Land Cruiser Solar Power
- Thread starter LandCruiserPhil
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- Thread starter
- #42
You should be fused at 10A between the junction block and the solar. If I follow GW post his concern and valid is if there was fault on the solar side you could see high amperage backfeed through the panel wiring from the battery.
Probably preaching to the choir... but just in case someone is new to car wiring and hasn't given it a lot of thought.
Generally speaking, fuses are there to protect wiring from high current sources like a battery. Think fire protection - a hot wire is a really good way to set off a gasoline leak in cases of accidents.
Fuses are rarely used to protect gear like radios/motors/lights/etc. Fuses are slow acting devices, often taking seconds to "open" when overloaded. Electronics are often fried in microseconds. So when you see a fuse on a radio, it's there to protect the wire coming into the radio if the radio electronics fail. These fuses are usually sized near the normal - e.g., a 50w radio will have a 6 amp fuse (13v*6A = 78W), giving some room for surges.
Some circuits were once accepted to not be fused, e.g., battery to starter - though this is changing. But almost everything thing else goes into a fuse then to a fuse block for distribution. The entire purpose is to keep a minor wire defect from burning up the entire harness, or catching the car on fire. Nearly all car fires these days (that aren't arson) are caused by user added circuits that are improperly fused (or where a 20A fuse was placed in a 5A fuse socket). I rented a plane from an FBO in Camas, and mid flight the radio cut out. So, when I had a chance I popped the fuse. The prior pilot or owner had decided a wrapping of tin foil sufficed to make the radio work and flew on. Deciding a cabin fire at 10,000 feet wasn't a grand way to end a flight I landed sans radio.
Basically, a fuse is just a small wire. That's it. No special metal, no special electonic stuff. Just a short piece of copper or tin alloy wire that melts just like any other wire when a certain amperage flows through it. What's known as the fusing current of a wore. A 10AEG wire has a 333A fusing current. So if you want to fuse your starter, add an inch of 10AWG to that 00 wire and you're good to go, fused at 333A. There are fast and slo blow fuses, beyond the scope, but it basically means how fast the fuse wire melts. Want a fast fuse, use smaller wire. 10 AWG will melt in about 10 seconds at 333A, or under 1 second at 1,600 amps. The wire melts because it resists current flow and heats up.
With normal use, wires get warm when current flows through them. More current, more heat. That's partly why you'll see temp ratings on wires. It helps dictate what the current rating is for a particular application. Good wire for cars is almost always rated 105 degrees C. That means the insulation won't fail when the wire hits the boiling point of water. That's combined enviromental temp plus load heating. An engine compartment is already at 90C (195F is about where most engines run). So any serious mechanic will only use 105C wire on a car. Yes, 105C wire is more expensive than wire you buy at HomeDepot (THHN is 90C until it gets wet, then its 75C); or the better short spools at Autozone are rated 80C. Check before you buy.
Those basics aside, 10AWG wire heats up as currrent runs through it. Wire is resistive, so as current flows its resistance invokes the I-squared-R rule for power. 10AWG is handy as it's about 1 milliohm per foot. At it's common 30 amp rating, that's a 30 millivolt loss per foot, and a heating effect of 0.9 Watts per foot. It's inconvenient to determine the temperature rise that adds to the wire, just too many variables, but suffice it to say a pair of 10AWG five feet long wires carrying 30 amperes is a 9 Watt heat source. If you have 80C wire in an engine compartment, it's already underrated and with the added self heating it will cook the insulation. So one needs to add this self heating factor to ensure the insulation will not fail in a given application.
Always buy 105C wire for autos as a minimum; higher if you are running something really important in the engine compartment. And yeah, you can buy teflon or similar hi-tech insulated wire that survives temps higher than 400C for running along exhausts.
I kind of like Belden... but Allied makes good wire, too.
http://www.belden.com/marketsolutions/Industrial/auto.cfm
More marketing spiff, but a few useful tips:
http://www.awcwire.com/producttoc.aspx?id=automotive-wire-battery-cable
Generally speaking, fuses are there to protect wiring from high current sources like a battery. Think fire protection - a hot wire is a really good way to set off a gasoline leak in cases of accidents.
Fuses are rarely used to protect gear like radios/motors/lights/etc. Fuses are slow acting devices, often taking seconds to "open" when overloaded. Electronics are often fried in microseconds. So when you see a fuse on a radio, it's there to protect the wire coming into the radio if the radio electronics fail. These fuses are usually sized near the normal - e.g., a 50w radio will have a 6 amp fuse (13v*6A = 78W), giving some room for surges.
