House Battery Reading “zero”

[Sharphooks]

I just got back from a long boat camping trip and had power management issues the whole time with my house battery. I thought it was the daily refrigerator use that was the issue but when I got the boat back to her dock, I killed all switches on the 12V panel. This morning I couldn’t get any reading on the battery (a large 4D, only two years old) The multimeter is reading 300 mills volts, essentially zero.

I‘ve had it hooked up to a charger for the last three hours—-no change. Do deep cycles go off a cliff like that and reach a point where they can no longer take a charge? Yes, I know it’s time to try and track down a parasitic draw but is the battery toast now? Seems strange behavior for a two year old deep cycle

 

[CBsqrd]

Sounds like the battery may have been fully discharged (or close to fully discharged) before your trip and the damage done then. Lead acid batteries don't really like being taken below ~50% charge - once you start going below that their lifespan starts to decrease. And the deeper the discharge, the more damage / shorter life. So yes, if the battery had been run right down a few times it could be significantly damaged or toast.

Might be worth trying a "normal" automotive battery charger (i.e. something like a NOCO Genius) that has a "repair mode" and run that to see if it helps. Probably won't fully restore your battery, but if you are just using the boat for day trips until next year it might get you through.

Do you have a battery monitor? Easy to install and gives you lots of useful info (current draw, state of discharge, remaining time at current draw til empty, time to fully charged, etc.). The Victron Smart Shunt is a nice little unit as it outputs everything over bluetooth to your phone and doesn't require an external display.

If you are thinking of going lithium let me know - I switched the house battery over to lithium last winter and have been impressed so far. The prices have come down significantly and for my set up the benefits (a fraction of the weight, ability to tolerate a greater depth of discharge without damage, longer life, higher nominal voltage at partial discharge, etc.) outweighed the extra cost.

They are not a simple drop in though. Your onboard charger is new enough that it probably can be programmed for lithium batteries, but charging direct from the outboards (via a DVSR) is a no-no and requires a DC-DC charger for each engine.

 

[Sharphooks]

Thanks for that, CB—-I took your advice and put it on a automotive charger...I’ll see if I get any reading tomorrow AM

You’re probably right—I recall seeing extreme low voltage on the starter battery before my trip —-I left the VHF on but even if I get voltage back up I think I’ll still have to do a search for parasitic draw....I suspect I have that going on......meanwhile, I’ll probably stick with flooded although I noticed the on-board charger will accept lithium—-I just put two G32 flooded batteries on the boat for start batteries and they’re excellent....not sure I want to put lithium into the mix at this point

 

[Sharphooks]

The over-night charge on the automotive charger got her back up to 12 V.....now it’s time to find out what’s causing the parasitic draw...thanks for the suggestions!

 

[CIVANO]

If you used the NOCO genius, run the repair mode after charging full

 

[BCI]

I just got back from a long boat camping trip and had power management issues the whole time with my house battery. I thought it was the daily refrigerator use that was the issue but when I got the boat back to her dock, I killed all switches on the 12V panel. This morning I couldn’t get any reading on the battery (a large 4D, only two years old) The multimeter is reading 300 mills volts, essentially zero.

I‘ve had it hooked up to a charger for the last three hours—-no change. Do deep cycles go off a cliff like that and reach a point where they can no longer take a charge? Yes, I know it’s time to try and track down a parasitic draw but is the battery toast now? Seems strange behavior for a two year old deep cycle

Often when using a higher end marine charger, the charger won't charge if it doesn't see at least 10-11 volts on the battery to be charged.

Had a situation where we depleted my house bank so much that the Magnum 3000W charger inverter wouldn't see the battery/load, and so wouldn't charge. Voltage was below the threshold for that charger. Hooked up an automotive charger to the house batteries. Once that was in place and running the Magnum immediately saw enough voltage to see the load and started to charge the house bank. Removed the automotive charger and let the Magnum do the 100A heavy charging.

So it could be the 3 hours on the charger where you saw no results was because the charger didn't actually come on-line for you then. Something to check if it happens again. And a reason to bring a 12V automotive charger in your tool kit for extended trips... just in case...

