Why Solar Panels

D/S,

I've got a dual battery setup with a 100 amp AGM and I like to keep the AGM topped up so that it does't get low and thus not shorten its life. I'm thinking a panel is the easiest way to do this. I'm sick of having to idle the car a few times a day or having to go for a drive.

Cheers,

Jim.

Drivesafe

While the dual battery set up is cheaper there are several reasons why I did not go for this and use solar.

1. No room to easily fit a second battery in the engine bay. Hence I bought a 100Ah AGM battery ($270) put it in a box ($17) with a solar controller ($70) and an ampmeter ($17) and a few terminals and fuses ($20). So for about $400 I have a battery that is significantly larger than a 48ah Waeco Thumper at nearly half the cost.

2. Now that I have a battery in a box, I need a source to charge it. The options were: put it back in the car (or leave it in there) every time i go for a drive, run a thick cable from the front to an anderson plug and charge controller (cost ~$250-300). Since I did not want to do that (the battery weighs in at a heafty 35kg) I oped for solar. I recognise that it is more expensive, but it means I can leave it all at camp and not have to worry about carting things back and forth to the car. Solar cost (80W) was $A450 bought in the USA - so not that much more. Since most of the camping I do is on the beach in Sunny SE Qld, I have found 80W ample so far . I move it 3 time per day (at night to get the morning sun, after morning smoko for midday sun and then after lunch). I only run a 50L evakool and a few lights, so I reakon I am using 20-30A per day depending on the ambient temp. I can get ~4.5A going in in full sun, which means I need about 6-7h of sun a day (ignoring the fact that the charging rate decreases when it is near full). I normally have a near full battery by about lunchtime (especially when the sun rises at 5am!). If for some reason I get 3 days of overcast weather I always have the option of idling the car and charing the battery with jumper leads (yes it can be done with an AGM). Even a 10Ah per day deficit will allow me to sit in one spot for 6 days before I have to worry.

So I guess that it a long winded way of saying why I went solar

Hope this helps in some small way

Tim

I dont run any gadgets for my dual batteries , I just have them connected in parralel . This also assists in winching . I carry a $ 88 jumber pack in the rear that is plugged into the 12 volt system when traveling to keep it topped up. Its there as a emergency if I do flatten both batteries . haven't used it yet , Have had the car sitting in the driveway for 4 days with fridge running , car started fine.

Drivesafe, you are correct. If only staying for short periods of time, or base camping but driving out each day, a Solar Panel is not a necessity. I do use one, but as you say, only when staying at one spot for more than 2 days, and no vehicle usage.

I will be the first to admit, there IS the NEW TOY value, and we all need to have toys!!

I guess too, that you can do sums, and say that you can buy x brand batteries, or y brand panels, and try to compare costs. Panels will outlast batteries, so that needs to be taken into the equation.

I dunno.............. I just really like the look of my campsite, with my tripod mounted Solar Panel, tracking the sun. Sort of start dreaming, thinking I am part of SG1, on an off-world sortie!!! ( If ya don't watch Startgate SG1, ya won't understand...).

Oh, nearly forgot.............. and this could be really important........... my panel has all these numbers on the back, and they are all scratched off............ Like it was really cheap!!!

Cheers

Receiving Dubious Goods Wolfie

At this stage I'm a weekend or 4 or 5 day camper. Our chance to do a long trip is far off. I went away the weekend before last for 5 days fishing in the one spot. Running an 80 L fridge (keeping the beer really cold, around 0 C at the element end) and some lights, in warm weather, the battery needed daily topping up to keep it above 12.0 volts.

Looking for something that will stop the need to run the car. I was lucky at the last spot that no-one was bothered about me running the car, but some people are sensitive and I don't want to aggravate anyone. Hence I don't see a generator as an option. I had a 2 stoke genny a while back and it was noisier than my car and I reckon it used more fuel than the car on the idle.

Can't see a viable option to solar. Next hurdle is getting the GLW to get used to me spending another $800.

Cheers,

Jim.

