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RE: Feedback on 12V water heater element as solar diversion load
Manual has quite a bit of language about minimum and maximum diversion load elements, but I thought I was within spec. Now I'm not so sure.
https://www.morningstarcorp.com/wp-content/uploads/technical-doc-diversion-manual-en.pdf
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ewarnerusa
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05/04/23 12:55pm |
Tech Issues
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RE: Feedback on 12V water heater element as solar diversion load
I have never run the element dry. There were instances where I had it in a cup of water when on and a bit of water evaporated. But element was always >90% submerged I would say.
Multimeter ohm reading on the element is 1.5 ohms.
What is the math for how you came up with what the resistance should be? I only took one circuits course in college and I remember
V = I * R
and
P = V * I = I^2 * R
But with R = 1.5, if I saw 21A from panels at one point and assume 19A was going to element, I was pushing 19^2 * 1.5 = 542 watts. Way over rating. ****, do I have too much solar for this?! Ironic...
Another element was only $15. I'll take a resistance reading on it before doing anything and see what it says. But it will be weeks before it makes it across the sea to my door.
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ewarnerusa
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05/04/23 12:06pm |
Tech Issues
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RE: Feedback on 12V water heater element as solar diversion load
...so your hot rod is rated for 12V and I didn't see a +/- range on the website. how much voltage were your solar panels sending to the heater?...
I have also wondered about the voltage at the diversion load. When I connect to the SCC via laptop, the software provides me a diversion load current measurement as well as a load voltage. The current value is consistent with what I expect based on the other meters I have (one on solar array output, another bi-directional one on primary battery connection). But the load voltage confuses me as it is fluctuating at levels well below 12V and I wonder if it is not what I think it is? I have not taken a multimeter to leads, although now I have some wire exposure to take a measurement from!
During my test run, the element wiring began to feel warm as soon as diversion current began to pass to it. And it began to "cook" when there was <10A of current. This seems like well below any scenario where there could be more than 300 watts of power. The panels' open circuit voltages are 22.4 and 24.3 (2 different types of panels), so it seems to me that there isn't a V*I scenario that exceeds 300 watts.
In diversion load configuration, the wiring is for the panels to be directly connected to the batteries rather than to the SCC. The SCC leads that were formerly array input become diversion load output. A diversion load configuration is applied and DIP switches must be changed on the SCC.
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ewarnerusa
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05/03/23 11:13am |
Tech Issues
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RE: Feedback on 12V water heater element as solar diversion load
Yes, the element says "12V 300W 22-12"
The insulation on the unit I have was white. I'll repost a pic from a page or 2 before this one. To show the writing and a better look at what the insulation looked like before it was cooked.
https://i.imgur.com/PdfFeZnl.jpg "border=0"
https://i.imgur.com/m3zZPvb.png
https://i.imgur.com/CgbmOWEl.jpg "border=0"
https://i.imgur.com/m3zZPvb.png
The elements from the same supplier now look like this
https://i.imgur.com/tnzfbR6l.jpg
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ewarnerusa
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05/02/23 08:52am |
Tech Issues
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RE: Feedback on 12V water heater element as solar diversion load
Hi temp:
https://www.amazon.ca/010832-Black-High-Temperature-Shrink-Tube/dp/B001HYQQ9W?th=1
Thick wall construction and remains flexible
Operating temperature range: -67°F to 275°F; apply at 120 to 180°F using heat gun
Thanks, I'll try that stuff out. The heat shrink costs about the same as another element, and the pics of the elements suggest a different type of heat shrink/insulation at where the wire terminates at the element. Maybe I got old-tech before and now they're using new tech? :h Only $15 and a month waiting for shipment to find out.
Anyone experienced with heating element wiring? Does that wire connection look normal and is it normal for the wiring to get so warm as well?
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ewarnerusa
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05/01/23 10:02am |
Tech Issues
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RE: Feedback on 12V water heater element as solar diversion load
Success and failure today in a test run in the driveway. Nice clear sunny spring day.
I had spring fever so I dewinterized last night. Rinsed and filled fresh water system. It got down to 45F overnight and I'm assuming water started at that ambient temp.
Batteries were in 14.5V absorption by mid morning. All seemed well, but the wires got quite hot where they terminate at the element. This was with <10A current from the panels, well below the 300 watt rating. I confirmed that the element was not drawing from the battery.
