Bow thruster turning off chart plotter and sounds weak

So I'm bringing the boat over to the west coast of FL this weekend, and I noticed today when I used the thruster in a lock it sounded weak and my new Garmin plotter also turned off (I'm guessing from low voltage). The thruster does not have its own separate battery.

The battery system has 4 group 27 AGM wired parallel and then there is a separate start battery for the engine and gen. The starter also sounds weak on crank up.

How do I load test for a bad battery?

I put a multimeter on the start battery when the engine was running and it only showed 12.7 volts. Is that low? It has a Balmar 110 amp alternator and a Balmar Max Charge regulator. The house bank showed 13v when underway.

Greetings,
Any marina mechanic should have a battery load tester. Aside from that are your drive belts tight?

12.7 is low with engine running. Should be 13.8-14.2. Check alternator terminals with digital volt meter with engine running at elevated rpm of say 1200. Could be weak alt or crapped out isolator or switches in wrong position.

With batts at 12.7, no suprise that thruster dropped volts enough to kill plotter.

Ok. Thanks y'all. Getting ready to pull into FFs dock. I'll check it out then. After a beer. ?

Dirty, loose and/or bad connections is what I'd look for first. Both Pos and ground.

cardude01 said:

So I'm bringing the boat over to the west coast of FL this weekend, and I noticed today when I used the thruster in a lock it sounded weak and my new Garmin plotter also turned off (I'm guessing from low voltage). The thruster does not have its own separate battery.

The battery system has 4 group 27 AGM wired parallel and then there is a separate start battery for the engine and gen. The starter also sounds weak on crank up.

How do I load test for a bad battery?

I put a multimeter on the start battery when the engine was running and it only showed 12.7 volts. Is that low? It has a Balmar 110 amp alternator and a Balmar Max Charge regulator. The house bank showed 13v when underway.

Click to expand...

Yes, that's low if measured with the engine running, depending. Since you say it's sounding weak when you start... that battery may just be old, tired, ready for being put out to pasture.

Are the thruster and plotter running off the house bank (4x G27s) or the separate start battery? If they're running off the engine start battery, maybe that'd be an indication you're using all the amps your alternator can provide (electronics and thruster), none left over for charging.

What charges the house bank when underway? The engine alternator? Or...?


If your house bank is showing signs of weakness, you could read threads about upgrading to 4x G31 (about 400 Ah) or to 4v 6V golf cart batteries (about 440 Ah) in essentially the same footprint.

-Chris

Thrusters really work best on their own properly sized bank which eliminates this sort of problem. A Group 27 sounds pretty small for a thruster, let alone powering the whole shebang, and a thruster can cause a big voltage drop when engaged. If you are out of gear, in neutral at the time, you can try revving the engine and seeing if that gives you more oomph, problem is one often times IS in gear and using the thruster at the same time.

Alternator puts out 14.2V at 1200 RPM and all cables are tight on top of batteries.





And yes the thruster works off the battery bank.





There is also this regulator and splitter thing but I don't know how to check it.

I'm thinking all these batteries maybe be OEM, so they could be 2008 vintage, just FYI.

I guess the alternator is supposed to keep all the batteries up underway, but by the time I docked my danfoss fridge compressors shut down from lack of juice. I'm not sure much charging is going on underway.

Nice batteries and a nice installation. 7 years is beginning to reach the lifecycle of Lifelines, but I'd check out the alternator first. Sounds like you are near Ortona? If so Mark Richter is a great electrician and frugal cruiser. 863-517-1152

Mark is the next dock over. Forgot all about him. Thanks.

Edit: called him up but he's at a party.

Changed the oil and filter on the genny today so I might use that as another charging source underway tomorrow. Wait, will the genny running the battery charger and the alternator get along?

If alt is putting out 14.2 and batts are at 12.7, somehow the alt is not connected to the batts. Do you have a 1-all-2 switch or a charge relay?

Some boats you need to put switch in all for house bank to charge with engine and start bank.

Also check start bank batts and make sure they are seeing alt voltage.

Ok. Let me check that.

This is how I was running while underway.

From my "owners manual"



Hooked up to shore power and battery charger has the batteries up to this:



But underway it is a different story. Start battery was at 12.7 and house batteries at 13.2 a few hours into the trip.

Could it be that Balmar "duo charge" or maybe the regulator? How do I test that ?

Here is that Balmar regulator and "duo charge" thing that I think splits the charge between the house and start battery.



I was afraid to put the multimeter on that thing for some reason...

With engine running 1200 and charger off, check the volts on the duocharger thingy- one red lead at top is input, other at top is output. Use digital volt meter with neg lead going somewhere to a decent ground or bonding.

If that thing is in operate mode, both batts shoud be connected and volts on the two top terminals should be the same within a few mV.

