Solar panels...

[tramcar trev]

I found these 12V 5w solar panels on eBay at a sensible price. I shall try bargaining with the seller. I want one to power a 120mm 12V fan as an extractor fan on the back of the Caravan fridge. 5w @12V is around 380 mA so they would be ok (with a regulator) to trickle charge a 12 V lead acid battery. For use on a model railway they would be ok to charge batteries etc or provide power where mains power was an issue to get it onto site.
5Watt, 380mA; http://www.ebay.com.au/itm/5W-WATT-polyCrystalline-solar-panel-12v-solar-DIY-system-5Watt-poly-solar-module-/390662003126?pt=AU_Solar&hash=item5af54519b6&_uhb=1&autorefresh=true

10Watt; http://www.ebay.com.au/itm/10-Watt-12-Volt-Solar-Panel-Monocrystalline-Silicon-Cells-/161349185078?pt=AU_Solar&hash=item2591292e36&_uhb=1

For battery charging a regulator needs to be in series with them; http://www.ebay.com.au/itm/Digital-PWM-10A-Solar-Charge-Controller-Regulator-12V-24V-Autoswitch-120W-240W-/310904756500?pt=AU_Solar&hash=item48635e1914&_uhb=1

 

[ge_rik]

Hmmmm.... Been wondering how to power the lighting and semaphore signals at each station - if I hooked one of these up to a lead acid gel battery ........

Rik

 

[bobg]

I've been looking at this for a while. I thought it would be a good idea for signals and other lighting (Not forgetting I'm mostly steam). ATM I run an extension lead out to a transformer.

 

[tramcar trev]

You do need a deep cycle battery e.g. ;http://www.ebay.com.au/itm/YTX4L-BS12V-4AH-GEL-BATTERY-DEEP-CYCLE-YAMAHA-125-SCOOTER-50CC-CY50-RIVA-JOG-/121367635610?pt=AU_Motorcycle_Parts_Accessories&hash=item1c4213269a&_uhb=1

 

[bobg]

I was thinking more like a burglar alarm battery. The drain wouldn't be that much on my setup, a few leds and occasional use of a point motor.

 

[ge_rik]

I was thinking more like a burglar alarm battery. The drain wouldn't be that much on my setup, a few leds and occasional use of a point motor.

Yes me too. Maybe something like this:

http://www.ebay.co.uk/itm/NP3-2-12-3-2Ah-12v-Yuasa-Lead-Acid-Rechargeable-Battery-/111084043643?pt=UK_ConsumerElectronics_Batteries_SM&hash=item19dd1ffd7b

Rik

 

[G-force1]

A minor (?) problem has occurred. My Solars have been up a couple of years and today I found one of the batteries to be completely dead (I have two completely separate systems at each end of the garden). I tested the panel and found no output (we have Very bright sun today) so I was expecting at least something.



On the usual all-or-nothing basis I decided to see if it would come apart easily, and lo and behold it doth! The fault was instantly obvious, and completely unrepairable, and unnecessary. For want of a splodge (technical term) of epoxy, the whole unit is destroyed, every wire and connection to the control circuit is completely corroded away. I'm now wondering if I should apply that to the new panel that is so obviously required, before fitting?



Also, should I, at this late stage, attempt it with the second panel, which may well be heading for a similar state (not solid!!!)?

 

[daveyb]

nasty,,,,,

 

[ebay mike]

Also, should I, at this late stage, attempt it with the second panel, which may well be heading for a similar state (not solid!!!)?

I would. Had a not dissimilar problem with the cheapo solar garden lights from Poundland a few years ago. Water gets in around the panel mount and destroys all electrical gubbins beneath fairly quickly as everything appears to be of interior use quality. Problem alleviated by smearing clear silicon sealant around the edges of the panel to ensure a watertight joint.

 

[G-force1]

I thought silicon sealer was a no-no round electronics because of the acetic acid.

Late edit!

I checked out the second panel and found that that too was beyond redemption. Ordering problem solved as two panels cost more than the minimum for free postage.

 

[stockers]

These panels never seem to last long. Disposable world we live in I suppose.

 

[G-force1]

Hmmmm! Looks to me that if they put 20p worth of epoxy in it, and it lasted for more than two years they could charge at least another £5 for them.

