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-   -   17 volts on a 12 volt system? (http://www.sailnet.com/forums/electrical-systems/54165-17-volts-12-volt-system.html)

FlyinNOE 05-06-2009 09:17 PM

17 volts on a 12 volt system?
 
Hello All,

I just got back from a rotation in Afghanistan to find my fridge on my Beneteau 400 Oceanis non-operational.

The fridge is a Frigoboat Frigamatic AH35.

While troubleshooting this afternoon I found the 12v system of my boat sending 17.2-17.4 volts to the Frig controller! The Frigomatic manual mentions that over 17 volts but under 22 and the controller won't allow the compressor to start.

I keep the boat on shore power when away and it was on shore power today during my troubleshooting.

I'm guessing that my charger/ inverter is the culprit? It is a digital unit and is showing 13.4 volts out with AC power in while charging.

Any ideas?

My plan is to take the boat off of shore power tomorrow and further investigate.

Thanks very much!

Brian-

camaraderie 05-07-2009 12:16 AM

No charger should be sending 17V anywhere...nor should any battery bank.
13.4 volts out is a CORRECT float voltage for properly maintaining fully charged wet cell batteries. WHERE are you measuring 17 Volts??

If you've been gone...how is the battery WATER? If the plates are uncovered anywhere...you have found your problem.

FlyinNOE 05-07-2009 10:32 AM

Thanks very much for your reply.

I'm measuring 17.2 or more at the power leads to the controller as well as out of the controller to the compressor.

Today after work I'll measure the voltage again with a different multi-meter to remove any error.

The first thing I'll do is check the electrolyte in the Batteries!

Brian-

Cruisingdad 05-07-2009 10:41 AM

You don't by chance have any solar panels on there, do you?

OsmundL 05-07-2009 11:19 AM

Quote:

Originally Posted by FlyinNOE (Post 483439)
I'm guessing that my charger/ inverter is the culprit? It is a digital unit and is showing 13.4 volts out with AC power in while charging.
Brian-

I'd follow through on CD's question if I were you. The same applies if your boat has a wind generator or other second source. It need not be your inverter or the other unit per se, but the circuit.
Remember that current flows where there is a voltage drop, and you may have more than one "drop" in the system if several sources run simultaneously. It is possible for the current to push from the shore power circuit into the solar/windmill system when the voltage of the latter is lower, with some unexpected results. There needs to be separate voltage regulators on each device, and diodes blocking the current from taking wrong paths.

I had a related issue with only the engine generator and windmill running while at sea, pushing the voltage up to 16V in the worst case. In this case the engine generator was the main fault, but at a boat show I cornered a Finnish superguru who went gaga at the question; he'd been waiting to launch into a half-hour lecture on the intricacies of such circuits.

camaraderie 05-07-2009 12:53 PM

You did not mention them so I assume you have no panels or wind generator. Your battery charger is putting 13.4V into your batteries and the voltage reading at the controller is over 17V.
There is something wrong with your batteries if your voltage is that high.

That said...you misunderstand your manual I think.
The controller/compressor you have will work at either 12V or 24V ...
From the frigoboat manual:
5:1 Voltage
A supply voltage of either 12 or 24 volts dc is required. The controller will run from either voltage without any special settings or adjustments, switching automatically to 24v mode if the voltage is above 17v.
5:3 Safeguards
Protection is provided for the following:
(1) Low voltage. To prevent the batteries from being totally discharged, the compressor will be stopped if the voltage at the terminals on the controller falls below 10.6 volts (23.4 on a 24v system). It will not re-start until the voltage rises above 11.7 volts (24.0 on a 24v system).
(2) High voltage. If the voltage exceeds 17v, the controller stops the compressor and switches into 24v mode, but will not attempt to start the compressor until the voltage reaches 24v.

Alden68 05-07-2009 06:36 PM

Quote:

Originally Posted by FlyinNOE (Post 483439)
Hello All,

I just got back from a rotation in Afghanistan to find my fridge on my Beneteau 400 Oceanis non-operational.

FlyinNOE:

I have no input on your fridge problem but I just wanted to take a quick second and thank you for your service.

You do us all a great service by your actions. Thank you!

FlyinNOE 05-07-2009 08:58 PM

Quote:

Originally Posted by Alden68 (Post 483778)
FlyinNOE:

I have no input on your fridge problem but I just wanted to take a quick second and thank you for your service.

You do us all a great service by your actions. Thank you!

Thanks you Sir for the kind words.

I'm blessed with great guys to work with and an understanding wife (who was in the Army as well until recently).

It's easy to serve these days in comparison to the folks that served during the 60s and 70s. They paved the way for us, thatís for certain.

Thanks again,

Brian-

FlyinNOE 05-07-2009 10:27 PM

Gentleman,

I purchased an inexpensive volt meter enroute to our boat "Mairoa" this afternoon after work to verify the previous findings.

The new voltmeter found 13.2 volts at both terminals. The cause of all of your work posting and my sleepless night was the bad (and expensive) Voltmeter!

As for the Frigomatic, either the compressor or the controller is bad (I'm guessing the compressor).

I used the quick disconnects so that no R134A wasn't leaked to atmosphere (thereby effectively keeping the system closed) to remove the compressor/ evaporator from the "ice box" this afternoon. My wife will run it North to Seattle (while I'm at work) to the only guys in 200 miles that fix these things.

We are headed North to Canada and Orcas Island for 12 days of cruising at the end of the month. I hope to have the frig challenge rectified by then.

The timely and intelligent responses on SailNet with its community of likeminded folks make it a pleasure to be part of. 180-250 days a year I miss out on your postings, experiences, and advice. It's nice to be home.

Thanks for all of your help.

Brian-

camaraderie 05-08-2009 12:54 AM

Ahh...well...at least you didn't fry the batteries while you were gone. Check any on board fuse holders or auto type fuses in the compressor and/or controller before you take it up the road. Good luck with it.

It's nice to HAVE you home safe and sound. Enjoy it and thanks to you.


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