Voltage Loss

[Phil23]

I have a problem which is driving my bank manager and I crazy!!!!
I appear to have a voltage loss on my house bank which has now cost me 2 batteries and I am onto my third.
When the house bank is on over night it will go from full (12.6V with cold batteries) down to 12.2 +-. at this time I am mainly running riding light and 2/3 reading lights, all LED and an occasional heads flush and water pump use.
I have done an appraisal of my total amp draw if all items were own but of course this is not the case overnight. I did not run the radio/TV or any other drawing items.
Is there any way I can check/trace my voltage loss.

 

[wwestman]

I would start with turning off all circuit breakers you are not using. You might also think about putting an amp meter on your system so you can see how much you are actually drawing. Then watch the meter as you turn breakers on and off. Once you have found which circuit is drawing all the juice, trace that until you find the culprit(s).

 

[diver dave]

Sure, with an Ammeter. But first, what does your charge profile look like? time vs voltage.

 

[ranger58sb]

Fridge(s)? Hidden loads like CO detectors, shower sump pumps, bilge pumps?

-Chris

 

[Martin J]

Invest the $50-60 in a DC clamp on ammeter. Make sure its a DC one not AC. Then clamp on your battery cable start turning it on one breaker at a time, the discharge will show quite quickly.

 

[Screaming04]

^this^

 

[Action]

I deal with this type of thing in the automotive world. It is called a parasitic drain or draw. (You can google) here is a link but you don't have to follow those instructions https://www.wikihow.com/Find-a-Parasitic-Battery-Drain Post 2 & 5 are also good as well.

 

[High Wire]

35 ft and no fridge? Another case for the clamp-on DC ammeter.

 

[O C Diver]

How is your house bank charged? Do you have an inverter?

Ted

 

[Choices]

You said 12.6 to 12.2vdc.

When your batteries are fully charged for a day, then the charger is turned off, what do they show? 12.6 to 12.2 might not be that much power on old or small batteries. Your not starting with a full charge, and your going to half state.

Also, are you charging each battery separately or as a bank?

Another easy test is turn the batteries off at the main switch, and see where it is in the morning.

If you spend two hours on this forum reading the results from a "battery", search, you will know a tremendous amount about batteries.

More info!

 

[FlyWright]

Try to disconnect your alternator. I had a shorted diode (not blown) that caused a significant parasitic load. It would suck my start batt to 12.4 almost immediately upon shutdown. It also cost me 2 batts before I found it.

 

[fractalphreak]

^this^

+1. You can really dial in you energy use with one of these. We ended up getting a clamp meter that does DC and AC amps. Useful for determining individual component loads for both systems.

 

[FlyWright]

Invest the $50-60 in a DC clamp on ammeter. Make sure its a DC one not AC. Then clamp on your battery cable start turning it on one breaker at a time, the discharge will show quite quickly.

The same can be done by monitoring a SOC meter while selecting loads.

But if the parasitic load is a short and/or not on a breaker, it won't isolate in this manner.

 

[diver dave]

Try to disconnect your alternator. I had a shorted diode (not blown) that caused a significant parasitic load. It would suck my start batt to 12.4 almost immediately upon shutdown. It also cost me 2 batts before I found it.

gotta add "check alternators for temperature" as part of the cold start checklist.

 

[Phil23]

I have isolated the voltage drop to when battery is on all day or over night at stand down/batteries all of for say 5 days voltage loss not discernible.
I have purchased a 0 to 20amp meter/dash instrument to permanently monitor my amps, what is the correct way to install this instrument. I currently have 1 Deep cycle battery on my house battery switch (soon to become 2) and two starter batteries on my starter switch. I am charging my batteries via an alternator and general achieve between 14.1 to 14.7 volts when banks fully charged.

 

[ranger58sb]

I have isolated the voltage drop to when battery is on all day or over night at stand down/batteries all of for say 5 days voltage loss not discernible.

Say what??

I currently have 1 Deep cycle battery on my house battery switch (soon to become 2) and two starter batteries on my starter switch. I am charging my batteries via an alternator and general achieve between 14.1 to 14.7 volts when banks fully charged.

That might be part of the issue, if you find your amp usage is more than you expected. Might just be a single battery isn't enouch capacity...

You didn't say what size and type of "deep cycle" you mean, but it might depends on that to a certain extent, too.

-Chris

 

[diver dave]

I am charging my batteries via an alternator and general achieve between 14.1 to 14.7 volts when banks fully charged.

Using a hygrometer? or ?

 

[kchace]

A voltage reading alone while charging tells you very little about the state of charge of the battery. 14.1 volts *while charging* is not fully charged by any stretch and a battery can have 14.7V applied to it for some time before it is fully charged.


There is a lot of info missing here. What size is your house battery? How old is it? Is it a true deep cycle battery? Is this a new problem or has it always been like this?


A 0-20A dash mounted meter is normally installed using a current shunt attached as closely as possible to the battery, but a 0-20A meter is far too small for the kinds of current you may see, and far too large to tell you if you have a small parasitic load (under 1 amp). The clamp on meter which has been suggested is a far better tool with many more uses than the dash meter.


Ken

 

[MRD]

If you don't want to buy a clamp meter pick up a decent multimeter that shows DC amps. Set the meter to DC amps. At your battery remove the main ground cable. Touch one probe on the the battery ground post and the other on the ground cable you just removed. The meter will measure any any current being drawn through it. Start with the setting on the highest amp setting usually 10 amps. If nothing shows move the meter setting to miliamps. If no parasitic draw is detected have your batteries checked for problems.

 

[rgano]

Do yourself a long term favor and install a battery monitor for your house bank like this; https://www.emarineinc.com/LinkLITE-LinkPRO-Battery-Monitors. I never left my trawler at night (moored behind my house) before ensuring the house bank current was reading zero unless charging with the charger which I only did occasionally. Once I saw a tenth of an amp and spend half an hour finding that the entertainment radio on the flying bridge was in the off-but-vampire mode. It seems that cycling the battery selector had reapplied power to it after I had killed it good by holding the radio power button until all lights went out on it reinitialized the radio. I immediately put a cutoff switch up there to remove any possibility of it getting power unless I wanted that to happen.

 

[koliver]

An inverter will draw 5 or 6 amps continuously even though you think nothing is on.
A fridge, especially one that is so called "AC/DC" will draw up to 10 or more amps while running, so even if it runs less than 1/2 the time, it will add up to a huge amount overnight.