Solar Panel Battery Recharge

[molongmick]

Hi Everyone,
Just wanting to pick your brains.:icon_bonk:

I was talking to a mate of mine about using a solar panel to recharge/trickle charge the 100amp battery my camping caravan.

The next day he gave me a new 20w mono crystalline solar panel. :clapping:

I have bought a charge controller from Jaycar which drops the voltage to 12v, as the output on the panel is 17.6v.

Will this set up be enough to trickle charge the battery in the van? The only items running off the battery will be lights, soon to be converted to led, small water pump for the sink and the occasional charge of portable lighting.

The battery is set up to charge while driving, so the battery should be fully charged upon arriving at camp site.

What do you think, will this be enough or do I need more?

[Bigrig]

Hi Everyone,
Just wanting to pick your brains.:icon_bonk:

I was talking to a mate of mine about using a solar panel to recharge/trickle charge the 100amp battery my camping caravan.

The next day he gave me a new 20w mono crystalline solar panel. :clapping:

I have bought a charge controller from Jaycar which drops the voltage to 12v, as the output on the panel is 17.6v.

Will this set up be enough to trickle charge the battery in the van? The only items running off the battery will be lights, soon to be converted to led, small water pump for the sink and the occasional charge of portable lighting.

The battery is set up to charge while driving, so the battery should be fully charged upon arriving at camp site.

What do you think, will this be enough or do I need more?

Hey mate - dad has just installed a solar panel for his caravan/battery setup. I can ask him how it's performing for you today and let you know. I'll find out what model etc also to make sure it's a similar setup.

[BillsGU]

It really depends on two things: usage and sunlight. If you start out with a fully charged 100 AH battery and you only use it spareingly, then it should last you for days without any worry. The 20W panel will assist in prolonging the charge in the battery - but at best you are only getting about 1.5 amps out of it. The main problem with solar is that people put their vans in a shed between trips and start out with a less than full battery. Not only does this stuff the battery - but you are always playing catch up to charge it. It is a good idea to buy a 240V smart charger to connect to your battery when it is at home so you ALWAYS have a full battery.

I have a panel on my van and it is great to be independant with power. I can even run the caravan frige on 12V during the day as we are travelling without worrying about a charging system from the car. My panel is 120W though. Panel prices are going down all the time now. It works so well that I haven't used my generator in over two years.

[Bigrig]

It really depends on two things: usage and sunlight. If you start out with a fully charged 100 AH battery and you only use it spareingly, then it should last you for days without any worry. The 20W panel will assist in prolonging the charge in the battery - but at best you are only getting about 1.5 amps out of it. The main problem with solar is that people put their vans in a shed between trips and start out with a less than full battery. Not only does this stuff the battery - but you are always playing catch up to charge it. It is a good idea to buy a 240V smart charger to connect to your battery when it is at home so you ALWAYS have a full battery.

I have a panel on my van and it is great to be independant with power. I can even run the caravan frige on 12V during the day as we are travelling without worrying about a charging system from the car. My panel is 120W though. Panel prices are going down all the time now. It works so well that I haven't used my generator in over two years.

Hey mate - can you throw up some snaps if you get the chance? I will eventually be getting the fridge, and after seeing tuf42's setup, and hearing about yours, I am thinking this is the go.

[molongmick]

It is a good idea to buy a 240V smart charger to connect to your battery when it is at home so you ALWAYS have a full battery.

I can even run the caravan frige on 12V during the day as we are travelling without worrying about a charging system from the car.

Thanks, the van has a smart charger built in, and yes I charge it before we head off. Our fridge in the van is three way and runs off gas while camping, so no need for a great input of power into the battery. I will use a cable and place the panel in a good sunny spot. You are right, the amperage of the panel is 1.26/1.14 amp.

As I said I only want to ensure that the battery is topped up. I am sure I can get another two or three panels for next to nothing off my mate, which would make it 40 to 60 w.

*edit typed battery instead of panel*

[BillsGU]

Hi BigRig,
Haven't got any photos handy - but if you can imagine two roof bars on top of the van - the solar panel fits between them using two lengths of ally angle. The installation was simple - the only trick is getting the cable through the roof without water getting in. I used a gland nut and sealed everything with GoldSeal. I started off with a portable panel - but it was a pain in the end. Now this one just sits there and does its thing.

I did make sure that my solar charger (from Jaycar) and the wiring could handle double the current. If 120W is not enough I can put a third bar on the roof and put another panel bewteen the centre bar and it. So far 120W seems to be plenty.

[Bigrig]

Hi BigRig,
Haven't got any photos handy - but if you can imagine two roof bars on top of the van - the solar panel fits between them using two lengths of ally angle. The installation was simple - the only trick is getting the cable through the roof without water getting in. I used a gland nut and sealed everything with GoldSeal. I started off with a portable panel - but it was a pain in the end. Now this one just sits there and does its thing.

