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Discussion Starter · #1 ·
Hiya one'n'all,

Here's another Mallow1 hair-brained scheme. My bird lives in the open air nowhere near a power outlet. So if she doesn't get an outing I need to run a battery tender out to her on an extension lead (not great when it's raining) else swap out batteries regularly.

So I had the unoriginal idea of using a solar panel to help compensate for the drain of my alarm and Bluetooth battery monitor. Yep I'm lazy enough to just look at my phone indoors to see if the bike will start or not.

Now being me I had to go and over complicate the task. Let's build it into my double bubble screen so no one notices it let alone tries to make off with it.
 

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Discussion Starter · #2 · (Edited)
Considerations:
- solar panel to be hidden from view
- I like having a blacked out windscreen (to match the BB since mines in black)
- most off the shelf panels are flat and inflexible else only flex in one direction. Problem is dbl bble screen is curved in two directions.
- spec. Seems a middle of the road off shelf would be a 12V 5W set up.
- screen is a finite size (roughly 45cm x 40cm).
- weather and power wash proofing

Having done the maths (Watts =Volts x Amps) plus considered losing say 25% power due to light tinted screen. I've opted for these little flexible jobbies:

61tqvYwOU9L_1539877957925._SX466_.jpg

new-0-3w-1-5v-flexible-solar-cells-amorphous_1539877977399.jpg

Flexible, waterproof and 6cm x 12 cm rated at 0.3W 1.5-2.0V each

The screen will take 18 of them (EDIT: untrimmed, possibly up to 22 trimmed now I've tried cutting the first 18 to be a touch smaller without killing them).

So looking at the maths I need to get the voltage north of 12V. So half of them connected in series would give me a range between 13.5-18V and produce about 2.7W. That's half the screen used. Repeat the same on the other half and connect the two together in parallel then gives 13.5-18v for 5.4W and 400mA. NB the alarm and Bluetooth drain c 100-150mA so per day the screens 8-14 hrs daylight should generate enough to replace the 24hr drain… ??).
 

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Discussion Starter · #3 · (Edited)
Ok that's the theory. Still need to control it (protect battery from overcharging, reverse polarity, discharging through the cells at night etc).

Fortunately such things are readily available. I've gone for a waterproof 12-24v max 10A MPPT controller. It supposedly will setup/ step down the variable voltage from the panels to give a constant voltage suitable to charge a 12v battery.

MTTP refers to the method by which it switches from rapid charging, to normal charging to float charging (final trickle charge). There's cheaper and smaller units out there but the combo above sounded worth getting an "over spec'd" unit (I'm producing 400mA not anywhere near 1A let alone 10A max).

s-l225_1539880110077.jpg
 

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Discussion Starter · #4 · (Edited)
Progress so far:

Cells placed on screen (double sided taped) to coat the underside of the screen and leave a clean path to solder the two lots of serial cells to then join them in parallel. NB the +ve and -ve contact points on the back of the cells seem to be exposed by a cookie cutter type of piercing through the waterproofing. That leaves the central "cookie" behind. I've removed each cookie and cleaned off the residual glue in preparation for soldering (else you'll end up with one gooey mess of solder, glue and melted waterproofing… I know as that's what happened on my first attempt).
IMG_20181018_140735_1539880329582.jpg

The cells have moulded to the shape of the double bubble quite well.
IMG_20181018_140941_1539880679732.jpg

And aren't really visible from the outside.
IMG_20181018_140752_1539880746479.jpg
Once I spray the rest of the underside black it'll end up looking just like my dark tinted one.
 

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Discussion Starter · #5 · (Edited)
All soldered up and kicking out 13.5v according to my voltmeter.

IMG_20181018_180022_1539882218812.jpg

Hmm, that was in the midday sun. May have to link all of them in series and consider half the ampage (and/ or cramming in the other possible 4 extra cells I now know may fit once trimmed) but for longer periods of >12v to avoid testing the step up nature of the controller too much. I'll need to run a few days of tests.

After that I'll be ready to encase the whole thing in clear resin (to laminate it to the screen as I'm sure the double sided tape will be inadequate in the peak of summer). Then finally blacken the underside and install it (controller in the nose cone, sae quick release waterproof connectors to allow the screen to easily be removed) then see if I end up charging the bike a little less often!

I'll post final pics once I'm happy with the config/ power output so can seal/ laminate it for good.
 

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Discussion Starter · #8 · (Edited)
So, I presume you never foresee the need for a full "tuck" behind the windscreen?

Great job of engineering though
Too much of am old fart with a stiff back these days (hence planning on fitting lower pegs and VFR bars this week too… besides once I get the INNOVV K2 camera system I can simply watch ahead and behind on the camera screen under the windscreen or in my helmet HUD… ok too many projects running concurrently)

Mallow1 has been on a Jaws/ Amazon/ eBay/ AliExpress/ Top Sellerie/ Auctmarts/ Corbin/ Sargent/ eTint mega binge fest!!!

Thanks re the kind words on the build. I'm still hoping someone with a good tech background kicks in too as I'm making this up as I go along. Shhhh don't tell anyone.
 

