Battery charger always on?

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Oh, I see. That charger has three separate output fet’s. It can support three banks separately. He jumps them so all three outputs are loaded evenly. I don’t know if this really helps or not. But if one fails, the others will take up the slack.
It is clear what cable is incoming from the charger because it’s labeled as “in battery charger.”
His labeling may be confusing till you make sense of it.
What he does, is label the in and out on the fuse ends, and the function in the middle. So the charger label, starting from the cable towards the buss bar would read, “in battery charger x amps out”
Or something like that. Only confusing till you see his method.

alternator is a separate charger when the engine is working. the main batt charger does not send current to the alternator. why is the alternator fuse also bused to the charger fuse? when both the main batt charger and alternator is on, will the battery be fried by the current doubled?

(source: marinehowto.com)
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No, batteries won’t be harmed. Each charging device will “see” each other electrically, and will reduce its output accordingly.
The battery bank meanwhile, will only accept what it can. It’s resistance increases as it charges, and the charge source has to increase voltage to keep putting in the amps. When the volt/amp threshold is reached, charger output drops off.
All the charge sources need to end up at the battery terminal in the end. One does need to choose the equipment wisely to make sure it all plays together nicely. Being able to program all of the volt settings is important to me, so I can ensure compatibly.
Your monitor should have an alarm as well. You should have a high and low volt alarm.
 
so only one batt monitor is needed. is it installed to any one house or start battery?
Most battery monitors will have inputs for more than one bank. Usually though, it will have just one shunt for measuring amp hours, and the other inputs will be voltage only.
The idea is, you need to monitor the usage of the house bank more closely, so you can practice best management procedures to extend battery life. The start bank will typically top off quickly, so monitoring voltage is good enough.
 
No, batteries won’t be harmed. Each charging device will “see” each other electrically, and will reduce its output accordingly.
The battery bank meanwhile, will only accept what it can. It’s resistance increases as it charges, and the charge source has to increase voltage to keep putting in the amps. When the volt/amp threshold is reached, charger output drops off.
All the charge sources need to end up at the battery terminal in the end. One does need to choose the equipment wisely to make sure it all plays together nicely. Being able to program all of the volt settings is important to me, so I can ensure compatibly.
Your monitor should have an alarm as well. You should have a high and low volt alarm.

the current coming from the batt charger to the battery as i understood is flowing along the green arrow line. when the batt is working, the current flows along the orange arrow line. can the two opposite DC currents exist at the same time, i.e. the battery provides power while it is being charged? or will the DC power be solely provided from the batt charger when the charger is on (the batt will contribute 0 amp draw)?

(source: marinehowto.com)
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Yes, the dc power can coexist there. Remember, the power follows the path of least resistance. If it’s easier to go power a device somewhere than return to the battery it will do so. If there’s still some left over power after handling the device, the rest will go to the battery.
 
With my inverter meter I can see a charge of say +25 amps. With my shunt there may be +10 Amps going into the battery. The other 15A is directly powering a device. So, yes the current can flow to where needed in the same wires.
 
With my inverter meter I can see a charge of say +25 amps. With my shunt there may be +10 Amps going into the battery. The other 15A is directly powering a device. So, yes the current can flow to where needed in the same wires.
is the inverter here the same as an inverter/charger you mentioned earlier?

I only turned on inverters when the boat is underway. Besides to convert dc to ac, what other functions do they have so people would leave them on?
 
Yes I have an inverter/charger. It is always on inverting and/or charging fully automatic.
You appear to have dedicated equipment a charger and separate inverter.
Unless you have a smart charger that knows when to stop charging do not leave it on all the time.
 
Yes, the dc power can coexist there. Remember, the power follows the path of least resistance. If it’s easier to go power a device somewhere than return to the battery it will do so. If there’s still some left over power after handling the device, the rest will go to the battery.

The "Charger In" cable is overlayed with another cable that is going to the Genasun GV-10. The cable leaving GV-10 goes to a "Batt bank #2" fuse (in the photo, bank #1 fuse is the 2nd fuse from the left side, bank #2 fuse is the 1st from the right side). Both cables connecting GV-10 reads "ACR...". From his language below, I think this GV-10 is referred to as the ACR (automatic combining relay), bank #1 is the house bank, #2 is the starting bank.

