solar cell

Submitted: Saturday, Apr 17, 2004 at 22:04
ThreadID: 12143 Views:2471 Replies:14 FollowUps:23
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I want to run a 50 litre Engel fridge plus a couple of flouros from a gel cel deep cycle battery behind the cargo barrier which is charged from a solar cell.

Could you suggest the minimum size solar cell?

What's the latest best deals of solar cells and deep cycle gel cells?

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Reply By: Member Eric - Saturday, Apr 17, 2004 at 22:14

Saturday, Apr 17, 2004 at 22:14
Keep an eye on my post on solar cell Jimbo . I got my hands on one , now looking at finding out what i have lol . Once i figure it all out ill post it here . The one i removed had the specs posted on the solar panel question . The battery was fitted behind on of the draws in the rear . The draw was shorter to alow this . The bloke I got the car off , also ran a inverter of the same set up , it was 800 watt inverter .
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Reply By: William - Saturday, Apr 17, 2004 at 22:21

Saturday, Apr 17, 2004 at 22:21
Jimbo it really depends on how and when you want to run the fridge.
In summer if you are prepared to change the angle of the panel during the day, you may get away with a 100w panel, but would preferably recommend 120w panel. In winter you would need a minimum of 2 x 100w panels.
For others with a 40 litre Engel or 50 litre Evakool you may get away with 1 x 80w panel and 2 x 80w panels in winter.
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Reply By: Jimbo - Saturday, Apr 17, 2004 at 22:24

Saturday, Apr 17, 2004 at 22:24
Thanks for that. I did a topic search but couldn't find an answer to the specific question ... what's the minimum wattage to run a 50 litre Engel?
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Follow Up By: Jimbo - Saturday, Apr 17, 2004 at 22:39

Saturday, Apr 17, 2004 at 22:39
Oh dear ... that much, eh? Far too expensive for me. I was hoping to get away with a 40 watt. I guess I'll just have to go back to my orignal plan of carrying as much stored battery power as I can and plan the trip accordingly. I's a Jackaroo, you see, and an under bonnet dual battery set-up will be just too far away from the original under bonnet setup. I can get a 70 amp hr deep cycle gel battery for $300. My plastic battery box will take a battery 195 mm high x 300mm long x 170mm wide. I asked the battery man for a price on a 200 amp hour deep cycle gell cell and he said over $700 plus it would be a huge battery. But an old ad from someone in Victoria offerred a 200 amp hr deep cycle for $300!
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Follow Up By: William - Saturday, Apr 17, 2004 at 22:49

Saturday, Apr 17, 2004 at 22:49
Jimbo gel cell batteries have little capacity bang for the buck. If you use the correct size cable it is no issue whatsoever mounting the auxiliary battery in the back of the Jackaroo. If you are prepared to wire your vehicle correctly and shock horror happy to manually change a switch, you can effectively get a decent setup quite cheaply. I would go for a lead acid battery every day over a gel cell.
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Follow Up By: Roachie - Sunday, Apr 18, 2004 at 21:00

Sunday, Apr 18, 2004 at 21:00
G'day Jimbo & William,
I agree with William about the GelCell's being a bit over-priced as far as output per dollar is concerned. I've also decided the solar panel system is pretty bloody fiddly and I've steered clear thus far. I am fortunate that I could fit a 2nd batt under the bonnet (GU 4.2 t/d), but do reckon you'd be okay having a batt in the cargo bay and running heavy cable from a manually operated isolator, via a fusible link. Only problem is that I'd be a bit reluctant to have a "normal" batt in the cab area due to possible gas discharge. I run a Exide Orbital in my camper trailer and have it wired up to 2nd batt in truck....works well but only has to run a few lights and a water pump.
Jimbo, I didn't know Engel made a 50 litre fridge???
Cheers,
Roachie
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Reply By: ianmc - Saturday, Apr 17, 2004 at 22:32

Saturday, Apr 17, 2004 at 22:32
I agree with Willem on that as I have used a 60-70 watt panel which in cloudy days does drop its output substantially. Must have generous cable sizes and as short as possible to reduce resistance & loss. Probably need 2 panels as quoted by Willem & good exposure to sun.
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Follow Up By: ianmc - Saturday, Apr 17, 2004 at 22:34

