Friday, February 8, 2019

Now Chillaxin at 3.5 to 4 amps!! DROK DC-DC 4-30V to 1.2-30V 12V Continuously Adjustable Step-Down Voltage Regulator Buck Volt Converter Module Board is a HUGE success!!

OK so I just did a "run" or I mean "bicycle ride" to make sure the new Drok DC/DC buck converter was doing its job. Amazingly I put 10% increase in battery charge in about 1 hour of bicycle riding - and this is the LOWEST gear - so I'm "chillaxin."

Now - last time I was chillaxin?
 I got out the multimeter and amazingly I was now getting 80 volts and 3 amps! So suddenly I realized - this was in my highest gear that I had been using before - and the volts were way too high.
Wow! So I'm in the lowest gear and getting MORE amps - then the highest gear!

I have the potentiometer set at 12.2 volts. This DC/DC buck converter is very precise - so maybe it's 12.1 volt sometimes. But even if I pedal slowly in the lowest gear - it still "steps down" the higher volts to 12.2 volts. So it stays ABOVE 12 volts no matter how slow I pedal. That is the crucial key I needed to confirm. This seems hard to believe - but a solar battery charger also regulates at just above 12 volts!

A solar panel is a current source, not a voltage source. The spec on the [100 watt] panel is 18 volt Vmp and 5.55 Imp. When connected to a discharge battery the voltage of the panel is pulled down from 18 Vmp to match the battery voltage of around 12.1 volts and is supplying its constant current of 5.55 amps. Do the math 12.1 volts x 5.55 amps = 67 watts. You loose 33% of the panel power
So as I confirmed in my last blogpost - the Chafon 500 watt has an internal volt regulator that does not accept a charge until it hits 12 volts. So that means when I had the multimeter set on volts - while also plugged into the Chafon - I saw the load kick in and the volts dropped to about 11.5 volts.

Also this means I can use the DC/DC buck converter for the 100 watt solar panels also - to increase the charge (instead of losing the watts as above PWM controller that came with the Harbor Freight panels).

Now this morning - I had HUGE resistance since I was at very high volts and the Chafon was stepping them down to below 12 volts. So apparently it has a higher cut off for charging at high volts. That makes sense since it can charge from 120 volts also.

OK so this morning I was sweating big time with HUGE torque load resistance. The multimeter showed - again - the battery load was still pulling the volts down to below 12 - so I figured I was still "charging" but I just could not keep up that level of resistance.

But now I'm pedaling nice and easy - which means I can charge as long as I want - and my volts are around 30 with amps around 3.5 to 4 amps. So the top voltage on the DC/DC  buck converter is 36. So it fits PERFECTLY for what I needed - since the treadmill volts are about 36 if I pedal the fastest possible in the lowest gear.

So instead I just "chillax" and crank out an amazing 3.5 to 4 amps at 12.2 volts!! It's the lowest voltage I can go so that means it's also the highest amps I can crank out - but it's also the SLOWEST gear on the bicycle! An amazing configuration!!

 So I promised myself - I was not gonna watch any DVD movies until I got up to 70% charge on the Chafon 500 watt. So I started at 60%. Now before - this would have been impossible! I would have been out there way too long. But tonight? No problem. In about an hour I was at 70% charge while on the bicycle generator - putting a load into the battery.
So it's 31 amp hours for the battery. I'm putting in about 1 amp. So it should be 1 amp an hour or 1% point in 20 minutes on the 100% charge level (more or less).
Now notice on my last "chillaxin' post - It's actually 1/3rd of an amp as 1% on the charger since 100% is 31 amps. So 3% is 1 amp and 90% is 30 amps - approximately. So oh I guess I did do the math correct.

So I was saying I could do 3% in 1 hour - and now I'm saying I can do 10% in 1 hour!

Now keep in mind - I'm going the same speed with the SAME resistance! Just Chillaxin!!

This DC/DC buck converter is very tiny - fits in the palm of the hand. Like I said - I used my thumbnail to adjust the voltage. Also my wire connections are very fragile. So I need to pick up some connections I think - to put the wire in - so it's more solid. Also I need one of this super tiny standard drivers. Also I could "mount" the DC /DC buck converter to the actual bicycle generator frame. But I'm not sure I want to.