Some circuits were once accepted to not be fused, e.g., battery to starter - though this is changing. But almost everything thing else goes into a fuse then to a fuse block for distribution. The entire purpose is to keep a minor wire defect from burning up the entire harness, or catching the car on fire. Nearly all car fires these days (that aren't arson) are caused by user added circuits that are improperly fused (or where a 20A fuse was placed in a 5A fuse socket). I rented a plane from an FBO in Camas, and mid flight the radio cut out. So, when I had a chance I popped the fuse. The prior pilot or owner had decided a wrapping of tin foil sufficed to make the radio work and flew on. Deciding a cabin fire at 10,000 feet wasn't a grand way to end a flight I landed sans radio.
Basically, a fuse is just a small wire. That's it. No special metal, no special electonic stuff. Just a short piece of copper or tin alloy wire that melts just like any other wire when a certain amperage flows through it. What's known as the fusing current of a wore. A 10AEG wire has a 333A fusing current. So if you want to fuse your starter, add an inch of 10AWG to that 00 wire and you're good to go, fused at 333A. There are fast and slo blow fuses, beyond the scope, but it basically means how fast the fuse wire melts. Want a fast fuse, use smaller wire. 10 AWG will melt in about 10 seconds at 333A, or under 1 second at 1,600 amps. The wire melts because it resists current flow and heats up.
With normal use, wires get warm when current flows through them. More current, more heat. That's partly why you'll see temp ratings on wires. It helps dictate what the current rating is for a particular application. Good wire for cars is almost always rated 105 degrees C. That means the insulation won't fail when the wire hits the boiling point of water. That's combined enviromental temp plus load heating. An engine compartment is already at 90C (195F is about where most engines run). So any serious mechanic will only use 105C wire on a car. Yes, 105C wire is more expensive than wire you buy at HomeDepot (THHN is 90C until it gets wet, then its 75C); or the better short spools at Autozone are rated 80C. Check before you buy.
Those basics aside, 10AWG wire heats up as currrent runs through it. Wire is resistive, so as current flows its resistance invokes the I-squared-R rule for power. 10AWG is handy as it's about 1 milliohm per foot. At it's common 30 amp rating, that's a 30 millivolt loss per foot, and a heating effect of 0.9 Watts per foot. It's inconvenient to determine the temperature rise that adds to the wire, just too many variables, but suffice it to say a pair of 10AWG five feet long wires carrying 30 amperes is a 9 Watt heat source. If you have 80C wire in an engine compartment, it's already underrated and with the added self heating it will cook the insulation. So one needs to add this self heating factor to ensure the insulation will not fail in a given application.
Always buy 105C wire for autos as a minimum; higher if you are running something really important in the engine compartment. And yeah, you can buy teflon or similar hi-tech insulated wire that survives temps higher than 400C for running along exhausts.
I kind of like Belden... but Allied makes good wire, too.
http://www.belden.com/marketsolutions/Industrial/auto.cfm
More marketing spiff, but a few useful tips:
http://www.awcwire.com/producttoc.aspx?id=automotive-wire-battery-cable
Wanted to let you know that I am just thinking through options now, and do appreciate you sharing your knowledge! Thanks!!
I added a 10amp circuit breaker this morning from the junction to the solar controller. Thanks guys for the heads up.
I also added some split loom to cover the wires near any sharp metal edges.
Thanks again for the info GWcruiser.
I also added some split loom to cover the wires near any sharp metal edges.
Thanks again for the info GWcruiser.
Slight highjack but somewhat related. One of the wires in my pickup truck got so hot today. There was smoke and rubber burning smell. It is the 10 gauge wire between battery and 80A fusible link. The wire is ruined and fusible link is good. I guess Toyota should have used thicker wire or fused this wire
Yeah - 10AWG is only rated to caryy 30A with normal insulation, 40A if is has a special higher temp insulation. At 40A or more the insulation will suffer. Fuze links are very slow blow and can take minutes to open if currents are remain close to 80A. I think I read somewhere a fuze link will still keep working at twice its rating for a while.... at that level 10AWG is almost glowing. A case where the designer expected a hard fail and no problems in-between. Also, read that fuze links are notorious for not fuzing as rated (100% to 200% varitions, e.g.). All signs they are intended for catastrophic failures such as in accidents.
Nothing beats a good old wire fuse or magnetic breaker for turn off at overload; or slow-blow fuse or thermal breaker when inrush may exceed the wire rating for a second or two.
Nothing beats a good old wire fuse or magnetic breaker for turn off at overload; or slow-blow fuse or thermal breaker when inrush may exceed the wire rating for a second or two.
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Departing from the electrical engineering side of this for a quick second (primarily because it's not my strong suit 
), whenever I get around to doing a solar addition, I'd been contemplating a sliding drawer to mount the panel to. It would behave similar to a sliding drawer in your kitchen (or drawer system in the back of a lot of your rigs) and would mount underneath the rungs of the top rack (I also have a Baja).