Saturday, Apr 17, 2004 at 22:34
I qualify that post as U did not say how long you would remain stationary between runs. One panel to top up may be OK if you are not more than 2-3 days between trips.
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Follow Up By: William - Saturday, Apr 17, 2004 at 22:50

Saturday, Apr 17, 2004 at 22:50
IanMC 2-3 days is to much, 1 to 2 is better at max otherwise the auxilliary battery gets down too much and will not last.
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Follow Up By: Jimbo - Saturday, Apr 17, 2004 at 23:01

Saturday, Apr 17, 2004 at 23:01
Our last trip from Central West NSW to the Flinders & Innaminka was 14 days. Max 3 days in one spot then ran the fridge from the main battery while driving all day. Had powered sites for all except Flinders (3days)and Coopers Creek (2 days). Our small 38 amp hour power pack lasted around 12 days but flattened the poor thing. There's always the little gennie, I spose, but there's always the chance of a flying beer can, eh!
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Reply By: Jimbo - Saturday, Apr 17, 2004 at 23:06

Saturday, Apr 17, 2004 at 23:06
Every bit of advice I've ever had said never put a wet cell battery behind the cargo barrier, battery box or not. All that acid flying around in a prang is a scary thought.
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Follow Up By: GO_OFFROAD - Sunday, Apr 18, 2004 at 16:03

Sunday, Apr 18, 2004 at 16:03
Its not only the battery acid in a crash in the back which is an issue, but the flammable fumes when charging that the battery puts out.

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Reply By: Jimbo - Saturday, Apr 17, 2004 at 23:34

Saturday, Apr 17, 2004 at 23:34
Have a nice life, William. No wonder the 4x4 fraternity has to work so hard at retrieving our reputation.
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Follow Up By: Andrew - Sunday, Apr 18, 2004 at 00:04

Sunday, Apr 18, 2004 at 00:04
hahahaha.

tosser
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Follow Up By: GO_OFFROAD - Sunday, Apr 18, 2004 at 16:01

Sunday, Apr 18, 2004 at 16:01
William,
Good to hear what you have to say, but perhaps in a topic to do with what you have to say would be good.
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Reply By: Member - Nigel (QLD) - Sunday, Apr 18, 2004 at 18:36

Sunday, Apr 18, 2004 at 18:36
I put a powerdive AGM in my camper trailer, as they are lighter and more rugged than gel cells.
AnswerID: 54838

Follow Up By: Jimbo - Sunday, Apr 18, 2004 at 19:29

Sunday, Apr 18, 2004 at 19:29
Talk about a solution staring a bloke in the face! We pull a camper, too! Never thought of putting a wet cell deep cycle in the camper! Ah! A whole new area to investigate ... AGM, you say ... Thanks, mate.
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Follow Up By: Member - Nigel (QLD) - Sunday, Apr 18, 2004 at 21:24

Sunday, Apr 18, 2004 at 21:24
my dad just bought a slightly smaller powerdive AGM (98 Ah) for the back of his rodeo for $309. Coz they are designed to go in the bilge of boats they are fully sealed and compliant with all the marine regs, so plenty safe enough for the 4by
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Follow Up By: The Publican - Sunday, Apr 18, 2004 at 22:37

Sunday, Apr 18, 2004 at 22:37
AGM batteries explode
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Follow Up By: Member - Nigel (QLD) - Monday, Apr 19, 2004 at 08:41

Monday, Apr 19, 2004 at 08:41
as do all batteries and so do LPG cyclinders
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Follow Up By: Member - Nigel (QLD) - Monday, Apr 19, 2004 at 14:43

Monday, Apr 19, 2004 at 14:43
I did a bit more research on AGM's and the only cases I could find of AGM's exploding is when "thermal runaway" occurs. This can occur when the battery is being charged and is extremely hot (eg in the engine bay while driving slowly). This can cause the battery to keep accepting excessive amounts of charge until the molten contents of the battery are expelling through the vents.