Dear Drivesafe
You make some valid points about the advantages of duel batteries over solar, but your calculations are a little off. 160W of solar pannels over 2 1/2 days will provide much more usable power than a second battery, especially if you want a half resonable life out of the battery.
Lets do some practical sums with real examples.
Assume Melbourne in October staying for 2 1/2 days.
Solar
160 W solar provides in real terms puts out about 8 A afer derating.
Melbourne in October is 5.2 eqivalent sun hours.
The solar pannels would put out on average 8 X5.2=41.6 per day or
105 Ahrs over 2 1/2 days.

Battery
I we take an 80 Ahr battery it would appear close but it also has to be derated for several reasons. Here are the main ones
1. If you consistintaly drain it more than 50 % it will have a short life.
2. A car alternater will only charge it to about 75 %
3. The battery performance will degrade with age, temp and dischare rate.

If charing with a car alternater we therfore only have a capacity of (80 X0.75)-40 =

20 Ahr usable

These calculations are only rough and for one location and month, but you get the idea
If you factor a resonable short battery life of perhaps 3 years compared with solar pannel life of perhaps 30 years. Then solar is more attravtive.

Cheers John

Hi folks, thanks for the postings and the life span of solar panels verses expected battery life is a point I should have added. I have a set of solar panels that have been working well for just under 20 years.

The expected life of a battery is not really a consideration though, as they will die whether they are charged by solar or other means. Having said that, solar can extend the battery life but by how much is debatable as the biggest factor that effects the life span of batteries is how the are cycled.

If you use deep cycle batteries you can take them down to 10.5 volts and not do any harm to them as long as it was not caused by a single heavy load and you charge it back again within no more than a few days. This is what they are designed for.

Solar panels, if you have the correct power to meet the discharge usage, also have the advantage over an alternator, as someone has already pointed out, of being able to boost charge a battery.
As for the actual power you can get out of a battery depends on what you are using it to power. In the case of Jeff M, I think you would need a substation to maintain yours, but this answer and the others are the reason I posted this question based on a 2 to 3 day usage.

90% of customers are weekend worriers and as such first off, cost is a factor and I still think that extra battery capacity is by far the way to go.

I also think and have had my opinion strengthened by your postings that the only way to go when it comes to setting up a came site for more than 4 days, is to use solar as the charging mode but please keep the posting coming.

Cheers and I will explain more about the reason for the posting after I get some more replies

Having travelled with the full set up of dual batteries in Nissan, and the deep cycle in the caravan, we still found if the power supply got low, the little portable solar panel brought it back heaps quicker than driving.

Horses for courses, Drivesafe. I have a dual battery set-up in the Pajero and it works fine for me as I like to keep moving and explore wherever I'm camped, so going for a drive each day is what it's all about AFAIC.
My battery (150 AH deep cycle) will run the the Waeco 50LT and a fluoro quite comfortably for 2 nights but needs charging after that.
The question is then, what method do you use to charge it? Going for a drive is my current method and it works for me, but if your planning on being stationery for longer periods then the choice is Generator or Solar (or both). If you rely on the vehicle charging system then your up for long periods of fast idle or regular long drives. I guess the ideal would be a Solar set-up backed up by a small Genny for when the clouds get in the way.
Cheers, John.

hi drivesafe. I use solor. we go prospecting and sent up camp for 2-3 weeks at
a time.had a gen set to noisy especaily? in the bush where noise travels and you
like to feel hiden.we may only drive a couple of kms from camp each day. have
a rodeo only single batt set up.to fit duel batts under bonet got to do air con
plumming.also here in wa winter up north in the goldfields is great blue skys
mid 20,s. so you can say i am hooked on solor.
cheers brian

Hi folks, I would just like to thank everybody for the responses to my question and I have tried to respond to all of your posting and again want to thank you. The info I have posted is correct to my Knowledge but no matter what you get off the net, it still pays to talk to some local to you and double check that the info is right.
Or using the info I have supplied, carry out some tests of your own and see how much of what I posted is correct.

But before this descends any further into a slinging match ( I can’t help but point out the error of our shop assistant’s ways, and lets face it dave, that’s all you are, a glorified shop assistant ). The postings has been very informative and My fun is probably an inconvenience to others so I will leave it at this point.
Thank you all again

I’m wrong, all the portable fridge manufacturers are wrong and all the people who have been using this type of equipment for years without any problems are wrong but johnny come lately is right?
Get a Life.

Dave,
Why have you stopped using the name we all know you by
and have grown to luv --> "0ziExplorer"