Pros:
Thoughts?
Great thread, keep at it!
), whenever I get around to doing a solar addition, I'd been contemplating a sliding drawer to mount the panel to. It would behave similar to a sliding drawer in your kitchen (or drawer system in the back of a lot of your rigs) and would mount underneath the rungs of the top rack (I also have a Baja). Pros:
- You wouldn't lose the rack space similar to the pic seen earlier in this thread since the panel itself would be "under" the rack vs. mounted atop it.
- When parked/camping, slide the panel out to get the desired exposure. It could theoretically be mounted in a way that would accommodate tilting/rotation to follow the sun without periodically moving the vehicle.
- When "under" the rack, you're only getting partial sunlight (possibly none if you've got a rack full of gear - e.g. during transport).
- More work/material/cussing to "get it right"......half the fun in my book.
Thoughts?
Great thread, keep at it!
^^I thought of doing a sliding panel. The truth is, I don't really need a roof rack as I am single and can fit all my gear in the cab. I opted to mount the panel as I did in the rare case I need to haul something longer than 7 feet.
A sliding panel would be cool though, I did see a few variations online whilst I was researching the project.
The mounting system that Phil linked earlier would be the best for me, the cost is hard to swallow though.
A sliding panel would be cool though, I did see a few variations online whilst I was researching the project.
The mounting system that Phil linked earlier would be the best for me, the cost is hard to swallow though.
- Thread starter
- #51
After
I recently did some testing on panel output from 10AM - 2PM. Didnt see enough advantage in moving the panel to justify spending any money on a mounting bracket to adjust the panel.
I recently did some testing on panel output from 10AM - 2PM. Didnt see enough advantage in moving the panel to justify spending any money on a mounting bracket to adjust the panel.
Good to know...
Do the trig - I should've done this first 
- the added "area" of even 20 degrees is pretty small over all. But add one shadow - disaster (my own experience, newer panels might be better).
Here's the (dated) paper it's from:
http://userwww.sfsu.edu/ozer/engr300-solar1N.pdf
- the added "area" of even 20 degrees is pretty small over all. But add one shadow - disaster (my own experience, newer panels might be better).Here's the (dated) paper it's from:
http://userwww.sfsu.edu/ozer/engr300-solar1N.pdf
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- Thread starter
- #55
Trig 
- Thread starter
- #57
I added a 10amp circuit breaker this morning from the junction to the solar controller. Thanks guys for the heads up.
I also added some split loom to cover the wires near any sharp metal edges.
Thanks again for the info GWcruiser.
Are you making power daily? Performance report
Yes, positive gains each day sitting in the sun for 9 hours with the fridge running (32°).
Voltage is between 12.4-12.9 when checking throughout the day.
I'm sure at lower ambient temps I'd get to float mode and the controller would stop sending power to the battery.
I'll find out for sure next month when I'm in Ouray for a week.
- Thread starter
- #59
Sounds great!
Side note - Once ambient temps go over 100° panel output drops. I find this to be true with all systems even the one on my house. Panel peak daily output was about a month ago. I was surprised the study Tim posted did not include any temp data.
Numbers aren't adding up to me - I'd be interested to hear a full report after the trip whether an alternative means of charging the house battery is needed along the way (using jumper cables for an hour or so a day - or if there is already a battery combiner, etc.).
To answer Phil - semiconductors like the diodes in solar panels are temp sensitive, the warmer they are the less voltage drop across them. I*E=P [current(I) times voltage(E) equals watts(P)] - so as the panel heats, the diodes produce less voltage and less overall obtainable power. This by the way is fairly linear and usually a small effect for small changes (you can study Boltzman's work on electron mobility on your own time :~), so there shouldn't be any large or abrupt changes with temperature. Anything "stepping" in power levels would be things like inverter fans turning on or something else like that.
http://www.pveducation.org/pvcdrom/solar-cell-operation/effect-of-temperature
http://www.teachengineering.org/col..._lesson02_fundamentalsarticle_v6_tedl_dwc.pdf
To answer Phil - semiconductors like the diodes in solar panels are temp sensitive, the warmer they are the less voltage drop across them. I*E=P [current(I) times voltage(E) equals watts(P)] - so as the panel heats, the diodes produce less voltage and less overall obtainable power. This by the way is fairly linear and usually a small effect for small changes (you can study Boltzman's work on electron mobility on your own time :~), so there shouldn't be any large or abrupt changes with temperature. Anything "stepping" in power levels would be things like inverter fans turning on or something else like that.
http://www.pveducation.org/pvcdrom/solar-cell-operation/effect-of-temperature
http://www.teachengineering.org/col..._lesson02_fundamentalsarticle_v6_tedl_dwc.pdf