Anyway it is quite an amazing device!! To about triple my power! Now remember the "commercially" produced "bicycle generator" version is about 3 amps. So I am going better and I don't need to pedal as fast as that version. Also the Chafon will hold more amp hours - and has an inverter, etc. And you don't want to use more than 1/3rd of the  Chafon a day (to get a 4 year use rate on the battery). So that means 3 hours of easy pedaling - which is a couple movies.

Well the thing about using an AC load is it loses 20% of the charge to convert it from DC - so you have to increase the amp loss. So I can't plug in the t.v. unless I'm at least 80% of the charge (to cover the surge wattage on the t.v.). Yes I don't want to smell "magic smoke" again! And luckily I didn't blow the fuse.

 Wow - I am stunned that my nefarious off-grid Treadmill motor bicycle AC/DC converter generator with a DC/DC transformer - WORKS!! haha. I had no idea about "back-EMF fields" from DC motors - I studied that yesterday. haha. So this morning I had wired in the multimeter in a McGyvered connection - and the battery load was still pulling down below 12 volts even at higher bicycle gear. But the Ohm resistance was too high since my bicycle was probably at 80 volts. haha.

But anyway luckily the Chafon survived that experiment - and I was all sweaty and sore leg muscles. Then amazingly the mail delivered from China direct - the new power transformer! So I McGyvered more connections - it's fragile - and now the multimeter voltage was stepped down to 5.6 volts (the factory preset).

So I had to use my thumbnail since I don't have that size tiny driver. So anyway I then discovered the Chafon generator does not draw a load until the volt is over 12 volts. So I set the DC/DC buck converter to 12.2 volts - and I can bicycle in lowest gear - going slow - and I still get 12.2 volts. So the max voltage on the DC buck converter is 36 volts - but if I pedal as fast as possible in the lowest gear then I hit 36 volts. So it's a perfect match for the bicycle. I'm not gonna pedal that fast.

I just "chillax" - and when I switched to amps - then with no load I am getting 4 amps!! Now this morning - I could barely get 3 amps since the resistance was so strong with no load (the driving torque to load torque ratio caused too much back-EMF force)....

 So you wanted to be updated on my bicycle generator. Yesterday I had to study "back-emf" fields for DC motors. Something I discovered when realizing the resistance was overwhelming without the battery load hooked up. Anyway so I had the multimeter wired in today - and then direct from China (no Amazon order) - I got the DC/DC buck transformer! So this morning I was literally all sweaty and sore muscles while only getting maybe 3 amps (with huge ohm resistance from too high voltage). Tonight I was chillaxin' in lowest gear with hardly any resistance - due to this little electrical circuit board (that fits in the palm of my hand)!! The DC/DC buck transformer.

So am now getting 4 amps charge from my bicycle - in the lowest gear - just chillaxin' - and it steps down the voltage from around 30 to 12.2 volts. So that is the minimum for the Chafon 500 watt battery generator to take the charge. Yep - it works all according to my nefarious evil power planning!!! So I just put 10% charge into the battery in 1 hour of chillaxin' bicycling. Yes - this is 3 times faster than without the DC/DC buck transformer.

There is only one other person on youtube who designed this same power system (bicycle generator with DC/DC buck transformer charging into a battery with AC inverter to plug in "normal" appliances).

 I'm pretty excited - I had to figure out a lot of stuff just from trial and error and then researching. I did have "magic smoke" earlier when I plugged in the CRT 27 inch JVC tv - forgetting about the surge charge. haha. Luckily I didn't break the Chafon - it just let out a loud alarm and shut down. I did not have to replace the fuse. Anyway I guess once I get it charged up past 80% then I could plug in the TV and DVD player - the TV is a monster at 125 watts but has amazing "popping color" due to the 3D (horizontal/vertical) cathode day tubes - and also a high "horizontal line" number - it's the D-series JVC from 2000. I got it free on Craig's List, just as the treadmill DC motor was free.