This site has a good run down on deep cycle batteries (from a resellers perspective :)
http://www.wind-sun.com/Batteries/Battery_FAQ.htm - it states that "AGM's do not have any liquid to spill, and even under severe overcharge conditions hydrogen emission is far below the 4% max specified for aircraft and enclosed spaces. The plates in AGM's are tightly packed and rigidly mounted, and will withstand shock and vibration better than any standard battery."
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Reply By: Jimbo - Sunday, Apr 18, 2004 at 18:40

Sunday, Apr 18, 2004 at 18:40
GO_OFFROAD ... how do you feel about sealed batteries behind the cargo barrier?
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Follow Up By: GO_OFFROAD - Sunday, Apr 18, 2004 at 22:20

Sunday, Apr 18, 2004 at 22:20
sealed as in maintenance free, or sealed as in fully sealed with no breathers, like a gell cell?
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Follow Up By: Member - Nigel (QLD) - Monday, Apr 19, 2004 at 10:27

Monday, Apr 19, 2004 at 10:27
Flooded cell batteries will always create hydrogen and oxygen gases (and in greater quantities if overcharged).

VRLA (valve regulated lead acid) batteries such as AGM or Gelcells will only release gas if they are not charged correctly - check with the manufacturer as to how the batteries need to be charged, but many (esp gelcells) won't like being charged directly by an alternator - they will need further regulation.

AGM batteries were designed to bring together the benefits of normal and gel batteries - and in some cases they acheive that goal :)
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Reply By: tessa_51 - Sunday, Apr 18, 2004 at 18:41

Sunday, Apr 18, 2004 at 18:41
william you are annoying me please go away
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Follow Up By: Jimbo - Sunday, Apr 18, 2004 at 18:48

Sunday, Apr 18, 2004 at 18:48
Lordy! Ressa_51, don't encourage him! Still, I can't help wondering ... are you there, William? Wi-ll-iam?! ... How DO you get your fun out of life if you're not into 4x4? Why are you hanging around this site waitng to bite someone? I really do mean it, William. I DO wish you a happy life ... put a smile on yer dial, mate!
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Reply By: Jimbo - Monday, Apr 19, 2004 at 11:48

Monday, Apr 19, 2004 at 11:48
Thanks for all that advice, people. You can see I'm a complete dill when it comes to anything electrical. I think the solution is to give the solar cell idea away completely; put a deep cycle wet cell in the battery box in the camper trailer after I find out more about what "sealed battery" means; continue with the strategy of carrying as much stored electricty as I can. Thanks Roachie, yes it is a 40 litre Engel ... I was just trying to give a rough idea of our 12v requirements. Incidentally, we did manage to squeeze 10 days out of the 38 amp hour battery pack. Obviously, while we were driving we we charging it from a cigarette lighter socket behind the cargo barrier and running the fridge from another socket, constantly swapping leads and sockets over, topping up the battery pack with 240v when we had powered sites, etc etc. But as I say, ran the poor thing flat.

One last question ... if the 38 amp hour battery pack was say 30% full, how long would it take to charge it from a cigarette socket while driving at say 80-90 km hr? Is it really an effective way to top them up or were the 240v top-ups the more likely way I was keeping it going?

But then again ... seems you'd have to have that battery fairly well secured in the camper, eh? Maybe have to think about the draw bar ... all that hydrogen etc. ... and a chain and padlock ... what do motel rooms cost at Innaminka!!? :-)

Cheers Jimbo

ps keep smilin', William!
AnswerID: 54946

Follow Up By: Member - Nigel (QLD) - Monday, Apr 19, 2004 at 15:06

Monday, Apr 19, 2004 at 15:06
most of those low AH battery packs use a slow charge system (around 1 amp) so would take approx 30 hours to recharge from 30% to 100%.
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Reply By: Rosscoe - Monday, Apr 19, 2004 at 14:32

