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RE: Charge controller recommendations
I am happy with my LandStar 20a PWM controllers of the Series three stage (vs older type Shunt on/off method). I was concerned the two- hour timed Absorption Stage was too short, but it is working out in real life no problem.
I picked up a unit too to play with a while ago. Nice quality and functionality and great price.
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DSchmidt_2000
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05/20/13 11:41pm |
Tech Issues
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RE: Just witnessed MPPT voltage drop below 14V
Wonder if a full scan is even needed. I'm guessing the MPPT 'graph' for a panel would be monotonic. So small scanning could continually occur.
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DSchmidt_2000
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05/20/13 11:40pm |
Tech Issues
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RE: Eco-worthy 20a MPPT controller
Hi DS,
You would have to use a buck circuit to keep the voltage constant into an inverter with light bulbs as a load.
Don't think that is going to work - load needs to change to keep the input voltage side the same regardless of the sourcing capability of the 'power' source, be it a battery or solar panel.
Was thinking of something generic. I test batteries all the time, but mostly small lithium or nimh cells and packs. No more than 5AH capacity but with high discharge capability. I own a CBA II battery analyzer but am limited to 140W.
Thinking of building an electronic load with a much higher wattage capability. Feedback would be on the current sense leg if I wanted a constant current electronic load. Feedback would be the input voltage side if I wanted to make an 'infinite' AH rated battery simulator for solar testing. Basically the load would increase or decrease to keep the input voltage the same.
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DSchmidt_2000
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05/19/13 11:10pm |
Tech Issues
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RE: Eco-worthy 20a MPPT controller
I use this device for testing... It provides about a 13 amp load.
Thanks. I have no shortage of loads, but I'm looking for essentially a 'calibrated' load (electronic smart load), or at least a very consistent one for ANY setup (within reason). The hope is to use this as a ruler to get AH output for various different setups.
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DSchmidt_2000
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05/19/13 09:06pm |
Tech Issues
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RE: Eco-worthy 20a MPPT controller
BTW, I'm up the coast from you in Goleta. Today is a great sunny day to run solar tests. Will be looking forward for further results.
I work in Goleta, which unfortunately means my solar testing can only be done on weekends. Should be able to get some signal snooping done during the week though.
Was a beautiful weekend (and still is - love the long days).
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DSchmidt_2000
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05/19/13 07:05pm |
Tech Issues
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RE: Eco-worthy 20a MPPT controller
It would be worth running your battery down to 11 volts or so and running similar tests.
Jim
Yeah, was thinking about how to create an ideal load. Basically create a constant voltage load. If I built two of them then I could have one panel on the MPPT controller, the other on the PWM, set them out in the sun with a Watt's up on each and at the end of the day get the AH difference between the two.
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DSchmidt_2000
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05/19/13 04:13pm |
Tech Issues
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RE: Eco-worthy 20a MPPT controller
Thanks for the testing. The 0.1A gain compared to direct charge does seem quite low; especially when battery is at 12.5V. Is the controller's operating current high that it impacts your measurements? Perhaps using a panel that's greater than 100W will provide better results.
Sounds like there's a relay in your controller. It may be measuring open circuit voltage of the panel. Time to pull out the scope.
Sal
There is no relay in there. The clicking is faint and sounds more like the oscillator driving the inductor in the buck circuit is turning off. Don't know if they're taking a measurement during that time, or it's an interrupt being handled by the PIC to do something else so they have to turn off the PWM output or what.
I have not measured quiescent current draw of the unit 'officially' but the clamp on meter which has 10mA resolution is showing 20mA draw during standby/snooze.
Yeah, probably not so great due to me operating it really low in its power handling capability. I do have 2 qty 45W panels though I'm only using one right now, but one of the tests I want to do is compare the charging amps with the panels in parallel vs in series going through the MPPT controller, and also vs in parallel going through a PWM controller or direct to the battery.