Note the thing may have some sort of timer before it connects.

????

Thanks. Will try that tamale. Very quite around here now...

Besides sorting out the charging/battery problem, it may be worth swapping the power supply for the plotter over to the house bank.

Balmar has some pretty good troubleshooting techniques on there web site. Go to the manual for the duo from there web page or just google Balmar digital duo trouble shooting and you will get a link to the manual. It should be a big help.

So underway again this am. Checked the electric panel and there is a battery test switch that checks bank one and bank two. 1 was at 14.2V and 2 was at 13.8V at 2200 rpm. Yesterday when I checked the batteries themselves at idle I got 13v and 12.7v. Maybe the rpm is the difference, or maybe my check at the batteries was not accurate.

So maybe the batteries are charging, but just old and weak?

If you were on charger all night, that likely topped up batts. See if volts drop during the day. Do the check on the duocharger from a couple posts up.

Ok. Will do. Thanks ski.

The voltage going into the "duo charge" is only 13.1 and 12.9 coming out, so something is wrong I guess.

Tried calling Balmar but they aren't open today.

Can I run the genny to power the battery charger while underway? Or will that confuse the alternator?

Looks like you have an amp meter as well as a voltage meter on your panel that monitors your batteries. How many amps are you drawing when you are running. A weak battery usually takes a heavy charge and may be loading down you alternator. If the amps are higher than what they had been when things were working well then I would be leaning toward batteries but it could be a load that is drawing excess current. Ski, does this sound right?

I would not trust any voltage readings on your panel. A multimeter at the battery terminals is going to give you more accurate information. I think the Duo Charge is essentially a battery combiner that allows your alternator to charge both battery banks. When the house bank is full it separates the banks and charges the start battery alone.

Which battery banks are the thruster and chart plotter hooked up to?

Voltage numbers on the batteries are not going to give you all the information you need. The real question is how many cranking amps your 7 year old batteries can provide to the thruster. A good battery tester can give you this information.

Running your generator and the engine at the same time will not hurt anything.

Thruster and plotter hooked to house batteries.

So when I use the thruster should I measure the amp draw at the house bank? How do I do that?

Panel says pulling only 2 amps underway. When I hit the thruster it didn't change, so that's not accurate.

Sorry for all the questions, very new at this obviously!

From reading the Digital Duo manual, the duo stops combining and shuts down when loads exceed 30 amps. From the manual,
"In applications where the Duo Charge is used to support larger capacity starting batteries (such as 4D and 8D models) or windlass and/or thruster batteries, there may be instances when the 30-amp capacity of the Duo Charge’s circuitry may not
provide sufficient current to satisfy demands. When used as a stand alone charge source, the Duo Charge is designed to discontinue charging when demands exceed its capabilities. At that point, the Duo Charge will wait for a short period and
query if the demand has diminished to below its 30-amp capacity. If so, the Duo Charge will continue charging. If demand continues to exceed capacity, the Duo Charge will continue to shut down, while checking periodically to see if demand has
diminished."
Given this I would check your amp draw with loads as you are typically running and then also when you use the thruster. Check on both house and engine bats. If your typical load is often above 30 amps, IE using an inverter to run fridge, then it may be normal given the electrical design and would lead to run down house bats. Here is the link to the manual for the duo. http://www.balmar.net/pdf/duo charge manual.pdf
Keep in mind this is best guess without actually being there....

Thanks so much. Will have a look at it again after we dock.

I did not see your message above mine till now. I would expect that the amp meter on the panel switches with your voltage monitor switch. Not sure though but many are wired that way. If you have an electrical diagram of the boat it would show that. Otherwise you would need a clamp on DC meter and clamp it over the large red feed wire coming from Each of the battery banks. I will be out of touch for the next week and a half starting tomorrow, so if I don't answer that is why. I will be in and out rest of today and this evening. I strongly suspect all your batteries are getting weak but it would be nice to confirm everything else is working correctly and that there is no minor design issue with loads and the duo as I mentioned above.

Rogerh said:

From reading the Digital Duo manual, the duo stops combining and shuts down when loads exceed 30 amps.

Click to expand...

Ah yes, you are reminding me why I didn't buy one of these. If you have a big battery bank and/or you draw your bank way down such that it will accept more than a 30A charge rate, this thing shuts off and leaves you hanging. Why is doesn't just current-limit to 30A is beyond me. At least then it could get you charged back up over time, but the way it operates now, if you get too low you are shut out of luck.

This sounds to me like old batteries. They can't put out the power when the thruster needs it and the volts drop. The charger or alternator is not designed to put out the current that a thruster needs.

Do a load test on each battery when it is disconnected from the charger and the other batteries. After seven years it may be time for new batteries.