I did make sure that my solar charger (from Jaycar) and the wiring could handle double the current. If 120W is not enough I can put a third bar on the roof and put another panel bewteen the centre bar and it. So far 120W seems to be plenty.

Champion! Thanks for the response mate.

[the evil twin]

That combination will put about 8 maybe 10 Amp Hours a day back into the Battery on a nice summer day. If you are using lighting only and the pump for camping then that will prob keep the Battery up BUT you will need to park the Van in pretty much full Sun all day... 1/2 a day of Sun (say mid morning to mid arvo) will put in about 5 Amp/Hours as the Panel and Angle of the Sun will be at optimum efficiency.

[Finly Owner]

http://www.batterytraders.com.au/solar-product-cat.asp
try link for all brissie boys and tell Lorna, Tim from Kennards sent you.

[BillsGU]

Hi E.T.

Even with and average of 4 amps per hour on a day of say only 6 hours of sunlight, you are still putting 24 A/H per day back into the battery. Mine is usually a LOT more than that.

[the evil twin]

Hi E.T.

Even with and average of 4 amps per hour on a day of say only 6 hours of sunlight, you are still putting 24 A/H per day back into the battery. Mine is usually a LOT more than that.

I agree however his is only a 20 Watt panel flat on top of his Van so he isn't going to get anything like a 4 amp average...

[molongmick]

I agree however his is only a 20 Watt panel flat on top of his Van so he isn't going to get anything like a 4 amp average...


I will be chasing the sun for part of the day with the panel. I think I might have to get a bigger panel by the sounds of things. Thanks everyone for your advice.

[the evil twin]

I will be chasing the sun for part of the day with the panel. I think I might have to get a bigger panel by the sounds of things. Thanks everyone for your advice.

Maybe, maybe not... whilst the 20 will probably not bring the Battery up to 100% State of Charge (SOC) in a day it will go close so will significantly extend the time for the Battery use.

IF you do and IF you are still only powering lighting and water you won't need much bigger IE a 40 would be heaps and should replace the overnight useage and keep your battery at or near 100% SOC.

IF, however, you want to future proof it a bit then maybe go for a 60... depends on your budget

I assume you have a 3 Way fridge in the Van and if that is the case the majority pull heaps of current so running that on Solar is problematic and you are better to keep it on gas.

[trollman]

Fair bit of chatter on batteries so i thought i could offer 2 cents.....

http://i186.photobucket.com/albums/x213/krustytheklown/Picture013.jpg

http://www.amaronbatteries.com.au/

I guess after the 'Union Carbide' disaster in the 80's. R&D was maxed on these. had them for about 8 months now and cant think of any real probs with them. Just replaced my starter motor, so i guess the old starter applied extra work for them. Run a 60 litre engel all day for months at a time, lighting for fishing on beach almost everyday. I would recommend to consider them. But i havent had them long enough to 'Know' just how good they are.

http://i186.photobucket.com/albums/x213/krustytheklown/Picture014.jpg

80 watt solar panel on roof rack.

[Cuppa]

A 20w panel will be fine for 'trickle charging' the 100Ah battery, ie. keeping it topped up when vehicle is not being used. However it is way too small for practical re-charging, it would take too long.

I note that the OP says "The battery is set up to charge while driving, so the battery should be fully charged upon arriving at camp site." This is not quite how some might expect. Consider that to get a reasonable life out of your expensive battery it is good practice not to discharge it beyond 50% capacity. So in a fully charged 100Ah battery you would have 50Ah useable capacity. Further consider that an alternator will quickly bring a battery up to around 70% capacity, but to charge the battery beyond that would require you to be driving for many many hours. Around 70% is a practical expectation of charge from the alternator.(And quite sufficient for starting a vehicle). If you only discharge to 50%, you can see that in effect you are only able to access 20% of your batteries capacity - ie 20Ah in a 100Ah battery! There are a variety of solutions to this problem, which all focus upon more efficient charging of the battery. Essentially, in the absence of sufficient solar input via a reasonable quality regulator you need a multi stage smart charger. The two common ways of doing this are A) a battery to battery smart charger (Eg. Sterling) or a cheaper alternative & widely used in motorhomes B) run an inverter off the cranking battery to power a smart charger to charge your auxillary battery. This will effectively more than double the useable capacity of your battery.
Please note that I am not a battery or solar expert, but have managed to set up a system in our bus that allowed us to be self sufficient off grid for an 18 month around Oz trip.
The following link may explain better what I have tried to say. fridge-and-solar (http://www.fridge-and-solar.net/info.htm)

regards
Cuppa

http://www.nissanpatrol.com.au/forums/images/imported/2011/02/14.jpg