Still not sure about battery switches

M

matt_unique

New member
I used a multimeter to test the voltage on my batteries to get a baseline. They were all between 12.49 and 12.80 or so. I then changed the position of the switches to see if I had system power and power to start one of the engines. My logic was....if system and start power is available, once the engine is started, I should be able to measure a charge on the battery supplying the power by a higher charge level. This is what I found:

Port Switch
1 - Port start battery
2 - Starboard start battery
Both - Port and Starboard start

Starboard Switch
1 - Nothing
2 - Starboard start battery
Both - Starboard start battery

With engines running and in every possible combination I could never show a charge going back to the house battery. However, when connected to shore power with the battery charger switched on I was able to read a charge going to the house (and both starting batteries).


The dealership said the switches are fine and working. I don't understand the schematic they sent me and it does not match with my multimeter readings. It is certainly possible I made a mistake in my testing, but on two separate days I could not once get a charge reading on the house battery with engines running. Also the post apparently behind position 1 on the starboard switch is empty - no wires connected to it.

The dealership is saying that the house battery is wired in parallel to the starboard start battery. (Thus it is not possible to isolate the house battery). They are also saying the port switch in position 2 is using the starboard "bank". But if this were the case, wouldn't I read a charge going to the house and starboard start battery?


Thanks
 
Upon closer review of this situation and a few more calls to the dealer I found out the person doing the work never even tested the charge with a multimeter. He also said starboard position 1 was for the starboard start battery and position 2 was the house battery. I know for a fact there is zero power from position one....

Unreal....a lot more to follow...
 
Matt,
Many of the boats are rigged at the dealers, plus the factory has been known to miss wire the boats. I rewired mine--and you will probably want to do the same. Two batteries are not enough for the C Dory. The Stb engine should charge the stb battery and port engine the port battery. The boats should be wired so that 1 is the engines start. 2 on stb bank is "house", Stb 1 is engine start and 2 is combined both port and stb batteries. I added VSR to both start batteries, and have two house banks. One house bank for the usual house, and electronics--best to not have electronics wired to the engine start battery because of voltage drop and spikes. The second "house bank" is for inverter and refer/freezer--but can be combined to the console.

If you are just on a mooring, then the fatory 5, 5, 10 batter charger will be OK. If you want more power, then a larger charger--up to 50 amps will be desirable.
 
thataway":1p0utd75 said:
... Two batteries are not enough for the C Dory. ...
Click to expand...

I know...there are three batteries on the boat but only two of them are wired ;) I'm trying to get the dealer to correctly wire the existing house battery. Should know today if they did it....

Thanks for the help.
 
Matt, Some info from my "user" experience. I got a $30 cigarette lighter plug-in meter which I plug into 12V sockets I had installed to check out the battery level/charging process.

Also, you really need TWO house batteries on a TomCat, esp. if much electronic equipment or accessory use is planned. It is easy to do, just parallel the 4th battery to the the singel house battery. My 4th battery is under the aft dinette cabinet and it is paralleled to the 3rd (single house) battery under the port transom.

Even with two house batteries, I have run them down with stereo, TV, computer, etc., while anchored.

Good luck, It sounds like you're on the home lap! John

btw, I am still loving my TomCat and am even spending a 3 day weekend on it right now... with a new USB Broadband card...
 
drjohn71a":16fs6z88 said:
Matt, Some info from my "user" experience. I got a $30 cigarette lighter plug-in meter which I plug into 12V sockets I had installed to check out the battery level/charging process.

Also, you really need TWO house batteries on a TomCat, esp. if much electronic equipment or accessory use is planned. It is easy to do, just parallel the 4th battery to the the singel house battery. My 4th battery is under the aft dinette cabinet and it is paralleled to the 3rd (single house) battery under the port transom.

Even with two house batteries, I have run them down with stereo, TV, computer, etc., while anchored.

Good luck, It sounds like you're on the home lap! John

btw, I am still loving my TomCat and am even spending a 3 day weekend on it right now... with a new USB Broadband card...
Click to expand...

I envy your weekend accomadations! I sure as hell hope I'm on the home stretch with this process...ugh.

Your system to test charge sounds pretty good. I have a multimeter that I can use right on the battery terminals so that works out.

I found out the "house" battery they put on is actually a start battery. I suspect I will replace with a deep cycle battery and perhaps add a 2nd deep cycle house battery based on numerous recommendations.

The first thing I will be doing when I get the boat is to test the charging/wiring....hopefully tomorrow.
 
Back
Top