Kings Solar Panel to Kickass DC-DC Charger

Solar panels are made up of cells connected together in series . Two lots of seriesed cells may be connected in parallel.

So, two scenarios

1 Your blanket has only one set of cells connected in series. If you shade one, output will be seriously affected. It's just the way they work.

2 If your blanket has a series/parallel arrangement, then shading one cell should approximately halve the output, not stop it altogether. In this series/parallel cell arrangement, if it stops altogether then I would suspect a defective blanket.

What is the claimed wattage of the blanket, or can you provide a photo of the deployed blanket? That might give us an indication of the cell arrangement.

.
Hi Chris,

For the panel to cease all charge when just one section is shaded is normal behaviour. The panel cells are connected in series like the links of a chain and when one is shaded its resistance rises so high that it blocks the other cells hence no current flows.

I suspect that when the blanket "is in the shade" as you have put it, although the sunlight is diminished, there is still enough light falling on all the cells to produce some output.

Hi Frank & Allan,

Thank-you for your replies, from your explanations which made sense and explained in common english, it prompted me to seek further info on the internet.

I thought I had one solar panel unit but in fact I've got six panels wired together (120W) output and as both of you have explained, one gets shaded and its all over rover.

I would of like to have had one panel but as space is a premium in my vehicle Subaru XV the blanket was a
necessary choice.

So I just have to manage what I have, the solar set-up is only a back-up if the vehicle is not run for a couple of days on a trip around the Western part of Aus which is unlikely touch-wood.

Many Thanks
CJ

Just to add to this we had an older 80w bp single panel and if you covered 10% of the panel then you lost 90% of the output.

Chris
It seems you have a DC DC unit far more capable than what the panel outputs. You mentioned the vehicle, if you use a wisely designed roof rack, perhaps to carry gear if needed, but a fixed panel can be used on a roof rack. Alternatively, with gear on top, a good design will allow a slim solar panel to be slid out from under the rack when stopped. This can be plugged into the DC DC unit too. Maybe in parallel, if similar/match to the folder unit

Update:

I went and purchased a fixed 80w Renogy Panel of eBay to try and solve the issue I was having,
here are the results.

Kings Blanket: Open voltage 21~22 Volts, but when connected to the DCDC charger and voltage measured at the anderson plug where the wiring enters the charger I get fluctuating voltage readings 17-18-19 volts and then suddenly a 0.5 volts reading and the charger drops out and restarts after 10 seconds and then the process repeats itself.

Renogy Fixed Panel: Open voltage 22 Volts and then when connected to the DCDC charger reading of 18 volts, the charger does cut out occasionally if I suddenly partially shade it. I can live with this one !!

It appears that the King blanket may? be faulty or just not up to par.

The Kickass DCDC charger seems to cut out if it starts to see large fluctuations in solar voltage input maybe as a safety device or to protect itself ???

Anyway I am going to go with the fixed panel for my three month trip. The solar will be rarely used I just want it as a back-up if I camp somewhere longer than planned.

I am not 100% sure if my testing process proves that any of the mentioned items are faulty. I don't want to bag any product unless I am completely sure they are faulty or not fit for purpose.

I did contact the suppliers when I first had this issues 14 months ago but they were of no help and warranty has since expired, I haven't used the products yet other than to set-up and test, due to COVID causing the cancellation of my trip in 2020.

CJ

I did some more testing today:

Kings Blanket:
Open voltage 21~22 Volts, but when connected to the DCDC charger and voltage measured at the anderson plug where the wiring enters the charger I get decreasing voltage 19-18-17 and then suddenly a 0.5 volts reading and the charger drops out and restarts after 10 seconds and then the process repeats itself. (see video around 15 second mark)

Renogy Fixed Panel:
Open voltage 22 Volts and then when connected to the DCDC charger readings of 18 to 17 volts.

Kings video:
https://vimeo.com/532086121

Renogy Video:
https://vimeo.com/532085727