I had to buy the DVD player because I wanted "component" connections for better color image - and the thrift store DVD players either did not have the remote or had busted eject drives (the belts get loose). I was gonna try to replace a belt on one and then realized the tools were just as expensive as a new DVD player. haha. So you can buy a "commercially" produced bicycle generator - but it puts out less amps than mine and also requires pedaling FASTER - and also .... well that's about it. Making my own was cheaper also even though i had to buy all the tools I needed to take apart the treadmill, and built the bicycle/generator stand and do wiring, etc.

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Synchronous Rectification Adjustable
Module properties: non-isolated buck module
Input Voltage:DC 4-30V (limit 36V)
Output Voltage: DC 1.2-30V (adjustable,default 5V)
Minimum Voltage Difference: 1V
Output Current Range: 0-10A (default 6A)
Output Constant Current Range: 0.3-10A
Operating temperature: -40°c to +85°c
Working frequency: 150KHz
Conversion efficiency: up to 98%
Installation: 4x 3mm screws
Wiring: Terminals, Needn't solder, V-IN input, V-OUT output
Cutting size: 60mmx26mm
Have operating indicator

Protection function
Short circuit protection: YES ( Limit current is the constant current value)
Over-temperature protection: YES (Over-temperature auto reduces the output current)
Input reverse polarity protection: None (If need please install diode at input port )
Output install diode protection: None ( please install diode at output port )

Current voltage adjust:
Voltage adjust: clockwise increase,counterclockwise reduce
Current adjust: clockwise increase,counterclockwise reduce
Please note that when setting the constant current value,voltage should higher than 1.2V

Some Application:
DIY Voltage Regulator
Power supply for electronic equipment.
For battery charging,Setting the charging voltage and current according to the different voltage&battery capacity,with indicator, convenient to observe the state of charge.
Solar panels power supply for battery charging, overcharge protection.
Car power supply, for cell phone, laptop, etc.

Typically the multi-turn trimmer pots don't have a hard stop at Max, though they do stop changing in value.

36 pieces, 3.7 V, 26000 mAh 18650 lithium battery

2.18 V is the maximum.
PER CELL FOR CELL BALANCING 
so 
36/2.18 volt= 16.5 volts for cell balancing -  (36/16.5 volts = cell balancing of 2.18) the internal volt regulator in the Chafon.
14.8 volts is the 4 cell max at 3.7 per cell.

So a lower TOTAL volt = a higher voltage per cell. 

So 2.18 volt is the "differential charging current" when one cell has higher capacity than another cell.  So more current is drawn from that cell to balance it with the others. So a power transistor and current limiting resistor exists for each cell - to enable current to bypass the cell if necessary. So then a differential amplifier is necessary to boost the voltage internally for the 16.5 voltage with an input range of 2 to 4.5 volt.


 built-in 36 pieces, 3.7 V, 26000 mAh 18650 lithium battery, so the theoretically capacity is 36 * 3.7*2.6 =346.32 watt hours (with 20% loss at AC). So 276 watt hours (surge on TV = 160 watts).

they last even longer when used in less-than-100% cycles, in fact for simplicity you can use a linear relationship: 50% discharge cycles means twice the cycles, 33% discharge cycles and you can reasonably expect three times the cycles.

But wait! There is more yet!…
A LiFePO4 battery also weighs less than 1/2 of a lead-acid battery of similar capacity. It can handle large charge currents (100% of Ah rating is no problem, try that with lead-acid!), allowing for rapid charging, it is sealed so there are no fumes, and it has a very low self-discharge rate (3% a month or less).

LFP batteries too have their limitations. A big one is temperature: You cannot charge a lithium-ion battery below freezing, or zero Centigrade. Lead-acid could not care less about this. You can still discharge the battery (at a temporary capacity loss), but charging is not going to happen. 

 https://www.solacity.com/how-to-keep-lifepo4-lithium-ion-batteries-happy/

cycling down to 50% SOC (state of charge) seems to show around 3x the cycle life vs. cycling 100%.
 https://batteryuniversity.com/index.php/learn/article/bu_808b_what_causes_li_ion_to_die


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