Various Electronic's

[numberonekiwi]

I have a theory about PWM units and that is they have a adjustable frequency as well as an adjustable duty cycle

and that last part may be the key here ( just an idea for now )

Here is an idea ( Bob you need a light bulb above the head pix thingie forgot their proper name ) I have been thinking about lately to possibly reduce by half our power consumption for our cell  YES HALF POWER if it works and I think it might

If we were to say a 50% duty cycle it would mean the cell would only have power for 50% of the time ( no brownie points here LOL ) but while it is in the off state have another bank of mosfets turn on and run a second cell !

Now depending on what timing circuit you use this is quite possible and my theory is if you have 2 cells that are seperated and each draw 30 Amps connecting them in parallel with no PWM would result in you guessed it 60 Amps now take my idea ( it proberly has been mentioned before ) and feed each cell alternatly you are still only drawing 30 Amps as only 1 cell is ever powered at any fractionth of a second you have say 40 Khz freq or higher this sort of frequency could be near resonance as well therefore giving even better production

Well may work for those following the PWM path anyway why not use the off part of the duty cycle to our advantage

[scratch1676]

I didnt get to work on my stuff.  I had to go out in the country to my dad's and work on his furnace.  My face hurts from the root canal yesterday.

[scratch1676]

make it so numberone ( that's a star trek joke ).  I am thinking about your ideal on the pwm and if you supply 30 amps to the on position of the mosfet and then you supply 30 amps to the other set of cells with another mosfet you will only be supplying 30 amps at any given time.  30 amps pulsed and 30 amps brute force doesnt give the same productions results.  Example, if you measure the brute force connection with a amp meter you get exactly 30 amps and when you measure the pulsed connection you will get a lower amperage reading.  I think pwm's work more for current control.  They might do something along the lines of resonating with a frequency sweet spot but I have not seen any miracle works.  I am not saying your ideal wont work or be a benefit, I am just throwing some other brainage out there.

[Manta]

There is a theory going around that it is the fast rise and fall of the (essentially) square wave that gives an improved production.  Don't know if it is right though.

Manta

[Painless]

To gain production efficiency improvements with a PWM you need to use a maximum concentration of electrolyte and then use the PWM to control the amps to where you want them.  The higher electrolyte concentration (28% by weight for KOH), the less resistance in your electrolyte and the less current needed to obtain the same result.  This also reduces heat in your cell as resistance = heat.

To give you an example, the last dry cell I built produced jumped from 5.4 to 6.4 MMW just by using a PWM and maximum strength electrolyte to achieve the same amp draw and output.

Reducing resistance in every part of our cells is the holy grail to efficiency

Russ.

[Bob]

Very True Russ !
the problem is finding a PWM that will handle 200 to 300 amps !
because at the output I am shooting for 15LPM to 20LPM I will need that much amperage to
get that kind of output...
 if and when I do get that much LPM output I will try to run my 2.4liter toyota P/U on 100% hydroxy gas....  I may not accomplish it but I will sure give it a good try !
HAHAHHAHA
Bob........

[Tink]

Bob,
Just a thought but have you toyed with the possibility of using a potentiometer? It would be big and bukly but might do the job. No pulse but you could control the current by adjusting the voltage or maby not? I've only seen these for AC and don't know how they would work with DC.
Tink

[Painless]

Very True Russ !
the problem is finding a PWM that will handle 200 to 300 amps !
because at the output I am shooting for 15LPM to 20LPM I will need that much amperage to
get that kind of output...
 if and when I do get that much LPM output I will try to run my 2.4liter toyota P/U on 100% hydroxy gas....  I may not accomplish it but I will sure give it a good try !
HAHAHHAHA
Bob........

Bob,

If your cells are connected in parallel, then wire in several PWM's and run them all seperately'

Russ.

[Manta]

I think that the easiest way to envisage how a PWM works is to see it as a very fast on-off switch. It does follow that if the mark-space ratio is 1:1 then the power is off for the same length of time that it is on. So you only consume half the power over the same length of time as you would if you were connected directly.
Hence half the heat.  It doesn't need to switch quickly.  Once per second will probably do. Then you can always control the duty cycle to tweak the power.
So a heat sensor in the electrolyte that kicks in a simple PWM with a 50% duty cycle ( 1:1) will stop you overheating the cell.

Or am I wrong here ?

Manta

[scratch1676]

nope, your right.  But I have not had any greater output of hydroxy with a pwm.  I do prefer the Pwm, its way better for controlling amps and heat.

[Bob]

I think the only way you'll get more LPM output with a PWM is if you go from say a 20 amp electrolyte mix to a very rich electrolyte mix and run the same amperage with the PWM, or perhaps a bit more because there is less heat, and it allows you to do so...
but if you keep everything the same you should Loose production because the PWM is turning on and off , where before the supply was constant.
...
BUT increased production because of a PWM is reported all the time , but I think that is because it allows the stronger Electrolyte and higher amp settings due to lower heat
...(less resistance in the water due to a higher concentration of KOH)
.......
so if your keeping real close track of Output and amps used you should see a drop in production when useing a PWM...but to combat the heat its usually worth it
because its not just the 50% on and 50% off that reduces the heat so much but its mainly the higher concentration of electrolyte that does the heat reduction... less resistance in the water makes less heat... and that changes it a great deal... from boiling to a moderate temp all the time... so in some cases a PWM is realy nessarry... for that reason,
more than the controling of the amp ishue, because you will be feeding it as much as you can all the time anyway... with or without the PWM, so that hasn't changed.
...
thats how I see it anyway !
Bob....

[scratch1676]

It also gives you another knob to play with on the truck  he  he

[Bob]

Oh yes ! now that we need ! another knob to help us mess up the running of an other wise good running engine ! HAHAHAHAHAHA
if your like me you'll drive along and not be satisified with the adjustment and constantly fiddle with it... so you'll never realy know where the adjustment is at... somewhere in that area is the "sweetspot".... a bit more to the right on cold days and a bit more to the left on hot days , works real good.... while all the time your driveing like a mainiac, flooring it at stop signs and such, and wondering why your gas milage is so crummy ! HAHAHAHHAHA
...been there done that !
hehehehe
Bob........