 

[Sharphooks]

Funny you should bring that up, BCI—that’s exactly what happened to me.....I thought the on-board charger had gone side-ways: it’s a high end sophisticated one but it was strangely silent when I turned it on yesterday. I swapped it out for an automotive charger before going to bed last night, got the 4D back up to 12 volts this morning, and now the on-board charger is responding the way it should....valuable to know this stuff...next year the automotive charger goes in the boat for any long haul trips! I was in a nuts rock garden this summer and house battery voltage got so low I didn’t have chart plotter functions—-there was some heavy breathing going on while trying to get back out to deeper water without hitting a rock

 

[Rain City]

Has anyone (@BCI ) ever dealt with having a start battery tied into a double 6V house setup? That's what I currently have and it seems to complicate things when trying to figure out what's doing what. There's two start batteries, one port and one starboard. The port alternator charges the house bank but is still started by it's own start battery. My kicker is supposed to be charging my house bank but it doesn't seem to be working. I'm having electrical gremlins pop up and I'm thinking it has to do with the house bank not running at full capacity any longer. I've heard once the 6V go things will just stop working because they aren't getting the full voltage needed. Even though the batteries are fully charged. That or it's a bad ground. Sorry that's a lot to digest. I think there's a question in there somewhere

 

[BCI]

Has anyone (@BCI ) ever dealt with having a start battery tied into a double 6V house setup? That's what I currently have and it seems to complicate things when trying to figure out what's doing what. There's two start batteries, one port and one starboard. The port alternator charges the house bank but is still started by it's own start battery. My kicker is supposed to be charging my house bank but it doesn't seem to be working. I'm having electrical gremlins pop up and I'm thinking it has to do with the house bank not running at full capacity any longer. I've heard once the 6V go things will just stop working because they aren't getting the full voltage needed. Even though the batteries are fully charged. That or it's a bad ground. Sorry that's a lot to digest. I think there's a question in there somewhere

It would be helpful to see/understand the wiring more completely. Most kickers put out 6A approx when revving out... won't really charge much but should keep your chart plotter running. If I recall correctly you have a 15hp Merc Pro-Kicker which puts out 12A when revving. From that 12A assume you have 5A left after house loads (chart plotter, fridge, etc).

If you have a 100A 6V+6V string you'll take far in excess of 20 hours to charge with the kicker if everything is 100% good.

If your batteries are old / dying, they won't get to a full charge or give you a full capacity... so a few things to ask;

Battery Health;
How old are the batteries? Load test them?

To understand the existing engine charging system;
What does port engine charge?
What does STDB engine charge? Is there any combiner/BEP VSR system which takes the alternator output into
whatever battery needs it? (Usually starting strings are priority #1).

To understand the shore power charging system;
Does onboard charger have enough capacity for your house and starting strings? i.e. are you getting 100% charge on shore power before taking off for the morning?

Could be battery banks undersized for your usage, or battery banks on last legs and need replacement, or charger just not getting them charged up enough for you overnight, or loose wiring / terminals.

I wouldn't count on the kicker doing anything except keeping your kicker running and your GPS running etc... alternator output just too small on kickers to make a big difference.

I know you hate the noise, but you could run a Honda 1000W generator for one hour and if you have a 100A charger onboard that'll do a lot more than the kicker ever will for recharging...

I put a 150W solar panel on my roof of my boat and I see 10A-12A being fed to the battery bank on a sunny day... Wasn't too expensive and really helps. Another option for you on the list...

These days with labour rates being what they are, I tend to just replace the batteries when I think they're time is up... rather than spending on diagnostics which are probably just going to tell you to replace your batteries anyways...

 

[Rain City]

It would be helpful to see/understand the wiring more completely. Most kickers put out 6A approx when revving out... won't really charge much but should keep your chart plotter running. If I recall correctly you have a 15hp Merc Pro-Kicker which puts out 12A when revving. From that 12A assume you have 5A left after house loads (chart plotter, fridge, etc).

If you have a 100A 6V+6V string you'll take far in excess of 20 hours to charge with the kicker if everything is 100% good.

If your batteries are old / dying, they won't get to a full charge or give you a full capacity... so a few things to ask;

Battery Health;
How old are the batteries? Load test them?

To understand the existing engine charging system;
What does port engine charge?
What does STDB engine charge? Is there any combiner/BEP VSR system which takes the alternator output into
whatever battery needs it? (Usually starting strings are priority #1).

To understand the shore power charging system;
Does onboard charger have enough capacity for your house and starting strings? i.e. are you getting 100% charge on shore power before taking off for the morning?

Could be battery banks undersized for your usage, or battery banks on last legs and need replacement, or charger just not getting them charged up enough for you overnight, or loose wiring / terminals.

I wouldn't count on the kicker doing anything except keeping your kicker running and your GPS running etc... alternator output just too small on kickers to make a big difference.

I know you hate the noise, but you could run a Honda 1000W generator for one hour and if you have a 100A charger onboard that'll do a lot more than the kicker ever will for recharging...

I put a 150W solar panel on my roof of my boat and I see 10A-12A being fed to the battery bank on a sunny day... Wasn't too expensive and really helps. Another option for you on the list...

