how to properly hook up power in pop-up camper battery

[Pest]

I had a feeling i was heading towards solar


Solar is darn confusing - anyone have a kit recommendation, if i'm going to do it i might as well get an 80w unit

We got our pieces from amsolar.com. Not the cheapest prices, but idiot proof instructions for installing everything, and the components are excellent quality. No problems at all with our 150 watt panel and maximum power point tracking charge controller.

[pods8]

There were some really low priced panels on solarblvd for a number of months, nothing at the moment. Can check back in from time to time, they had panels in the 60-130watt range for $1.35+ a watt which is rather low.

[dags]

Maybe i should start a thread on solar, but one thing i don't understand is can you have the solar attached plus have shore power and the hookup to the car alternator power?

[Pest]

Maybe i should start a thread on solar, but one thing i don't understand is can you have the solar attached plus have shore power and the hookup to the car alternator power?

Yes, as long as the solar charge controller is either 1) turned off when connected to shore power or 2) has a "shore power" charge mode, like ours, which just decreases the peak output voltage of the unit to be at or below the shore power charge controller. Otherwise the solar charge controller can raise the charging voltage higher than the shore power charge controller and potentially back feed the shore power charge controller.

Having the solar on while the vehicle is running creates no problems if connected via the trailer plug, it will prevent back feed.

[dwh]

Yes, as long as the solar charge controller is either 1) turned off when connected to shore power or 2) has a "shore power" charge mode, like ours, which just decreases the peak output voltage of the unit to be at or below the shore power charge controller. Otherwise the solar charge controller can raise the charging voltage higher than the shore power charge controller and potentially back feed the shore power charge controller.

Having the solar on while the vehicle is running creates no problems if connected via the trailer plug, it will prevent back feed.

Wait...what?

I'm sorry, but this makes no sense to me.

What solar charge controller do you have? I've don't think I've ever heard of one that has a "shore power charge mode".


One of the purposes of a solar charge controller, is to PREVENT backfeed from the battery to the solar panel when the sun is down (otherwise, the solar panel becomes a heating element and consumes the stored power from the battery).
In other words, no worries about "backfeed" IN to the solar charge controller from the battery side.
The solar charge controller doesn't accept a backfeed.

As for a solar charge controller feeding power into the 12v bus at a higher voltage than the mains powered battery charger and overpowering (backfeeding) the mains powered battery charger - where is the power going to backfeed TO?
The electrical grid? That won't happen.

So what if the solar charge controller raises the voltage on the 12v bus? It won't matter. What if the battery was at 14.4v and the solar charge controller is disconnected and then you hook up a mains powered charger to the battery? Wouldn't the BATTERY backfeed the mains charger - even without the solar charge controller connected?

No, because the mains powered charger doesn't accept a backfeed. If the voltage on the 12v side is higher than what the mains powered charger can overcome, then it won't be pushing any power into the 12v bus, but it won't be accepting a backfeed and converting it into 120v either.


A device designed to hook up to a battery and charge it, isn't going to allow itself to be overpowered from the battery side. At least, it shouldn't. Not by any voltage in the normal "12v nominal" range anyway.


And a trailer plug has got nothing to do with anything, except for hopefully being controlled by a relay so it's disconnected when the key is off, so the engine battery doesn't get drained along with the aux battery.

[SChandler]

There were some really low priced panels on solarblvd for a number of months, nothing at the moment. Can check back in from time to time, they had panels in the 60-130watt range for $1.35+ a watt which is rather low.

I doubt that prices will be that low again for a while: http://www.oregonlive.com/business/i...ffs_china.html. Without getting into the politics of the situation, the Chinese panels won't be nearly as cheap as they were a month ago.

[dwh]

I doubt that prices will be that low again for a while: http://www.oregonlive.com/business/i...ffs_china.html. Without getting into the politics of the situation, the Chinese panels won't be nearly as cheap as they were a month ago.

