multiple kid water heating question

Started by bennyspoon, November 03, 2018, 04:04:15 AM

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bennyspoon

Hey guys, just trying to extract maximum water heating from my kids using pwm diversion.

Would there be any issue with running the load outputs of both kids {from the same battery bank} into a dedicated positive and negative busbar to combine them together then feeding them into the dc element, provided the element has enough capacity?

Would the load current from one kid backfeed into the other kid and cause issues/damage?

Also, is there any issue with having an element capable of greater capacity than the kid can put out?

E.G. for a single kid @48v using a 2kw 48v element like mws sell.

Cheers,
Ben.
48v system, 2 solar kids synced{1500w x2 arrays of trina honey 250w}with a 3rd kid synced for hydro f+p 700w turbine{early days!}, classic 150 for 4275w solar ,classic 250/ac clipper for wind {coming} , schneider xw+ 8548 inverter 645ah ex ups exide  jtt12v4800 ,3 strings{fingers crossed}.

Doug

Hi Bennyspoon,

The KID is overcurrent protected but it would be a bad idea to overload it intentionally.
What could work is to have the KID drive a large enough relay and have that switch on and off the loads.

HTH,
Doug

ClassicCrazy

I agree with Doug - better to use the output to control a relay that will turn on and off your loads

Larry
system 1
Classic 150 , 5s3p  Kyocera 135watt , 12s Soneil 2v 540amp lead crystal for 24v pack , Outback 3524 inverter
system 2
 5s 135w Kyocero , 3s3p 270w Kyocera  to Classic 150 ,   8s Kyocera 225w to Hawkes Bay Jakiper 48v 15kwh LiFePO4 , Outback VFX 3648 inverter
system 3
KID / Brat portable

FNG

The real issue would be the timing of the FET that does load control, they would not switch at the same time and one would end up switching 2x the current, While the kid has current limit it wouldn't help as all it can do is open the fet and it will be loaded 2x its capability.

bennyspoon

Righteo,

all good points indeed, thanks for the explanation chaps.

trying to only have relay's on the classic at this stage, will have to rethink my options.

Cheers,
Ben.
48v system, 2 solar kids synced{1500w x2 arrays of trina honey 250w}with a 3rd kid synced for hydro f+p 700w turbine{early days!}, classic 150 for 4275w solar ,classic 250/ac clipper for wind {coming} , schneider xw+ 8548 inverter 645ah ex ups exide  jtt12v4800 ,3 strings{fingers crossed}.

Highflyer

Benny,
If you can install two heating elements, each could get its power from a single Kid in PWM divert.  This way you will be able to extract the maximum power from your panels and heat your water.

I have run several water heater elements off of Kids and find it very useful to get the extra heat from the system(s).

You can also look into using 110 or 230 volt elements to limit the current draw.  V/R = I  (Ohm's law)

I currently use a 110 volt heater element in my 24 volt system to send about 3.6 amps to the heater and add just under 100 watts as the batteries near float. When Rosie is ready, I'll convert to 48 volts and then I'll have a new max around 400 watts per heater which is well under its capability.
Brian

The one thing is the one thing