I noticed the warm wires during bench testing, too. Wires feel progressively cooler the further from the element. The 8 gauge wiring I put in for supplying the current did not get warm. The heat shrinking around where the wiring terminates at the element started giving off smoke. I kept an eye on it and after 15 min or so it stopped smoking. What was once rubbery is now brittle.
https://i.imgur.com/lIJSyfyl.jpg
I saw a max of 21A from the panels. I didn't have the laptop running at this point to see what the SCC said the diversion current was. I'm kicking myself for not putting my clamp meter on the wire at the element, but my hunch is around 19A. By early evening the water was hot! I measured 117F out of the kitchen tap.
But unfortunately the wiring looks cooked and I don't really trust it now. It needs some kind of high temperature heat shrink reapplied first. I just broke away the brittle stuff that was formerly the heat shrink and this is what is beneath it.
https://i.imgur.com/T49f1gxl.jpg
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ewarnerusa
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04/30/23 07:20pm |
Tech Issues
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RE: Feedback on 12V water heater element as solar diversion load
StirCrazy,
It has definitely crossed my mind from the start of this little project. I admit that I have been hoping that the 6 gallons of water as a heat sink will never be able to reach the blow off valve setpoint with this diversion load. Assuming I am leaving the propane water heater burner off. But if the diversion load gets disconnected, then I have all my panels directly wired to the batteries with no control. Which scenario is worse?
I also don't know why my sig won't show up? The box is checked.
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ewarnerusa
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04/12/23 09:08am |
Tech Issues
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RE: Feedback on 12V water heater element as solar diversion load
Wow, it is working great! I'm shutting this test down as the water is getting hotter than expected and I'm not available for continuous monitoring. 66F to 130F in a couple hours. I realize this is just a tiny volume compared to 6 gallons, but this little sucker is cranking out heat just using current that the battery isn't needing for absorption charging. Panels are harvesting 15 amps, looks like between 7-10 amps are going to the diversion load element, the remainder is going to maintaining the batteries at absorption setpoint, the laptop charger to run the laptop in order to monitor stuff, and any other camper parasitic loads (not that there is much, it is sitting in storage at home).
https://i.imgur.com/YotGiWRl.jpg "border=0"
https://i.imgur.com/m3zZPvb.pngClick For Full-Size Image.
Laptop hooked to the SCC to monitor things. Interesting that when wired up for diversion load, the charge current shows 0. I believe this is because the panels are not actually hooked to the SCC in diversion load mode. They are hooked directly to battery and SCC monitors battery voltage, allowing anything in excess of charging setpoints to flow to the diversion load.
https://i.imgur.com/lcYvEKol.jpg "border=0"
https://i.imgur.com/m3zZPvb.pngClick For Full-Size Image.
Full current from panels right now is 15 amps:
https://i.imgur.com/MaW6y6bl.jpg "border=0"
https://i.imgur.com/m3zZPvb.pngClick For Full-Size Image.
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ewarnerusa
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04/11/23 11:12am |
Tech Issues
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RE: Feedback on 12V water heater element as solar diversion load
ewarnerusa,
I for one, will be waiting with baited breath on the results!
I've got a test scenario all rigged up right now! Should be a nice sunny morning but clouds and wind forecast for later. Sun has not yet crept over the trees and hit my panels yet, so nothing to report.
https://i.imgur.com/oAepUmKl.jpg "border=0"
https://i.imgur.com/m3zZPvb.pngClick For Full-Size Image.
When I first got to wiring up the diversion load circuit to the SCC, it wasn't what I expected since I had not read the manual for that part carefully yet. I know, I know, RTFM... But I got it figured out now. It requires connecting the panels directly to the batteries and the former panel input to the SCC is now the diversion load output. Thankfully I had purchased a pack of several Anderson style connectors and could make several convenient disconnects for swapping back and forth between normal setup and the new diversion load setup.
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ewarnerusa
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04/11/23 09:10am |
Tech Issues
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RE: Feedback on 12V water heater element as solar diversion load
Spring projects weekend. I got 3 projects done: installed auto transfer switch for the inverter, replaced main 12V feed to control center with 4 gauge wire, and got the diversion load water heater element wired in. No testing yet, 2 full days of crawling around on the floor and ground and I am done working for the weekend! I'll do some testing some evening this week or next weekend.
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ewarnerusa
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04/09/23 09:06pm |
Tech Issues
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RE: How long should a battery last?
If he's boondocking the way I think of boondocking, he won't be in a campground with rules but rather a dispersed spot with only the neighbors he traveled with. I do realize there are campgrounds without hookups so valid points on generator hours/rules.
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ewarnerusa
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03/27/23 10:12am |
Tech Issues
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RE: How long should a battery last?
