My Solar Install - Page 2 - Fiberglass RV


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Old 03-20-2014, 06:02 PM   #15
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Question about your system: did you wire in an on/off switch? Is there a need for one?

Thanks.
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Old 03-20-2014, 06:45 PM   #16
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Conrad stated in a prior post:

I have a fuse on the solar. 30 Amp. I may down grade it to a 25 in the future. I also have a DC disconnect between the battery and converter. Switches off and all DC loads are disconnected bit not the solar charging which requires the fuse to be pulled to disconnect.
A kill switch or access to the fuse from the solar panel is necessary for units that are permanently mounted, mostly to allow the installer the ability to work and maintain the unit. It is a generally accepted practice.

You can achieve this affect by covering the panels while working, not an accepted practice.

Portable units would not require the kill switch as they can be readily disconnected.
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Old 03-20-2014, 08:15 PM   #17
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My panel will be on the roof most of the time but will slide out of the roof top rack to go in a portable frame on the ground if I'm parked in a shady spot. I'll be able to disconnect the MC4 plugs connecting the panel to its harness and I have a difficult-to-access circuit breaker that disconnects the +12 battery terminal from everything but I'm really wondering if there is a reason to have a convenient off-on switch indoors.

Is there any routine (not maintenance) reason to turn off the panel?

How about when the battery charger is plugged in?

How about driving when the tow vehicle battery is connected in parallel to the trailer battery?

I'm starting my solar install tomorrow and this is the last question I have (right now).
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Old 03-20-2014, 11:24 PM   #18
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I would cover the panels with a tarp before making the connection. Then remove the tarp. That will prevent arcing.
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Old 03-21-2014, 10:51 AM   #19
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Quote:
Originally Posted by Paul Braun View Post
. . . I am not that familiar with gel battery, is there a reason why the specs would not show an equalization level for gel?
Yes. The equalization process creates gas bubbles through hydrolysis of the water in the battery at the surface of the plates. In AGM and traditional flooded batteries these bubbles float away. In gel batteries the gel holds these bubbles in-place, creating a dry spot on the lead plates where the chemical reaction that stores and releases the charge can't occur.

Equalization and rapid charging kills gel cell batteries, which is why most solar systems use either traditional flooded or AGM batteries.
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Old 03-21-2014, 09:45 PM   #20
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Some Gels should be equalized. East Penn recommends it for some of their batteries.

I chose a 35 Amp charger even though I was told my 225 amp Hour battery could tolerate up to 67 Amps of charging current by East Penn. (30%) is a much lower percentage than AGM or Flooded.

Some manufacturers recommend even less, 20% or even 15% for a maximum charge rate for a gel cell battery.

35 Amps seemed fine for me which is just above the lowest of these--33.75 Amps--the 15% charge rate. If I need to "Shore Charge" my batteries--a few hours would suffice at this rate and then it would taper off. My solar panels will typically charge less than this although they may go higher.

I have monitored my solar charge controller and it seems to do a great job of charging my battery. It keeps the voltage where it belongs and tapers off nicely. I would like to see what it does if my DC loads are disconnected over a period of several days. I've seen the current drop to 1-2 amps at 13.25 Volts which would theoretically take my battery to maximum charge. Although it might take a few days to get the last few percent of charge.

My LinkPRO considers it fully charge at either 96% or 98%...but I find the manual a bit confusing. I think I have it configured for the 98% value. Is have to check.

Generally, slower charging is better for all lead acid batteries. Also, recharging quickly after a discharge is healthy for a battery. Solar works well for this.
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Old 03-26-2014, 12:32 AM   #21
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I am nervous as a virgin on her wedding night. I have two more solar panels due in as early as Thursday. This will allow me to fully charge on an overcast day. We get a lot of those this time of year. I also orders an electric blanket which should be very nice and cozy.

