wired up my Inverter what a mess!!

cadillackid · 06-26-2016, 08:08 PM

and so I wired up my inverter today... its a Gopower 1500 watt Pure sine wave unit...

I have 2 group 31 AGM / VRLA deep cycle batteries..

I have a battery isolator that senses when the vehicle voltage drops below 12.6 to shut off and above 13.1 to start up..

I ran 2 Gayge wire from the batteries to the inverter.. about 12 cable feet..

I ran 2 gauge wire from the Main batteries / isolator to the auxillairy batteries.. 21 cable feet

the aux batteries are connected together by 1 gauge 18 inch connecting cables..

what works??

the isloator works perfectly.. turns on / turns off..

the inverter turns on and works though when i have 1200 watts on it the wires do get warm and I incur a bit of voltage drop to it.. thats expected to be normal..

the Load - running my portable inverter air conditioner it runs nicely on it.. as does my server rack test.. works great!

what doesnt work?

I cant charge my batteries!!
I get VERY LITTLE current going from the main battery set to the aux battery set.. literally like 8-10 amps measured with an amp-meter..

the voltage on the Aux side of the isolator is at 13.8.. then I get up to the aux battery packs and the voltage is way low with the inverter fully loaded.. and continues to drop till the cutout at 10.2 volts..

my wires dont get warm coming fro mthe main batteries to the aux... the voltage is just low .. if I take the positive main-aux wire off and then measure the voltage and then measure it is 13.8 volts ... when I connect it up theres no sparks or anything.. and again it doesnt get hot..

it just doesnt charge... what gives??

I did notice on the package for the wire it said copper coated aluminum... but 2 gauge is 2 gayge right? it should handle lots of current... or is the voltage drop just so great that the current doesnt get "eaten" up it just cant charge the batteries???

my next step is I just ordered some 2/0 pure copper wire... and going to try that.. for both the aux-main and the aux-inverter wires since my aux-inverter wires did get a little warm I thought I might need bigger wire..

ideas???

should I use house-style solid conductor wiring? that stuff a pain to run though..

-Christopher

Brad_SwiftFur · 06-26-2016, 08:39 PM

Who says 8-10 amps isn't charging your batteries? Typically when you start the engine, the main batteries will charge 30-40 amps for just a few seconds, then ramp down to anywhere between 1-10 amps "charge" when running. Mind you, these are high-amp starting batteries, not auxiliary, deep cycle batteries. Low amp discharge over long periods; low amp charge over long periods.

I assume your inverter is wired to the auxiliaries? And in turn, with the isolator on, it should draw from the auxiliaries and mains, until the mains drop to 12.6 at which point the isolator cuts out, the inverter continues to draw from the auxiliaries? If so, with the engine running and the inverter running a heavy load, you should be seeing 90+ amps going to the auxiliaries + inverter.

superdave · 06-26-2016, 09:54 PM

you should use welding cable between the inverter and the batteries,the shorter the better. 2 or 3 feet, also you should have a slow blow 300 amp fuse.

cadillackid · 06-26-2016, 10:51 PM

I am moving the inverter to shorten it's wires that helps the aix bat to inverter wire situation..

I have a 150 amp circuit breaker currently in that circuit . As well as 150 amp circuit breaker in the circuit between the main and aix batteries .. I did take them out briefly for testing to rule them out as an issue..

The thing I'm not getting is why am I NOT getting the high current draw from the mains when the inverter is loaded and the isolator engaged.. I would expect if my wife was truly too small and incurring serious drop that it would get warm but it did not.. The voltage was definitely low at the aux bats vs the leaving point of the isolator but the wires didn't heat up one bit .. Unless over 25 feet of wire the heat is all dispersed and I'm just left with low voltage..

I realize that at idle I may not be able to pull a full load off the inverter and make it up but is have expected quite a few amps pumping into the aix circuit since I had played so much the batteries had to be getting low..

The new wire will tell me more as 2/0 is quite a bit more surface area than 2 gauge and it's all copper and not copper coated aluminum..
I could shorten my main to aix connection but then my batteries have to live near the front of the bus.. I want them in the back.. My isolator is only 15" cable length from my main batteries and I think that connector is a 1 gauge cable ...

