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Boat battery troubleshooting


LachieS

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Hello, 

I am having trouble with my boat's battery system. The issue is that the battery bank is running out of power very quickly. I have recently purchased a sailing catamaran with a set of four Delkor M31 lead calcium marine batteries. The bank seems to run out of charge very quickly once disconnected from shore power, for example, the enerdrive inverter for the 240V power system has an alarm which sounds with a "low battery voltage" error after not even fully charging a phone battery fully through a 240V outlet on the boat. We have not experiences the 12V power system running out, i.e. the chartplotter, lights and autopilot have never had issues offshore. 

There is also a solar panel system with victron bluesolar mppt charge controller. We have got the bluetooth dongle for this system and upon analysis have seen that the battery bank is going back to the bulk stage of charging every day, spending about 4-5 hours charging the batteries back up to the float stage. Is this normal to be happening? As when offshore we are left without 240V power for most of the day unless we run the engines to charge the batteries faster. We also have an epower battery charger, should this be left on whilst connected to shore power or run whilst offshore? I am new to this world and not totally certain about how the 12V/240V systems work/interact. The batteries are not too old (5 years or so) I am at a loss for what could be causing this issue. Any sort of help or tests we could do for these issues would be fantastic to hear. Please let me know if you need any further information. If the batteries are dead which I fear is most likely, which type of battery would you recommend is best?

Thank you so much. Lachie 

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It’s hard to say what is wrong but some things to consider:

I think lead calcium batteries have an average of 5 year life span, it would depend greatly on how they were treated over their life.

You might want to check what might be/if anything is running off the 240v inverter when off shore power. I had an electrical set up once where I needed to timber to switch the inverter and certain appliances off. AirCon will run down batteries super fast.

Check your solar charging components are working. I once had a solar charger fail but it wasn’t totally obvious without individual testing.

I hope that gets you started on a solution path. Summary is to check your batteries individually, check in puts work (solar, chargers), check outputs (excessive current drain from appliances). 

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Given all in our family do some pretty remote trips away in 4x4's and boats, I invested in a decent battery health tester which I would advise anyone who likes boating and traveling off the beaten track should do.  Testing the battery health also helps save money when some less scrupulous sales people tell you that you need new batteries when you don't.

My boat has dual batteries and bluetooth so that I can see the battery charge while it's sitting on my drive, without the need to touch anything on the boat. If my boat isn't used for a few weeks I do charge either with home or using a portable solar blanket. I did upgrade the solar regulator to a victron, which again has bluetooth and many other functions. This is the tester I use Foxwell Battery Tester BT715 Battery 12/24V Analyzer.

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Check that your charging devices are suited to and set for calcium batteries, they need a higher charge voltage than a standard lead acid battery and gel batteries. Typically 14.7v for bulk charge and 15.5v for equalising. 

If you own and can use a multimeter you can check your battery voltage when the charger cuts off ( to check correct charge voltage) and again maybe an hour later ( make sure nothing is connected to them in this time - take a lead off the battery so it is isolated ) this test for any leakage or crook cells  - you will get a voltage drop but it should settle and not drop below 12v if it does your battery is buggered . 
You can test for any parasitic current draw ( less than 10 amps ) using the amp function of the meter - once again everything has to be switched off while testing this ( then switch the inverter on to check its standby current draw ) - nothing connected to its 240v outlet though . If you’re getting either zero or at worse 10ma current draw then at least if you fit new batteries it’s not going to kill them . Don’t try to do a full load current draw test ( ie while the inverter is supplying power to anything ) with a multimeter as they typically only handle 10amps - you need a a clamp type amp meter for this test as they can handle hundreds of amps .
You need to check that things like the fridge and bilge pumps  aren't running constantly also - fridge is easy , un plug it and see if your battery  life improves markedly and the bilge pumps try to put a hand on them to feel if they are vibrating or hot - you may be able to hear them running .

If you’re not good with electrical things get an auto or marine electrician or maybe a marine mechanic to check it for you - dumping hundreds of dollars of new batteries into a faulty system will just empty your bank account!

I would stick with a lead acid type battery ( calcium, gel or AGM - Deep cycle Marine batteries ) though as they are safe and don’t tend to burst into flames like lithium batteries do and you won’t need to change your chargers to lithium capable units either .

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