49 Owners and probably other large boat owners

[tkwhalen]

Can anyone explain the automated switch that won't allow shore power to engage and therefore cuts off battery charging if your battery amps fall below 8 amps. The circuit will only let shore power engage after an independent battery charger is brought aboard plugged in by 2 miles of extension cords (maybe a slight exaggeration) and used to bring the batteries above 8 amps. Once the batteries reach 8 amps the switch kicks in and allows shore power to kick on and you can finish charging with shore power. As I understand it the switch is wired into the 12 volt circuit and need the 8 amps to engage. Seems like a really dumb set up to me. My questions are:

why set it up that way ?
why is it needed?
can I eliminate it ?
are there better ways to wire it if it's needed?
where is it?

And if your asking how did my batteries get so low ...... some clown unplugged my boat while I was gone and the invertor kicked in running the frig and the freezer until it exhausted the batteries. This the third time I have had a some kind of loss of power problem in the last 6 years. Resulting in the hassle described above.

 

[ggrizzard]

I assume, when you say "other large boat owners", that you're alluding to 25 footers and up???

 

[BobH57]

Do you actually mean 8 volts instead of 8 amps? What model is your inverter/charger? Some will not charge below a specific depth of discharge.

 

[duality]

would it be faster to switch to start battery and start the engine, it should bring the battery voltage/amps up right away? just thinking out loud.
mike

 

[smokey73]

 

[Terry Cox]

Our boat setup seems a bit different. Both reefers operate DC so if and when the shore power disconnects for some reason, they will draw down the house bank to about eight volts. At this point the reefers will shut off due to low voltage. This has happened twice in the past ten years and both times the AGM house bank has recovered nicely without any appearance of harm or performance damage.

The first time boat movement from a storm caused the shore power cord socket to wiggle loose from the boat plug. Since then I have added a cord strain reliever to prevent this from happening again. No solid explanation regarding the last time. Arriving at the boat the Xantrex charger was off and the house bank was down to eight volts just as before. Manually restarted the charger and all systems returned to normal. Returned to the boat two weeks later and everything was normal. The only explanation is a possible marina power failure and when power was restored for some reason the charger would not recover.

What I like about the Freedom 25 is that the inverter does not automatically kick on when shore power fails; it has to be manually turned on. Unlike the original inverter where the inverter did automatically turn on when shore power failed and with a 115 volt AC space heater running, well you know what that would do.

 

[tkwhalen]

Yes sorry I mean volts not Amps

My invertor kicks in automatically which is the start of the downhill spiral ... I not sure if my frig and freezer shut off when volts get low I'll have to check that out .

I think Hunter tried to dummy proof the 49 and used all automated switching vs manual switching. At some point I'm going to have it all redone so that I can be in control. But short run I would really like to understand the purpose of the automated circuit that cuts off shore power when battery voltage is low,.

Oh and yes starting the engine and using the alternator would be an option if I hadn't already winterized it.

 

[MFD]

I am not sure what charger you have, the control unit for my 2009 41DS is from Magnum Energy. It has a variety of settings that can be programmed and I believe a 'low cut out' threshold as well. I can not recall when/why but it is my understanding that having a high amperage charger come on full force with severely depleted batteries can be dangerous. 8 volts is serious 'batteries ruined' level of discharge and for myself anyway, I would rather lose the batteries than have a fire.

For the inverter - if you have the same controller, it is easy to just leave it so it will not automatically switch over on power loss. That is how I use mine - we turn it on when needed and switch it back off when done and do our best to double check as part of plugging in the shore power cord when back home.

 

[tkwhalen]

Thank you MFD .... that is the best, heck the only, good explanation I have heard for the low voltage cut off . I could turn my invertor off as you suggest but then would lose refrigeration which means every thing in the frig and freezer would spoil buuuut that lose would be way less then the loss of my batteries. The reality is this is a sort of rare problem ...as I said before it's happened 3 times since 2015 when I bought the boat. My question was really to get an understanding of why which your explanation has given my a good reason to explore further.

Thanks

 

[artboas]

Thank you MFD .... that is the best, heck the only, good explanation I have heard for the low voltage cut off . I could turn my invertor off as you suggest but then would lose refrigeration which means every thing in the frig and freezer would spoil buuuut that lose would be way less then the loss of my batteries. The reality is this is a sort of rare problem ...as I said before it's happened 3 times since 2015 when I bought the boat. My question was really to get an understanding of why which your explanation has given my a good reason to explore further.

Thanks

Ok, I understand exactly what the problem is, and why you’re having this issue.
The AC systems, whether they be shore, or generator, run through some relays in the nav table AC breaker control box at the chart table.
These permit you to use the upper mini control panel to do things like select shore vs. Gen.
In the ver.,1 box, (which you have), they use 2 small relays with 12vdc coils. The coils on these are controlled by a spst switch on the quick panel.
These 12v relays then control the 220v AC coils of the large contactors, which switch either Shore or Gen onto the AC bus.
So, if you don’t have 12v supplied to the AC breaker box, then the small selector switch can’t energize the 50 Amp Shore / Gen relays.
The ver. 2 relay box did away with this.
They used a DPDT rocker switch in the quick panel, and ran the 220v directly up to the small rocker switch.
So, as soon as you had 220 on the boat, your 50 amp Stancor source selector relays could be energized, bringing either shore or gen live onto the boat.
Personally, I like the ver 1 system, as it doesn’t bring 220 v onto the quick panel.
This modification was done, I believe, to address the exact situation you are describing.
There are a few things you can do:
At the helm, there is a battery combine switch.. What this does is turns on the Blue Seas ACR, which is normally used to charge the start from the house charger.
By turning on this switch, it will dump voltage from the start battery to house, getting the house batteries enough of a temporary boost to get the AC control relays activated.
The other option is to start your engjne. This will have the alternator bring up the house batteries, and then you can get the AC systems going. At that point turn on the shore charger, and break out a cold one.

hope this has been helpful
Cheers

 

[tkwhalen]

Artboas

I've done a little more research and I've run across an explanation that I'm trying to tie into your comments. My understanding is that isolation transformer uses a 12volt signal to check ground and if it doesn't get sufficient feedback it isolates the boat eliminating the shore power connection. The 12 volt signal is considered to weak when the volts drop below 8 making the transformer isolate the boat. Any thoughts on this and how it may relate to your comments?

 

[JamesG161]

I had the same problem and got this for a simple portable fix.

WEST MARINE 700 Amp Jump Starter | West Marine

It is a battery charger, portable 12VDC plug, USB charger , etc.

I clamped that to the "low battery" and every thing lit up and allowed shore power to function again.
Jim...

PS: I see there is a smaller substituted now.

 

[artboas]

I had the same problem and got this for a simple portable fix.

WEST MARINE 700 Amp Jump Starter | West Marine

It is a battery charger, portable 12VDC plug, USB charger , etc.

I clamped that to the "low battery" and every thing lit up and allowed shore power to function again.
Jim...

PS: I see there is a smaller substituted now.

Artboas

I've done a little more research and I've run across an explanation that I'm trying to tie into your comments. My understanding is that isolation transformer uses a 12volt signal to check ground and if it doesn't get sufficient feedback it isolates the boat eliminating the shore power connection. The 12 volt signal is considered to weak when the volts drop below 8 making the transformer isolate the boat. Any thoughts on this and how it may relate to your comments?

I don’t believe this is correct at all.
The boat has a 12kw isolation transformer. All it does is isolate the boat, and prevent electrolysis.
There is no 12 v. Control on this.
This information is incorrect