Christipher

superdave · 06-27-2016, 05:38 AM

do you have a battery tester with the load option? harbor freight has them cheap. you could load test it , pull 100 amps and see how the isolator works. if its not that it would have to be a connection or the ground. did you run a negative wire also? good luck

bubb, the real one · 06-27-2016, 05:39 AM

what is the amp hour rating of your batteries, generally speaking you cannot draw more than about 10% of the amp hour rating of a battery without loosing voltage,

cadillackid · 06-27-2016, 06:23 AM

Quote:

Originally Posted by superdave

do you have a battery tester with the load option? harbor freight has them cheap. you could load test it , pull 100 amps and see how the isolator works. if its not that it would have to be a connection or the ground. did you run a negative wire also? good luck

I pulled 100 amps with the inverter and the isolator stayed in because it is measuring the Starting battery voltage as its gauge of whether to go in or not.. because im not getting much current from the mains to the aux the isolator doesnt see a voltage drop and stays engaged as it should.. I know its engaged as I see 13.8 volts on both sides of the isolator solenoid.. if I pull the engine stop and leave the electrical systems up on the bus the isolator disengages.. (esp if I leave the Engone-driven A/C fans running as they drop the MAIN battery voltage below 12.6 fairly quick and the isolator shuts off as it should)...

I expect to see voltage drop on my AUX batteries as I run up the current... which to me the more the voltage differential id expect to see more current flow from the MAIN to the AUX to attempt to charge them.. or see the MAIN voltage drop down if im over-running the charging system..

im goingto try the 2/0 wire from the MAIN to the Aux and see how that goes, as well as im moving the inverter to the back of the Bus which will place it withn 24" Cable feet of the batteries so that will help out any voltage drop i had between the AUX and the Inverter..

the cable I was using also had crimped ends.. while I didnt hit the battery ends with my temperature gun they didnt feel warm, however people say soldering the connectors on is a much better way to go.. so im going to solder up my ends on the new cables and see how that goes also...

a friend of mine suggested i add at least one more battery.. even though I dont necessarily need the run time, he said im exceeding the 5 hour drain rating for the batteries and even on deep cycle thats hard on them.. that going to a 3rd or 4th battery brings them up into the 5 hour discharge rating.. and if I really wanted to help things out to go to a 4th battery which brings me well above that...

at the point of adding 4 batteries at whatever the darn thngs weight.. (they seem heavy) I begin to wonder if im loading toomuch behind the rear wheels at the left side of the bus.. but then at 50 lbs a piece 200 lbs may mean nthing in terms of weight.. even though moving them around seems rather brutal to me as im just a little dude without much in the way of muscles..

-Christopher

somewhereinusa · 06-27-2016, 07:27 AM

Quote:

the cable I was using also had crimped ends.. while I didnt hit the battery ends with my temperature gun they didnt feel warm, however people say soldering the connectors on is a much better way to go.. so im going to solder up my ends on the new cables and see how that goes also...

I also researched this, I thing you'll fine much argument both ways. One problem is with solder if there is a bad connection, the solder will melt. I decided to go with crimp, and now have the tools to make my own. I can crimp up to 4/00. You can never have too many tools, right?

I haven't taken the time to draw out your setup, but your cables seem a bit long and small to me. I'm not familiar with your isolater, but pretty much all RVs just use heavy continuous duty solenoids. Pretty fool proof and don't use diodes that rob any power. In my setup when the engine is running the solenoid is energized to charge the house batteries with a switch on the dash to de-energize if I want to. When engine is running ALL batteries are being charged. Engine not running start and house batteries are not connected. An added bonus, I once ran down the start batteries, turned on the key for about half hour to let the batteries equalize and started right up.

Quote:

The voltage was definitely low at the aux bats vs the leaving point of the isolator but the wires didn't heat up one bit

If I'm reading this right you have different voltage at each end of the same wire with nothing in between? While generally trying to trouble shoot by feeling the wire isn't going to be of much use

Quote:

.. Unless over 25 feet of wire the heat is all dispersed and I'm just left with low voltage

in this case it would get hotter.

Dick

cadillackid · 06-27-2016, 07:39 AM

Quote:

Originally Posted by somewhereinusa

I also researched this, I thing you'll fine much argument both ways. One problem is with solder if there is a bad connection, the solder will melt. I decided to go with crimp, and now have the tools to make my own. I can crimp up to 4/00. You can never have too many tools, right?

