12volt system not working

[Rocketman]

Originally Posted by AC0GV

Can you please explain to me how a low battery can cause current to increase??

Actual behavior depends on the loads you have on the system. But assuming you have a load that's trying to draw constant power (wattage), like a voltage converter or regulating circuit, then it will react to the decrease in voltage, by increasing current draw. Basic formula for the power draw is P=IV

[Rocketman]

Originally Posted by AC0GV

Can you please explain to me how a low battery can cause current to increase??

But don't get me wrong, I understand that may sound odd. The first time I saw it happening on a circuit it surprised me. Took me a bout 5 minutes of running around to figure out what was happening. But when I opened the compartment with the resettable circuits, I could actually hear them tripping and resetting in concert with the blinking lights. I don't know how long it might have continued until both the voltage and current were to low to service the load, because I turned off the circuit and recognized the voltage was getting to low. The resettable breaker that experienced that event, failed about a month later too. Possibly damaged by the event?

[AC0GV]

Originally Posted by Rocketman

But don't get me wrong, I understand that may sound odd. The first time I saw it happening on a circuit it surprised me. Took me a bout 5 minutes of running around to figure out what was happening.

Think of voltage as water pressure, lowering the pressure will not increase flow of water, AKA current.
True that if you want the same POWER out with a lower voltage you will need more current. But just lowering the volts will not increase the amps with the same load. That's why car battery cables got smaller when we went to 12 volt systems.

[AC0GV]

Originally Posted by Rocketman

Actual behavior depends on the loads you have on the system. But assuming you have a load that's trying to draw constant power (wattage), like a voltage converter or regulating circuit, then it will react to the decrease in voltage, by increasing current draw. Basic formula for the power draw is P=IV

OP has a stock Scamp.

[Rocketman]

Originally Posted by AC0GV

Think of voltage as water pressure, lowering the pressure will not increase flow of water, AKA current.
True that if you want the same POWER out with a lower voltage you will need more current. But just lowering the volts will not increase the amps with the same load. That's why car battery cables got smaller when we went to 12 volt systems.

You are correct, but that's why I said it depends on the type of load you have. Converters and regulating circuits are all about maintaining a smooth or constant voltage on their output side. Consequently, when they are hooked to a source that 's less than stable, they are able to vary the input load parameters as necessary (within design limits) to try and maintain the desired output. But all of this is kind of off the subject. I saw the symptoms Joy noted and just tried to help her out with something else to check. Not really wanting to revisit all the physics behind it or challenge anyone opinion. I imagine if the load was a little different or the resettable circuit was sized slightly different, I would have simply seen that circuit trip and not reset.

[Rocketman]

Originally Posted by AC0GV

OP has a stock Scamp.

Unfortunately, I am not very familiar with the Scamp line, and don't know if they utilize resettable breakers or what type converters or regulators they might have in the system.

[jwcolby123]

Originally Posted by Joy A

Of course the battery is fine, Duh!! Fully charged.

There is no Duh!!! when something goes wrong.


You didn't specify that you tested that. When one comes to a forum for help, the first thing needed is "This is what I have already done to troubleshoot the problem".



The infamous joke "Is the On Off switch in the ON position" exists for a reason.

[jwcolby123]

Originally Posted by AC0GV

Can you please explain to me how a low battery can cause current to increase??

Easily explained.

Anything supplying a constant power to a load, needs a specific input POWER to do that. POWER is V x A. If V decreases A must increase to hold the power the same.

[CarlD]

Originally Posted by jwcolby123

Easily explained.

Anything supplying a constant power to a load, needs a specific input POWER to do that. POWER is V x A. If V decreases A must increase to hold the power the same.

That was already explained, please read all the posts.

[THene1713]

Originally Posted by Joy A

Of course the battery is fine, Duh!! Fully charged.

I have no 12 V operation even when plugged into tow vehicle.

Everything does operate fine in my trailer when plugged into shore power or plugged into the generator..

So there is a disconnect somewhere from the battery and as I said all the fuses are fine and I see nothing wrong or disconnected around the electrical panel and converter.

Many/ most/all RVs use 12vdc CIRCUIT BREAKERS in the battery cable between battery (NEAR/Next to Battery) and CONVERTER, and use FUSES on the converter end, so protection in both directions. The one/ two fuses at CONVERTER also protect against REVERSE POLARITY battery install mistakes, generally around (30a?). (SOME) REVERSE POLARITY fuses on older boards hidden on back of Fuse Board? BUT Loose fuse/ connections/ lugs, etc. also possible... sometimes, vibration takes a toll? WHAT IS BATTERY VOLTAGE Reading with a digital VOM? BTW, I had one 3yo battery once that read good w/ VOM and NO load and w/ Hydrometer, but would drop to ZERO when LOAD applied; new battery cured issue... NEVER seen that before/ since and 72yo.

