Battery Drain issue?

[bashr52]

I've been working on the boat for the last 12 hours trying to get it ready for memorial day so forgive me if I am not thinking things through clearly

Last year I had an issue with my battery going dead. Turns out the battery was going bad and causing my problem. This year I replaced the regulator/rectifier with a new universal one, new battery, and a good LED volt gauge to help me keep track of battery voltage/charging (paranoid now since it left me stranded last year). I started it up tonight and got a nice 13+ volts at idle so all it working well now. I did however pull the negative terminal off the battery, and hook a volt meter between the - post and ground wire. With the key in the off position and all accessories off, I got a steady 12 volts. I traced it back to my new regulator, and it looks like the + wire that is hooked direct to battery voltage, is passing voltage through the regulator. Now I know the way to really test battery drain would be doing this test with an ammeter instead of a voltage meter, but should I really be showing 12 volts with everything off? I notice the same results when testing the wiring for my trim system as well.....

 

[MH Hawker]

Re: Battery Drain issue?

One of the reasons a lot of people install a battery disconnect switch. One turn and no problems.

 

[Jlawsen]

Re: Battery Drain issue?

Your voltage reading is correct, the meter is the load that's causing current to flow. Take a voltage reading at the key switch between neg and positive. You should have nothing with the key off. Providing you don't have anything other than the alternator that's wired directly to the battery you should be good to go.

 

[glenn property of pam]

Re: Battery Drain issue?

if you are using a digital meter and there are solid state devices in the circuit then you can also get false readings as these modern types of relay/switchs tend to bleed voltage at practically zero ampage. for peace of mind a disconnect switch is a good idea or a car jumper pack.

 

[bashr52]

Re: Battery Drain issue?

Awesome thanks guys. It is not a digital voltmeter, rather an older analog type with a moving needle. I do have a digiital ammeter at my lake house, I will use this to verify current flow once I get the boat up there as well. I should see a tiny amount of drain from my radio due to the memory function, but that shouldn't be enough to drain the battery in a couple of days to a week I would hope.

 

[-Jim-]

Re: Battery Drain issue?

I'm a licenced Electrican (maybe I shouldn't tell folks that as I'll get a million questions...:redface but I thought I'd chime in to try to help out.

Having both a voltmeter and an ammeter, suitably connected, would be the best situation but most folks don't go there on pleasure boats - especially with smaller craft. One of the issues is under "normal" load, the net current flow to / from a battery is only a few amps (amperes); whereas during hard cranking it can easily be 10+ times that. Unless an auto ranging digital type Ammeter meter is used, a suitable analogue meter will barely register during normal situations so it doesn't "pin" to one side during hard cranking. (Not good for the meter)

A "good" battery should indicate 12 volts DC (or a little) better with nothing connected to it. A Battery in good condition that is less is in need of charging. Most charging circuits always push 13 VDC or above to the Battery. (Most specs I read are 13.75 VDC) By knowing this you can tell what is usually going on with just a voltmeter as long as you exclude the time when cranking during starting (then you will see a voltage collapes as the Battery delivers the maximum current (amps) needed).

I suggest you put the Voltmeter across the battery with a simple cut out switch (in series) as you really don't need it on that often. At rest you will typically see ~12 VDC and know the battery is okay. When your are running you should see the voltage at your charging rate (13+ VDC) so you know the charging circuit is operational and providing amps to the battery, keeping it up.

Of course the only 100% accurate method to judge a Battery's condition is using a load tester, but having one of those on board is not reasonable. As they age (after a few years) it would be worthwhile to pull them and have them tested at a good battery shop. (Around here they do it for free - hoping to sell you new ones.) I pull my Batteries at the end of every season anyway so this is not a big deal.

I hope this is helpful.

 

[jopes]

Re: Battery Drain issue?

I had the same issues last year when I got my boat and started using it. for some reason the radio draws enough current in it to kill a battery fairly quick. Now I do not know if I left it on or what but ever since I started popping the face plate off of it in the glove box it no longer drains on my battery.

 

[bashr52]

Re: Battery Drain issue?

post deleted due to further research into the issue.