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Coydon Wallham wrote:
But this brings up one of my main follow up questions about tweaking the system- if I do want to upsize the battery bank and add a couple more of those golf cart batteries to bring up the Ah to 450, how complicated is it to connect them in parallel? Could both pairs be 'balanced' keep the older ones from dragging down the newer ones? If I wanted one or more LFPs on the same system, are there solar charges that handle varied batteries? Could 2 chargers be connected through a bus to use the same panels and feed the same local grid of appliances?
Michael Qulek wrote:There is a simple formula to determine the optimal charging rate for a particular size of battery. I'll mention this first, because the number 1 cause of solar system failures is inadequate battery charging. Typically you strive for something along these lines, based on the amphour capacity of your battery. You then multiply the amps by charging voltage to get how many watts you need. I always include a "fudgefactor" or (FF) to compensate for panels putting out less then their rated output. I usually use 85% (reciprical is 1.175X) for my FF.
5%C, or 0.05C: bare minimum, might take two days to get a full charge: less than this and you will have ruined batteries
10%C, or 0.1C: good charging rate, will charge on most days, though maybe not in winter
13%, or 0.125C: best for lead-acid batteries, will fully charge almost each and every day
25%, or0.25C: for Li batteries. Too high for lead-acid batteries
Let's say you have a 12V string of 225Ah batteries that will charge at 13V. What you need is....
225Ah X 0.125C X 13V X 1.175FF = 429W of panels. So, your 290W is a bit less than optimal. To see what you are actually getting, you just rearrange the formula....
{(290W/13V) X 85%}/225Ah = 0.084C, or about 8%. That's somewhere about halfway between minimum and good.
Two of those panels would be better, but the problem is that you bought a 30A controller. This is an example of buying stuff before really knowing what you need. What you could do though to make it work is orient the two panels in slightly different directions, one facing SE and the other facing SW. This will tend to dampen your noon-time maximum, but broaden the charging curve over more hours of the day. I've been doing this for years now to good effect. My own 48V system would max out at 3600W, but I installed 4500W. Some are exactly as I described, pointed SE or SW. It works very well. It's important that all the solar strings be at the same voltage. It's OK to mix and match different panels, as long as your panel strings come out within 5% of each other.
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Michael Qulek wrote:There is a simple formula to determine the optimal charging rate for a particular size of battery. I'll mention this first, because the number 1 cause of solar system failures is inadequate battery charging. Typically you strive for something along these lines, based on the amphour capacity of your battery. You then multiply the amps by charging voltage to get how many watts you need. I always include a "fudgefactor" or (FF) to compensate for panels putting out less then their rated output. I usually use 85% (reciprical is 1.175X) for my FF.
5%C, or 0.05C: bare minimum, might take two days to get a full charge: less than this and you will have ruined batteries
10%C, or 0.1C: good charging rate, will charge on most days, though maybe not in winter
13%, or 0.125C: best for lead-acid batteries, will fully charge almost each and every day
25%, or0.25C: for Li batteries. Too high for lead-acid batteries
Let's say you have a 12V string of 225Ah batteries that will charge at 13V. What you need is....
225Ah X 0.125C X 13V X 1.175FF = 429W of panels. So, your 290W is a bit less than optimal. To see what you are actually getting, you just rearrange the formula....
{(290W/13V) X 85%}/225Ah = 0.084C, or about 8%. That's somewhere about halfway between minimum and good.
De-fund the Mosquito Police!
Become extra-civilized...
De-fund the Mosquito Police!
Become extra-civilized...
De-fund the Mosquito Police!
Become extra-civilized...
This sounds to me very much to be a faulty charge controller, that was NOT doing it's job. I've never heard of Bogart before, and I am suspicious that what you get was a lemon made by a smaller player in the industry. That wouldn't have happened if you had started out with a higher quality controller. Sorry that you ended up damaging batteries because of it.Sue De Nimh wrote:1 100 W panel from Home Depot and a 12V deep cycle marine FLA battery. I ordered the SC 2030 charge controller from Bogart Engineering http://www.bogartengineering.com/products/solar-charger-controller.html. What with one thing and another (like not having the cabin walls insulated yet) the charger stayed in its box while I just hooked the panel direct to the battery using terminal clamps from the local farm and barn. Attached a 12V camping light from Goal Zero, a 400 W inverter to charge my laptop, and a 12V lighter socket for plugging in phone chargers. I learned the battery was too small for the panel when I found it “boiled” off all the electrolyte. 2 deep cycle marine batteries are better (battery 1 is still in service for just the cabin light and occasional phone, using a cheap panel and charge controller from the farm and barn, coming up on 8 years now). But with 2, we started running my husband’s CPAP, which works for 1-2 nights, but can’t recharge enough with the shorter days during deer season. Add a second 100W panel. Then add a third battery when those start overcharging.