All current ... will feed to the house bank, and the starting bank will be charged via a Blue Sea Systems ACR relay

How does ACR work better at topping off the starting batt than simply jumping the two studs?

(source: marinehowto.com)
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Look closer, that is the blue seas ACR, not Genasun
i could only barely see "Genasun". the other letters are too blurry

Genasun as a separate charger, it should be wired to the batt banks? i cannot see it in the photo
 
There are two devices there. A blue seas ACR, and a genasun mppt solar controller. Both go to the buss. The genasun charges the bank via solar panels, and the ACR connects the two banks when voltage is high enough to permit charging. The ACR is merely a relay. When it senses one bank reaching a certain voltage set point the relay will close, making direct connection between the two banks.
This method will connect the banks for charging and separate them when discharging.
The ACR replaces the old method of using a diode isolator. Diode isolators have a 1/2 volt drop across them. Not ideal in these days of tighter battery charging profiles.
 
Most battery monitors will have inputs for more than one bank. Usually though, it will have just one shunt for measuring amp hours, and the other inputs will be voltage only.
The idea is, you need to monitor the usage of the house bank more closely, so you can practice best management procedures to extend battery life. The start bank will typically top off quickly, so monitoring voltage is good enough.
I found this victron bmv-712 on amazon, but it seems only have inputs for up to two batteries. my boat has 7 batteries (2 starting) - what monitor can cover them all?

photo: https://www.victronenergy.com/upload/documents/Quick-Install-Guide-BMV-712.pdf
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paulga, I think you are confused. The Genasun GV-10 (a solar panel charge controller) is the black box with white lettering on it thats about 3" tall and 5" wide. On its left side are 2 pairs of say 10 ga. conductors, red & yellow plus red & black. One of these pairs goes to one of your Battery Banks, the other pair goes to the solar panels. There should be fuses and or switches along the way.

Directly below the GV-10 is an Automatic Charging Rely, the 3" square black box with the 2 yellow tabs, which if you push them sideways allows you to take the cover off that exposes the large terminals. This ACR is nothing more than a fully automatic, voltage triggered switch that "closes" when either of these large terminals has a voltage greater than 13.0 +/- volts on it. The switch will also "open" when the voltage drops to something around 12.7 +/- volts. The ACR is constantly measuring the voltage and acts accordingly, it's automatic, you do nothing.

These ACRs are useful, here are a couple of examples.

- You have been on the hook overnight, watched a movie, with popcorn and now have made breakfast and coffee, all without running the genset. The house bank is depleted. You weigh anchor and get underway and 5 minutes later the alternator which is connected only to the start bank has raised the start bank's voltage to 13.1 Volts and bingo, the ACR "closes" which now connects the house bank to the start bank and naturally, the alternator and now you charge the house bank. Hopefully the alternator can handle the heat.

- After cruising for 5 hours to your next destination the house and start banks are both fully charged and the alternator is basically idling along, just producing whatever your running loads are, plus Metallica on the stereo. You drop the hook and shut things down, except Metallica. 5 minutes later the ACR "opens" as battery voltage dropped to the trigger voltage, which now isolates the start bank from the house bank as you don't want to deplete your start bank, unless it Mozart. In the morning, the start bank which is no longer connected to the house bank should easily start the engine.

Now to answer your question, jumping the 2 studs is likely the cheapest and most effective way of directing a charge voltage to both battery Banks. The problem is that you don't always want the two Banks combined as Metallica, while at rest, will certainly deplete the Start Bank. You would have to crawl down there and un-jump the Banks asap, should you want to start the engine in the morning. The ACR does this for you automatically.

The ACR monitors battery voltage, it does not know (or care) where the charge voltage came from. That being the case it will also combine the 2 Battery Banks (which effectively allows both Banks to charge) once one of them has it's voltage raised by the ac powered battery charger, your solar panels output, or the dynamo on your pedal bike.

As always there are lots of rules when using an ACR, you should do some reading.
 
paulga, I think you are confused. The Genasun GV-10 (a solar panel charge controller) is the black box with white lettering on it thats about 3" tall and 5" wide. On its left side are 2 pairs of say 10 ga. conductors, red & yellow plus red & black. One of these pairs goes to one of your Battery Banks, the other pair goes to the solar panels. There should be fuses and or switches along the way.

