DC leak to aluminum hull

[millsie]

Best method to check the hull is a simple analogue meter.
Or a small wattage 24v lamp test between neg and hull and pos and hull.
The hull should be negative grounded with no current paths from equipment.


The silver chloride cell is great but I feel that is not what you are asking.

[Oceanride007]

Just out of curiosity, I just did this check. Note my Solar feeds come in between House switch and Battery Positive.
First test is resistance with House switch "Open" 2nd Test, voltage with House switch closed.


Test 1.
Resistance Neg Bus to Hull = .7K ohm, Pos Bus to Hull = 7.7 K ohm.


Test 2. Voltage Neg Bus to Hull = .023V, Pos Bus to hull = 13.35V.


Thoughts welcome, I know its not great.



Should be a image here.

[Desertroseii]

Originally Posted by Manateeman

Mr.,Captain? Deseroseii. Thank you for your post and welcome.
What kind of boat and where do you sail.

It’s the tiny leaks I’m trying to avoid. I don’t have them but I need a new meter as suggested by Jedi.
I like the led idea. One of the big boats had two lights that the engineer would watch for even a slight glow. He had a cup with a pin hole to look ar them in the dark. Long before led. I have a Midnight Solar lightning protector on the DIN rail after the fuses but before the controller. It has two blue led lights to tell you it’s ok. That would be my ideal for knowing I had a bad wire or some carbon dust.
My electrical knowledge is very limited.
We have some very talented people reading and I hope they will comment.
Happy trails to you
Captain Mark and his vegetarian manatees.

Hi Manateeman
My base is Qld Australia. I have aluminium Adam's 45.
I also sail SE Asia when I can.
Millsie from the last post suggested the same method I use. The LED will give you a deem light at 5mA. That is a tiny current that the older electrical system will have when is intact.
For aluminum tanks watch for bio corrosion. Do not allow algae to grow. It will eat through the walls.
Avoid any dump areas eg wet wood touching aluminum. Or permanently wet and muddy anchor locker.
Keep bilges dry.
Cheers
Peter

[millsie]

The resistance at this point is relatively unimportant.


The pos bus to hull (12V) is unusual as if the hull has been bonded back to negative it should be 24V .If the boat is above earth start checking the 12v

Equipment EG stereos to make sure there earth goes to neg and not the hull.
Always use anologue meter not digital.

[johnn33]

I think you may find impressed current useful
https://www.boatcorrosion.com/retail-price-list.html


John

[Manateeman]

Thanks everyone who replied.
Today I did a test with my Wavetek 35 xl (not the best meter)
FLA 24 volt dc no connection to 12 volt starting battery system.
There is no connection between negative 24 dc and the hull.
I Shut off solar. Disconnected batt neg. ( slight spark) disconnected batt pos.
Reconnected negative cable to batt.
Connected positive meter to battery positive and negative meter to positive cable I had disconnected and kept disconnected.
Ran through the three dc amp scales high to low.
The microfarad reading was .2
So...is this good, bad or horrible.
I have not started to look for where this is occurring.
I was taught disconnect negative first, reconnect positive first.
Is this correct? When I reconnected neg cable to batt, no spark unlike when I disconnected it. I don’t understand why.

I looked around the web for DC leak detectors. Arga Controls makes a battery monitor and I’ll call them but I bet huge dollars.
I found others by NK Technologies, Thiim in Denmark and Kongter but I don’t know if they would work or the prices.
Happy thanksgiving.
Mark and his “send the pilgrims back” manatees

[millsie]

Always disconnect negative first as some electronics will let the smoke out

if you disconnect negative first. Particularly dc convertors.
Please use at lamp as suggested before getting new meters.
Try not to get to technical, it is a simple fault.



Have forty years + of experience with aluminium hulls on the west coast of Australia.