Dual Batteries or one single

[megatexture]

Yea if I was going to be that concerned i would buy a management system. Though with everything I have running off my batteries I don't expect my batteries to reach full charge during the day, I just like to see either that my alternator or solar panels are functioning correctly and that my batteries don't go below 11.8 and are above 12.2 minimum after dark if so I adjust my consumption.

[Cuppa]

Sounds like you have the familiarity with your system that I referred to MT.

In my case (in the bus - haven't used the Patrol enough to gain that familiarity yet) I expect to see the battery voltage at 12.6 or 12.7 after dark without the fridge cycling on. Most mornings before dawn & with the fridge not cycling on I expect to see 12.4v or 12.5v. Lowest it has ever been is 12.3v (reg has history since installation) & that was after a week of poor solar weather. My wife has been living in the bus for the past 3 weeks & has been recording these voltages & they are still remaining pretty constant, not bad for batteries & panels now approaching 9 years old!
This is a standalone solar system 300ah/375w running a 130 litre fridge, water pump, extractor fan, lights, radio/cd, phone & computer charging via an inverter & satellite tv via another inverter.

[Mitch.mccabe]

Thanks Cuppa, I knew you would spell it out for me in an easy to understand way, Since i'm really only using Led lights, and maybe a Waeco fridge, then my 130 amp hour AGM battery shouldn't get to stressed.
Cuppa, With the AGM batteries are you only suppose to run them down to half? so i would only have 65 usable amp hours when it is full. Is that correct?
I remember seeing a chart somewhere or calculator? for energy consumption?

If i can have the solar system on every afternoon and can use the 240v 25amp ctek every 5 days or so to fully charge it up I shouldn't have an issue.

I'll put up some pic during the construction of my battery box, Still trying to decide whether i'm mounting it under the bed in the camper, or buy a new lockable box and mount on the front of the camper?

[Cuppa]

Yep, 50%. They can handle 40% reasonably well, the important thing is not to leave them in a discharged state, if you can recharge within 24 hours you should ensure a long life. One reason (there are others) I have more battery capacity & the means of recharging them on a daily basis is so that they dont generally get discharged below 70% which should make them last even longer. 50% is a reasonable compromise. Your plan of attack sounds pretty reasonable given the space & weight constraints in a 4wd.

Given the battery weight of 35kg to 40kg keep your camper's weight distribution in mind when deciding where to put it. Also make sure you have sufficiently heavy cables between battery & fridge. Many fridge problems are caused by too light supply cables causing voltage drop & use circuit breakers rather than fuses. (Just lately I have heard several accounts of melted cables, one causing a fire, resulting from blade fuses which developed 'high resistance' without blowing).
Also don't use the thin cables supplied with many solar panels, invest in some thicker ones. There are charts on the net to suggest what gauge wire to use with what size panel/cable length. http://hobohome.com/news/?p=581

Whilst I'm at it here is a rather neat, easy to understand explanation of why voltmeters are not a reliable means of determining a battery's State of Charge I came across whilst looking for that solar wire gauge table. I thought it worth sharing. http://hobohome.com/news/?p=685

[Mitch.mccabe]

http://www.ebay.com.au/itm/281162804...84.m1497.l2649 Cuppa this is the solar unit I bought, I know you cant see the cable size, but shouldn't I just be able to hook this up straight to the battery? I was going to change the clips (of the solar unit) with an Anderson plug so when I'm charging the battery I can disconnect from everything else. I might draw up a bit of a diagram and post it on here to see if I'm on the right track or if I'm going to zap myself. haha,
By one of those tables , I have 160 watt solar panels, with a 5 mt cable , so I'd need to make sure that the cables are 4mm? is that right?

[megatexture]

Bit deals panels aren't too bad, a few mates have them but you will still benefit from a wire upgrade. I'm running 8mm on mine and I have 2x 10m (if needed but rarely used)extensions as overkill because not every campsite is ideal. Work out the recommended and add to it IMO, but that panel has got a reg though probably not a great one but it can go straight on your battery.

