10 W pannels

spaceHopper · 13-02-2015 3:59pm #1

Folks,
Because of family commitment I’m not getting to use may camper as much as I’d like to. In fact right now either the starter battery or alternator is dead. Because I’m not driving it as much as before the starter battery did drain but it appears to hold charge if I use a good charger - think the alternator is dead. After I’ve had the alternator fixed I’d like to fit two small panels to stop it happening again. What I’m thinking is two 10 watt semi flexi panels mounted on the front curved part of the roof. The thinking is to fully charge both batteries and then the panels will keep them in good condition. Because they are only 10W I believe I shouldn't need a charge controller – just a diode. The up side is they are light so can be stuck to the roof without drilling holes and I’ll remove old TV antennas and reuse the cable holes.

I don’t expect the panels to charge the leisure battery while I’m away- I use the van for weekend surf trips and don’t plan to be away from home for more than a long weekend – face it I’ve two year old twins at home I’m luck to still have the camper.

What do you think, am I missing something.

These are cheap but I’m not sure if they would take a knock from a branch of a tree
http://www.trueshopping.co.uk/product/Biard_Solar_10W_Semi_Flexible_Solar_Panel_with_Cables/6032/96627.html

Maplin claim these are very though
http://www.maplin.co.uk/p/10w-flexi-pv-solar-panel-kit-n64ng

13-02-2015 4:43pm

Too small. It won't have any output most of the year. My 150W only gives me ~4W for the winter months. Which barely pays to run my solar controller.

I'd say 50W as a minimum, rigid mono-crystalline.

Maplins are a rip off, I wouldn't touch them for RE tech. PV is about €1 per watt these days, I wouldn't pay more than €1.20.
Flexible panels aren't that flexible...only about 10° edge to edge, they cost more and have a lower light permeability, and they'll never be remotely ideally aligned to the sun.

If it doesn't need a solar controller it's not going to cut the mustard. Think about it if a device relies on it's own ineptitude to regulate then it'll never hold it's own.

moodrater · 13-02-2015 4:56pm

What makes you think the alternator is gone. Alternators aren't meant for charging flat batteries. You have to be driving around for 8 hours just to get 60-70% charge in a good battery. You could be driving around for 24 hours and you mightn't have a full charge.

If you already have a charger why solar just leave if plugged in on trickle charge.

spaceHopper · 13-02-2015 5:16pm

Last trip before Christmas I stopped close to home at a shop after driving home from Sligo couldn't start if when I came out. Charged it up and two weeks ago I drove the van to work for two days to give it a spin. The battery was flat after two days of driving. I charged the battery and I get 12.2V then 12.7 with the engine running. It's hard to get time to fully check it out I'm going to charge the battery again and check it maybe on Sunday. I if matters the battery is about 3 years old (at most).

It's not easy to level plugged in at home hence solar. The engineer in me say that long slow charging with solar will over come any drain on the battery and even slowly charge it over time but as Sir Liamalot says

% efficiency .

I'm not worried about bending the panel it's more where they will fit on the van and have a good angle to the sun. They also weigh SFA

Irishgoatman · 13-02-2015 5:55pm

Sir Liamalot wrote: »

Too small. It won't have any output most of the year. My 150W only gives me ~4W for the winter months. Which barely pays to run my solar controller.

I'd say 50W as a minimum, rigid mono-crystalline.

Maplins are a rip off, I wouldn't touch them for RE tech. PV is about €1 per watt these days, I wouldn't pay more than €1.20.
Flexible panels aren't that flexible...only about 10° edge to edge, they cost more and have a lower light permeability, and they'll never be remotely ideally aligned to the sun.

If it doesn't need a solar controller it's not going to cut the mustard. Think about it if a device relies on it's own ineptitude to regulate then it'll never hold it's own.