I am getting the impression my used battery does not have the capacity is hoped for. I plan to run it down to nothing and measure its true capacity soon. I'll use the inverter to run the fridge. That will take it down to 10.4 volts and then I'm switching all night light bulbs back to incandescent to kill the last bit of charge. I'm guessing I have about half of the rated capacity in this battery. I'd be better off with a lighter battery the same size or a new battery.
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Old 03-26-2014, 05:06 AM   #22
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Conrad, are you going ac or dc on the blanket? if d, which one did you pick?
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Old 03-26-2014, 07:39 AM   #23
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Night Sailor, could you withdraw, say, 100 ah from your battery using the link pro to gage this. Then let the battery rest with no loads at all for several hours and then measure the voltage? That would give you the state of charge and by inference the battery's actual capacity.

Also, the peukert effect will skew your results unless you do your measured discharge at 11 amps.
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Old 03-26-2014, 07:45 AM   #24
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Quote:
Originally Posted by padlin00 View Post
Conrad, are you going ac or dc on the blanket? if d, which one did you pick?

Biddeford Heated Plush Queen Blanket (84 X 90)- Blue

It is an AC blanket.
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Old 03-26-2014, 09:11 AM   #25
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Originally Posted by MCDenny View Post
Night Sailor, could you withdraw, say, 100 ah from your battery using the link pro to gage this. Then let the battery rest with no loads at all for several hours and then measure the voltage? That would give you the state of charge and by inference the battery's actual capacity.

Also, the peukert effect will skew your results unless you do your measured discharge at 11 amps.


I read that Gel cell no load "cut off" voltage is 11.6v. The loaded "cut off" voltage is 10.4v. My battery is going below these cut off voltage's if I use 60ah at night, which is typical for me with the furnace and inverter running. My numbers are 11.4 and 10.2. My conclusion is I am killing this battery with these nightly 50-60 amp discharges.

I could plug in the shore power during this cold weather and keep the battery topped up until things warm up and my night time needs drop. If my night time needs drop to 25-30ah I could get some more life out of this battery.

I just started keeping records of voltage so I can't give you more info, but it seems the voltage is dropping more and more as time goes on.

What do you think? My guess is that this battery is about done in. I could possibly repurpose it as a starter battery for my rarely use generator (mounted on a small trailer). I have another charge controller and solar panel I could use to keep it topped up indefinitely. That seems like a better option than abusing it in my camper. I'll have to check to see if that charge controller has a gel cel option. I could make a voltage divider a regulator to drop the bias Voltage slightly and make that work.

Back to my camper. I had one 92.5ah discharge when I accidentally had the refrigerator on AC. I did not realize it was wired to the outlet circuit. A few nights back my inverter cut off due to a low-voltage situation--the door blew open and my furnace was working hard while I was in the house. I decided to see if the battery could handle it. Perhaps I should've plugged in my shore power connection that night. I didn't because I want to know if my battery will hold up.

In any event I have a good idea of what sort of battery capacity I need 100 amp hours seems to be a minimum number if I want to use an electric blanket. So fo lead batteries I would need double that I AH rating...or more. My solar charging capability is pretty good. Once I have the two extra panels installed I should be able to recharge my night time loads easily.

Worried about this battery I have been researching other options.

I considered 100ah lithium battery. This would be a 130 lb weight savings. However, that might not be enough if I run an electric blanket--on medium that would be 60 watts, call it 5amps and 40 ah if I ran it all night.

Living without worries about energy use, I'll pick 100ah's as a design depth of discharge for my system. Whie lithium batteries can be depleted 90%, they don't perform well in cold weather--and I don't know way that means. They are wonderfully light but very costly.

Another option would be an 8d 270 ah AGM, weight savings 41 lbs. the AGM has more capacity and while gel cels have better cycle life, my experiences with them have sways been bad. The cost a lot and seem to die quickly. I would not have chosen this battery if it were not so cheap. I got it for $50.

My best bet would be two Master volt slim 200 ah batteries . Two of these would fit in my battery compartment--400ah at 238lbs. For a weight penalty of an additional 73 lbs, I could run a 25% depth of discharge ad these would last a long long time.

