PWM control of heavy cooking loads.

It will not work because you are not addressing the main issue of using low voltage to supply high power. To supply say 1200 watts @ 12 volts requires 100 amps period. That gives you two huge obstacles:

1. Is the internal resistance of a 12 volt battery. For example a Trojan T-105 at full charge exhibits .0125 Ohm's of resistance. It takes two of the T-105's in series to derive 12 volts which now double the internal resistance to .025 Ohm's. You now try to draw 100 amps and the battery terminal voltage drops from 12.5 volts to 10 volts. There is no getting around that problem other than much larger capacity of a battery with less internal resistance. As a general rulle of thumb you should not load any FLA battery more than C/8 of th e20 Hour rating. On a T-105 means 225 AH / 8 hours = 28 amps. So basically no 12 loads over 12 volts x 28 amps = 336 watts.

2. Problem is of course cable and wiring resistance. Again with low volts demands high amps for high wattage. Same problem with the, the resistance is going to eat you alive. At 100 amps the minimum size wire is a very expensive #4 AWG. To keep the voltage drop to less than 2% (.24 volts) at 100 amps means the maximum 1-way wire length of 7 feet. Anything longer will result in higher voltage drop. There is only one way to fix that by using larger even more expensive wire.

The real solution is to use much higher voltages with batteries properly sized to deliver the current at a maximum specific load wattage. That is why electric companies use 1 million volts and more to deliver electricity.

There you go jumping to conclusions again!!! I have EIGHT trojan T105RE's and by YOUR math good for 336 x 4 = 1344 watts. and 4 x 28A = 112 amps. at C8. Also I have TRIPLE #4 copper conductors.

Nothing wrong with my system just your reading!
Can't you try to stay ON TOPIC ???

It is not possible to boost current with a PWM controller as anyone familiar with PWM controllers knows the input current = output current. A first year engineering student would know that.

Only a boost converter will increase current, but to do that the voltage has to be reduced. It is impossible to boost both current and voltage at the same time as that defies all the laws of physics.

There is nothing to discuss ON TOPIC because what you think will work is impossible... It defies the Laws of Physics.

If you have what you say you have, there should be no real problem with voltage drop. If you have a problem it is a wiring or connection problem, or way to long of a wire run. You cannot fix that with a magic PWM controller that does not exist.

i would like to have intelligent conversations on this website but i am afraid i am forced to ignore all your future comments. You obviously just like being argumentative and to think i would use wire nuts on a 300 amp circuit is plainly ridiculous. Good luck to you but you need now to find someone else to irritate.

ACTUALLY, BritishPete, here's your warning about shouting at established, proven, free advice givers. You did not state in your post, the power supply . Don't shout when you don't supply all the info.


for a partial answer, it's POOR PRACTICE, to parallel wires, instead of using a single, proper size wire. even a tiny bit of resistance at a connector will divert power to other wires, heat the restive contact, and muck up the works. As you have noticed.

And most inverter internal wiring can't handle that current, even though it's "within spec". Just a heads up. Even if the inverter has 4 inputs and returns.

MIKE per NEC paralled feeders are perfectly acceptable provided thjey are all the same size and all the same length of run.

Also these triple #4's are ONLY between battery bank and main bus, feeders to the inverters are 2 OD copper. You are on my "home turf here"

There are two kinds of PWM controllers out there usable for your application - phase control and full cycle. Phase control turns on a portion of the AC cycle; full cycle allows 1, 2, 3, 4 etc full cycles out of (say) 10.

Both have their problems. The big problems with phase control are poor power factor and poor operation on mod-sine inverters (the lack of a sine wave really messes them up.) The big problem with full cycle is that each cycle is at full power; it is the average of (say) 2 full cycles of power and 8 full cycles of no power that gives you 20% total power. Thus you'll see a 6hz fluctuation on your AC line, which might be a lot more annoying.

Maybe track down why you're having this problem to begin with. Is it that the AC line is allowing too much drop? Is the inverter not regulating well? Are you seeing too much DC drop on the DC side of your inverter?

I know about the two types but at a cost of under $5 incl. shipping from China I shall take the chance, good points though and well appreciated.

When I stated voltage dipping before I should better have stated wide voltage fluctuation when the stat kicks in and out. Probably due to a high inrush current from a cold element. As I first stated the M/W and the Air conditioning do not have this problem. By not permitting the stat to work I hope to avoid this, maybe it will work maybe it won't anyway the parts are on order. and I am certainly not looking to increase current as some have suggested rather to decrease it as you have obviously realized.

Do you have a part number so I can take a look at it? I'm curious about which type it is.

LOL! it's China I would be lucky to get that. This is however the listing and yes I know it is 220v but it also regualtes down to 50V which is all I need.

OK that's a phase control dimmer. Please let us know if it works. Also if you have a scope take a look at the waveform in the rest of your system while the dimmer is working; you may see some interesting waveforms.

I've not "played" with a scope for 25 years, last time I did I really impressed some German Herr Doktors LOL. Anyway you are right I stated PWM and mean'r SCR.

I will be sure to let you know in about a week or two.

Thanks.

BS, again you are caught RED HANDED and you do not know what you are talking about. FWIW I sit in the NEC Code Making Panel 9 and now it is time to kick your butt again straight from the NEC:

310.4 Conductors in Parallel.
(A) General. Aluminum, copper-clad aluminum, or copper
conductors of size 1/0 AWG and larger, comprising each
phase, polarity, neutral, or grounded circuit conductor shall
be permitted to be connected in parallel (electrically joined
at both ends).

Last time I checked #4 AWG is a lot smaller than 1/0. Any more uninformed remarks you care to make and have shot down?