slow cranking diesel is always hard to start.

Posted By: fatjohnz
Date Posted: 08 July 2013 at 11:55am
Crinmar didn't have a regulator in stock so I did a little research over the weekend. I could see 'Saprisa' and '7172' stamped on the regulator. I found a cross reference/sub-up to a Saprisa 4172.
I found these available on the Italian ebay site and also Wood Auto distributor in the UK. So I spoke to a lovely lass at Wood Auto this morning. $50 for the regulator and $35 for 3-6 day shipping to New York.
Got my fingers crossed. js

Posted By: fatjohnz
Date Posted: 14 July 2013 at 10:36am
problem fixed! js

Posted By: Winner
Date Posted: 06 July 2019 at 5:44pm
Originally posted by fatjohnz fatjohnz wrote:

problem fixed! js

Hi Fatjohnz,

I think my regulator is pooched as well.  Did the one you ordered from Wood Auto have the same plug arrangement or did you need to use a new wiring harness?

Eclipse #240
Thunder Bay, ON

Posted By: fatjohnz
Date Posted: 07 July 2019 at 10:44pm
The large connector is attached to the regulator by a bunch of stubby discrete wires. The quirk was that the connector tabs on the new regulator are not the same size as the slip on connectors coming off the wiring harness.
I think I just opted to put the oversize connectors on the smaller tabs by squishing them a bit to ensure good electrical contact than wrapping a big tape loop around all the connections to hold them firmly in place (so they didnt vibrate loose).
I could take some pics. lmk, john

Posted By: frfletch
Date Posted: 11 October 2019 at 12:36am
That's weird. WE cruise Voila in the summer for 3 weeks at a time using whatever we want on the boat and never charge our 6 year old Category 24 AGM battery. All our lighting is LED. We carry a 14AMP lithium just in case, but have never had to use it. We race the Southern Straits race of 100 km taking nearly 24 hours with nav lights, instrument and radio and are still able to start the engine after finishing. Perhaps you are over using the air conditioner.

Print Page | Close Window

Forum Software by Web Wiz Forums® version 11.03 -
Copyright ©2001-2015 Web Wiz Ltd. -