dwh
Tail-End Charlie
If you ran it dead, it'll take at least 12 hours of driving, or a good long time on a benchtop charger to be fully charged again.
Help me figure out my house battery system...
- Thread starter HoboJen
- Start date
If you ran it dead, it'll take at least 12 hours of driving, or a good long time on a benchtop charger to be fully charged again.
too late! i spent $35 i think on a digital one.
now i have a dumb question. if i'm testing the voltage of the wires at the solenoid... um... so there's two leads, red and black. the red goes on the wire/screw/whatever... where do i put the other lead? i've read a lot of the directions but i'm not quite clear on that.
now i have a dumb question. if i'm testing the voltage of the wires at the solenoid... um... so there's two leads, red and black. the red goes on the wire/screw/whatever... where do i put the other lead? i've read a lot of the directions but i'm not quite clear on that.
Herbie
Rendezvous Conspirator
Generally, it's OK to measure against chassis ground - so find any clean, unpainted screw, bolt or other bit of chassis. If you see a bolt with a lot of black wires all going into it, that's one of the factory ground points and is a good choice.
The red lead will then read your +V at various points (battery, solenoid terminals, etc.)
The red lead will then read your +V at various points (battery, solenoid terminals, etc.)
here is my diagram for the system. i wrote (light, sink, pump but it should be light, sink pump, roof vent):
here is where the small wire going up front goes (it's the red wire). I don't know what that is:
here's the fuse box and switch:
i took the first few measurements at the solenoid and not sure if i'm doing something wrong...
test 1 (cold): both fat and skinny wires at solenoid were at 12.3V. when i tested the skinny it was on the screw that it connects to.
test 2 (engine running): fat at solenoid 13.7V, skinny at solenoid 14.3V
test 3 (engine off): both at 12.6V. measured resistance between fat to starter and fat to house and it was 35ish. i put each lead on the opposite sides of the solenoid... also not sure i did it right.. i did change the setting to resistance
i need to reread dwh's posts again to understand the other tests...
here is where the small wire going up front goes (it's the red wire). I don't know what that is:
here's the fuse box and switch:
i took the first few measurements at the solenoid and not sure if i'm doing something wrong...
test 1 (cold): both fat and skinny wires at solenoid were at 12.3V. when i tested the skinny it was on the screw that it connects to.
test 2 (engine running): fat at solenoid 13.7V, skinny at solenoid 14.3V
test 3 (engine off): both at 12.6V. measured resistance between fat to starter and fat to house and it was 35ish. i put each lead on the opposite sides of the solenoid... also not sure i did it right.. i did change the setting to resistance
i need to reread dwh's posts again to understand the other tests...
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Joe917
Explorer
That is some pretty ugly wiring!
The good news is at least someone fused it, but I don't know how long it will stay connected on the bumps.
I would get rid of that Mickey Mouse fuse block and go with something with a negative bus bar and modern blade fuses. Something like this:
http://www.bluesea.com/products/5025/ST_Blade_Fuse_Block_-_6_Circuits_with_Negative_Bus_and_Cover
That switch needs to be removed from the negative side and the main neg (the one wire nutted between the circuits and the battery needs to be large enough to take the max amperage of the combined circuits. Wire nuts have no place in mobile applications.
I cannot see it in the picture but I would assume your positive wire to the fuse block is also undersized, is it fused? it should be. This is where you should put a proper disconnect switch.
I would highly recommend an amp hour meter to keep track of battery use. I have a Trimetric and am very happy with it but there are other good brands.
The good news is at least someone fused it, but I don't know how long it will stay connected on the bumps.
I would get rid of that Mickey Mouse fuse block and go with something with a negative bus bar and modern blade fuses. Something like this:
http://www.bluesea.com/products/5025/ST_Blade_Fuse_Block_-_6_Circuits_with_Negative_Bus_and_Cover
That switch needs to be removed from the negative side and the main neg (the one wire nutted between the circuits and the battery needs to be large enough to take the max amperage of the combined circuits. Wire nuts have no place in mobile applications.