These days with labour rates being what they are, I tend to just replace the batteries when I think they're time is up... rather than spending on diagnostics which are probably just going to tell you to replace your batteries anyways...

I have the 2x100w solar as well which is really troubling. I'm probably just going to replace the batteries as you've suggested. I have no idea how this boat is wired and couldn't even begin to figure it out. Nothing is within reach and it's all buried behind panels and chases. Total nightmare, for me anyways. Noluck is coming to help me tomorrow.

 

[fish brain]

Might be worth trying a "normal" automotive battery charger (i.e. something like a NOCO Genius) that has a "repair mode" and run that to see if it helps. Probably won't fully restore your battery, but if you are just using the boat for day trips until next year it might get you through.

On really dead car batteries that wouldn't take a charge, my dad would put an automotive light bulb between the terminals to create a draw to "activate" the battery. Would this work on an intelligent charger?

 

[sly_karma]

On really dead car batteries that wouldn't take a charge, my dad would put an automotive light bulb between the terminals to create a draw to "activate" the battery. Would this work on an intelligent charger?

The Noco chargers appear to do something like this. In their Repair mode they can usually get a very dead battery to take a charge when the normal mode is unsuccessful.

 

[doug78]

Above video is a good example of a well thought out lithium install with lots of information. Inboards can better take advantage of the faster charge rates.

Solar is great and low maintenance, it just does it's thing quietly in the background.

 

[Fritz]

I just got back from a long boat camping trip and had power management issues the whole time with my house battery. I thought it was the daily refrigerator use that was the issue but when I got the boat back to her dock, I killed all switches on the 12V panel. This morning I couldn’t get any reading on the battery (a large 4D, only two years old) The multimeter is reading 300 mills volts, essentially zero.

I‘ve had it hooked up to a charger for the last three hours—-no change. Do deep cycles go off a cliff like that and reach a point where they can no longer take a charge? Yes, I know it’s time to try and track down a parasitic draw but is the battery toast now? Seems strange behavior for a two year old deep cycle

Out of curiosity are you running a combiner ACR (VSR)?
I discovered an issue with my ACR that when I was charging the batteries with my onboard charger that when the voltage came up on the start battery to 13.4V it was combing the batteries (like they’re supposed to) and my onboard charger was charging the crap out of AGM deep cycle. My onboard charger has settings for different chemistry batteries but tries to charge them like a big starting battery when they combine.
I solved the problem by installing a guarded switch for ACR disconnect when charging. You can also wire the ACR through the master switch to solve the problem but your batteries won’t combine if for example your bilge pumps started up at the dock when you’re away.
I also had a coworker have the same problem with his AGM house batteries getting savagely beaten by his onboard charger and the same logic was being created by his ACR’s.

Just something else to check that could be seriously cutting the life expectancy of your house battery down.

 

[Sharphooks]

I do have a Blue Sea ACR. In my understanding, they don’t combine when charging —-once they reach their required voltage they’re isolated by a switch. The biggest issue I found with those ACR chargers is if for instance the house falls below a certain voltage, it’ll start drawing from the starter batteries to compensate. I installed a switch so I could stop that process if necessary.

I have two Group32’s as starters and one large 4D house—-all three are flooded. I was warned not to throw an AGM into the mix for precisely the reason you mention. Meanwhile, I found the culprit that was killing my 4D house battery—-a short in the tilt switch of my Suzuki kicker

 

[Newf]

I do have a Blue Sea ACR. In my understanding, they don’t combine when charging —-once they reach their required voltage they’re isolated by a switch. The biggest issue I found with those ACR chargers is if for instance the house falls below a certain voltage, it’ll start drawing from the starter batteries to compensate. I installed a switch so I could stop that process if necessary.

I have two Group32’s as starters and one large 4D house—-all three are flooded. I was warned not to throw an AGM into the mix for precisely the reason you mention. Meanwhile, I found the culprit that was killing my 4D house battery—-a short in the tilt switch of my Suzuki kicker

Technical_Brief_ACR_Explained.pdf

Lots of info online for ACR's. This link gives a brief overview but other articles and videos give good explanations . If an ACR is wired in correctly your house battery could go totally dead and not affect your start battery. Batteries are combined when charging providing conditions are met. See first line in the link.

 

[Fritz]

Technical_Brief_ACR_Explained.pdf

Lots of info online for ACR's. This link gives a brief overview but other articles and videos give good explanations . If an ACR is wired in correctly your house battery could go totally dead and not affect your start battery. Batteries are combined when charging providing conditions are met. See first line in the link.

