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Battery charge from alternator

Old 05-29-2018, 07:44 AM
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Default Battery charge from alternator



I need help figuring out if my house battery is getting a full charge from the alternator. The pic is my battery switch set-up. One on- off for the starting battery, one for the house battery.

Here is my unscientific procedure I performed yesterday. The batteries have been tested and are fine. I put a multimeter to the starting battery 12.7 V good. The house battery was at 12.40 V. I then started the engine and retested. Starting battery getting 14 + V and the house battery still at 12.40 V.

I then ran the boat for 20 minutes to a fishing spot. House battery now down to 12.28 V. So we fished the day with minimal equipment use, ran home and I tested the house battery again. Now 12.33 V.

Some charge but not enough. Could the battery switch be bad? How could I further troubleshoot this issue?
Old 05-29-2018, 08:12 AM
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VSR prioritizes starting battery first. could be its not registering full charge or the house is on its way out. Does putting on a charger bring both to full 13.8 volts? Are your connections (grounds and hots) clean and making good contact? So many issues occur due to bad connections/grounds.
Old 05-29-2018, 08:28 AM
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The connections at battery are clean. I will have to check at the battery switch. How would I check if it's not registering a full charge at the starting battery?
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Old 05-29-2018, 08:32 AM
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I'm also using a deep cycle battery for my starting battery. Could that have any effect?
Old 05-29-2018, 08:32 AM
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Looks like VSR was an option and you did not get it. Install one. Or a manual switch tying the two batts together. 12.33 on one, and 14.00 on the other mean they are not connected.
Old 05-29-2018, 08:37 AM
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Originally Posted by snapper999 View Post
How would I check if it's not registering a full charge at the starting battery?
"VSR prioritizes starting battery first."
that sounds like more than it actually does;
it's a "voltage sensitive relay" - says right on it:

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as soon as it "senses" 13.7 volts at the starting battery, it closes -
and applies whatever current is available to the house, as well.

Since you measured >14 it should have closed.

Its possible the VSR has simply failed.

But look into exactly where it is connected;
youmay simply have a disconnected wire.
several places the wires could be run from, here is one way

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Old 05-29-2018, 09:50 AM
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Thanks Fwpratt. That's really helpful. I'll start with pulling the panel, cleaning connections and tightening everything.

I have a better understanding how this system works.
Old 05-29-2018, 05:17 PM
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You may have a VSR or on many larger engines there is a fused aux charging harness that charges the house batt without a VSR. Will normally appear as an extra heavyish red wire on the +ve of the house batt. Easiest test you can do just with a voltmeter is to use the fast idle function to bring the engine up to say 2000rpm and then check the voltages at both batts. They should both be the same or the house batt maybe 0.1 - 0.2v lower if the batteries are charged so charge the batts on a charger before doing your testing. If either battery is flat and you have a VSR you can get funny things happening until the charge levels come up depending on how much alternator output you have.
Note that when you turn everything off like you probably did after your last trip the voltage at the battery will rise a little once the load is removed. That is probably what you interpreted as 'some charge' getting to your house batt.
Old 05-30-2018, 04:02 PM
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When I get to the boat this weekend I'll take pics, but what should I expect to see as to wiring when I remove the panel. Main red from engine going to the engine switch and another red going to the starting battery. Another main red going to the house switch and another red going to the house battery. Each is an individual switch separate from the other. Unless there is a VSR back there.
Old 05-30-2018, 05:00 PM
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I have the exact same setup on my HS. Even the same panel. Here were my observations today:

Starting battery at rest - 12.8 volts
House Battery at rest - 12.5 volts

I did use the boat this past weekend. so I assumed I might have lost a little juice on the house battery.

With engine running I got 13.7 volts on both batteries. So I assume my VSR is working correctly. However, I never get a full charge on my house battery after fishing, it always seems to stay at about 12.5 volts. Both house and starting batteries are 1 year old DEKA 27M6's. I think my House battery might be going bad, because if I don't use the boat for a few weeks the voltage on the house battery drops and sometimes even goes dead.
Old 05-31-2018, 08:14 AM
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Thanks Catching Chrome. The HS is a real tank. The problem I have is that in a couple of weeks I'll be down to 12.0 v and will have to take the battery home to charge up. If your battery is in the same spot as mine you know that's a PITA. This is even after using the boat a couple of times a week. Have you ever looked behind the panel to see if there is a VSR module? I will try higher fast idle and see if I get something on the house battery. Something's not right.
Old 06-04-2018, 05:47 AM
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.

To wrap up this thread. I got to the boat this weekend and pulled the battery switch panel. The VSR module was behind the panel and works. BACKTOSEA had it right. Some of the screws were not tight. I cleaned all the connections and re-tightened all the screws. Both batteries getting a good charge in idle.
Old 06-04-2018, 06:16 AM
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For future reference - that panel looks like it's got an LED in the middle which will light up when the batteries are combined (as does every VSR I've come across).
Old 06-04-2018, 06:27 AM
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Glad you got it working correctly. Just a thought for you, my VSR has an LED which comes on when the starting battery has charged and the relay kicks in to charge the house battery. In your pic it looks like you have one on the VSR panel in the lower left of the VSR circle. Also, I wouldn't use a straight deep cycle as my starting battery. They can reach a point in life where it takes a long time to fully recharge and may cause the VSR not to activate as quickly. Just a personal preference.
Old 06-04-2018, 07:08 AM
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I'll peak in that hole and see If the LED light comes on. I also thought that the deep cycle battery as a starter would take longer to charge and therefore delay the switch over. I'll see how this plays out in the next couple trips. Thanks.

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