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Discussion Starter · #9 ·
Really nice Job, I might do the same if it works out let me know.
Will do. Biggest concerns so far are that it doesn't produce enough juice either coz I've got my knowledge sub-par, sh1t weather, the maths is wrong, I've slipped with the build (esp soldering) or the whole thing proves not to be robust out on the bike.

I guess only testing and time will tell. Looks promising though…
 

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Discussion Starter · #10 ·
Woohoo… 16.2v out of the screen this noon. So I think I'll leave the two halves of nine in series, then the halves joined up in parallel set up (but will order 4 extra cells to max out the real estate coverage plus a couple of spares to experiment on and as replacements for duds). Plus I'm considering adding diodes at the parallel junction to protect each half from each other (the controller should protect the panel from the rest of the bike's electrics).

Now to add the controller and measure what comes downstream of it. Final test will be to add the fuse and sae leads, hook up a stand alone battery and test that set up.
 

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Discussion Starter · #11 ·
Ooh, I could dispense with the SAE connectors and run contacts out to the screen bolts. So long as the contacts are isolated from the bolts and sealed from water ingress that would be the neatest seamless most convenient install.
 

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Ooh, I could dispense with the SAE connectors and run contacts out to the screen bolts. So long as the contacts are isolated from the bolts and sealed from water ingress that would be the neatest seamless most convenient install.
You'll probably suffer volt drop across the screws, good job on the panel- your not going to improve output without more or bigger panels I'm afraid, you'll also probably find a fairly high loss of what your able to generate n the controller once connected due to internal losses- If you keep the plug and socket connection, use gold plated connectors as will be lower loss, I think you are in the position where every little will help, hopefully.
 

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Discussion Starter · #13 ·
Hi Krisbiker,

Sage words especially as I've no idea yet what power loss the controller will take. It did have some stats in it's spec but I'm no sparkie and written versus measured will always differ. It'll be quite a disappointment if there isn't even enough juice to even power it!

FYI I wasn't aiming to pass the current through the bolt/ screw itself, just use it's clamping force to bring two contacts together while it clamps the screen to the fairing. Making that junction waterproof & isolated was my most immediate concern. You are right though, I hadn't focused on its impedance.

First attempt will be with simple eye connectors big enough to have the insulated bolt pass through the middle.

Liking the gold contact idea. Very bling ?. DIY electroplate or gold leaf or only source bought products?
 

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Discussion Starter · #14 ·
I'm buying 4 more cells to improve my output and max out the use of the available area. I'm also trying to find a source of the same cells but unencapsulated. I'd be able to get even more of them on the screen (for screen Mk2) then encapsulate it myself as part of laminating it to the screen re waterproofing and theft proofing. Anyone come across a source?
 

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Don't think you'll be able to get decent connection to gold leaf, but I could be wrong, home plating should work, buying would be easier if you can source- rs components sell some I think, or maybe decent audio place?
 

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I'm buying 4 more cells to improve my output and max out the use of the available area. I'm also trying to find a source of the same cells but unencapsulated. I'd be able to get even more of them on the screen (for screen Mk2) then encapsulate it myself as part of laminating it to the screen re waterproofing and theft proofing. Anyone come across a source?
Hey Malo! So!... What is the final verdict? MMMMmmm if it works out I WANT IN! LOL I can fabricate, paint, do decals, use Vvivid vinyl and anything mechanical that doesn't require going INTO the engine! BUT... I'm a electrical boob! I mean noob! :rolleyes: Soooooooooooooooo will need step by step instructions if you are successful!
 

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Discussion Starter · #17 ·
Hiya Lovin,

I see you've found another of my madcap ideas.

I'm at the stage of adding the additional solar cells just for that extra boost to thr current.

Then I'll be better placed to tests it's ability to trickle charge a battery (without being fitted to the bike as s furst step). My current concern is that the MTTP controller I bought is too beefy and won't pass on any useful current (or it's broken as my first attempt showed good voltage but bugger all coming out the other side of thr controller). I've spotted another MTTP controller on FleaBay (part of the arduino family) so I may buy that as an alternative to test.

Once I'm sure that the thing is electrically fit for purpose (and so far it does seem I got my maths right on the solar cells) I'd love to pick your brains re ideas of how to make it robust and esp weather proof.

In this current version the cells are only held in place with double sided thin foam tape. That'll be nowhere near durable of capable of staying in place in adverse weather let alone power shower/ hose.

Ideally it ought to be laminated so it and the screen become one. I have clear resin but have never attempted lamination, neither on a straight forward flat surface let alone a 3D curved one, let alone encasing electronics too.

Vvivid Vinyl may be an option to "shrink wrap" it. Esp if it can if nec be readily removed to repair say a loose connection.

Other idea was to take a mold of the underside of the screen and begin the encasing that way round. The cells could the be glued firmly down in place and adopt their 3D curved permanently . Wiring could then still be achieve on or through the rear. Final bonding to the screen ought then to be an easier process except how on earth to ensure no trapped bubbles/ air gaps.

Ideas?
 

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Discussion Starter · #19 ·
Ooh interesting idea.

That still leaves me with the solar cell surface to underside of screen interface. The challenge is to get the marriage optically clear as possible (limited bubbles, air spaces or refractive/ scatter flaws).
 
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