I have to disagree wth Sir Liam here. I bought a 12v-15w panel from Maplin 5 years ago just to charge a leisure battery that is only needed to power clock radio, 2 small lights, re-charge 'phone ect. No heavy duty as such. It is powerful enough that it keeps the battery charged even through the 4 months of the year that the camper is in the barn. Leisure battery has not once gone flat in this time. I mounted it flat on the roof.

[URL="mhtml:{E76ACC60-FC2C-4310-81C0-0B264AF6859B}mid://00000048/!x-usc:http://www.maplin.co.uk/p/solar-powered-12v-15w-battery-charger-n31cx"]http://www.maplin.co.uk/p/solar-powered-12v-15w-battery-charger-n31cx[/URL]

moodrater · 13-02-2015 6:07pm

Irishgoatman wrote: »

I have to disagree wth Sir Liam here. I bought a 12v-15w panel from Maplin 5 years ago just to charge a leisure battery that is only needed to power clock radio, 2 small lights, re-charge 'phone ect. No heavy duty as such. It is powerful enough that it keeps the battery charged even through the 4 months of the year that the camper is in the barn. Leisure battery has not once gone flat in this time. I mounted it flat on the roof.

[URL="mhtml:{E76ACC60-FC2C-4310-81C0-0B264AF6859B}mid://00000048/!x-usc:http://www.maplin.co.uk/p/solar-powered-12v-15w-battery-charger-n31cx"]http://www.maplin.co.uk/p/solar-powered-12v-15w-battery-charger-n31cx[/URL]

You cannae change the laws of physics captain. The 12-15w is rated at 1000W/m² - how many W/m2 do you think it gets in your barn. You wouldn't expect the battery to go flat in 4 months anyway with an old vehicle theres no central locking, timers, alarm, immobiliser unit etc. etc.

moodrater · 13-02-2015 6:11pm

spaceHopper wrote: »

Last trip before Christmas I stopped close to home at a shop after driving home from Sligo couldn't start if when I came out. Charged it up and two weeks ago I drove the van to work for two days to give it a spin. The battery was flat after two days of driving. I charged the battery and I get 12.2V then 12.7 with the engine running. It's hard to get time to fully check it out I'm going to charge the battery again and check it maybe on Sunday. I if matters the battery is about 3 years old (at most).

It's not easy to level plugged in at home hence solar. The engineer in me say that long slow charging with solar will over come any drain on the battery and even slowly charge it over time but as Sir Liamalot says % efficiency .

I'm not worried about bending the panel it's more where they will fit on the van and have a good angle to the sun. They also weigh SFA

Is yours a hiace mine had a standby current of a couple hundred milliamps with the factory stereo.
Is the charge light coming on and going off as normal? Probably due and overhaul by now anyway if you take it out they'd probably bench test it for free.

spaceHopper · 13-02-2015 6:24pm

Yea it's a 91 hiace jap import I think one or more of the diodes in the alternator is gone. It's finding the time to work on it I've lots of small jobs to do but to small people to help look after. One day I'll have time.

moodrater · 13-02-2015 7:54pm

spaceHopper wrote: »

Yea it's a 91 hiace jap import I think one or more of the diodes in the alternator is gone. It's finding the time to work on it I've lots of small jobs to do but to small people to help look after. One day I'll have time.

In old Toyota the charge and sometimes brake light bulb were part of the exciting circuit for the alternator so if you had a problem with those it mightn't start charging.

13-02-2015 8:20pm

spaceHopper wrote: »

but as Sir Liamalot says % efficiency .

Did I?

What was I wittering about then?

I don't understand why you'd want to buy a 10W module when you can get 50W cheaper

spaceHopper wrote: »

The battery was flat after two days of driving. I charged the battery and I get 12.2V then 12.7

Yeah could be diodes, could be knackered battery. Could be a high resistance too.
You'll have continuity on both polarities between B+ and casing if it's a dud diode.

Irishgoatman wrote: »

I have to disagree wth Sir Liam here. I bought a 12v-15w panel from Maplin 5 years ago just to charge a leisure battery that is only needed to power clock radio, 2 small lights, re-charge 'phone ect. No heavy duty as such. It is powerful enough that it keeps the battery charged

Is this measured?