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DSchmidt_2000
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05/19/13 03:40pm |
Tech Issues
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RE: Eco-worthy 20a MPPT controller
Did some testing today. (sorry for the data not being aligned- don't know how to post formatted text).
Setup:
45W 12V Solar Blvd panel with these specs
Maximum Power Voltage (Vmp): 18.0V
Maximum Power Current (Imp): 2.5A
Short Circuit Current (Isc): 2.73A
12V 35AH SLA battery which I depleted about 75% yesterday
Watt's-up meter in-line with the battery to measure current INTO the battery, battery voltage, and watts into battery.
DMM to measure the solar panel's voltage at the input of the MPPT controller.
I have Deans Connectors between the watts-up and the MPPT controller and between the solar panel and the MPPT controller so I can easily unplug things and make changes.
Testing: What I did was measure the current going into the battery if the MPPT controller was "in-the-loop", and then connected the solar panel directly to the battery. With the Deans connectors, I could do this switch around in seconds.
Here are the measurements in order they were taken (if no measurement listed - then I forgot to write it down)
With the MPPT "in-the-loop"
Solar V Batt A Batt V Watts
16.76 3.08 12.51
17.00 3.05 12.51
Solar direct to battery
Solar V Batt A Batt V Watts
2.89 12.50V 35.5
With the MPPT "in-the-loop"
Solar V Batt A Batt V Watts
17.05 3.02 12.51 37.4
16.94 3.07 12.52 37.1
Solar direct to battery
Solar V Batt A Batt V Watts
2.93 12.51 35.7
The battery voltage and watts were from the Watt's-up meter - it has uncertainty in its measurements hence the watts reported are not exactly that calculated just doing the math.
I'm a bit disappointed to not have a much greater charging amps (only ~ 0.1A greater) given the delta between the battery and the panel is about 4V. Thinking that I may just be so low in power that I'm not in a high efficiency zone for this MPPT controller.
Putting my ear to the MPPT controller, I hear a regular 'ticking' noise. Will at some point drag out my digital scope and take some measurements to see what is going on.
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DSchmidt_2000
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05/19/13 10:44am |
Tech Issues
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RE: Eco-worthy 20a MPPT controller
Wait it has a temp compensation thermistor?? Man if it is a PIC controller it would be fun to hack the code and customize it...tell us if you can read the code and update it!
On the Watts up did you blow the shunt like many of the rest of us lol? I desoldered mine by shorting it. If it is just the shunt, I was thinking of getting one to remote mount.
Jim
Looks like there is one, might only be used to derate the output when it gets hot. Not sure as there is no mention of it in the manual that shipped with it.
My 2nd Watts-up with a freebie from another RC flyer that broke the display. I replaced it but there is still no image as I think I need a 3.3V model which I just ordered.
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DSchmidt_2000
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05/18/13 09:35pm |
Tech Issues
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RE: It works! Manual MPPT controller v2.0
Nice! I might have to buy one to play with!
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DSchmidt_2000
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05/18/13 09:28pm |
Tech Issues
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RE: Harbor Freight Inverters
i have the 750 running 1500 max unit. I leave it on all the time. I used a 75 amp marine fuse.
I just bought this unit today. On sale for $41.99 in the store, used a 20% off coupon which made it cheaper than the $39.99 coupon they sent me in the mail.
Very good reviews on their website. Found it interesting that the manual states it has a 35A fuse inside though the inverter is rated for 750W continuous. Would think it would nuisance blow at 1.8X for the 750W rating but it worked fine powering up a bathroom fan for about 5 mins as a load (~600W)
Case is all plastic, would have liked metal but got me thinking about today's UPS's with their plastic cases and similar outputs. The only exception to this is you add your own battery!
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DSchmidt_2000
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05/18/13 09:24pm |
Tech Issues
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RE: Eco-worthy 20a MPPT controller
A second member just received one so we should be getting another review here soon.
