Charge battery from 12 volt power receptacle to charge controller to charge battery

[mariasman]

One idea I had was to use the 12 volt receptacle in my Ford Escape in the rear cargo area connected to the "solar in" connection on the charge controller, then connect the "battery" connection to the deep cycle battery I am charging. I will be using some sort of quick connect and disconnect connectors. Maybe sae or even male and female 12 volt power connectors ( otherwise known as cigarette plugs).
This way, when I am driving my battery will be charging, then if I am going to stay somewhere a few days or more, I can put out the panel and quick disconnect the ciggy plug and connect the solar panel. I don't see any problem with this because the charge controller doesn't care where the power comes from, it will charge the battery the same.
Am I overlooking something here? It seems like a pretty simple solution to charging the battery while driving without having the solar panel mounted permanently.

JMHO, but I assume you are doing no modifications to the vehicle alternator/battery system right? Therefore, the voltage in the charging system will be limited to the vehicle battery voltage. A charge controller normally takes an input voltage substantially higher than battery voltage, then after bulk charging mode it moderates the voltage to charge the battery at the proper rate. However, if the voltage to the controller is not sufficiently high, then it cannot do this. At most it can admit full voltage as when in bulk charging mode. However, this would be exactly the same as if you had no controller at all. Summary: there is no advantage to the set up, and in fact, the controller would only drop voltage that much more than dropped by the additional run of wire required to reach the back cargo area to the house battery and prevent a full charge. Also, when the house battery voltage is low, then it could trip the fuse on the ciggy plug circuit if the amp rating on the controller is higher than this fuse rating. The best solution seems to be to use wire of generous size and with excellent connections to connect the house battery directly to the vehicle charging system via a solenoid switch such as those continuous duty solenoids that shut when the engine is started.

 

[SoulRaven]

JMHO, but I assume you are doing no modifications to the vehicle alternator/battery system right? Therefore, the voltage in the charging system will be limited to the vehicle battery voltage.

Very good answer. I will consider doing the heavy wire and solenoid suggestion. But at this time I really don't want to add any modifications to the vehicle because it is under warranty and don't want to take a chance on voiding that, with adding modifications to the electrical system. I figure that the worst that can happen if the ciggy plug is overloaded it will blow the 20 amp fuse (and yes it is fused from the factory with a 20 amp square box type fuse).

The charge controller is rated at 30 amp, so it could put out more that the power plug is rated for and blow the ciggy fuse, which is rated at 20 amp.

I have hooked up a direct male to male charging plug between the 12 volt power outlet (ciggy plug), and the deep cycle 100 ah amg battery With the vehicle running it does charge the battery with no problems. The ends on the male to male charge wire stay cool to the touch. But of course, the battery is pretty fully charged. I will have to see what happens when the battery is in a low state and charging.

Oh, and I called Renogy (1-800-330-8678), and talked to one of their tech support people. He said that there is no problem with connecting the charge controller up to the vehicle 12 volt power port, as long as it doesn't go over the 42 volts the controller is rated for.  Even then it has things inside it that will protect it from high voltage. He did say however that the charge controller will not control the current at the 12 volt power port. It will (like you said), take what it needs to charge the battery. It will work exactly the same as it does when connected to a solar panel. Nothing will blow up or catch on fire. LOL

 

[SoulRaven]

I called Renogy (1-800-330-8678), and talked to one of their tech support people. He said that there is no problem with connecting the charge controller up to the vehicle 12 volt power port, as long as it doesn't go over the 42 volts the controller is rated for.  Even then it has things inside it that will protect it from high voltage. He did say however that the charge controller will not control the current at the 12 volt power port. It will, take what it needs to charge the battery. It will work exactly the same as it does when connected to a solar panel. Nothing will blow up or catch on fire. LOL

 

[SoulRaven]

A 20 amp fuse in a ciggy plug is a sure recipe for a fire.

Never do electrical half-assed on a wing and a prayer; the cost of failure is too high.

You want a 4 gauge cable from either the starting battery or alternator to the house battery. Put either a solenoid or on-off switch in between.
Bob

The 20 amp fuse at the power outlet comes that way from the factory. And from what I can see, the wires are heavier that what a normal ciggy plug is. It looks like they use heavier wiring for these power outlets, and fuse them accordingly. Of course trying to charge a 12 volt battery from it could be putting it at its limits. But, I have noticed that the wiring coming off the solar panel is not really much heavier that what is at the power outlet. And my 30 watt panel has wiring and adapter plugs with wire that is actually lots less heavy. These are all from the company that make the panel and controller. Even so, none of the wires from either solar company has the type of wires you are suggesting (4 or even 6 gauge), and the system charges the batteries with no problems or overheating. I don't understand that. Like I said, I am still learning about the solar stuff.