I cannot see it in the picture but I would assume your positive wire to the fuse block is also undersized, is it fused? it should be. This is where you should put a proper disconnect switch.
I would highly recommend an amp hour meter to keep track of battery use. I have a Trimetric and am very happy with it but there are other good brands.
oy, that sucks to hear!
the positive wire to the fuse block is the same size as the wires to the fuses themselves. you can see the small wire from the positive in the photo of the solenoid. sadly that wire isn't even solidly connected to the battery...
wire nuts... so that's what those blue things are.
i don't see any other fuses other than those 3.
maybe i can make some changes to the system when i do solar.. and maybe i can add that sooner. i still have a lot to learn though!
the positive wire to the fuse block is the same size as the wires to the fuses themselves. you can see the small wire from the positive in the photo of the solenoid. sadly that wire isn't even solidly connected to the battery...
wire nuts... so that's what those blue things are.
i don't see any other fuses other than those 3.
maybe i can make some changes to the system when i do solar.. and maybe i can add that sooner. i still have a lot to learn though!
Joe917
Explorer
This is not too complicated or a big deal. Wire sizing is easy add up your amperage loads and check a wire size chart. Fuse size is determined by the smallest unfused wire in the circuit. The fuse must fail before the wire, every positive wire needs to be fused as close as possible to its source. The corrections I noted can all be done cheaply by you and you will learn more about your vehicle.
the small wire is 12 gauge rated for 20 amps...
the current loads are
LED lights - says output is 6 amps max
Fantastic Vent 1200 - i can only find "low amp draw" - it has a 4 amp fuse, so a draw less than that.
sink pump - 3 to 5 amps? with the way it is installed, i can't get to any info about it. it's small and in a 5 gallon water jug.
so i think the 12 gauge wire might be alright there, unless i was to hook up something else.
the current loads are
LED lights - says output is 6 amps max
Fantastic Vent 1200 - i can only find "low amp draw" - it has a 4 amp fuse, so a draw less than that.
sink pump - 3 to 5 amps? with the way it is installed, i can't get to any info about it. it's small and in a 5 gallon water jug.
so i think the 12 gauge wire might be alright there, unless i was to hook up something else.
i took the first few measurements at the solenoid and not sure if i'm doing something wrong...
test 1 (cold): both fat and skinny wires at solenoid were at 12.3V. when i tested the skinny it was on the screw that it connects to.
test 2 (engine running): fat at solenoid 13.7V, skinny at solenoid 14.3V
test 3 (engine off): both at 12.6V. measured resistance between fat to starter and fat to house and it was 35ish. i put each lead on the opposite sides of the solenoid... also not sure i did it right.. i did change the setting to resistance
i need to reread dwh's posts again to understand the other tests...
The diagram all looks ok - just the wiring quality seems questionable. The test results seem odd - it implies that the small red wire from the engine bay is not connected to something that switches on and off with the engine! (Maybe its a sympton of solenoid failure tho?)
I would try disconnecting the small red wire from the solenoid and re-measure the voltage at the end of the small wire and at the place where it was connected to the solenoid. Hopefully the end of the wire is about 14v when engine on and 0v when engine off. Also - if the voltage of either side of the solenoid is the same with the engine running (the thick red and black wires in the photo), then it would confirm the solenoid needs replacing.