I'm the other guy that bought one of these from the Eco-Worthy website. $102.50/shipped, and it was shipped from a US address (I think it came from So. Cal). Bought it May 10th, I think it was in my hands on May 15th.
Opened it up and saw the large toroid in there for the buck topology. Power transistors and flyback Schottky are TO-220 cased and clamped to the sides of the case. The thermister is also clamped to the case to the upper right side.
Not 100% sure as I haven't poked too much at it, but I think the buck controller IS the microcontroller - a PIC 18F series chip. There are a pair of 25-turn trimmers on the board - not sure what they're used for but maybe to calibrate the current and voltage measurements. Not much else on the board semi-conductor wise.
There is a 5 pin header (or was it 6?) at the top of the PCB which looks like the same in-circuit serial programming header used for PIC controllers. I haven't tried to read out the contents of the chip to see if it is read protected.
As far as operation goes, my test setup right now is just a pair of 8AH 12V SLA batteries and a single 45W 12V panel. Again, this is just for playing - it's what I do.
I have a Watts-up meter right now in series with the battery to measure current INTO the battery. I have a second Watts-up that I need to repair and once I do will go in-line with the solar panel. For now I am measuring solar panel current with a DC clamp meter and measuring the voltage with a standalone DMM.
Around 9AM with the panel tilted to the sun, I was measuring ~ 2.5A into the battery and 2.05A from the solar panel. Measuring the voltage from the solar panel the controller was finding Vmp at ~ 17.4V (solar panel is marked Vmp at 18V).
Every 2 mins the controllers re-seeks MPPT as evidenced by the solar panel voltage shooting up to 21V, then dropping down to under 15V and quickly creeping back up.
As I do more testing I'll post more but likely not before I get my 2nd Watts-up meter repaired. Also will hookup a larger SLA battery (35AH) later but need to drain it a bit.
Lastly I do have a USB data logger (MCCDAQ 1208LS) that someday I'll get wired up to automatically track solar/battery voltage/current over time but I need to get some current measurement IC's on order first.
Happy with the 'performance' right now. As mentioned elsewhere, this will allow me to buy and play with those cheap 24V panels from Solarblvd.
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DSchmidt_2000
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05/18/13 11:13am |
Tech Issues
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RE: 5Watt solar panel - what else is it good for?
I use a 5W panel on a couple of my vehicles that rarely get driven - a Ranger and a Toyota MR2 Spyder. Works great except the discharge on the Spyder is such that the panel cannot be on the dashboard unlike the Ranger. Sitting on the trunk lit in the open however works fine.
Meanwhile I found this 5W mono-crystalline panel from Amazon for $15, shipped free with Amazon prime so I had to order one as it was the cheapest I've seen. Got it today - very nice quality. The only downside is the frame is a bit thick - like it's meant for a medium/full sized panel at just under an inch tall. Isc matches the label at 0.32A, Voc is 21V, Imp is 0.3A, Vmp is 16.6V
It's the rightmost panel in this photo (45W - 20W - 5W)
http://www.dschmidt.com/images/GMF/SolarPanels.jpg
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DSchmidt_2000
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05/14/13 11:11pm |
Class A Motorhomes
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RE: Ideal Inverter Generator
"The Best?"
A neighbor who says "I don't seem to need my never used Honda generator. It's yours if you'll come over and pick it up"
Just Sayin'
That's about what my ideal one would be.
That or fuel cell technology gets to be real cheap. Near zero noise, lots of power.
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DSchmidt_2000
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05/13/13 09:19pm |
Tech Issues
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RE: VEC1093DBD Smart Battery charger - amazon warehouse deal
FWIW, I've bought two things from Amazon's warehouse deals.
An MP3 player - used, like-new. It was brand new - still in the impossible to open heat sealed plastic but the box was beat up. All complete.
The other was something else I don't remember - may have been my Kindle. Same thing.