I haven't taken the time to draw out your setup, but your cables seem a bit long and small to me. I'm not familiar with your isolater, but pretty much all RVs just use heavy continuous duty solenoids. Pretty fool proof and don't use diodes that rob any power. In my setup when the engine is running the solenoid is energized to charge the house batteries with a switch on the dash to de-energize if I want to. When engine is running ALL batteries are being charged. Engine not running start and house batteries are not connected. An added bonus, I once ran down the start batteries, turned on the key for about half hour to let the batteries equalize and started right up.

I also bought a crimp tool to crimp the big stuff .. actually I had it from long ago.. building hotrods I always wanted to be able to make my own battery cables so I could dress them under the hood nicely.

yes my isolator is a continuous duty solenoid and a tiny little micro-processor that detects the voltage of the MAIN system and will energize the solenoid if the system voltage goes over 13 volts (noting the alternator must be charging then).. and De-energize the system at 12.6 volts (or when I throw out a switch)..

I wired a switch in where i can force on or off the solenoid at will..

this feature I'll likely use when Heating as my heater fans are all connected to my main system... I may put a circuit breaker bar up into the main electrical compartment for my Aux system, I havent decided yet.. then I could wire some of my heater fans to the Aux system.

my Diesel coolant heater will be on the Aux system so i should have a couple fans on it..

my bus has no glowplugs or grid heater.. that bothers me for the really cold temps I may drive in the winter, park overnight at a hotel and have no place to plug the block heater in... seems I'll heat the coolant and then start the engine right up..

-Christopher

somewhereinusa · 06-27-2016, 07:48 AM

Christopher, I edited previous post while you were posting. Do you have a diagram of your setup with wire sizes and lengths? A link to your isolater? I haven't seen those.

Dick

EastCoastCB · 06-27-2016, 08:46 AM

A properly running DT will have no trouble starting in the cold.
One group 31 started mine in 10* weather with icicles hanging off the bus.

family wagon · 06-27-2016, 10:58 AM

If I understood it correctly, you've got the isolator (a simple solenoid plus controller?) near the main batteries and the voltage at its output "looks good." But the voltage at the aux batteries droops after the inverter has run for a while, even though the isolator appears to be on, alternator is on, etc.

Nominal resistance of solid copper (per hyperphisics) is 0.1563 ohm per 1000 ft, or 156 micro-ohm per foot. Working with rough numbers, you were seeing 13 volts at the isolator and 10 volts at the battery with about 10 amps flowing through the connection? That looks like about 0.3 ohms resistance between them to create that voltage drop. You mentioned copper-coated aluminum, but I can't imagine it's that much higher-resistance than pure copper. There has to be more than just the metal type and gauge going into this.

If you could draw us a schematic, label several nodes, and measure voltages among the nodes that could help. Test with and without loads, ie inverter loaded or unloaded, aux battery fully charged or somewhat discharged (this affects alternator load when the inverter load is off).

cadillackid · 06-30-2016, 04:58 PM

welding cable 2/0 fixed the issue! batteries charge and my 200 amp alternator keeps everything running even at idle with the A/C on and a 1000 watt load on the inverter...

welding cable is a PITA to pull through holes but is nice and flexible..

no warm wires, no warm connections.. no massive voltage drops..

that other wire just wasnt conducive to conducting I guess...

-Christopher

EastCoastCB · 06-30-2016, 05:26 PM

Quote:

Originally Posted by superdave

you should use welding cable between the inverter and the batteries,the shorter the better. 2 or 3 feet, also you should have a slow blow 300 amp fuse.

Dave with the win!

aaronsb · 06-30-2016, 05:39 PM

I just read this thread, good job! I was going to post something about "if the wires are warm, they're probably too small" but you found that out. ;)

Quote:

Originally Posted by cadillackid

welding cable 2/0 fixed the issue! batteries charge and my 200 amp alternator keeps everything running even at idle with the A/C on and a 1000 watt load on the inverter...

welding cable is a PITA to pull through holes but is nice and flexible..

no warm wires, no warm connections.. no massive voltage drops..

that other wire just wasnt conducive to conducting I guess...

-Christopher

RC000E · 07-05-2016, 12:44 PM

Quote:

Originally Posted by cadillackid

welding cable 2/0 fixed the issue! batteries charge and my 200 amp alternator keeps everything running even at idle with the A/C on and a 1000 watt load on the inverter...

welding cable is a PITA to pull through holes but is nice and flexible..

no warm wires, no warm connections.. no massive voltage drops..

that other wire just wasnt conducive to conducting I guess...

-Christopher

Can you do up a basic schematic of your system to coincide with the thread? Could be of good use to searchers in the future.

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