House Battery Draw?

MonacoMike

Well-Known Member
Sep 15, 2009
14,721
Indiana lakes and Lake Michigan
Boat Info
2000 Cruisers 3870
8.2 Mercs
Engines
85 Sea Ray Monaco 197
260hp Alpha 1
The yard jockies failed to turn off my house battery switch when they put it in storage. The main DC breaker was on and the two shower sumps were on and the CO detectors. In 9 days the 8D battery was at 2.5 volts. Is this normal or too fast a depletion?

MM
 
How old is the 8D?
 
My battery charger failed last winter between March and May (I was on boat in mid March and it was fine). It had same items as you do and when I arrived in May voltage was 2.5.
 
That is drawing down WAY too fast. It sounds like either the battery was already toast and the charger was compensating for it or something that draws a lot more amps was left on (or, as mentioned, the charger is wonky). Either way, those pumps and the CO detector will not even come close to drawing down a little group 24 in that time period.
 
Mike, you may want to consider getting a inductive amp probe that can help diagnose, isolate and trace to the source of any parasitic draw that you may have. Some are stand alone and some plug into your DVOM/Multimeter. There tons of them out there with a wide price range but you don't have to spend a lot to get a half decent one and they are a great tool with many uses on many boat systems.
 
Mike, you may want to consider getting a inductive amp probe that can help diagnose, isolate and trace to the source of any parasitic draw that you may have. Some are stand alone and some plug into your DVOM/Multimeter. There tons of them out there with a wide price range but you don't have to spend a lot to get a half decent one and they are a great tool with many uses on many boat systems.

I will look into that. Thanks,

MM
 
Is the battery in the boat, or on your workbench?

What is the voltage reading, now?

Put a decent load on the battery for a good 5 minutes (isolate the battery). If this was a car, for comparison, I'd say put your headlights on. Then check the voltage again.
 
Is the battery in the boat, or on your workbench?

What is the voltage reading, now?

Put a decent load on the battery for a good 5 minutes (isolate the battery). If this was a car, for comparison, I'd say put your headlights on. Then check the voltage again.

It is in the boat and I have both a voltage and amps pulled gauge. It was showing 13.5 when I turned off the charger and had about 20 halogen lights on for about half an hour. The voltage had dropped to about 13 volts.

MM
 
Well I don't know how you got so lucky. If it was truly at 2.5V and you've charged it back up and it's healthy... that's pretty much unheard of. But at least it sounds positive for your wallet!

13V is higher than what a new battery would be - but that 13V could be due to inaccuracy of the gauge. If you have a DVM, check again in a day or two directly at the battery (leaving everything turned off in the meantime).
 
Well I don't know how you got so lucky. If it was truly at 2.5V and you've charged it back up and it's healthy... that's pretty much unheard of. But at least it sounds positive for your wallet!

13V is higher than what a new battery would be - but that 13V could be due to inaccuracy of the gauge. If you have a DVM, check again in a day or two directly at the battery (leaving everything turned off in the meantime).

Wish I could get to it that often I cannot get to it for a couple of weeks and it is plugged in now. It is a brand new battery.

Thanks Dennis,

MM
 
That'll be a good test, too. Then, if you have time when you're there, do the same thing with the lights and then give it as much time as you can with everything turned off - then measure the volts again. Using all of those lights for a short time is sort of a poor-man's load test.

Up above, when you said "two shower sumps were on"... were they actually running, or were the systems simply "hot"?
 
That'll be a good test, too. Then, if you have time when you're there, do the same thing with the lights and then give it as much time as you can with everything turned off - then measure the volts again. Using all of those lights for a short time is sort of a poor-man's load test.

Up above, when you said "two shower sumps were on"... were they actually running, or were the systems simply "hot"?

Should have been just hot. I did see that the Maxwell windlass breaker was lit too.

MM
 
I wouldn't worry about it at this time of the year. Charge it up and use in the spring and see what you have. Unless the battery was nearing the end of its useful life, you are likely just fine. We had a guest on our boat this summer who accidentally flipped a breaker off when their shoe hit it walking down a step in the cockpit. I did not notice it and was not on the boat for 3-4 days. Opened the ice maker to make a cold glass off water and all of the ice was melted. Still did not notice the breaker position. Checked the switches down below and was showing almost no voltage on the D.C. meter. Did not have enough power to turn on even a small reading light. Noticed the charger was not on and discovered the breaker in the cockpit was off. Not a sound when I turned the start key. Long story short. Half hour on the charger, got one engine started with the emergency start button pushed and then the other. We went for a boat ride with the genny running the charger. Seemed to cause no damage to batteries that are 8 years old. I had planned on replacing all of them next summer and will still go ahead. But I am doing that just to take the work load off my expensive alternators that Crusader installs on it engines. I'm quite sure the boat will start right up this spring.
 
Hate to say it MM but if it really did draw down that low, the battery is permanently damaged; it may serve you for some time to come but never to the performance you originally had and will terminate early. Always keep your charger connected, powered on, and the batteries at float charge. If you are going in for winter lay-up and can't power the boat then remove the batteries and keep them on a charger elsewhere or fully charged then completely disconnected at the battery terminals. Even if you have all of the systems turned off, the simple fact that wiring is connected to the battery posts there is current discharging and over a long period of time the batteries will eventually drop below 10.5 volts which is the bottom threshold.
 
Hate to say it MM but if it really did draw down that low, the battery is permanently damaged; it may serve you for some time to come but never to the performance you originally had and will terminate early. Always keep your charger connected, powered on, and the batteries at float charge. If you are going in for winter lay-up and can't power the boat then remove the batteries and keep them on a charger elsewhere or fully charged then completely disconnected at the battery terminals. Even if you have all of the systems turned off, the simple fact that wiring is connected to the battery posts there is current discharging and over a long period of time the batteries will eventually drop below 10.5 volts which is the bottom threshold.

That is my fear, that it killed a $300 battery. Are 8D any different from the normal deep cycle batteries?

MM
 

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