Directly below the GV-10 is an Automatic Charging Rely, the 3" square black box with the 2 yellow tabs, which if you push them sideways allows you to take the cover off that exposes the large terminals. This ACR is nothing more than a fully automatic, voltage triggered switch that "closes" when either of these large terminals has a voltage greater than 13.0 +/- volts on it. The switch will also "open" when the voltage drops to something around 12.7 +/- volts. The ACR is constantly measuring the voltage and acts accordingly, it's automatic, you do nothing.

These ACRs are useful, here are a couple of examples.

- You have been on the hook overnight, watched a movie, with popcorn and now have made breakfast and coffee, all without running the genset. The house bank is depleted. You weigh anchor and get underway and 5 minutes later the alternator which is connected only to the start bank has raised the start bank's voltage to 13.1 Volts and bingo, the ACR "closes" which now connects the house bank to the start bank and naturally, the alternator and now you charge the house bank. Hopefully the alternator can handle the heat.

- After cruising for 5 hours to your next destination the house and start banks are both fully charged and the alternator is basically idling along, just producing whatever your running loads are, plus Metallica on the stereo. You drop the hook and shut things down, except Metallica. 5 minutes later the ACR "opens" as battery voltage dropped to the trigger voltage, which now isolates the start bank from the house bank as you don't want to deplete your start bank, unless it Mozart. In the morning, the start bank which is no longer connected to the house bank should easily start the engine.

Now to answer your question, jumping the 2 studs is likely the cheapest and most effective way of directing a charge voltage to both battery Banks. The problem is that you don't always want the two Banks combined as Metallica, while at rest, will certainly deplete the Start Bank. You would have to crawl down there and un-jump the Banks asap, should you want to start the engine in the morning. The ACR does this for you automatically.

The ACR monitors battery voltage, it does not know (or care) where the charge voltage came from. That being the case it will also combine the 2 Battery Banks (which effectively allows both Banks to charge) once one of them has it's voltage raised by the ac powered battery charger, your solar panels output, or the dynamo on your pedal bike.

As always there are lots of rules when using an ACR, you should do some reading.

Thanks for explaining what a batt isolator is.
I first noticed it on xm1800 inverter's manual -. I have been wondering what/where that isolator is.

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my boat has a manual battery isolator/switch at the lower helm station. this allows to manually isolate starting battery bank (1) from the boat's DC system. I put it to 2 (house bank) all the time. I think there is another isolator b/t the starting and house batteries to regulate charging, just curious, could it be in the bilge or the electrical box?

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There are two devices there. A blue seas ACR, and a genasun mppt solar controller. Both go to the buss. The genasun charges the bank via solar panels, and the ACR connects the two banks when voltage is high enough to permit charging. The ACR is merely a relay. When it senses one bank reaching a certain voltage set point the relay will close, making direct connection between the two banks.
This method will connect the banks for charging and separate them when discharging.
The ACR replaces the old method of using a diode isolator. Diode isolators have a 1/2 volt drop across them. Not ideal in these days of tighter battery charging profiles.

I cannot see how the genasun is wired to the fuse bus in the picture
which fuse is genasun connected to?
 
I cannot see how the genasun is wired to the fuse bus in the picture
which fuse is genasun connected to?
I can’t be certain, but it looks like it’s unfused and lands on the buss opposite of the alternator fuse.
It’s possible there’s an inline fuse or breaker, but it’s out of the picture.
 
I found this victron bmv-712 on amazon, but it seems only have inputs for up to two batteries. my boat has 7 batteries (2 starting) - what monitor can cover them all?

photo: https://www.victronenergy.com/upload/documents/Quick-Install-Guide-BMV-712.pdf
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A group of batteries arranged in series/parallel connection can be read as one battery. You say you have two for starting, that leaves 5 for house bank unless there’s a thruster battery.
I find it almost hard to believe your boat doesn’t have a battery monitor already.
In any case, a lot of people like the Victron monitor, I’m sure it would be a valuable addition.
 
I can’t be certain, but it looks like it’s unfused and lands on the buss opposite of the alternator fuse.
It’s possible there’s an inline fuse or breaker, but it’s out of the picture.
Ok. I thought both wires above the alternator fuse are to the various dc loads like nav lights and depth sounder
 
Ok. I thought both wires above the alternator fuse are to the various dc loads like nav lights and depth sounder
I would think the house loads/dc panel would come off the middle lower cable that goes to battery switch 1. That is fused to protect the wire that goes to a breaker panel/distribution for smaller loads. It is not common to do individual take offs at the positive buss. An exception might be for a bilge pump circuit that is always live.
 
