[pkilty]

Hi All,

I have recently purchased a 1982 Pearson 37. I have spent the last month discovering the things that let's just say the previous owner failed to mention and the surveyor failed to find. It's a great boat, but in need of some love, cash and a lot of elbow grease. I have three batteries that I know are not properly wired. One deep cycle type 24 paralleled with a wet 4d for my #1 and a single type 24 deep cycle for my # 2. I think they are all of different ages and plan on scrapping them before next season. I have a "new" 85a alternator with internal regulator.

My problem is that with the selector switch off all three batteries will hold a
decent charge for several weeks. With only #1 or #2 battery on overnight with just a very small hotel load, both #1 and #2 are dead by morning.

I have checked draw on the main distribution panel and after thinking I had an aha moment found the vhf wired to the hot bus.This accounted for the draw when the panel was 1st energized.

The only thing common besides the switch is the alternator.

Any thoughts?

Thanks,

pkilty

 

[mitiempo]

Hi
Something is definitely wired wrong. Trace the wiring from batteries to main switch - I assume it's 1-2-both-off type. Find out if any wires go anywhere besides the switch and where they go. Make sure the main switch is wired properly. The hot from bank 1 should go to #1 position, hot from bank 2 should go to #2 position and common (output) should go to your distribution panel and the engine starter. Somehow I think your battery banks are common to each other regardless of the switch position and there is a draw on them with the switch on #1 or #2. I guess you should get in there with a multimeter and with the switch on 1 or 2 see which items are getting voltage. That's my best guess right now. Good luck and let us know what happens.
Brian

 

[badsanta]

Write it down and make a map. If you cant actually see and feel the wire the whole long way it is no guarantee it goes where you think. Label the wires as you figure out what goes to what. You also may have a bad battery that drains the system. I would take them all out to a battery store and have them charger and tested. Also batteries should be the same type and size and age as different types (gel and wet) charge at different rates.

 

[Zanshin]

Do you have a multimeter? If so, perhaps your alternator is either wired incorrectly or broken. Can you disconnect the cables from the alternator and measure resistance (simple "infinite" or "full'" continuity is enough)?

 

[btrayfors]

Hi All,

....

The only thing common besides the switch is the alternator.

Any thoughts?

Thanks,

pkilty

There you have it! If the alternator is indeed "common" to both banks, then they are effectively paralleled, unless there is a battery isolator installed.

Bill

 

[mitiempo]

btrayfors
yes, but that doesn't explain the dead batteries with only a small load overnight. There has to be another issue.
Brian

 

[Zanshin]

Here I assumed that your alternator had 2 outputs and that an internal diode might have been broken. With a multimeter, measure the voltage across the + and - poles of one battery after the switch has been set to "off" for a while. With all devices switched off and breakers off, switch "on" and see if the voltage changes - even a small short dip will tell you that you've got a consumer switched on or have a current drain in your power lines. Short of an ammeter you'll have to start disconnecting devices one by one to find your problem source.

 

[SteveInMD]

I think you need to use a load test device on the batteries to see if they are actually good or not. If not, trouble shooting is going to be difficult.

 

[davidpm]

I think you need to use a load test device on the batteries to see if they are actually good or not. If not, trouble shooting is going to be difficult.

I second this option. First thing to find out is the condition of the batteries.

Some bad cells can cause all kinds of odd behavior. They seem to hold a charge unders some conditions then loose the charge way too fast.

First rule of troubleshooting. Don't go first to the exotic problems, rule out the mundane first.

I have taken my batteries to the nearest NAPPA store and let them charge and load test them.
They can tell you their exact condition.

 

[timebandit]

I thinking the batteries also.

It seems like with three batteries you should be able to pull 10 amps all night and not kill the batteries and it should be easy to find a load that big.

 

[SteveInMD]

If you don't want to take the batteries to a shop for testing, you can buy, borrow, or rent a load tester. Or a marine electrician can test them in place too.

Once you know you have good batteries that are properly charged you can carry on trouble shooting, if you still have problems.

 

[btrayfors]

There appear to be two things going on. Your first question was why does an apparently disconnected battery drain? I believe you answered that yourself with the "common" wire to the alternator.

I completely agree with the other posts re: checking the condition of your batteries. Batteries lose capacity as they age, particularly if they aren't well cared for. This is not the same as "ability to hold a charge".

It's perfectly possible for a battery to appear to take a charge, and to hold at around 12.6VDC for quite a while with no load on it. However, the capacity of the same battery could be seriously compromised, so that it will only deliver a small portion of it's rated capacity before the voltage drops to unusable level.

The only way to know the condition of the battery's capacity is to give it a proper load test. The quickie load tests used by garages, and the battery condition devices which measure internal resistance (like the Micronics series) are indicative and reasonably accurate, but the only way to know for sure is to put a "20-hour" load on them and see how much energy they deliver over time.

