A lot of folks in US believe in about 8 to 10 times the W-hrs to the solar panels. You have 200 W panel, so you want about 1600 to 2000 W-hrs (130 to 167 amp-hours). So that single battery might be enough. More is always better (to limits of pocket book and space/weight/cube of rig)
Reed and Elaine
Just a question on what size battery I should use ....
I have a 70 ltr 12 volt Eva Kool fridge / freezer drawing 2.7 to 5.4 amps of power.
I have a 200w solar panel fitted to the roof of the tug to keep battery charged.
I was thinking of 130 ah (deep cycle AGM ) battery.
would the be enough? As long as the sun is shining
Thanks in advance guys.......Sarg.
I practical terms it should be fine. I have a 120w panel that feeds aux battery (which is my old N70ZZ engine starter battery NOT deep cycle) and it runs 50l Waeco fridge fine (drawing same power as your roughly). If it's cool fridge doesn't run as much obviously and if hot chancer are it's sunny and panel works well.
If need be turn it off overnight and on again next day when solar charging,,,, be practical and guided by theory IMHO.
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Why is it so? Professor Julius Sumner Miller, a profound influence on my life, who explained science to us on TV in the 60's.
Ohhh Ohh forgot to add that I have another 140w portable solar panel to add if needed. And will be getting a small genny.
I would add in another 130ah battery to match the one you have there already... fit it in Parallel connection..
its not a good idea to mismatch Solar Panels... but I would stick with the 200 watt Panel for the moment and see how you go
your fridge should be running a fused system already but make sure you also have a "battery discharge protector"...
-- Edited by Blue on Tuesday 28th of October 2014 09:32:22 PM
-- Edited by Blue on Tuesday 28th of October 2014 10:10:52 PM
Sorry Blue.. and the Other's But I think your statement is a Loaded Question....
1 - you don't take into account the need to recharge the Batteries, as Lead Acids Don't like to be Discharged and not full recharged before they are used again.. ie Try to get the Battery fully charged in the same day period..
It Like Saying.. " OH I don't seem to have enough charge in my battery to run everything.. So I'll just add another battery to cover the Load.." then 6months down the track they say Why is my Battery not holding a charge..
Sarg.. Go the 130Ah Battery if you think that will cover the Load you have.. Remembering that you need to NOT draw the Battery below 50% state of charge...
- Add another solar Panel to your system if you have roof space... [ Remembering that a solar Panel on the Roof is only about 50-70% efficient to a panel that is tacking the sun ]{Yes this is a figure from experience}
Depending on the heat in the area where the Fridge is [ Ability to draw in cool air and exhaust hot air [ Ambient temperature ] the fridge can be expected to run for 1/3 of the day so you can expect to use about 40Ah of Battery.. which should give you a buffer..
So yes try the 130Ah Battery, but at the same time increase the amount of solar you have..
-- also Run a Cable of sufficient size from the battery to the Fridge with Protection[ ie a Fuse close to the Battery ] to help reduce Voltage Drop.. Most supplied Cables with fridges are designed to be short run to the Battery..
Juergen
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IF I say something Dumb.. Just Smack me..
I'm full of Knowledge.. I don't profess to know EVERYTHING, but I'm constantly Learning new thing's..
from my experience I'm just giving a "point of view" ...
I find that you can recharge a 100ah battery on an "approx"100 watt Panel, so adding another Battery to his current system should still be ok while using his 200watts..
its a little light on but this is his cheapest option to see how things "go"
you won't know how things go until he gets "Real life" running and use...
if he has unlimited funds then put in 3 x 130ah batteries and 2 x 200 watt panels..
also
you should never discharge the batteries below "approx" 11.5 Volts and needs to monitor this... to be honest I don't like going too much below 12v
Jurgen, I think you are spot on with the 50-70% efficiency for roof mounted. I have 180 watts roof mounted & the best I can get on central NSW coast is 10 amps (about 66% efficient) This improves going north & decreases going south.
The benefit of roof mounted is that it's there from sun up to sun set, no matter what you're doing.
I run a 32 lt waeco fridge, TV for 2-3 hrs & led lights. This run fine with 100a/h agm battery & 80 watt panel in good conditions. I've added a 105 watt panel for bad conditions. I've never seen the battery below 12.6 volts.
Blue, I think if you run batteries down to 11.5 volt you will considerably shorten the number of cycles you'll get out of the battery. I believe you shouldn't run lead acids below 12.2 volts & agms below 12 volts for maxium life.
Errr... im in no way advocating in any way that you should rum your battery down to 11.5 V ... i said that you need protection to stop it discharging below that...
thats what mist battery protectors are set at... 11.5 maybe 11.6v.. the more expensive battery discharge protectors have adjustable settings on them... id set them at around 11.8v...
btw... i only use GEL batteries for my van
Blue, I think if you run batteries down to 11.5 volt you will considerably shorten the number of cycles you'll get out of the battery. I believe you shouldn't run lead acids below 12.2 volts & agms below 12 volts for maxium life.
Errr... im in no way advocating in any way that you should rum your battery down to 11.5 V ... i said that you need protection to stop it discharging below that... thats what mist battery protectors are set at... 11.5 maybe 11.6v.. the more expensive battery discharge protectors have adjustable settings on them... id set them at around 11.8v... btw... i only use GEL batteries for my van
HI
Then perhaps YOU should be more specfic when giving advice
PeterQ
-- Edited by oldtrack123 on Thursday 30th of October 2014 11:11:37 PM
We are happy for others to answer and save us from doing so - provided they give accurate advice. PeterQ and I have worked with caravans and electrics for a long time. We just attempt to reduce the amount of rubbish that gets posted on forums.
-- Edited by Webmaster on Thursday 30th of October 2014 07:03:50 PM
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PeterD Nissan Navara D23 diesel auto, Spaceland pop-top Retired radio and electronics technician. NSW Central Coast.
As long as the sun is shining 