Monday, Apr 19, 2004 at 14:32
Jimbo,

Colyn Rivers has written a book on both Caravan and Motorhome Electrics and Solar. Well worth the read. I think the website is:-www.caravanandmotorhomebooks.com.au.
Word of caution. I have an electrical background and I found I had to read the books two times before I stared to understand what he was on about (Maybe I'm slow)
The general thrust of his books is that you can never charge a battery from the vehicle alternator/voltage regulator system to more than 80% (some reckon 70%). AND if you want your battery to last longer than a couple of months you never discharge it lower than 40%.
So, of your 38AH unit you effectively only ever have just over 15 AH available at anyone time.
Colyn strongly advocates Solar and gives you enough info to calculate what size Solar panels you need. Expensive though, methinks.
I'm currently investigating the ARRID TWIN CHARGE unit which the manufacturer claims will charge the aux battery to 100% and operates between 8 and 15 V DC. It uses "pulse technology" which is said to help prevent sulphation of the battery plates and extend battery life
I bought a Low Batterry Cutout by the same manufacturer at the show on Saturday.
Like most things with camping/4wding it's a compromise and dollars play a big part but if you know the limitations of your equipment and can understand a bit about why things behave as they do it helps. At least that's my opinion.
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Follow Up By: Member - Nigel (QLD) - Monday, Apr 19, 2004 at 14:53

Monday, Apr 19, 2004 at 14:53
3 common ways to charge a battery to 100%:

* use a good mains charger regularly.
* carry sufficient solar panels.
* upgrade the regulator on your alternator to an expensive 3 stage regulator

I'd be interested to hear how the twin charge goes if you get one - they do look like a good product.

One advantage of AGM's is that they can charge to almost 100% off a 14.4-14.8v system, whereas a wet cell will only get to 70%

I've got Collyn's book and definately recommend it for factual advise on mobile systems.
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Follow Up By: Rosscoe - Monday, Apr 19, 2004 at 15:28

Monday, Apr 19, 2004 at 15:28
Hi Nigel,

I put a post on the forum about the ARRID and have a response. Sounds like this unit has a good reputation. Only down side is the driving time it takes to fully charge the battery. That maybe a function of the deepcycle battery rather than the unit, perhaps.
Still going to investigate the $78.00 option!
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Follow Up By: Member - Nigel (QLD) - Monday, Apr 19, 2004 at 15:37

Monday, Apr 19, 2004 at 15:37
it will be limited by the amount of current the electronics in the box can support - yes it is a bit on the expemsive side (tho not compared to good quality 3 stage alternator regulators, which are far beyond the budget).
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Reply By: Jimbo - Monday, Apr 19, 2004 at 21:59

Monday, Apr 19, 2004 at 21:59
Geez, people. I think I'll go back to powdered milk! So a wet cell only charges to 70%! Crikes! I found a nice 75 amp hr Exide today for $125 ... 70% = about 50 amp hr ... I can only run it down to 30% ... that's gives me 40% between 30% and 70% ... so 40% of 75 amp hours is about 30 amp hours ... but he fridge taked 2-2.5 amps per hour ... so that gives me ballpark of about 12 hours of chillin!

Hmmm ... 2 bags of ice fills the esky ... can't always depend on powered sites where we want to eventually trek ... I'm back to the little Chinese gennie again!

Many years ago in a silly spasm of youthful spontaneity, I ran away and joined the army and found myself at RAEME Bandiana doing a Radio Tradesmans course with a poor National Serviceman electrician up the front filling the blackboard with drawings that looked a bit like city maps and asking me what the resistance would be across the thingo in the bottom left hand corner! ... that's when I ran away to officer training school ... but that's a whole new and even sadder story! :-)
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Follow Up By: Jimbo - Monday, Apr 19, 2004 at 22:50

Monday, Apr 19, 2004 at 22:50
Ahah! Re-reading all this great advice, if I use a mains charger, I can recharge a wet cell to 100%
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Reply By: Jimbo - Monday, Apr 19, 2004 at 22:14

Monday, Apr 19, 2004 at 22:14
Back to the sealed 38 amp hr battery box : charging it with a charger running from the gennie ... I can't get to the battery terminals so do I just hook the charger leads up to the battery box's jumper leads to charge it?
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Follow Up By: Member - Nigel (QLD) - Tuesday, Apr 20, 2004 at 08:34

Tuesday, Apr 20, 2004 at 08:34
If it's a gelcell it won't like being charged by a charger designed for wetcells and will most likely form bubbles between the plates and the gel, reducing your batteries capacity. If it's an AGM then should be right.

Some chargers have a switch for gel/wet battery selection so can do either type.
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Reply By: Jimbo - Saturday, Apr 24, 2004 at 19:16

Saturday, Apr 24, 2004 at 19:16
Thanks, Nigel. That's an expensive battery pack that almost bit the dust. Thanks all for your patience and great advice. Jimbo
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