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Date Posted |
Forum
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RE: Water tank has a drain?
Fresh water drain caps are sometimes stashed inside the outside access to water heater. Open that panel and see if there is a random cap lying in there.
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ewarnerusa
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11/15/23 09:17am |
Fifth-Wheels
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RE: 100w panels
Google "cloud edge effects"
However, I think measurement inaccuracies are a more likely answer in this instance.
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ewarnerusa
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08/24/23 08:55am |
General RVing Issues
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RE: Feedback on 12V water heater element as solar diversion load
Bummer news on the 24V 1000 watt element. I went to test fit it in the hot water tank and it cannot be fully inserted due to obstruction. The exhaust flue inside the tank interferes. So major bummer :(
I went ahead with the bench testing to explore the concept. Element was directly connected to 12V battery system to take measurements. I used the wiring I have put in place for diversion load which is about 30' of 8 gauge wire terminating at the outside access of the water heater with an SAE connector. The element is wired up with an SAE connector so I can plug it in at the outside access of the water heater.
Overcast day so solar wasn't contributing much. I think it was about 3 amps during testing.
Measured 10.7 V at the heating element. Battery voltage was about 12.8V and gradually dropping as load pulled it down.
Measured 23 amps with clamp meter at the element
Measured 0.7 ohm resistance for the element
It was heating up, I sure wish I could take it further and use it in the tank. When prepping the connections, I went ahead and slid some of that high temp heat shrink on the wiring in case the original heat shrink cooked off like during the previous test with the 12V 300 watt element. I didn't activate the heat shrink, I was waiting to see what would happen first. It seems like the wire heated up enough to activate it on its own and on one lead it split. I only had things running for 10 minutes or so. I don't know if it would have cooked the original heat shrink or not. The original stuff looks to be in great shape though after the 10 minutes.
https://i.imgur.com/ZeDHjM3l.jpg
https://i.imgur.com/M2Qm26il.jpg
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ewarnerusa
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06/24/23 11:44am |
Tech Issues
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RE: GPS for eBike
The big 2 in cycling GPS computers are Garmin and Wahoo, although there are certainly others. I have only used the Garmin Edge units, but Wahoo has a strong following. Probably not as inexpensive as you're hoping for, but the more you spend the better the navigation features.
Garmin Edge
https://www.garmin.com/en-US/c/sports-fitness/cycling-bike-computers-bike-radar-power-meter-headlights/?series=BRAND482#shopallcycling
Wahoo
https://www.wahoofitness.com/devices/bike-computers/view-all
Hammerhead Karoo
https://www.hammerhead.io/collections
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ewarnerusa
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06/13/23 03:15am |
Technology Corner
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RE: Feedback on 12V water heater element as solar diversion load
Test is up and running. I disconnected one of the panels so I'm back to 280 watts total solar array capacity. Using the older of my 12V 300 watt elements. Things seem to be working as expected - battery voltage rose until reaching the absorption setpoint and then diversion started occurring while battery voltage remained constant. I took voltage readings on the diversion load and they are unexpectedly low. When battery voltage is 14.5V, the diversion load voltage is 9.2V with about 9 amps being dumped into heating element. It started the day at lower voltage than this and has settled around this value.
SCC is now in float mode (battery at 13.6V) and the diversion load voltage and current remains about the same. I measured voltage at the SCC terminals and at an Anderson quick-connect close to the SCC and both read 9.2V. I measured at the heating element and it was in the 7V range - voltage drop from 8 gauge wire running the entire length of 27-foot TT? Is this what anyone else expected? I thought I'd be seeing battery voltage or even panel voltage. Current at the element measured via clamp multimeter concurs with laptop SCC monitoring software. The diversion load voltage measurements at the SCC also agree with the array/load voltage value reported by laptop SCC software.
Temperature gun said that the wire leads leading into the heating element are 330F. These are the now-exposed wires that cooked off the heat shrink during initial day-long test run where I suspect I was simply putting too much wattage into the 300 watt element.
https://i.imgur.com/9dHF7mql.jpg
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ewarnerusa
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06/07/23 02:02pm |
Tech Issues
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RE: Feedback on 12V water heater element as solar diversion load
My multimeter is probably the cheapest one you could find, I don't remember where I got but probably Harbor Freight or a department store. It read 1.5 ohms for both the old and new 12V 300 watt element.
My clamp multimeter is also a budget model off Amazon. It measured 0.9 ohm on old 12V 300 watt element and 0.6 ohm on new 12V 300 watt element.
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ewarnerusa
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06/06/23 05:19pm |
Tech Issues
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RE: Feedback on 12V water heater element as solar diversion load
To do the calculation one needs to know the voltage under load.
I'll do a run soon and measure, but the manual suggests using 15V for a 12V nominal system. It relates it to maximum battery voltage vs array voltage. But I agree, let's see the measured data vs what the manual suggests.
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ewarnerusa
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06/06/23 11:20am |
Tech Issues
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RE: Feedback on 12V water heater element as solar diversion load
Pianotuna and Stircrazy, you're giving me hope again! After reading stevenal and your input, as well as rereading the Morningstar manual again for sizing the diversion load, I think a 24V 1000 watt element will work.
The manual goes over the power rating adjustment of ratio of the voltages squared. It also points out that the adjusted lower power also lowers the current it can accept at those voltages and that elements for much higher voltages like 120V will typically require several in parallel in order to accept all of the diverted current. At least that is how I'm reading it, they don't explain it but show the de-rated current in a table and make some statements using those currents when discussing the number of elements needed for a scenario. With a 24V 1000 watt element, I think the math works out OK with just one element. It suggests using 15V as the max battery voltage to use in a 12V nominal system for adjusting power ratings.
https://www.morningstarcorp.com/wp-content/uploads/technical-doc-diversion-manual-en.pdf
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ewarnerusa
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06/05/23 04:43pm |
Tech Issues
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RE: Feedback on 12V water heater element as solar diversion load
Question: what would happen if it was a 500 watt element for 24V DC?
500 watt 24V DC cartridge heater 1/2 inch NPT
If that fits it would still be worth it. wouldn't blow it up at any point because of too much voltage. If they are all the same thread even a bit bigger like the 800 or 1000 watt one might be worth a try.
I need to take readings still to confirm, but my hunch is that the element receives full panel wattage at the full potential array voltage (18V?) when it is getting diversion current. Does that change the math?
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ewarnerusa
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06/05/23 08:56am |
Tech Issues
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RE: Feedback on 12V water heater element as solar diversion load
Question: what would happen if it was a 500 watt element for 24V DC?
500 watt 24V DC cartridge heater 1/2 inch NPT
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ewarnerusa
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06/03/23 05:12pm |
Tech Issues
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RE: Feedback on 12V water heater element as solar diversion load
New element arrived. Measured 0.6 ohms. The heat shrink is not white but gray is shown in the picture, but it feels the same. I don't think I'll put it to use, it feels like running a 300 watt rated element when I have nearly 500 watts to give when batteries are full is just not adding up to success. Sourcing a 500 watt 12V element has been a dead end. I can find NPS threaded ones but not the right 1 1/4" for swapping out the OEM 120V AC element. And this 300 watt one is the highest wattage 12V cartridge heater that I can find with 1/2" NPT for using in the drain plug.
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ewarnerusa
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06/03/23 04:10pm |
Tech Issues
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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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