Michael Qulek wrote:I used a dremel tool to cut my wire very cleanly. I never bothered purchasing lugs. I just made my own out of copper pipe/tubing. It works.
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De-fund the Mosquito Police!
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Michael Qulek wrote:Now that you are "on-line", what are your final, working specifications? It's 12V? How many Watts of panels do you have connected now? Which GoWise did you go with?
De-fund the Mosquito Police!
Become extra-civilized...
De-fund the Mosquito Police!
Become extra-civilized...
Iterations are fine, we don't have to be perfect
My 2nd Location:Florida HardinessZone:10 AHS:10 GDD:8500 Rainfall:2in/mth winter, 8in/mth summer, Soil:Sand pH8 Flat
Michael Qulek wrote:
Keep in mind that any load on the battery will effect it's voltage, so you only get an semi-accurate "state of charge" reading from a battery after sitting "off" for a couple of hours. That's why battery voltage is so inaccurate as a gauge of charge. Get the hydrometer. Most accurate way to determine charge. Just be careful of drips.
One more thing. Keep a gallon of distilled water handy at all times. My local grocer has it for 1$/gallon. At the start, you might want to MONITOR water levels in your batteries on a weekly basis, and then top them off with distilled water when they start to get low. I find I need to top off about every three months or so. But, YOU should check weekly until you are comfortable with when YOUR batteries need water. Good luck!!!
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Michael Qulek wrote:Yes, the system should be grounded, for your protection. There's a lot of terminology confusion concerning grounding, so let me first divide things up into two groups, what I'll refer to as below-ground earthing elements, and above-ground earthing elements.
Below-ground elements are things that are actually physically in contact with the earth, such as ground-rods, cold water pipes, steel well casing, ect.
Above-ground earthing elements are things like your electrical panel's grounding bussbar, the ground wires leading to all your NEMA sockets, and all the grounding terminals on your electronics, such as the inverter.
You may have multiple connections between below-ground elements, and multiple connections between above-ground elements, but you MUST have one and only one connection between all the above-ground elements and all the below-ground elements. If you do not follow this rule, you create what is called a ground loop, which is known to attract lightning.
You decide where that junction will be. I have mine at the main power panel directly under my inverter. The heavy 4 gauge ground wire leads from my ground-rod outside to the grounding bussbar in the main panel. Everything else, the inverter, charge controller, generator, and all NEMA sockets and lightswitches in the cabin get attached to that bussbar.
Let's say you have three below ground spots to tie together, a ground-rod, a well-casing, and the rebar in the concrete of your foundation. You would run one heavy copper wire, serially connecting the rebar, casing, and rod, with no breaks/splices in the wire. That heavy wire leads into your bussbar, or where-ever else you decide to make the meeting point. Then everything else gets attached to that one single meeting point.
That will create a code-meeting ground connection. BTW, for less than 100A service, bare 6 gauge copper is acceptable to run to the ground rod. For 200A service, 4 gauge is required. Above 200A is professionally engineered only.
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S Bengi wrote:How many KWH do you plan on using per day.
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Coydon Wallham wrote:
I'll need to wait until I order a DC fridge to hook up and put it and the sat dish on my Kill-a-watt monitor for a few days to have ballpark numbers. .
De-fund the Mosquito Police!
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De-fund the Mosquito Police!
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Coydon Wallham wrote: I decided to leave it running as the only load on the system while I went on a 4 day trip rather than carry my items to a friend's house. Coming home I found that the power cord had been plugged in upside down, meaning it was heating the interior the whole time rather than chilling it. I'm guessing the heat function uses more energy than cool.
The batteries showed no signs of life. They are testing at 7.xV. Fluid levels are still normal. I left the system plugged in when the sun came up, but nothing registered on the solar charger. Would I be able to restore any functionality, either by leaving it plugged into the panels or charging it off my car or on the grid?
Michael Qulek wrote:I have no clue as to how that happened, but it sounds like you totally destroyed your batteries. Maybe this is the best reason to avoid DC appliances in the future. What I would do right now is disconnect the batteries and try to get them onto some kind of external charger ASAP, either at a friend's house, or by connecting them to your running car engine. They possibly could just be totally depleted, or they might be ruined. Can't tell you what from a distance.
As a general rule of thumb, anything producing heat from electricity is the single biggest drain on your system, and the system being on the small side to begin with just made it worse. Poor design, and poor judgement combined together is a deadly combination. You are finding that out the hard way.
If you can save the batteries, then you can move on and live and learn. If in fact they are dead, I think this would be a good point to redesign, and start over with an AC oriented system. Designed from the ground up as an AC based system, this would probably not happen again.
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