You are correct and so are those refrences,

Just to be clear though, the condition that I was talking about is when you have an ACR wired correctly, and if you have different battery chemistries (like I do) with an AGM Deep cycle and a flooded start battery, if you are trying to charge with a smart charger that has 2 different charging schedules selected and two different sets of leads connected to the batteries the ACR will combine them. You will see the combine LED on the ACR if you do this, and it will most definitely charge the crap out of your deep cycle when connected to shore power no matter how smart your charger is. I use an inline ACR disconnect switch like they show in the diagram (I circled it in red) when I am connected to shore power. It allows me to charge my two batteries on different schedules applicable to their type (house/starter).
Where I think in my original post I caused confusion was the alternate method of wiring the ACR where you can make it so “off” is off. You run your ACR through the master switch instead of directly between the positive terminals of your battery (running them from B,A to 1,2 respectively on the master switch).
Another way of achieving this of course is just to pull the inline fuse to deactivate the ACR.
I attached the diagram in hopes that what I say makes sense to any folks interested in what I’m trying to convey.
The whole point of an ACR is most definitely to “Combine”the batteries from a single charging source and isolate them from each other if they are discharged below 12.7’ish volts so a load can’t discharge both batteries to a non recoverable point. Unfortunately ACR’s aren’t as smart as the chargers we use.

Thanks for putting up the link Newf

 

[gunnerlove]

Funny you should bring that up, BCI—that’s exactly what happened to me.....I thought the on-board charger had gone side-ways: it’s a high end sophisticated one but it was strangely silent when I turned it on yesterday. I swapped it out for an automotive charger before going to bed last night, got the 4D back up to 12 volts this morning, and now the on-board charger is responding the way it should....valuable to know this stuff...next year the automotive charger goes in the boat for any long haul trips! I was in a nuts rock garden this summer and house battery voltage got so low I didn’t have chart plotter functions—-there was some heavy breathing going on while trying to get back out to deeper water without hitting a rock

Navionics?...on a phone....on a tablet. Multi hour stand alone.

 

[Newf]

Hi Frtiz, My post was not in reference to anything that you had posted earlier. My reason for posting was to clarify comments by Sharphooks that "they don’t combine when charging" and "if for instance the house falls below a certain voltage, it’ll start drawing from the starter batteries to compensate."

I'm pretty much illiterate in understanding electrical systems but have read quite a bit since I have an ACR installed on my boat and like to understand how things work. As article that I've read indicate, one of the main purposes for an ACR is so you can combine battery charging and also it isolates your house and start battery so you don't inadvertently discharge your start battery. On a simple installation it takes the guesswork out of having to turn off an isolation switch that some have between the two batteries so there's no drawdown on your start battery.

On two occasions I have drawn down my house battery where, after launching, it would not turn on anything (VHF, GPS etc etc) In both of these cases I had left something on and forgot to turn off my main isolation for the house battery. In both of these case my start battery was still fully charge because it with isolated by the ACR. Also in both of these cases, I fired up the engine and jumped the start and house battery with a small set of cables I keep on board and as soon as the ACR sensed a particular voltage it recharged the house battery. (So no time lost fishing)

Again, my limited understanding is that nothing should be tied into your start battery that could drain it. I'm sure there may be reasons for doing otherwise but on mine it's simply to start the engine with no draws from anything else.

I shouldn't comment further as I will continue to confused myself and others.

 

[Fritz]

Hi Frtiz, My post was not in reference to anything that you had posted earlier. My reason for posting was to clarify comments by Sharphooks that "they don’t combine when charging" and "if for instance the house falls below a certain voltage, it’ll start drawing from the starter batteries to compensate."

I'm pretty much illiterate in understanding electrical systems but have read quite a bit since I have an ACR installed on my boat and like to understand how things work. As article that I've read indicate, one of the main purposes for an ACR is so you can combine battery charging and also it isolates your house and start battery so you don't inadvertently discharge your start battery. On a simple installation it takes the guesswork out of having to turn off an isolation switch that some have between the two batteries so there's no drawdown on your start battery.

On two occasions I have drawn down my house battery where, after launching, it would not turn on anything (VHF, GPS etc etc) In both of these cases I had left something on and forgot to turn off my main isolation for the house battery. In both of these case my start battery was still fully charge because it with isolated by the ACR. Also in both of these cases, I fired up the engine and jumped the start and house battery with a small set of cables I keep on board and as soon as the ACR sensed a particular voltage it recharged the house battery. (So no time lost fishing)

Again, my limited understanding is that nothing should be tied into your start battery that could drain it. I'm sure there may be reasons for doing otherwise but on mine it's simply to start the engine with no draws from anything else.

I shouldn't comment further as I will continue to confused myself and others.

All very pertinent adventures with ACR’s

Cheers