48V charging via ST generator and solar charge controller (no ST mod)

[BruceM]

Thanks Bob.   I did some more web research and reading on the subject tonight and now I'm convinced that PF correction isn't going to do much for generator fuel consumption.  For Geno's setup that means that for affecting his fuel economy, there is no need to add an inductor for DC filtering.

When I wrote about inductors helping PF correction, that is for primary filtering of a linear (non switching) DC supply only...for inductive loads like motors, inductance after the generator would  only make the problem worse.  When capacitors alone are used for linear DC supply filtering, a lousy PF results;  the same problem as with too much capacitance added for inductive motor PF correction.

[mobile_bob]

Bruce,

thanks, that makes sense!

i really never gave much thought to power factor issues with switch mode stuff, mainly was more interested in motor loads
and that sort of thing.

it doesn't appear as though pf makes a significant difference in fuel economy in most applications, i guess it is something one
should be aware of, and if it is economically relatively inexpensive to keep the power factor up and the engine is required to run
long hours everyday,, maybe then it would save some fuel over the long run?

there are probably other reasons why having  a good pf is beneficial, if not for saving fuel.

probably the biggest argument for keeping the power factor high is you get more work down with the installed capacity.

if the 6/1 can only make 3.5kwatts, i would suspect getting as near 3.5 kwatts of work done with the power has a certain
attraction.

bob g

[Lloyd]

Hi Bruce, and the rest of the gang.

Bruce you may like this site, Bob I'm sure you will...and for everyone else looking for transformers.

http://www.toroid.com/custom_transformers/dc_filter_chokes.htm
Toroid Corporation has developed a new concept for low frequency chokes based on its in-depth knowledge of toroidal design. Our chokes are smaller in size, have less weight, run quieter, and have smaller losses than ordinary chokes. The low strayfield also permits mounting of our chokes flush to the chassis.

I was just reading on another site about using torids for chokes as to capacitor, and that torids provide a smother/less ripple for dc rectification.

This is a great "Technical Bulletin No.1" Application Notes on Rectifier Transformers http://www.toroid.com/custom_transformers/technical_bulletin_1.htm

Bruce, you may be a good one to decided if it's all corporate hype..but their price seem reasonable.

Lloyd

[Geno]

The #s on the Killawatt and Flexmax bounce up and down a bit with MPPT doing its thing so I look at them for a minute and guesstimate. I'll do a longer test today and record more data. Total kwh from the Flexmax and KAW should be useful. I don't have an easy way to measure fuel consumption. I'll think about that one.
My transformer is a 5 kva, 208-120/240 volt unit.
Flexmax efficiency graph. By sheer luck I was right at the peak.

Thanks, Geno

[BruceM]

Llyod, No, it's not hype, toroids do perform better, and I have used this company's products myself and specified them for other projects for the last 18 years.  For non-custom transformers, Antek, who sells on ebay is reputable and their full load/no load voltage data has proven to be very accurate. For smaller toroids, Digikey carries a couple different vendors products.  For the smallest ones, I like Talema brand, which are made in India.

The only problem with toroidal transformers and chokes is the price; otherwise you'd see them used a lot more.  Because my epilepsy is affected badly by low frequency magnetic fields, I use toroidal magnetic products exclusively; the stray magnetic fields are dramatically lower than E-I cores.  You will rarely see toroidal transformers over 1000 watts; around that size is commonly the largest core.  

[BruceM]

I'm sure your transformer stays nice and cool, Geno.  You sure have more capacity there as well as with the Flexmax, right?   Did you limit the charge rate via the Flexmax setting for max battery charge current?

It was nice that your setup came out right at the Flexmax maximum efficiency point!

Thanks again, Geno!  You've shown that Flexmax user's can get away without filtering the DC input, at least at moderate power levels, and with decent PF, too.  When I look at the prices for high current AC chargers this looks like a very good solution, and one that takes good care of the batteries, with the battery temperature compensation probe and 3 phase charging.

PS- the new Midnite Solar "Classic" looks very good for this use too,  and even the Tristar PWM units (the cheapest option) look like they could do a decent job.  Lets hope Midnight will add a feature like an external input to select a secondary charge current limit- that would make their "Classic" a real classic for this application, in addition to their wide input voltage options and voltage boost capability.

[mobile_bob]

Geno:

i have a question about the numbers and the flexmate if i may

the input volts and amps,
and the output volts and amps

are they presented on the screen?
or did you measure these independent of the flexmate using other meters?

thanks
bob g

[Geno]

All my FM #s come off the screen. I can test the voltage's independently with my meter but not DC power. I do have a clamp on amp meter and will do some comparative AC testing with it today to see how close it is to the KAW. I suppose I could test the low voltage side of the transformer as well. I won't be starting the test till this afternoon. If there's anything else I should test for let me know and I'll add it to the spreadsheet.

Thanks, Geno

[Geno]

I'm sure your transformer stays nice and cool, Geno.  You sure have more capacity there as well as with the Flexmax, right?   Did you limit the charge rate via the Flexmax setting for max battery charge current?

I think the FM is set at 20A which gives me 1200-1300 watts into the batteries. I have 8, T105s and if I figured it out correctly I don't want to put much more than 150 watts into each one.

Thanks, Geno

[mobile_bob]

Geno:

if you could test the input voltage and output voltage
as well as the input and output amperage on the transformer with your clampon meter
so we can compare to the killawatt meter that would be helpful

by most accounts the killawatt is pretty accurate in measuring amps, volts, hz and calculating watts, pf and kva

i just wish we had the same for the lower voltage DC side of things

the wattsup meter and the turnigy meter are the dc equivalents of the killawatt, but both are limited to 60vdc
a threshold that is very close to the 57.6volts that i test at.  personally i wish they had a limit of maybe 80-90volts
so we could get more useful testing done with one of them.

thanks for going to the trouble Geno, it is appreciated

bob g

[Geno]

No testing today. I had everything setup and ready. I shut the engine down to hook up a fuel tank with .5 gallon markings on it and the ST quit on me. I flashed it, scraped the brushes, cleaned the slip rings and replaced the rectifier. I don't have time to t-shoot further. I have to get ready to be away for a few days. It's probably time I take it into the shop for a full cleaning and rewire things to get rid of the doghouse anyway. What a bitch. I hope it's nothing too bad.

Thanks, Geno

[BruceM]

Geno, that really sucks.  Murphy sure knows how to time breakdowns.  I hope it's something simple and easy to fix. 

[mobile_bob]

if one of you guys ever get ahold of ole murphy, you hang on tight and i will grab a board and beat
the summabeech senseless..

sorry to hear about the st giving you fits, if it isn't one thing it seems like it is another.

bob g

[Geno]

I have a good 3000 hours on it and as long as it's something cheap I won't complain. I will complain and go find that Murphy guy if we get an ice storm in the next couple weeks. Moving that ST head the first few feet will a pain, it's in there pretty tight and things have gotten dirty.
I'm now off to Lk. Placid NY for a few nights on business. New computers at a client I've known for a long time. Good people. It should be fun. The resort I stay at is right next to down town.

Thanks, Geno

[BruceM]

I remember Lake Placid, Geno.  A very beautiful part of the world.  Hope your job there is productive and fun.