Electrical Draw/problem?

C

Coach T

New member
Over the past few weeks I installed a VHF radio and a Stereo. I wired each to separate circuits on the fuse panel. All work well, but the next day my house battery was dead. (Did not leave radio or stereo on) I charged the battery and disconnected the Stereo 24 hours later dead battery. Disconnected VHF and no problem with battery draining. My question is why would my (New) Cobra Vhf draw the battery down overnight (turned off). I checked connections to make sure they were tight. I also changed circuit locations (i guess that is what they are called) to make sure it wasn't a bad circuit. I also have a fuse trip button just above my house battery. If i trip this, I don't have a problem so I have ruled out the battery. (Battery is 2 years old). Any help or advice would be appreciated.

Thanks
Coach T
 
Well, after you check to see if the VHF is causing a parasitic draw, and I assume it is since your battery is going flat, here's a couple of suggestions. BTW, if I read it right, a parasitic draw is just an unknown draw, and indeed that's what you have.

First disconnect the VHF power plug and see if that gets rid of the draw. If it does, you've found the problem, right? If not the wiring to the VHF is the problem. And you get to start disconnecting all the wiring you put in until you find the problem. Good luck.

Now if the radio is the problem, and it's new, exchange it for a new one. Some considerations are: does it have a GPS? They draw power continuously in some devices, so you have to find out how to shut it off. Next, if the radio is operating normally and somehow stays on, all it's doing is waiting for an incoming signal in stand-by and that doesn't take much power and shouldn't run the battery down. So send it back under warranty.

And finally if all else fails have the battery checked. Just bought a new Bosch battery for the Toyota and after 3 mos, it died. So it happens.

Boris
 
Some electronics have two + wires--one for the power to the main unit (red) and to the memory (orange). Usually these would not be over 100 milliamps (clock, memory, GPS etc). Even with 100 or 200 milliamps, the battery would not be discharged in 24 hours, from that.

I suspect that your battery had been abused in the past (and it has been now--since it was "flat"--not like child abuse, but often un realized abuse.

The battery will be damaged in small ways each time it is deeply discharged. The usual boat batteries have xX cycles at 50% discharge or 12.2 volts. I prefer to never discharge a battery to less than 12.2 volts--and thus get much longer life out of the battery.

In your case, now at least once the battery has been badly discharged…

I would have the battery load tested--and also do the tests that were suggested above.

I always put in a separate switch for the VHF radios and Stereo, which completely cut off the power to that unit, when I am not using it. That way there is no question. The way we use our boats, it is no big thing to reset a clock, or re-aquire a GPS position.

I'll throw in the usual plea for a battery monitoring system, such as the Victron BMV 700 or 702 (two battery voltage) or the Link systems.
 
I installed a battery monitor in Our Journey, the last sailboat we had, and it was useful. However, that one was lass than $100 and the new ones are $165 (1 battery) and $250 (2 batteries, which is more than I want to pay.

So, instead I installed a Radio Shack voltmeter and a 2 pole switch for under $25. I wired the connections back at the batteries, so there's no voltage drop under a load. Now I can tell:
1. If the batteries are being charged, since the voltage rises to 13.6 Vdc (and on the Honda, to 15 Vdc at end of charge)
2. Approximate state of charge (as Bob said above, 12.2 VDC is a great minimum)
3. Voltage under load, which checks the battery condition
4. Voltage drop between the battery and distribution panel, since a few accessories have voltage readout.
5. The difference in rest voltage between the batteries. The golf cart batteries have a lower rest voltage than the starting battery, for example.

Just a handy, cheap, easy to install device. And a C-Dory cabin is a warm, dry place for a voltmeter, so one doesn't need a waterproofed one.

Boris
 
As usual thank you all for the great advice. I will be fully diagnosing the problem this weekend and hope to have a fix soon.
Thanks again
Coach
 
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