Help me to find what's wrong!

Guys
Since I launched my boat I have had something wrong with my electrical set up. I knew from the beginning that electricity, would be the least perfect of my systems as I had to rely on others to set it up. My knowledge in this field is minimal not to say that it is null.

I have 5 x 150 Amp/hr house batteries which I always keep charged. They only supply other systems but engines. There are dedicated batteries for engines, and pretty soon for the BT and Windlass when I connect 2 x 220 Amps/hr for the purpose.

So, why every time I turn on pumps, salt water, fuel transfer or even the fresh water one while opening the tap, my lights dim when they start? Is this normal? if the batteries are fully charged, why they cannot keep up with a pump starting?
Somebody told me that I should review the wiring sizes as I may have inappropriate size cabling all over. Is this a factor? What else should a think of?

Thanks for your ideas.

Fernando

I'd start by checking all your battery connections. Especially the ground connections. Take them apart and clean them even if they look good.

If that doesn't help start looking for the drop down stream of the batteries. Get a good test meter.

You have a voltage drop somewhere.

This is all assuming you have proper battery voltage to start with.

Capt.Bill11 said:

I'd start by checking all your battery connections. Especially the ground connections. Take them apart and clean them even if they look good.

If that doesn't help start looking for the drop down stream of the batteries. Get a good test meter.

You have a voltage drop somewhere.

This is all assuming you have proper battery voltage to start with.

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+1

Agree w/ Capt Bill - many possible sources of problem...wire size only one but likely no the most probable...bad connections or weak batt'ys more likely.

A good resource for learning more about electrical is a book by Nigel Calder

It has sections on troubleshooting procedures to follow.

BTW - Nice looking ER

This may be a silly suggestion, but check to make sure that your battery bank is actually connected properly and that the terminal connections are good. While it is unlikely, the installers could have mistakenly cut out two of the batteries from the house leaving you with a small bank.

What Bill said. Clearly there is high resistance somewhere. Corroded battery terminal are usual cause. Has this happened from the very first use or is it new? Since it is all those pumps look for problems between the common point and the battery. Don't forget the ground return side. If the wire is too small it may feel warm. A poorly made crimp on a connector is also possible. Look at all of them in the circuit from battery to switches.


Are you certain the batteries are actually charged. Use a hydrometer if they are flooded cell batteries. Other wise hook a voltmeter to the actual battery posts and watch voltage when a pump comes on. Any cheap digital multimeter is fine.

Do you have a good meter that shows system status, SOC etc? We need more information. Does this happen when you are on charge connected to shore power? If there is a voltage meter, you should watch the voltage as different loads come on. What is the age of the batteries?

When a higher draw, such as a pump comes online, there will be a short term voltage drop in the system. It is possible that your batteries are not "cabled optimally" such that all batteries contribute equally to system loads.

I would suggest you bring a good marine electrician onboard to provide advice.


Jim
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Lots of good advice above.

Check size of pos and neg leads going from batt bank up to panel. If a long run for the leads, they need to be pretty thick to avoid a volt dip.

And a bit of a volt dip is unavoidable when motors start, and some lights are more sensitive to volt dips, making it more visible.

Jim & All
Yes it happens so and all the other situations, connected to shore power or not. Batteries are 2 years Old. They have been measured and tested and all are in excellent shape

Rgs
Fernando

Fernando, do you have a battery monitor or voltmeter installed? Do you see a drop in the voltage when the pumps start and run?

Great advice so far in this thread.

sounds like you may have a corroded cable connection, check connections not only at batteries, but at the other end, at the dc panels, etc.
A simple digital volt meter should point out the problem for you. start at the batteries, checking voltages, then at the busses in the DC panel, at that point if the system was built right you should have no more than a 3% voltage drop if that panel supplies voltage for navigation lights and bilge pump.

It just sounds to me like you have a corroded connection somewhere. Also check the straps between your house batteries for corrosion as well.

Fernando, do you have a battery monitor or voltmeter installed? Do you see a drop in the voltage when the pumps start and run?

Great advice so far in this thread.
__________________
Al

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Al, that's the weird issue. There are no drops visible on the voltmeter.
I have put together a check list with all the advises above and I will start from pumps to batteries this time.

Thank you all

Portuguese said:

Al, that's the weird issue. There are no drops visible on the voltmeter.
I have put together a check list with all the advises above and I will start from pumps to batteries this time.

Thank you all

Click to expand...

There might not be till you put a load on the line.

Well then....if the batt bank is not dropping V, it's not a weak bank. I'd start looking at connections for dropping V with a DVM, starting at a common point like a bus where the various systems are connected.

It'll take a partner to activate the items while you check V. Shouldn't cost more than a 6-pack if he's a good friend.

Hook a DVM to one of the lights that dims the most and read the before and during voltage when you start a pump. < 10% for something non critical like a cabin light. <3% for a nav light. This will verify you have a real problem or not. I can't remember being on a boat where the house lights did not dim a little when a house load kicks on.

No electrical system can intuitively be ready for you to flip a switch. Does your home when the AC kicks in? Brief fluctuation is not abnormal. No/Slow recovery is a problem. Momentary amp draw is the issue which is not an issue.

Your fourth pictures shows two sets of batteries wired to the same cable going to the battery switch, if I am looking correctly.
Each bank of batteries should be ran independent to the on/off switch. The cable needs to be copper and should be marine rated. Your vessel looks really clean. When looking at the battery runs make sure the wire is one size bigger than it should be. Check out the power plates in your electrical panel and make sure the common wiring between them is Large. Duplicate the connecting power cables behind the panel if you are in doubt. Your problem is going to be easy to fix. You just need an educated set of eyes.

High Wire said:

... I can't remember being on a boat where the house lights did not dim a little when a house load kicks on.

Click to expand...

bilge53 said:

No electrical system can intuitively be ready for you to flip a switch. Does your home when the AC kicks in? Brief fluctuation is not abnormal. No/Slow recovery is a problem. Momentary amp draw is the issue which is not an issue.

Click to expand...

This was my thinking too. Motors draw a very large current when they start up. A 7A motor might draw 35A at startup. That could easily be enough to drop the battery voltage by 0.1-0.2V. Your eyes are very sensitive, you would quite likely see the drop in brightness of you lights for an instant. I'm not yet convinced you have a problem.

Richard

I'm no electrician, but I've done a lot of electrical 'stuff' on my boat, if you know what I mean, and I know the sort of issues that can tax the old brain, for sure. My ten cents would be..
1. with the boat and batts so new, poor contacts and dud batts unlikely the cause, just based on logic, alone.

2. the dimming, if more than just the usual, as others have mentioned, does make me wonder about 2 possibilities. That there is some kind of short occurring when the pumps are turned on, making for a bigger drain than they normally would...or...

is it possible there is a mismatch between the voltage of the pumps, and the voltage of your DC circuit. Is the boat wired for 24v DC or 12vDC, and is it possible your are meant to be wired for 24, but only getting 12, or vice versa, or the pumps in question might be rated wrong..? Just a thought...probably dumb...but I'll chuck it in anyway, as the others appear to have covered most else.

Fernando, what type of light bulbs do you have? Incandescent, CFL or LED?