My guess is that the batteries are shot, and you'd be well advised to:

1. be sure you've sorted out any problems in the wiring of your DC circuits;
2. replace the batteries with new ones; and
3. take very good care of them, 'cuz they ain't cheap!

Bill

 

[badsanta]

Please report back with the diagnoses. my bet is $800 for batteries and $150 for an Eco charger

 

[pkilty]

Thanks to all for the good advice. Here is the latest on my battery drain problem.

1. My battery switch is wired correctly. My #2 battery is bad.

2. I have isolated the hot feed for the fuse/switch panel and have no unexplained current draw.

3. I do have an off the scale draw on the ignition/alternator circuit with the ignition switch off. I have an off the scale draw on the ground side of my alternator.

4. My alternator is charging at 14+ volts when running and has good continuity.

My suspect list includes the ammeter gauge or the voltage regulator. I have enclosed a link to the wiring diagram for the universal M25 that is very close to my boat. Thanks is advance for any help.

Universal Diesel Engine Owners Manual - Wiring Diagram - Marine Diesel Direct / Torresen Sailing Site

pkilty

 

[mitiempo]

To solve the possible ammeter problem replace it with a voltmeter and run the alternator output direct to the battery - house battery if using an Echocharge, or direct to the Main switch and thence to the batteries. With a heavier gauge wire of course such as 4 or 6 gauge depending on alternator output. This will not limit the charge your batteries are getting. I can't see how the voltage regulator would cause this and you say your alternator is charging ok - 14+ volts. You say you have an off the scale draw on the ignition circuit with the switch off. What are you measuring between to get this?
Brian

 

[pkilty]

Brian,

Thanks for the suggestions. I think I will plan on changing a few things around before next spring. I have always thought an ammeter is a more useful gauge than a voltmeter for judging the loading and charging of the electrical system.I have a voltmeter for both battery banks on my distribution panel.I am open to other ideas regarding this position.

When I look over the wiring diagram the battery/instrument panel feed and the alternator output are on a common post on the ammeter. The next possible draw point is the ignition switch which is brand new. If the ammeter was grounding out back to the battery it would account for the draw. I am thinking out loud not stating facts so any and all suggestions are welcome...

Thanks,
pkilty

p.s. I was checking current amps on the ground side of the alternator with my multimeter.

 

[mitiempo]

Off the scale between the ground side of the alternator and what other connection? As far as ammeter vs voltmeter, the voltmeter will tell you that the alternator is charging which is just about all an ammeter on the engine panel will tell you. The problem with the ammeter is that unless you have a meter with a separate shunt the charge current has to pass through the meter. These went out of fashion when charging systems started to have a larger output - larger than they could handle. The best solution to battery status is a Link type product from a company like Xantrex or Victron. These tell you much more than a simple ammeter or voltmeter will. All you need at the engine panel is an indication that the alternator is charging.
Brian

 

[lynger1]

Hi yes batt should be the same but this is not the main problem
1- change alternator to on with build in regulator best 80 amp
Just go to yhis site this will help you a lot
http://www.tb-training.co.uk/cover.html
Lynger1

 

[witzgall]

I will double the suggestion of a AH gauge type meter like the link. We have one for our house 48v battery backup system. I actually "Borrowed" it for the boat, and the info is so helpful. With reasonable certainty, you KNOW how much capacity you have, how much you have used, and at what rate. It also will tell you if you have a large ground fault, and if you turn things of and on, how much juice each electrical item on the boat uses. If your ammeter is analog you will get the instantaneous reading, but not as accurate as a digital meter.

I think the mack daddy of these is the Pentametric meter Bogart Engineering: manufacturer of the TriMetric battery monitor which measures volts, amps and amp-hours for battery systems used in homes, RV's and boats. It does everything the link meters do, for more banks, and also can output to a computer for analysis. We don't have this, but the Xantrex we do have is a rebranded tri-metric meter from them.

Chris

 

[pkilty]

Thanks for all the great info and monitoring suggestions. I plan on doing a major overhaul of the engine and charging systems before next season and I will incorporate much smarter battery monitoring. I will for the time being replace my old ammeter with a strait voltmeter and run the output from the alternator to the common post on my battery switch with a heavier wire. I think it only has a 10 gauge wire running to the ammeter and it is a 80 amp alternator.

It is funny, when I was talking with the surveyor about this boat he said the hull, deck, rig and sails where in great shape, but the lack of maintenance could lead to a "death by a thousand cuts". I think a feel a really good paper cut coming on. If she didn't sail so dam well I might get depressed.

pkilty

p.s. the current draw I measured was from the alternator ground and the main ground to the engine.