[Cuppa]

http://www.ebay.com.au/itm/281162804550?ssPageName=STRK:MEWNX:IT&_trksid=p398 4.m1497.l2649 Cuppa this is the solar unit I bought, I know you cant see the cable size, but shouldn't I just be able to hook this up straight to the battery? I was going to change the clips (of the solar unit) with an Anderson plug so when I'm charging the battery I can disconnect from everything else. I might draw up a bit of a diagram and post it on here to see if I'm on the right track or if I'm going to zap myself. haha,
By one of those tables , I have 160 watt solar panels, with a 5 mt cable , so I'd need to make sure that the cables are 4mm? is that right?

Hi Mitch,
I would agree with what MT has said. Rich panels are of reasonable quality, but like all of the panels being sold cheaply on ebay there are major compromises in the bits they include with them. IMO you buy the panel with the view that the other bits are throwaway items. Considering how much the cost of panels has dropped I can live with that. The kyocera 125w panels i have on the roof of our bus cost me over $1100 each almost 10 years ago, without any cabling or regulator. The regulator cost a further $600.
The advice to have longer cables is good, it is not uncommon to need the extra length when you want to park in the shade & have the panel out in the sun. I have 10 metres for the Patrol, would like to have MT's extra 10m, but because I am using 13mm cable (for 300w portables) 10m is the compromise due to weight. Upgrading to 10m of 8mm cable would be worthwhile for you. Bear in mind that 8mm relates to the cross section of copper in the cable, NOT including the insulation. Many people buy autocable which includes the insulation in the measurement, & has significantly less copper. Eg. 6mm autocable is actually only about 4.6mm copper.
The included regulator will also be worthy of replacing for two reasons. Quality & positioning.

Quality - there is a reason why you can buy this sort of regulator for $10 to $20 but pay several hundred dollars for other regulators. Basically like oils ain't oils, regulators ain't regulators. What you have will 'work' but spending a bit more will get you something that will work more efficiently & treat your battery more kindly. This Morningstar reg would be a huge improvement (Morningstar make good quality gear) http://www.ebay.com.au/itm/Morningst...7eab36a&_uhb=1 or if you wanted to spend less but with a digital readout (useful) this Steca will do a good job for you. http://www.ebay.com.au/itm/SOLAR-CHA...d34cc50&_uhb=1 At the cost of regulators we are talking about mention of MPPT is no more than a joke. Better to get a good quality PWM reg with temperature compensation.

Positioning. Having a regulator mounted on the back of a solar panel might be convenient for marketing purposes, but it far from desirable as far as charging your battery goes. It will behave according to the voltage it 'sees', which will be quite different at the panel than it will be at the battery, especially if those thin cables are used. We are talking efficiency here, & with the output of a single panel, you want as much of it going into your battery as possible. Therefore it makes sense to have the regulator mounted close to the battery. I would advise you to simply bypass the reg on the back of the panel, instead attaching a short length of cable from the panel's junction box to an anderson plug, & attach to a corresponding anderson plug on the cable you run to the car. You can leave the supplied reg in place, or remove it carefully if you wish.

Posting a diagram would be a good idea to get reassurance I expect.

[megatexture]

FYI links not working cuppa.. Well not for me on safari anyways.

[Drewboyaus]

With a solar regulator, I intend to mount one inside the vehicle, on the cargo barrier I expect. This will top up my second battery, which can only be a max of about 60 odd Ah due to available space, while I am in camp
My question is what happens if I want to use the panels with my battery box if I take the fridge from the car when base camping with the family (the solar input on the ArkPak bypasses the internal charger/regulator)?

Sent from my iPhone using Forum Runner

[Cuppa]

FYI links not working cuppa.. Well not for me on safari anyways.

Thanks MT, not sure what i did wrong. Fixed now.