Safe to leave solar hooked to batteries unattended?

[OregonTRX4]

I leave my trailer in a rural area where we camp with no hook ups. I have been looking into solar. A friend leaves his batteries hooked up to his solar and the batteries disconnected from the trailer so that they are charged when we come back to the property every 1 to two weeks. Is there any risk to this? Any known mishaps in regards to fire or something I am overlooking? It would be terrible to have something go wrong while I am not around and have it burn the property down.

Thanks.

[mena661]

X2 Niner and PT

[pianotuna]

Here is a simple flow chart.

Budget-->Energy Audit-->Battery bank size-->number of watts-->PWM or MPPT.
One rule of thumb is between 60 and 150 watts of panels per 100 amp-hours of storage. The smaller the battery bank the higher the wattage needed (per 100 amp-hours). Here is a link to the rather special spreadsheet which includes an energy audit, that N8GS has created to help size solar battery charging systems!
Solar Spread Sheet N8GS

For a nice explanation of solar, try this link: Golden rules of solar

[NinerBikes]

OregonTRX4 wrote:

NinerBikes wrote:

What is your intent... to maintain the batteries fully charged while in storage?

Disconnect the battery from the trailer in storage, buy a PWM charge controller on ebay for $10, and a 40 w panel for storage.

40w 12v panel

Buy a bigger panel if you want to recharge your batteries while camping. Calculate your daily amp usage first, then buy panels. 1 to 1.5 watts per amp you use per day.

Extensive selections of 12v panels.

I have two standard 12v deep cycle batteries but I don't have their specs right now. I would be using this system to charge my batteries while camping. My Honda eu2000i would be used for the microwave etc. I like the kits because they come setup already.

Calculate your daily amp usage first, then buy panels. 1 to 1.5 watts per amp you use per day.

You'll have no idea what or how much to buy, nor will those trying to help you, until you perform your homework above. Do a search on BFL13 he has a spread worksheet to help you figure out your estimated amp usage, per day.

If you dry camp, a lot, the first change I would make is converting all incandescent light bulbs to LED's to save current draw and amps needed to be recharged. It's cost effective in the sense that it allows you to buy less amps /watts in solar panels to recharge on a daily basis, less % loss on the batteries.

[red31]

I suspect 100 watt panel in OR, June would ave 36ah/day and in Dec 6 ah/day

[OregonTRX4]

NinerBikes wrote:

What is your intent... to maintain the batteries fully charged while in storage?

Disconnect the battery from the trailer in storage, buy a PWM charge controller on ebay for $10, and a 40 w panel for storage.

40w 12v panel

Buy a bigger panel if you want to recharge your batteries while camping. Calculate your daily amp usage first, then buy panels. 1 to 1.5 watts per amp you use per day.

Extensive selections of 12v panels.

I have two standard 12v deep cycle batteries but I don't have their specs right now. I would be using this system to charge my batteries while camping. My Honda eu2000i would be used for the microwave etc. I like the kits because they come setup already.

[MEXICOWANDERER]

A string of panels in parallel. O.K.?

Feeder pairs from each panel running to a wire "manifold". Those two wires run to the controller.

Direct freakout copper touching copper short in a pair of feeder wires.

All of the panels will then feed that short in the two feeder wires. The feeder wires are smaller in AWG. O.K.?

On an RV system with it's LIMITED NUMBER of panels (Don't give a damn how many are bolted to the roof plus a tow trailer on behind)...

If those two feeder wires burn, you undersized the gauge of the feeder wires or do not know how to run a balanced manifold wire from all feeder wires to the controller. A two foot long 12 gauge wire can carry EIGHTY AMPS without burning. Been there, done that, got the tee shirt and secret whistle.

[doughere]

NinerBikes wrote:

OregonTRX4 wrote:
I am on a budget and was wondering how this kit looked for the purpose discussed?
http://www.amazon.com/dp/B00BFCNFRM/ref=wl_it_dp_o_pC_nS_ttl?_encoding=UTF8&colid=EWWQQYUK3TWE&coliid=I2Y8GFT7NY2D0N

120 watt solar panel kit

More watts, for almost the same price, and portable. Better value, in my eyes.

The only problem I see with the SolarBlvd kit is the controller is at the panel, and there will be some voltage drop between panels and battery; the controller is probably not programmable so you couldn't allow for the drop.

I'd get two panels, hinge them together, and get an inexpensive e-bay controller (mount close to battery). I've seen a number of do-it-yourself videos on this. I have 2-60watt solarblvd panels flat mounted with an e-bay controller, works very well. I also have a portable 100 watt solarblvd panel that I wire directly to the battery.

Regards,
Doug

Doug

[NinerBikes]

OregonTRX4 wrote:
I leave my trailer in a rural area where we camp with no hook ups. I have been looking into solar. A friend leaves his batteries hooked up to his solar and the batteries disconnected from the trailer so that they are charged when we come back to the property every 1 to two weeks. Is there any risk to this? Any known mishaps in regards to fire or something I am overlooking? It would be terrible to have something go wrong while I am not around and have it burn the property down.

Thanks.

What is your intent... to maintain the batteries fully charged while in storage?

Disconnect the battery from the trailer in storage, buy a PWM charge controller on ebay for $10, and a 40 w panel for storage.

40w 12v panel

Buy a bigger panel if you want to recharge your batteries while camping. Calculate your daily amp usage first, then buy panels. 1 to 1.5 watts per amp you use per day.

Extensive selections of 12v panels.

[westend]

I put in one of these CB manual trip breakers (25 amp) between the module and the controller. It serves mainly as a disconnect switch but also offers circuit protection on the input side of the controller.

[red31]

OregonTRX4 wrote:
I am on a budget

Have no idea min wattage needed to maintain xx ah battery(ies) in Dec, OR.

A 40 watt panel, a temp comp controller and some landscape wire could be had for $100.

[pianotuna]

Hi RJ,

I could not disagree more. Top of the line solar controllers do a far superior job to any of the plug in converters that I am aware of. Solar is ideal for long term maintenance charging.

RJsfishin wrote:
But having said and read everything, given a choice of battery maintaining methods (including a quality converter) while long term unattended, solar would be a last resort !

[RJsfishin]

But having said and read everything, given a choice of battery maintaining methods (including a quality converter) while long term unattended, solar would be a last resort !

[mena661]

SCVJeff wrote:
Mines on a CB so it can make multiply attempts at welding safely... 🙂

LOL!

[SCVJeff]

Mines on a CB so it can make multiple attempts at welding safely... 🙂

(Edit: iPad spellin)

[mena661]

Thanks MEX. I meant panel to controller fuses. Reading your post puts me back onto the confusion train. LOL! If you had a shorted panel in a parallel string, wouldn't the max amps just be the Isc of that panel? Which can happen in normal operation and that wouldn't be a problem. If you shorted two parallel strings together, now you have one series string which would up your Voc but drop your amps big time which might fry your controller but not your wiring. Still don't understand the point of extra fusing on panels to controller.