New Kid Questions

[RetiredTech]

I just set up my new Kid and starting to get some of the features working. I want to use the aux port and AGS to turn on a charger at night. I've ordered a 12V relay to switch the AC to the charger. The Kid  shipped with Firmware 1811. I contacted support and upgraded to 1856. The aux connector in the unit is different from the illustrations in the manual. The manual shows screw terminals,  the unit appears to have some sort of terminal that has a tiny push button to lock the wire in. Not familiar with that particular push terminal and it looks very delicate. Support didn't answer that question so is any one familiar with that terminal strip? What gauge of wire will it take?

Here is a brief synopsis of my current setup and future plans.

Kid Mppt Controller

12V 300AH Battery plant consisting of 6 Hawker SBS60 AGM batteries negative grounded

4 Canadian Solar 260W 60 cell panels currently only able to use 1

1000W pure sine wave 12V inverter

Desktop computer and internet modem powered by a 700W UPS with source AC switchable between mains and inverter.

HF and VHF Amateur radio gear powered by 12V battery plant negative grounded

20A Astron power supply modded for charging batteries set at 13.6V previously on a nite timer for 7:00 pm to 7:00 am, cheap TOU (time of use) electricity.

Remote Voltmeter / Bidirectional Ammeter 100A shunt monitoring the voltage and net current in/out of batteries Charge current-load current = in or out current

I am looking to optimize what I have without too much further expense. I am somewhat committed to the 12V battery to power ham gear so can't make use of all my panels for this system. Considering buying 2 more 200W panels to optimize the 430W limit of the Kid at 12V and use my 260W panels on another project. If I up the battery voltage I need to buy a new  inverter and a 24/12 or 48/12 DC/DC converter to power Ham gear. If I read the manual right I can delay genstart after dusk to guarantee I am charging from mains after 7:00pm. Would have to use 3 or 4 hours delay with worst case sunset at 5:00 pm plus dusk much earlier on a cloudy day.
Currently computer and internet modem use creates a  22A draw from the inverter. That would be a somewhat intermittent use throughout the day although sometimes I spend way too much time on the computer. So at full output from 1 panel I have a battery   discharge current of up to about 4A. Depending on duty cycle of the computer I may get ahead of the game and get to a float stage. Any suggestions on settings for rebulk if I reach float and then  start using the computer? Current battery settings are Absorb=14.3V, Float=13.6V, and  EQ= 14.3V.
If I opt for a hefty 24V inverter I could use the Astron power supply to power the Ham gear. That would let me bump  up my PV input to 3 panels Although 30A into 24V 150AH battery plant may be a bit high so I guess i could limit charge current.
A bit more history of what I have tried so far. I first set the system up with two of the 260W panels in series. At this point I had the original 1811 firmware. The first two days it was overcast and things were OK. Day 3 nice and sunny and as soon as full sun was on the panels the controller started woodpeckering with the OVR LED flickering and the input relay chattering. At the time the amps were showing bouncing around 29 to 31 amps. The charge current limiting was set at 30A at that time. At that point I changed to a one panel setup. So much for peoples comments that if you over PV the current limiting would handle it. Since upgrading to FW 1856 I tried paralleling two panels today and set up a 50 ohm load across the PV input to the Kid to lower the PV power a bit. Without the  preload load applied in clear sunlight at midday I was not getting more than 405W at about 27 or 28 amps. Maybe the difference was with 2 parallel panels with  lower PV input voltage and higher current gave me a bit more losses in my PV wiring. I tried applying the pre input PV  load at several times and was able to knock the charge current back an amp or two at times as it hunted for a new MPP. After this I  set the charge current limiting back to 29A for a bit more safety margin. The load across the PV may initially be a short term solution to the excess PV input and I may try to adjust the load to keep input power to the kid under 400W. I just used the 50 ohm load as it was a convenient 100W dummy load from Ham radio.

I have attached my Kid panel sizing printout.

Thanks for reading

Regards

Brad

[Westbranch]

Hi Brad, you said:

appears to have some sort of terminal that has a tiny push button to lock the wire in.

Any chance of a pic of what you are refering to?n You've got me there..

[ClassicCrazy]

Brad ,
What is your ultimate goal for PV ?
I also have ham radio stuff and want 12v for my radios.  I have a large PV system at 24v with a Midnite Classic. I also have a Kid and was using it with a few older panels to charge an AGM for my 12v loads. But then I decided to use the panels for something else and am running 24v from larger battery pack to the Kid to drop the 24 v to charge the 12v batteries.

But I have also considered getting a high quality 24 to 12v converter and doing away with the 12v battery and Kid setup. I would get a Samlex DC-DC converter if I did though there are some others on the market but not sure how noisy they might be. Wonder if you have noticed any noise on  your radio's from the Kid ?

If you want a larger PV system then I think it is better  to go up to 24v and put all your panels on that at a higher voltage  and get the converter and that way you can do away with the 12v power supply .   I am thinking the DC to DC converter is pretty efficient depending on what amp size you need.   

I guess you have to decide what size PV system you want to have . With PV prices low it seems like the best thing to do is put the max on the Kid that it can handle - better to have too much PV than too little - especially on cloudy or overcast days. Not sure if you live in the sunny part of the country or not. 

Do you have the Whizbang on your Kid ?

Not sure why you would have any strange charging behavior from the Kid with those settings . For MPPT to work properly you do need to be a certain voltage above the battery voltage so at least 24v input is going to be needed to charge your 12v battery in MPPT though there might be a different mode on there that will work with lower voltage. I forget . Midnite said they are rewriting the Kid Manual for the most recent firmware.