The other problem, is that the Solar Cynergy panels were made with solar cells from the German company Q-cells - which went bankrupt a few weeks ago.

http://www.businessweek.com/news/201...krupcties-rise


<off-topic, illegal, against the rules political rant follows - please ignore>
(Personally, I'm a big fan of trade protectionism. If we could get enough of it, we might actually be able to force the corporate gangsters to bring the jobs back to the U.S. instead of farming them all out so they can get away with paying some poor Chinese guy a dollar per hour. Then maybe the .gov wouldn't have to lie about the "Unemployment Rate" which only counts those currently receiving unemployment benefits - and ignores all those whose benefits have already run out but still don't have jobs.

Nah...they'd just find something else to lie about...)
<end off-topic, illegal, against the rules political rant (rules are meant to be broken )>

[Pest]

Wait...what?

I'm sorry, but this makes no sense to me.

What solar charge controller do you have? I've don't think I've ever heard of one that has a "shore power charge mode".

HPV-22B, bought from AM-solar.com. If you will look on the right side of the picture below, you'll see a shore power selection.

MPPT.jpg

One of the purposes of a solar charge controller, is to PREVENT backfeed from the battery to the solar panel when the sun is down (otherwise, the solar panel becomes a heating element and consumes the stored power from the battery).
In other words, no worries about "backfeed" IN to the solar charge controller from the battery side.
The solar charge controller doesn't accept a backfeed.

Right, when did I dispute this fact?

As for a solar charge controller feeding power into the 12v bus at a higher voltage than the mains powered battery charger and overpowering (backfeeding) the mains powered battery charger - where is the power going to backfeed TO?
The electrical grid? That won't happen.

Correct, it would not feed the electrical grid. I said it could POTENTIALLY backfeed the mains charger. Not meaning that power would flow anywhere, but that it could damage the mains charger. Depending on the design of the charger (ie. the circuit protection features), this could happen.

Let's say that the mains charger is a full wave rectifier. If the battery voltage is significantly raised above the output voltage of the mains charger, it could be possible that one of the rectifying diodes becomes forward biased when it would otherwise not be, thus creating a short in the rectifying circuit and causing damage.

So what if the solar charge controller raises the voltage on the 12v bus? It won't matter. What if the battery was at 14.4v and the solar charge controller is disconnected and then you hook up a mains powered charger to the battery? Wouldn't the BATTERY backfeed the mains charger - even without the solar charge controller connected?

No, because the mains powered charger doesn't accept a backfeed. If the voltage on the 12v side is higher than what the mains powered charger can overcome, then it won't be pushing any power into the 12v bus, but it won't be accepting a backfeed and converting it into 120v either.


A device designed to hook up to a battery and charge it, isn't going to allow itself to be overpowered from the battery side. At least, it shouldn't. Not by any voltage in the normal "12v nominal" range anyway.

Right, 14.4V from a battery is not quite the 17V or so that a panel or a solar charge controller could potentially output. As I stated above, if the protection circuitry is not sufficient enough in the mains charger, 17V could POTENTIALLY cause a problem.

And a trailer plug has got nothing to do with anything, except for hopefully being controlled by a relay so it's disconnected when the key is off, so the engine battery doesn't get drained along with the aux battery.

I'm not sure why you are arguing this? He had asked if having the solar on while the vehicle was running would be a problem. I had simply stated that there would not be a problem...?

[dwh]

HPV-22B, bought from AM-solar.com. If you will look on the right side of the picture below, you'll see a shore power selection.

MPPT.jpg

Oh yea. Forgot about those. Don't think AM makes or sells those anymore. That switch to drop the float voltage from 14.4v to 13.2v isn't used on modern multi-stage chargers that drop to float automatically.

Right, 14.4V from a battery is not quite the 17V or so that a panel or a solar charge controller could potentially output. As I stated above, if the protection circuitry is not sufficient enough in the mains charger, 17V could POTENTIALLY cause a problem.

Okay, but the solar charge controller will never raise the voltage on the battery side to 17v anyway. Unless it's broken, and then all bets are off.

I'm not sure why you are arguing this? He had asked if having the solar on while the vehicle was running would be a problem. I had simply stated that there would not be a problem...?

Oh. I thought you said the trailer plug would prevent backfeed.

[Pest]

Okay, but the solar charge controller will never raise the voltage on the battery side to 17v anyway. Unless it's broken, and then all bets are off.

Didn't say it was likely, but you never know how things can operate when you start using cheap china electronics, solar or shore charger. :-P