Yes, the dc power can coexist there. Remember, the power follows the path of least resistance. If it’s easier to go power a device somewhere than return to the battery it will do so. If there’s still some left over power after handling the device, the rest will go to the battery.
I didn't quite get how the potential works. so when charging is in progress, the current should flow along the green lines, forking into 2 branches. Could there exist the orange current from the battery, as a net effect, it offsets the current (1) by a bit while increases current (2)?

(source: marinehowto.com)
12closeUpWithCoverRemoved.jpg
 
I didn't quite get how the potential works. so when charging is in progress, the current should flow along the green lines, forking into 2 branches. Could there exist the orange current from the battery, as a net effect, it offsets the current (1) by a bit while increases current (2)?

(source: marinehowto.com)
View attachment 155114
Sort of, I guess.
The buss is just a meeting place. Anything that produces power will raise the voltage on that buss. Anything that consumes power will reduce the voltage on the same buss.
When the voltage drops, the charging devices increase their output (current) in an effort to maintain the proper voltage.
Which direction the electrons actually travel isn’t really important.
 
A group of batteries arranged in series/parallel connection can be read as one battery. You say you have two for starting, that leaves 5 for house bank unless there’s a thruster battery.
I find it almost hard to believe your boat doesn’t have a battery monitor already.
In any case, a lot of people like the Victron monitor, I’m sure it would be a valuable addition.
the only batt monitor on my boat is the analog amp meter at the main dc dist panel

this picture shows the area to the right of the ACR. is the DC neg buss bar here wired to the DC neg buss bar in the electrical box behind the main dist panel? Does the dc system have a bonding or earthing buss bar, like the grounding bar for the AC system?

(source: marinehowto.com)
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(quote: marinehowto.com)
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you would benefit from the installation of a good battery monitor. something that counts amp hours and gives you an accurate readout of exactly what you have in the house bank. without one, you're just guessing what you have based on voltage and amp draw. letting the bank rest without any loads for 24 hours and taking a vot reading can give a good estimate of charge as well, but who can do that while using the boat?
that dc negative buss does indeed have a large black wire routed to the dc distribution panel in the living area somewhere. the pictured buss could be considered the main dc negative buss, and it's likely a 600 amp buss bar. most if not all of the large negative cables would be routed there. from there there would be one connection to the battery monitor shunt (if a monitor is used), and one connection to the house battery bank negative. the house bank can be one or more batteries connected series/parallel.
the boat should also have a bonding system separate from the dc negative. usually this would have a main connection point at or near the engine. all of the underwater metals and case grounds(if required) should be connected to it, and there should be one connection from the negative buss to it as well. then the dc negative and all of the underwater metals are at the same voltage potential.
many times this bonding system is missing or in disrepair. especially on older vessels. if you ever do a deep dive into your dc system you should consider bringing this up to current standards.
 
I may be confused by the OP posting pictures from MHT instead of his own boat but I thought he had a shunt which would have a battery monitor more than just volts.
 
I may be confused by the OP posting pictures from MHT instead of his own boat but I thought he had a shunt which would have a battery monitor more than just volts.
he only mentioned an analog amp meter.
 

You are correct. Analog volt and amp for the dc panel, but the ac panel has only two amp meters.

Does a batt monitor provide similar info? Or do I need to have multiple shunts to monitor all banks of paralleled batteries?

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I may be confused by the OP posting pictures from MHT instead of his own boat but I thought he had a shunt which would have a battery monitor more than just volts.

You are correct. Analog volt and amp for the dc panel, but the ac panel has only two amp meters.

Does a batt monitor provide similar info? Or do I need to have multiple shunts to monitor all banks of paralleled batteries?

View attachment 155126
 
My shunt displays amp +/-, volts, SOC %, SOC amps.
if you have a shunt it is not hooked up to anything
 
My shunt displays amp +/-, volts, SOC %, SOC amps.
if you have a shunt it is not hooked up to anything
is this the sum of amp and collective SOC from all batteries?
what monitor do you use to check the volts of the individual batteries?
 
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