The nearest equivalent lithium that would fit in my battery compartment is a 300ah 8D size at three times the cost and 3/4 the capacity and 40% the weight ( weight savings 171 lbs). Wow!

If I used only one of the master volt batteries. My weight would decrease 46 lbs and my depth of discharge would be 50%, and much less in the summer. That seems like the best option if I need a new battery.
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Old 03-26-2014, 08:00 PM   #26
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My Solar Install

I found a chart that said for a gel battery 12.35v is 50% soc, 12.00 is 25% and 11.8 is 0%. From this web site http://www.energymatters.com.au/rene...-discharge.php. Note the battery has to "rest" at least four hours before taking the voltage measurement.

If you are going from full charge to 11.2v with 60 ah withdrawal then your battery has lost about 75% of its capacity.

If your design load is 100 ah/day with lots of solar capability to recharge even on a cloudy day I'd think a couple of 6v golf cart batteries (130# for the pair) would be a good choice. Trojan T105s are popular. I think I paid $135 each for mine at a golf cart shop. They are two years old and seem to still have full capacity. Have to check the water every few months though.
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Old 03-26-2014, 09:49 PM   #27
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6V 220 Ahr Golf cart batteries are available at Costco. Last year, in the fall, they were $69 each, for about a month.

If you ever come to Calgary, I can give you as many 74 Ahr group 24 batteries as you want. I have filled up all the storage space that I will use on batteries and I no longer go for the free ones that I can get.
Gell Batteries

I believe that they are MK brand:
MK Battery: HME Mobility Products

I suspect that there would be a source of these for free, in every city. It probably just depends on who you know.
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Old 03-27-2014, 01:12 AM   #28
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Quote:
Originally Posted by MCDenny View Post
I found a chart that said for a gel battery 12.35v is 50% soc, 12.00 is 25% and 11.8 is 0%. From this web site http://www.energymatters.com.au/rene...-discharge.php. Note the battery has to "rest" at least four hours before taking the voltage measurement.

If you are going from full charge to 11.2v with 60 ah withdrawal then your battery has lost about 75% of its capacity.

If your design load is 100 ah/day with lots of solar capability to recharge even on a cloudy day I'd think a couple of 6v golf cart batteries (130# for the pair) would be a good choice. Trojan T105s are popular. I think I paid $135 each for mine at a golf cart shop. They are two years old and seem to still have full capacity. Have to check the water every few months though.

I agree with everything you say. I wish I could use the Trojan batteries. They are powerful, relatively light for their capacity. However, they would be impossible to maintain. My battery box is accessible from the outside it's about a 1' x 1' square in about 22 inches deep I would have to disconnect all the cables and remove both batteries just inspect the fluid level. Plus there is metal trim running around the outside and I'd have to extra care to see they did not short out when removing them. Way too much work for routine maintenance. While they make the best economic sense, I would strongly favor an AGM sealed battery because my experienced with gel cells have not be favorable. I lost $600 worth, (2) 4D batteries several years ago when a battery monitor blew to circuit boards in my charger. A Xantrex technician explained how it happened and it was not uncommon. In any event I do not eat to baby sit batteries unless it is easy as lifting a lid and adding water.

Sadly, while I can do more testing, my data suggest exactly what you stated. I feel I am full discharging this battery nightly. I'll be rigging up the shore power connection until I replace this battery. I plan to sleep on it. Perhaps I can rig a sliding drawer and longer cables to make access a bit easier.

On the plus side, my last two panels come in this afternoon. I hope to have then installed by the end of the day. On overcast days I'm pulling in 41-46ah, so I can expect not quite a 50% increase as there may be a bit if shading on these aft end panels. I can remove a vent hood to help with that, but I for plan to do that right away. A 50% increase would be an overcast production of 61-69ah which right about the high end of my power consumption o these cold nights. .
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