[David Tilston]

Originally Posted by AC0GV

Think of voltage as water pressure, lowering the pressure will not increase flow of water, AKA current.
True that if you want the same POWER out with a lower voltage you will need more current. But just lowering the volts will not increase the amps with the same load. That's why car battery cables got smaller when we went to 12 volt systems.

Not related, but hey, that's how I roll. AC motors will draw more current when the voltage drops.

[TeresaT]

For my every simple old electric I found a converter that I have to occasionally flip off and back on. It’s on the front of the dinette bench under the table. It probably gets bumped off or half way…
At some point it needs an upgrade but working on a few other things before replacements. Currently I have no battery just shore power for 12v

[David Tilston]

Originally Posted by TeresaT

For my every simple old electric I found a converter that I have to occasionally flip off and back on. It’s on the front of the dinette bench under the table. It probably gets bumped off or half way…
At some point it needs an upgrade but working on a few other things before replacements. Currently I have no battery just shore power for 12vAttachment 143318

I have the same converter, but in a spot less likely to get kicked. But mine doesn't have a blue fuse holder. Did yours come that way?

[TeresaT]

Originally Posted by David Tilston

I have the same converter, but in a spot less likely to get kicked. But mine doesn't have a blue fuse holder. Did yours come that way?

Yes, it came that way.
the fuse is interesting for sure-and the far left button of some sort is broken off

[David Tilston]

Originally Posted by TeresaT

Yes, it came that way.
the fuse is interesting for sure-and the far left button of some sort is broken off

There are push button breakers, and push/pull, (on/off) breakers. Yours has gone from a push/pull to a push only. I suspect that it still functions as a breaker. Since it is a 10A breaker, you can test it by plugging in a 1500W, (12.5A) heater, or blow dryer into the plug, on a hot day, and run it for up to half an hour. If it doesn’t pop, then I would replace it.

It can be replaced:
https://www.ebay.com/itm/203415042938

[Choosethisday]

I'm a licensed master electrician with a degree in electronics. I think it likely it is the battery. Lead acid batteries, when they reach the end of their of there life or have been damaged by leaving them discharged too long, may show a good voltage even though they have lost any real capacity. To test this check the voltage and then put a light load on the battery. If the voltage drops quickly more than a couple of tenths of a volt the battery is no good.

[gordon2]

Originally Posted by Joy A

OK are you electricians out there here's what is happened...What do you think!

Originally Posted by Joy A

After 21 years, I know where all the fuses are, ...
As I said I have checked everything and it all appears good so I'm just going to keep tinkering along until I find out what the problem is.

Once again I thank you all for your comments......Bye

Funny that Joy asked for electricians and then when the discussion got technical she appears to have bailed on us. I doubt we will learn if the problem has been solved so we can continue the electricians talk I guess. BTW, the camper A/C does draw more current when the voltage drops.

Originally Posted by Choosethisday

I'm a licensed master electrician with a degree in electronics. I think it likely it is the battery.....

You are of course completely correct about the nature of the battery and I concur that it is a likely suspect. However I was not about to argue with the OP over it myself...

Originally Posted by Joy A

Of course the battery is fine, Duh!! Fully charged.
....

[TeresaT]

[QUOTE=David Tilston;825540]There are push button breakers, and push/pull, (on/off) breakers. Yours has gone from a push/pull to a push only. I suspect that it still functions as a breaker. Since it is a 10A breaker, you can test it by plugging in a 1500W, (12.5A) heater, or blow dryer into the plug, on a hot day, and run it for up to half an hour. If it doesn’t pop, then I would replace it.

It still works! surprised me tho when it popped out and none of the 12v lights worked but the 120 outlet on shore power and tail lights did 😆
This camper has been an electrical education for sure

[AC0GV]

[QUOTE=TeresaT;825549]

Originally Posted by David Tilston

It still works! surprised me tho when it popped out and none of the 12v lights worked but the 120 outlet on shore power and tail lights did 😆
This camper has been an electrical education for sure

Most RVs have three electrical systems. The 12 VDC (from the RV battery ot the converter) that runs the stuff "in house", the 120 VAC from the pedestal that runs the Air conditioner, converter,and plugins and the third is the 12 VDC from the T/V that lights the DOT required lights.

[Choosethisday]

Originally Posted by Rocketman

Joy, You mentioned the blinking lights prior to the failure. Do you know if your camper uses automatically resetting breakers? Automatically resetting breakers look more like a junction terminal than a fuse. If your battery starts to go dead and voltage on the system drops, causing the current to rise, the those breakers will sometimes trip, then reset, then trip, then reset, etc. until you take appropriate action. I have also seen them behave that way before they fail, and then just won't reset at all. Several camper manufacturers use those devices as front end protection between the batteries and the DC system. Just Google Fastronix automatic reset circuit breaker to see what one typically looks like. Hope it helps.

"If your battery starts to go dead and voltage on the system drops, causing the current to rise"
Whatever happened to Ohm's law?