Also worth checking the solenoid is grounded properly - measure the voltage difference between the negative at the battery and the case/outside of the solenoid - should be 0V.
i tried again and here's what i observed. The solenoid is very hot even though the van had just been sitting for a couple of hours.
van not running:
fat to starter - 12.4
skinny wire itself - 12.5 (supposed to be zero, right? have we found the problem?)
solenoid where skinny wire connects - 0
van running:
fat to starter 14.1
fat to house 12.2
skinny wire itself 14.4
solenoid where skinny wire connects 0
both the negative at the battery and the case of the solenoid were at zero, both running and not running.
van not running:
fat to starter - 12.4
skinny wire itself - 12.5 (supposed to be zero, right? have we found the problem?)
solenoid where skinny wire connects - 0
van running:
fat to starter 14.1
fat to house 12.2
skinny wire itself 14.4
solenoid where skinny wire connects 0
both the negative at the battery and the case of the solenoid were at zero, both running and not running.
dwh
Tail-End Charlie
Does that wirenut have black going into it AND those three reds?
If so, then your diagram must be wrong.
It looks to me like the black feeds to the switch, then to the wirenut, then to the three fuses - which then feed out to the lights, etc.
So the switch kills power to the fuses.
In which case, the switch gets power from + not from - as in your diagram.
Which is fine, except for the wrong colors being used (and the horrible workmanship).
Wrong color is also happening at the solenoid, where one battery + is black, and the other red.
You don't need to test resistance at this stage - just voltage and/or continuity.
Your test 1 shows a problem.
If the ignition is turned off, then there should be NO voltage at the skinny wire where it meets the solenoid.
In the photo, it appears to be wired directly to the battery + terminal of the alternator.
That would be the same as wiring it straight to the + on the engine battery.
And that is WRONG.
Wired that way, the solenoid is engaged and tying the engine and house batteries into a bank FULL TIME. (And the solenoid is drawing a bit of power out of both batteries 24/7.)<*>
This is further indicated by test 2 (engine running).
The batteries are at 13.7v, but the skinny wire feeding the solenoid is getting power directly from the alternator at 14.3v.
<*>I think I see what's happening there - whoever did it, didn't understand how it works.
I think they thought it was like a diode isolator (the ones with the heat sink you can buy at the auto parts store).
With a diode type, you run the charging wire to the center terminal of the diode isolator, and then run one wire out to each battery.
Which looks like what they did on your truck.
BUT
Yours is a solenoid type called a "split-charge relay" and doesn't work the same way as a diode type at all.
The skinny wire activating the solenoid should normally be wired so that it only has power when the ignition switch is on.
Disconnect it from the alternator ASAP and hook it to an ignition circuit.
If so, then your diagram must be wrong.
It looks to me like the black feeds to the switch, then to the wirenut, then to the three fuses - which then feed out to the lights, etc.
So the switch kills power to the fuses.
In which case, the switch gets power from + not from - as in your diagram.
Which is fine, except for the wrong colors being used (and the horrible workmanship).
Wrong color is also happening at the solenoid, where one battery + is black, and the other red.
You don't need to test resistance at this stage - just voltage and/or continuity.
Your test 1 shows a problem.
If the ignition is turned off, then there should be NO voltage at the skinny wire where it meets the solenoid.
In the photo, it appears to be wired directly to the battery + terminal of the alternator.
That would be the same as wiring it straight to the + on the engine battery.
And that is WRONG.
Wired that way, the solenoid is engaged and tying the engine and house batteries into a bank FULL TIME. (And the solenoid is drawing a bit of power out of both batteries 24/7.)<*>
This is further indicated by test 2 (engine running).
The batteries are at 13.7v, but the skinny wire feeding the solenoid is getting power directly from the alternator at 14.3v.
<*>I think I see what's happening there - whoever did it, didn't understand how it works.
I think they thought it was like a diode isolator (the ones with the heat sink you can buy at the auto parts store).
With a diode type, you run the charging wire to the center terminal of the diode isolator, and then run one wire out to each battery.
Which looks like what they did on your truck.
BUT
Yours is a solenoid type called a "split-charge relay" and doesn't work the same way as a diode type at all.
The skinny wire activating the solenoid should normally be wired so that it only has power when the ignition switch is on.
Disconnect it from the alternator ASAP and hook it to an ignition circuit.
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