I may have missed some of your points in your post - read it a few times and trying to get it !

Larry 

[dgd]

Brad,

The KID is designed to only allow a maximum of 30A current output to charge batteries. It does not matter what the PVs are capable of, the limit is 30A
Over PVing the KID is ok as it allows greater power in bad weather.
You cannot damage the KID by having PVs that could provide much more than 30A.

Placing a lowish value resistor over the KID input terminals to 'burn off' excess PV power is just plain crazy. What happens when the PVs stop producing power, you have a load over the KID's input terminals and that could a problem as the KID input stages try to backfeed the resistor load.
I'm pretty sure the KID is not designed to do that and I would seriously doubt it would be covered by warranty if you blow it up because of this.

Maybe MN tech could respond (and I could be wrong)

dgd

[RetiredTech]

West branch
When I get it back open I'll get a picture. It's such a pain to open once it's wired.
dgd
If over PVing is OK then why does Midnight limit the the system designs to 1.2 in the sizing tool? I would much prefer to over PV for the short cloudy days. Whats up with the woodpeckering in my initial setup ? Is it a fact that the Kid input can backfeed power out of it? To me the Kid is a microprocessor controlled DC to DC converter and I can't see how a load across an input could draw any current.
ClassicCrazy
No ultimate goals yet. This project is to finally get my feet wet with some solar and power up some stuff in the shack (office). Mostly get the computer and internet modem loads off the utility company. Any thing else I do will be based nearer the electrical panel and water heater. Thoughts of a Net metering on a carport breezeway or back yard Gazebo to keep the panels off the house roof. That means a structure has to be approved and built first. No noise noticed on the Ham gear . That's why I chose the Kid reviews on some of the others reported RFI. No whizbang  not a data addict yet. I do have a volt/ammeter in place that can give me watts, AH, and % SOC but I'll worry about studying performance after I get some of the design bugs worked out.  When I wrote support about my issues I got the links for FW 1856 and a link for the 1856 manual. Here is the manual link. http://www.midnitesolar.com/pdfs/kid_manual_rev_1856.pdf .

Thanks for the replies

Brad

Brad

[ClassicCrazy]

Thanks or the link to updated 1856 manual Brad.
I see they have finally posted both the new firmware and manual on the Midnite webpage now.
Larry

[dgd]

If over PVing is OK then why does Midnight limit the the system designs to 1.2 in the sizing tool? I would much prefer to over PV for the short cloudy days. Whats up with the woodpeckering in my initial setup ? Is it a fact that the Kid input can backfeed power out of it? To me the Kid is a microprocessor controlled DC to DC converter and I can't see how a load across an input could draw any current.

The sizing tool only deals with the PV's OCV and MPV. It does not take account of a PV only working at a fraction of its rating due to bad weather.
No idea what woodpeckering means, my several KID's are are well overpanelled to ensure some decent current to battery on bad weather days.
On full sun days its unlikely that the KID is doing any MPPT as there is more than enough PV current available to maintain the max 30A output.
I have noticed in this situation the opv led will sometimes come on but it makes absolutely no difference to normal KID operation.
WIth all those xtra PVs you have it may be worthwhile investing in a cheap PWM controller (like the Brat) so that you canget some use from them, or wire them direct to a water heating element and at least get the occasional warm shower

dgd

[RetiredTech]

Hi dgd
This is my description of "woodpeckering" from my original post

I first set the system up with two of the 260W panels in series. At this point I had the original 1811 firmware. The first two days it was overcast and things were OK. Day 3 nice and sunny and as soon as full sun was on the panels the controller started woodpeckering with the OVR LED flickering and the input relay chattering. At the time the amps were showing bouncing around 29 to 31 amps. The charge current limiting was set at 30A at that time. At that point I changed to a one panel setup.

Brad

[RetiredTech]

Westbranch
I've posted pictures of the Aux connector in another post titled "New type of Aux connector CAUTION"
Brad

[Westbranch]

Woodpeckers!!

http://kb1uas.com/mnsforum/index.php?topic=3350.msg31993#msg31993

Re: How do I get RID of the (WOODPECKER) Gremlin in my KID?  http://kb1uas.com/mnsforum/index.php?topic=3359.msg31992#msg31992

[dgd]

Brad,

input relay chattering = wookpeckering     ok, an annoying noise.
The several KIDs I monitor is done remotely via web so although I can see when max output current is reached and maintained I am not at the KID location so cannot hear any relay chattering.
Maybe I will now visit a KID at max current time and see if it chatters, or install a mic to get noise feedback to web display

Also if this is a common occurance then Mario needs to know so that a firmware fix can be done to insert a timing delay to prevent unnecessary relay chattering

dgd

[RetiredTech]

Thanks Westbranch for the links. I read those before. Not quite the same issue. The woodpeckering described there is during dawn startup.On startup in the morning mine will click 3 or 4 times . My woodpeckering was occurring during full sun and OVR flashing with current max  at 30A and current bouncing 29A to 31A.

Brad

[Westbranch]

How 'new' is your KID?  there are some early ones that had hardware as well as software issues IIRC...

[RetiredTech]

Westbranch
It came from HES PV In Barrie Ontario a couple of weeks ago. Serial #KB 078XX loaded with FW 1811
Brad

[AdoraKalb]

Hi...i am a new user here. As per my knowledge if you want a larger PV system then I think it is better  to go up to 24v and put all your panels on that at a higher voltage  and get the converter and that way you can do away with the 12v power supply . I am thinking the DC to DC converter is pretty efficient depending on what amp size you need.   

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