I know for a fact I only get 3W at midday in the shade (low Winter sun it's always shadey) on a sunny day in December from a 150Wp module.

Despite advice of good counsel, my mother's partner has knackered 2 old but serviceable batteries now trying to trickle charge them off a 10W Aldi job in the Winter on a little Corsa that can run but doesn't.

Irishgoatman · 13-02-2015 10:13pm

moodrater wrote: »

You cannae change the laws of physics captain. The 12-15w is rated at 1000W/m² - how many W/m2 do you think it gets in your barn. You wouldn't expect the battery to go flat in 4 months anyway with an old vehicle theres no central locking, timers, alarm, immobiliser unit etc. etc.

Please don't baffle me with science :eek:.
I was just pointing out that, depending what you want it for, a solar panel from Maplins that just needs natural light, not just sunshine which we can get a shortage of here in Ireland:), works fine.

Do the things you mentioned, central locking etc, actually run from the leisure battery on modern campers then?, I would have expected them to be connected to the drive battery (or whatever its correct name is).

13-02-2015 10:53pm

Irishgoatman wrote: »

Please don't baffle me with science :eek:

If you want to pay 5 times the going rate for a module work away.

I'd say you just have a very low or no parasitic load on your leisure battery and it is discharging very slowly.

Mono panels are better in diffused light (cloudy skies) than amorphous. Amorphous are better than mono at producing power under partial shading conditions. Both work under grey skies, neither work in barns.

Irishgoatman wrote: »

Do the things you mentioned, central locking etc, actually run from the leisure battery on modern campers then?, I would have expected them to be connected to the drive battery (or whatever its correct name is).

Just the starter (engine) battery.

In a lot of conditions...especially the Summer with short nights the diode will cost you more power than it saves.

spaceHopper · 13-02-2015 11:32pm

4 ÷150 is just under 3 % I'm a nerd ok think we want different things from sola now where do you stand on peel and stick panels

14-02-2015 1:07am

Yeah I worked it out Space.

Peel & stick? Had to look them up myself tbh.

Twice the price for your average photon. Pretty neat. I guess if you can hold a spoiler on with sticky tape you can hold a film on no probs.
Dunno do they scratch?

The thin film amorphous panels are physically bigger than their mono equivalents.

I rather the flat glassy kind so the PV cells are balanced and rugged...hardly makes much of a difference the minor flex...much like having more dirt on one side of the glass.
A benefit of the regular kind is it's easy make a tilting frame.

Yeah if you are after something very small they're neat, I don't know if 10W would be up to the job though.
Best measure your ghost load first and see how much solar exposure your motor's roof gets where you park it. (24 hour drain versus 4-16hour PV with loads of losses).

You'll still have to use another charger though to charge the batt's after a cycle...they won't have reached full charge in under a week on their own which is a bit sulphatey.

I don't know if the slope on the roof is the best place for them either. Flat mount is better for trickling, the slope will give you a lot more in direct light but less in indirect and more liable to shadow in the normal course of things.
Plus when they're flat only the trained eye will see them which is more stealth/secure.

I don't like the idea of making them a permanent fixture. At some stage I know I'll be breaking/ugrading my motor and salvaging the gubbins.

If I was to do mine again, I'd be considering 24V because then I can get cheap 250W domestic panels. ...second truck alternator more batteries...less copper... :rolleyes:

At the end of the day price per watt is the benchmark, I reckon 50W is as small as useful gets for most of the year, and I'd get a solar regulator with room to add on a few more modules later.

Rough rule of thumb I find works quite well without shading factors; Spring to Autumn you get 3 times your module's rating in watt-hours on a cloudy day and 6 times on a sunny day.

So say (roughly) you have a 10W panel = 30Wh per day = 100mA parasitic drain offset.

Irishgoatman · 14-02-2015 1:08am

Sir Liamalot wrote: »

If you want to pay 5 times the going rate for a module work away.