 

[PhilP]

Problem is wires on resistors etc. are steel these days.. So they will rust.
Also, a bit of damp, and a constant small current.. All the metal will migrate from positive to negative.

All for the sake of a brushful of conformal coating..

 

[stockers]

Hmmmm! Looks to me that if they put 20p worth of epoxy in it, and it lasted for more than two years they could charge at least another £5 for them.

And cheapskates will always buy the cheaper ones.

 

[G-force1]

The fix (too late, I've bought the new ones!) is so simple as to be beyond stupid. The useful part of the circuit is just a diode. The rest is bunce! By removing all (? the diode) the circuit from the array casing, and transferring it to the battery box (with a coat or two of clear lacquer) problem gone away. The only problem I'm left with is starting the dead battery re-charging. Sod these sensed chargers!!! Maybe, just maybe, when I try it will have a coupla volts left in it.

Very late edit.

Overnight the thought occurred that it might not be a simple diode, but a Zener diode. Difficult to say as there are no discernable markings on it other than polarity. I will double check with a jeweller's glass.

 

[trammayo]

The fix (too late, I've bought the new ones!) is so simple as to be beyond stupid. The useful part of the circuit is just a diode. The rest is bunce! By removing all (? the diode) the circuit from the array casing, and transferring it to the battery box (with a coat or two of clear lacquer) problem gone away. The only problem I'm left with is starting the dead battery re-charging. Sod these sensed chargers!!! Maybe, just maybe, when I try it will have a coupla volts left in it.

Could you give it a flash from a charged battery?

 

[PhilP]

Could you give it a flash from a charged battery?

Or better still, a bench supply, if current limited..
Else parallel it with a 'good' battery. Give it half-a-minute, then hit the parallel-pair with the charger for 5-10 minutes..
Keep an eye on it, and make sure neither battery is getting toastie!

Then try the 'duff' battery on its own charging..

 

[Rhinochugger]

These panels never seem to last long. Disposable world we live in I suppose.

Better off going for a caravan or boat panel, and hooking it up to a lead acid 'leisure' battery (as opposed to car battery).

You can buy the panels complete with a controller for reasonable money

 

[G-force1]

No such luxury as 'bench supplies' round here mate! The new panels have arrived (and new 'Welsh Poets' for the old panels are on their way) and before fitting, I've stripped them and several coats of clear lacquer have been applied to the circuit boards. The mounting double-keyhole slots have been sealed with mastic and the panels mounted on a slight slope to allow the rain to run off. I can't think of much else to protect them except mount them inside a glass case.

The battery (alarm battery, meant to be on permanent charge) when tested had a whole 0.3v. Ouch. I connected the charger and it showed 'fully charged' (surprise, surprise!). I left it for a few minutes and tested it again and I got 9.3v diminishing - rapidly, so i've left it on, to see what happens.

 

[Rhinochugger]

No such luxury as 'bench supplies' round here mate! The new panels have arrived (and new 'Welsh Poets' for the old panels are on their way) and before fitting, I've stripped them and several coats of clear lacquer have been applied to the circuit boards. The mounting double-keyhole slots have been sealed with mastic and the panels mounted on a slight slope to allow the rain to run off. I can't think of much else to protect them except mount them inside a glass case.

The battery (alarm battery, meant to be on permanent charge) when tested had a whole 0.3v. Ouch. I connected the charger and it showed 'fully charged' (surprise, surprise!). I left it for a few minutes and tested it again and I got 9.3v diminishing - rapidly, so i've left it on, to see what happens.

I'm not sure that alarm batteries are necessarily ideal for this use - alarms are only meant to off occasionally, not be constantly discharged and re-charged. (Having said that, I'm ignorant of the type of cells that you have there.)

But the leisure batteries (lead acid) are what Tramcar Trev had referred to as deep cycle batteries - they are intended to be charged and discharged. That's why they're different from car batteries which deliver a on-off wallop (when you start your car) and are then trickle charged as you drive around.

The problem with providing night lighting from this sort of arrangement is that it probably doesn't fit either scenario perfectly, although as you can't rely on the solar panel to re-charge the battery every day, I prefer the deep cycle principle