 

[rvpopeye]

A 30 watt panel will put out around 2 amps depending on conditions.
A 100 watt panel is about 6 amps.

The heavier guage wire (lower numbers =thicker wire) will minimize the loss from resistance.
You can connect 2 or more wires together to effectively create a heavier guage.

Your controller will reduce voltage but too much amperage will hurt it.

I guessing your alternator probably has 60 or more amps output rating , some have only 30amps but others are capable of 100amps or more .

Using , or charging @ 10 amps for 1 hour = 10aH (amp hours) the measure of battery capacity/usage.

Take all the info in this thread in little bites and it will all come together eventually.
No one here was born with all this info , we had to soak it up slowly too.......I've been soaking since I was 10yrs old !!!

OK OK no comments you guys! Well , maybe a few for S+G's..

 

[SternWake]

I thought the alternator trying to feed the Solar charge controller would cause the magic smoke to be released from the charge controller, but if the manufacturer say it can handle it, then I guess not. I'd still not do it. One can take the leads of a Solar panel and short them out together and nothing happens. Try doing that with a (+) and (-) on your vehicles system, and poof go some fuses, or worse.

As stated, the vehicles charging voltage is well less than what a solar controller is expecting. I do not see the point in trying to run vehicle current through a solar controller. If you want to try and get some juice from vehicle to trailer battery, there are multiple better ways to do it, warranty not withstanding.

I once thought I could feed my adjustable solar controller with a DC power supply set at a certain voltage, and A bunch of Electrical engineers gave a plethora of reasons why this would not work, I'm no EE. My Solar controller allows the setpoints to be adjusted that no automatic charger available will allow, such as how long to hold absorption voltage before triggering float voltage, or when amperage required to hold ABSV falls below a certain threshold, then float voltage is triggered. If only somebody made a grid powered charger with these user configurable settings for less than 600$.

I'll refrain from my usual Ciggy receptacle rant.

When i first realized they were a problem, I switched to 12v SAE connectors with 10 awg and 18 awg leads, but even the 10 gauge ones would heat excessively passing more than 25 amps. I am in the process of removing them all

I now Use Anderson Powerpoles in the 45 amp flavor for all my connectors. The Ciggy plugs are more convenient as one only needs one hand to seat it, and the SAE connectors or powerpoles need more careful alignment and usually two hands. I do have 9 Ciggy receptacles though out my Van. Mostly unused now. All but two are wired with 10AWG directly to fuse block.

I'd never try and recharge a full size depleted battery through them. My stock dashboard Ciggy plug was wired with 18 awg. from the fuse block, and there is about another 15 feet of circuitry from the battery through multiple connectors.

Checking voltage at ciggy plugs when the circuit is not loaded tells nothing. When there is a 5 amp load on the circuit, the voltage drop becomes apparent.

I saw on another forum where some used a DC booster such as the following product to raise the voltage to the trailer and cause more current to flow tpo recharge the batteries back there. Looked like a lot of effort.

http://www.amazon.com/10-32V-12-35V...11&sr=8-6&keywords=dc+to+DC+booster+converter

Perhaps you can use this to increase charge to trailer batteries.

I'd just run fatter copper through a better connector for the trailer, and not worry about DC conversions, mixing the solar controller into the loop.

The Double male ended 120V cords some use to electricy their RV's are called suicide cords. A double male ended Ciggy plug cord is not going to shock you, but if one nipple tip touches anything grounded while the other end is still plugged in, there goes the fuse, and fuses are not cheap.

 

[SoulRaven]

Here is what I finally decided to try, and it worked. I have a Black and Decker smart charger that works with all different kinds of batteries. It will charge at 2, 10, or 25 amps. So, I hooked up my 1,000 watt inverter to the power outlet and then plugged my B&D charger to that and hooked it up to the 100 ah battery in the vehicle. I set it at the 2 amp setting and started the car and let it run for about 15 minutes. Then I shut it down and pulled the ciggy plug out and felt the end. To my pleasant surprise it was not even warm. I then set the charger to 10 amps and run the same test for 15 minutes. This time the plug was pretty warm to the touch, but not excessive. Still, I don't want to take any chances that it will blow a fuse. I will run it at 2 amps while driving. This should help keep the battery charged while I am driving. I will keep the fridge hooked to the power plug in the rear of the cargo area and at the same time keep the charger plugged into the power port in the second row seating. This way I can run the fridge and charge the battery independently and switch to just battery power when stopped. Here is a link to some pics of the set up.
https://onedrive.live.com/redir?res...10&authkey=!AJZoH-6nbQnlVIQ&ithint=folder,jpg