Help with battery power-possible upgrade

[daveb]

Take up boywonders offering. Without knowing the tech data of your build it's kind of hard to say what's happening. On most newer builds SMB did, there is a battery separator. Older vans had isolators. So typically with the engine off you'll usually see different voltages between the dash power port that run off the starting battery and the rear power posts that run off the house battery. When you start the engine the separator or isolator begins to allow charge current from the alternator to flow to the house battery. As soon as the alternator starts to charge, the voltages between the starting and house battery systems should be fairly close. When the engine is shut down the house battery will provide all the power to your fridge after the separator opens. Once open if you see the voltage drop quickly into the sub 12v level there is something wrong. But if it last for 3 days w/o a charge, depending on the size and health of the battery you might be OK.

[DerPo]

Originally Posted by daveb

Take up boywonders offering. Without knowing the tech data of your build it's kind of hard to say what's happening. On most newer builds SMB did, there is a battery separator. Older vans had isolators. So typically with the engine off you'll usually see different voltages between the dash power port that run off the starting battery and the rear power posts that run off the house battery. When you start the engine the separator or isolator begins to allow charge current from the alternator to flow to the house battery. As soon as the alternator starts to charge, the voltages between the starting and house battery systems should be fairly close. When the engine is shut down the house battery will provide all the power to your fridge after the separator opens. Once open if you see the voltage drop quickly into the sub 12v level there is something wrong. But if it last for 3 days w/o a charge, depending on the size and health of the battery you might be OK.

The dash port and the sink port both have about the same charging volts when the van is running.

What I will do is attempt to plug in the van, then see how long I get out of a potentially full battery.

So, now the next question- What adapter do I need to be able to plug my SMB into my house. I think the power cord has the sideways prongs. Do I just plug it in and thats it?

[boywonder]

DerPo: Can you post a picture of your shore power adapter? Sounds like a 20A plug/receptacle....

With the van off measuring by the sink (10V) is that with the fridge running? What is the house battery voltage when you are seeing 10V at the sink?

As Dave mentioned, there are battery separators and battery isolators. One down side of an isolator is that it drops around .7V (typical diode forward voltage drop) when connecting the batteries. When you only have 12-13V to start with .7V is a lot. Separators do not suffer from this since they don't use diodes. That .7V voltage drop also implies that you will struggle to completely top off your house battery.

Even a modest/moderate solar setup is usually enough to keep a fridge running for days if its sunny outside.

[DerPo]

Thanks again for all you help and patience through my learning curve.

I have some photos of my set up.

Heres the sink plug after diving for a day with the ignition off
http://imgur.com/YxIZagl
12.11 volts

sink with ignition on-
http://i.imgur.com/VfJiL1b.jpg

Dash w ignition
http://i.imgur.com/gk6uOqT.jpg


setup-
http://i.imgur.com/zDJV1xU.jpg


The inverter -
http://imgur.com/AOQQyqa

the shore plug-
http://imgur.com/41N7pOV

the shore line ( found an adapter!)

http://i.imgur.com/hUapqq2.jpg



Let me know if you need any other photos!


So I turned on the fridge and the volts didn't immediately drop. The meter showed 12.33V then 12.12V. the little light went from orange to red, whatever that means.

[reelchef67]

seeing as you ran your battery down to what looks like 10v by running your fridge on max. I would dsiconnect your house battery put a deep cycle charger with an AGM setting on it for a couple days.FWIW you may have a ruined the battery running it down to 10V's is 0% charge.
A 50% charge is 12.06 volts. so. battery might be toast

[daveb]

The deal is even with a .7 voltage drop from the alternator, the house battery should be keeping a voltage of about 12.8 for a substantial time and then slowly drops depending on the load. More load added obviously makes it drop faster. You're seeing 13.6 with the engine running so the battery should be getting a charge.
It's probably time to take voltage off the battery lugs themselves. As mentioned you should put a good hard charge on it for a day or so then test the battery voltage after no load or charge has been put on it for a few hours.





It sounds like a bad battery but a bad connection also can produce low voltage issues so you need to look over everything. Some batteries can be equalized and be brought back to better health. Each battery size type and manufacture will have different stats. You need to find the manufactures data on the battery. Here is Concorde's data:
http://www.lifelinebatteries.com/manual.pdf