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Old 04-25-2014, 08:57 AM   #71
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I'll give this a test next weekend camping. The power pack has a rating of 33AH, this should be enough for 1 night, I hope.

Can I use any metal part of the TT for ground? The power pack has a clamp which I use for ground connection.
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Old 04-26-2014, 12:00 PM   #72
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The 40W solar panel charged the TT battery to 12.2V or at 60% charged level, this is several days of charging.

If I parallel another 40W solar panel will it fully charge the battery?
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Old 04-26-2014, 12:51 PM   #73
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Originally Posted by ko777 View Post
The 40W solar panel charged the TT battery to 12.2V or at 60% charged level, this is several days of charging.

If I parallel another 40W solar panel will it fully charge the battery?
This info comes from here:

BatteryStuff Articles | Everything You Need to Know About Solar Chargers

In short:

As a rule of thumb a rating of 15 watts delivers about 3,600 coulombs (1 AH) per hour of direct sunlight; Panels loose 20-25 percent of rated power during the course of a charging day due to sun position) so a 40 watt panel will deliver an average of 30 watts or 2 AH per hour of daylight (say 10) or 20 AH.

TWO panels (assuming they receive the equivalent sun) will generate twice that or 40 AH per day.

An average OEM Deep Discharge battery is about 70 AH total capacity so with a 40 watt panel and good average sun, will take 70/20 or 3.5 days to recharge a used up battery. (less obviously if charging one that is only 50%).

So 80 watts will take a bit over a day and a half.

HOWEVER,

1) You can NOT use the battery(s) while it is charging for these numbers to work.
2) LARGER batteries (banks) take LONGER to recharge since there are more amps to replace.
3) The solar charge controller will manage the charging rate to avoid boiling the batteries as they fill resulting in longer recharging times than above.
4) (With PWM controllers) If the panel's voltage drops below battery voltage the charging will stop. Shade will rapidly decrease generated voltage and if the battery has a higher voltage that the incoming charge voltage it just won't accept it. This happens "a lot" as the battery nears "full". (More expensive MPPT controllers will trade charging current for voltage as the sun sets)
5) Always size your panel to generate your anticipated usage plus extra to charge that battery.

Hope that helps...
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Old 04-26-2014, 03:07 PM   #74
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Yes, thanks for the information. I will wait for a solar panel sale and get another to accomplish what I plan to do. After my next trip, I'm leaving my trailer there for a week or more then come back to camp their again...repeat. I am hoping the solar panel will fully charge the battery before I get back. For now I'll use my gas generator to top up.

Can I mix different Watt sizes solar panel parallel charging?
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Old 04-26-2014, 03:36 PM   #75
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Quote:
Originally Posted by ko777 View Post
The 40W solar panel charged the TT battery to 12.2V or at 60% charged level, this is several days of charging.

If I parallel another 40W solar panel will it fully charge the battery?
80 watts of solar panels will provide approximately 20 amp hours of juice per day.
Lets assume you have an 80 amp hour battery discharged to 50% (which MOST charts will tell you is 12.2V for a wet cell deep cycle battery)...which you should never go below. That means you need to put back in 40 amp hours or 2 days worth of sun to recharge IF you have no draw on the battery during that time. If you do have a draw on the battery...you need to add the necesscry extra time into the mix.

It does not matter WHAT size panels you use...just stick to the same chemistry & output max voltage to keep things easy.
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Old 04-26-2014, 05:59 PM   #76
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It does not matter WHAT size panels you use...just stick to the same chemistry & output max voltage to keep things easy.
Ditto. If the max voltage is different I am not sure what the controller will do if you pigtail them together.
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Old 04-27-2014, 12:09 AM   #77
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Battery cut off switch

Started working on the cut off switch today, here is my final schematic
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When the key is taken out, the line is cut off.
The spare battery connection is temporary, to use this spare, take the key off for the main battery.
When the spare is not use, take the key off for the spare battery, this will make sure the wires to connect the spare battery is not hot.

Take both keys off when TT is parked or when charging the main battery with a solar panel; the spare battery could be on while charging the main battery.

I finished installing the first cut off switch but had to stop because the first test failed. I use a multimeter to find the fault and found the switch to be defective. There goes an hour wasted. I learned my lesson...always check the parts for defects before using it.
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The wiring connections to the battery is completed.
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A battery tender with a fuse is installed for connecting the solar panel directly.
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Cut off switch part
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The test failed, no current going through when key is on.

I have to get a replacement part and should be able to complete this project tomorrow.
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Old 04-27-2014, 09:12 PM   #78
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Battery cut off switch

Cut-off switch mod is complete. I tested both main battery and spare battery connections, both passed.
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Both keys off, this is how the TT will be set when parked and not in used. The blue and black cables are for the spare battery connections
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For emergency use only, use the power pack battery to power the TT, the booster cables worked like a charm

I'll test the power pack this coming weekend, the last night of my trip. If this last for the night that will be awesome. I'll post the outcome.

Happy Spring Camping!
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Old 05-06-2014, 12:00 PM   #79
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Cutoff switch photo

Here is a photo of the way I setup the cutoff switch. I use the neg. side for the wiring. For what it's worth.
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