... you can fire up your tow vehicle ... it is equipment you already have.
How long should I run it for if the battery goes down below 12V?
...
I like the idea of jumper cables instead of 7 pin. Pull in forward so you're close enough to run jumper cables between your tow vehicle battery and trailer battery. Idle the tow vehicle while hooked up this way, the alternator will push amps into your trailer battery. I have no idea for how long though.
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ewarnerusa
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03/25/23 03:36pm |
Tech Issues
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RE: How long should a battery last?
...They don't install absorption fridges anymore.
That's what I've gathered from the forums. Followed by grumpy scoffs from boondockers! LOL You mentioned that you're in a one-off boondock situation so not worth investing in any more gear. So you can fire up your tow vehicle and plug in the trailer via 7-pin to get some juice into the battery. Without upgrades to that wire path, it will not provide a whole lot of current for charging. But it is equipment you already have.
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ewarnerusa
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03/24/23 09:04am |
Tech Issues
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RE: Water saver for shower.
I've got this video bookmarked as a "someday" project. It is a DIY take on the ShowerMiser product linked to earlier.
RV Recirculating Hot Water Line Don't Waste Water Complete Installation
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ewarnerusa
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03/23/23 02:00pm |
Do It Yourself Modifications and Upgrades (DIY)
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RE: How long should a battery last?
That's about right. You should not be running an electric fridge on that battery. The battery will be shot before the end of the year.
We have no choice as it is a 12v/120v fridge. I typically do not use it on 12v except for while driving.
If boondocking you'll have to run it on 12V, right? Is that how you're testing it during your 24hr test?
With a propane absorption fridge, a single group 24 would probably be be pretty low after a weekend of fridge and lights (also water pump and maybe fans). A 12V electric fridge would be a much larger load on the battery.
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ewarnerusa
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03/22/23 05:39pm |
Tech Issues
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RE: 12v? 24v? 36...48v????
I've heard that a higher DC baseline can help reduce the impact of voltage sag. This can allow for skinnier wires, as mentioned. Or from another angle, a higher DC inverter won't be as negatively impacted by the voltage sag when you really draw down hard to meet a big AC load like microwave or even go for the air conditioner. But if you're not devising a way to run big loads off the battery, I can't see why you would want to add the complication since your entire camper DC system is setup for 12V.
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ewarnerusa
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03/08/23 08:24am |
Tech Issues
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RE: Feedback on 12V water heater element as solar diversion load
I did some "bench" testing on the heating element today. It pulled 24 amps and got nice and hot. I had the element in a mug of water and it heated it up quickly.
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ewarnerusa
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03/05/23 12:06pm |
Tech Issues
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RE: Feedback on 12V water heater element as solar diversion load
Check this thing out. 300 watt 12V element that is swappable with the hot water tank drain plug. It dry fit well in my tank. Hopefully with thread tape it seals up perfect. The white plug is one of my spares.
https://i.imgur.com/PdfFeZnl.jpg "border=0"
https://i.imgur.com/m3zZPvb.pngClick For Full-Size Image.
https://i.imgur.com/rL6A2sOl.jpg "border=0"
https://i.imgur.com/m3zZPvb.pngClick For Full-Size Image.
https://i.imgur.com/CgbmOWEl.jpg "border=0"
https://i.imgur.com/m3zZPvb.pngClick For Full-Size Image.
https://i.imgur.com/M7GQMt4l.jpg "border=0"
https://i.imgur.com/m3zZPvb.pngClick For Full-Size Image.
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ewarnerusa
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02/25/23 06:59pm |
Tech Issues
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RE: Negative and ground wire questions
Thank you for the input enblethen. That is the answer I suspected and hoped for.
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ewarnerusa
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02/24/23 10:15am |
Do It Yourself Modifications and Upgrades (DIY)
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Negative and ground wire questions
A spring project I have in mind is to upgrade the OEM power wire between the battery and converter to a larger gauge. I think it is currently 8 gauge and I want to upgrade to 4 gauge. The OEM setup is a long positive wire from 12V panel in the camper to circuit breaker on the tongue and then to the battery. The negative wiring from 12V panel is a short run from the panel to the camper frame.
Should I replace the short negative wire run with 4 gauge wire to same frame grounding connection? Or is it better to run negative all the way to the battery? Does a ground wire from battery to frame need to be of same gauge as the largest in the system?
Thanks.
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ewarnerusa
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02/24/23 09:21am |
Do It Yourself Modifications and Upgrades (DIY)
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