I'd say you just have a very low or no parasitic load on your leisure battery and it is discharging very slowly.

Mono panels are better in diffused light (cloudy skies) than amorphous. Amorphous are better than mono at producing power under partial shading conditions. Both work under grey skies, neither work in barns.

Just the starter (engine) battery.

In a lot of conditions...especially the Summer with short nights the diode will cost you more power than it saves.

Look, all I was doing was pointing out that not everything from Maplins is "a rip off", to use your words. I paid 60 euro for a solar kit that does exactly what I wanted it to do. Nothing more and nothing less.
My 1986 camper wasn't designed with a leisure battery and this solved the problem. It's a case of horses for courses.

There is no parasitic load on the battery as it's only used when I'm in the camper.

Thanks for pointing out that solar panels don't work inside a barn. I never would have figured that out:rolleyes:.

14-02-2015 1:38am

And all I'm pointing out is that Maplins are a rip off for solar PV

Example here.

Sir Liamalot wrote: »

Maplins are a rip off, I wouldn't touch them for RE tech.

RE tech = renewable energy technology...sorry for confusion.

spaceHopper · 22-02-2015 5:43pm

So what's the verdict
Measured the starter battery I knew it wasn't fully charged it read 11.65V, the leisurely battery read 10.2. With the engine running at the starter battery I read 12.65. I took off leisure ground then the starter ground. Finally saw 14.4 Switched on the light fogsfog/spots and full beams voltage drops back to 12.7. With the lights off again back to 14.4. Add back in the starter grground and I get 13.9V

So what do you think bad connection or bad diode pack or battery or all of the above. Have starter battery on charge at moment and will check again with highrr revs and lights on

23-02-2015 6:00pm

spaceHopper wrote: »

Finally saw 14.4 Switched on the light fogsfog/spots and full beams voltage drops back to 12.7. With the lights off again back to 14.4. Add back in the starter grground and I get 13.9V

Can you be more specific space I'm not following you.

Sounds like it could be the alternator is fully loaded charging a flat battery. Higher RPM aren't going to do a whole lot more for you.

Leisure battery probably dead. Starter terminal, I'm surprised that'll turn the engine.
Did you disconnect the batteries while running the alternator?

Measure the output voltage at the terminals of the alternator compare this to the terminals of the battery a difference of 0.1V is a bad connection or under-wiring.

Turn off the engine and measure the current between the Battery + and the alternator B+ at the alternator to find a bad diode (should be none). Also check continuity between alternator B+ and ground (scratch the corroded aluminium gunk off with the probe first); should be OL (out of limit).

The alternator might be ok. I'd remove the leisure altogether and test the cell voltages, steal a similar capacity car battery and stick it where the engine battery lives and use the car battery to test the alternator.
Also measure the parasitic load on the starter battery with the engine and everything off.

spaceHopper · 24-02-2015 11:21pm

Its not easy to get at the alternator as I have to take the drivers seat out.

Charged both batteries engine is holding 12.7v the leisure battery had just come off charge so was reading about 13v.

With the engine on and both batteries in circuit i get 12.7V

With engine on and full head light I'm getting 14.04V if i take the leisure battery gnd off.

Not sure what's going on it looks like the engine battery is ok but I did have a flat battery after driving back from sligo and I was able to jump it off the leisure battery not good to do but it was a last resort. That would suggest the leisure battery has got some life in it. Maybe it's got a weak cell and is pulling the alternator voltage down to below a charging voltage. I'm going to leave the leisure ground off and take the van for a good spin to see if the engine battery holds up.

25-02-2015 2:05pm

What gauge and distance is the conductor to the leisure batt?
Leave the leisure battery a full day before you take reading. See how much it self discharges.

Does your fridge always run when you start the engine, any similar heavy loads off the leisure?

25-02-2015 6:34pm

Are all these measurements being taken from the same place or are you metering the starter battery at the starter battery and the leisure battery at the leisure battery?

10 W pannels

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