It'll be interesting to hear the quality of these B&D units.
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DSchmidt_2000
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05/13/13 09:15pm |
Tech Issues
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VEC1093DBD Smart Battery charger - amazon warehouse deal
Used "like new" for just under $56.
Black & Decker VEC1093DBD Smart Battery charger.
Click on the 'used' prices and it will come up. I put one in my shopping cart and it said there were 9 left.
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DSchmidt_2000
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05/12/13 04:13pm |
Tech Issues
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RE: Solar so cheap that cells can be wasted
Are you gonna wire it up? Connect those other cells?
No way! Again, I don't want to damage the PVA.
The reason for the 45W panels is just something small for car based tent camping and also a small test setup for kids to learn about solar power. Going to either hinge the pair so they can be folded up or just go with one panel.
I have a nice metal 'key lock box' to put a couple of 7AH SLA batts and a PWM controller into it. Can probably fit a small laptop inverter too.
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DSchmidt_2000
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05/11/13 11:18pm |
Tech Issues
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RE: Solar so cheap that cells can be wasted
It's is wired in series, 36 cells in series.
I an completely convinced that the manufacturer wanted to build a more square'ish panel vs rectangular and put un-wired ones in there because nobody would want to buy a panel with white space in it.
The panel puts out what it is spec'd to do. The non-wired cells look perfect. Same hue/color, no chips or cracks, completely blemish free.
Again, I wish they were connected so MPPT users could take advantage of it, though it would be more of a mismatch when paired with different panels. No way I'm tearing into the PVA to attempt to wire up these extra cells. I don't see how they can be meant to wire in for yield losses either for another cell as the re-routing would be extensive and why do that before the PVA is in when you can just remove and replace a cell easily.
As far as weight goes, what they say online is not exactly what it weighs. I just weighed one at 11.7 lbs. I'm guess SolarBlvd pads the weight up to take care of handling charges, plus they did add heavy edge protection all around plus strapping.
Nice panels - put out what is rated as far as Isc and Voc. I have the inexpensive Chinese 20A MPPT controller on order that JiminDenver has. It'll be my first MPPT controller to dip my feet into. Hoping to take a trip to SolarBlvd one day to pick up one of those screaming 24V panel deals soon.
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DSchmidt_2000
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05/11/13 04:04pm |
Tech Issues
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Solar so cheap that cells can be wasted
I bought a pair of $1/watt W Solar 45W monocrystalline panels from Solar Blvd which arrived today.
First thing I noticed was there were 40 cells on the panel, not 36 like usual for a '12V' panel, but the open circuit voltage was not 4 cells higher.
Took it outside to do some measurements and when checking shading performance I was VERY surprised to not see the amps drop when I shaded one cell, then another, then another.
Hmm, I don't see blocking diodes on the cells. Blocking some of the other cells, there was an immediate drop. "What is going on?"
Closer inspection showed that though this panel has 40 cells, only 36 are wired up. 4 cells appear to be wired up but are not as seen in the 2nd photo.
I guess it was more important to make a square'ish panel vs a rectangular panel even if it meant wasting 11% more cells. Too bad they were not wired up - would have liked to have used that extra voltage for an MPPT controller.
Performance wise, Isc and OCV matched the label even at 4:30PST sunlight with the panel facing the sun.
Green arrows show cells not wired up
http://www.dschmidt.com/images/RVNet/WEnergy45W-1.jpg
Green arrow shows connector ribbon not extending beyond edge of cell.
http://www.dschmidt.com/images/RVNet/WEnergy45W-2.jpg
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DSchmidt_2000
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05/10/13 06:26pm |
Tech Issues
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RE: K&N intake air system
Here's a study of factory vs K&N vs. . .
K&N became restrictive faster, and passed more dirt than the ACDelco paper filter.
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DSchmidt_2000
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05/04/13 01:57pm |
Tech Issues
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