Solar / Battery Setup (Top Hat 25!!!)

Hi Toyboata,

Can't comment on all your questions but I have an Adams 28 with a 60w solar panel, an isotherm utecectic ASU fridge/freezer (150lt) and 2 batteries - 600cc 130rc and 720cc 160rc. I have only had the boat for about 18mths. In that time I have never not been able to start the 20hp 3 cylinder diesel Kubota engine never run-out of power. My boat lives on a swing mooring and the 60w panel has always kept the batteries topped up perfectly. I was told by the previous owner that the fridge is extremely energy efficient and the panel is sufficient to run the fridge too. I have to say that so far I have been unable to verify this as I sailed the boat in 2 stages from Esperance to Fremantle and managed to fry (suspected as there is nothing visually wrong with it) the circuit board on the fridge due to a leaky exhaust hose. I have only just replaced the board so we shall see. As the previous owners other claims have been proven to be accurate so far I am inclined to believe him in relation to the panel coping with the fridge.
Hope this is of some interest if not value to you.
I feel a need to add that my solar panel is on a frame so is very rarely in shadow.

Toyboata
WaecoCoolpro21, might be a problem. Thermoelectric Cooler / Warmer
has Peltier device - not a compressor, means amperes thirsty. Can't find
how much. You can try 120 w panel plus 2 sets of batteries , see how you go, monitor voltage, if too low start the engine.

My experience for what it is worth:

I have a Compass 28 which has a 60W solar panel and MPPT regulator for the house battery, plus a separate 5W panel that trickles the start battery, hence they are always as close as possible to 100% charge when I go to sail.

On my multi-week cruises (Bass Strait, plenty of cloudy days) I have found that this set-up comfortably handles the loads, which include tiller-pilot, lights (almost all LED now), VHF, BiData log/depth, GPS/ plotter, laptop and sound system. I monitor things pretty closely as I am a retired electrical engineer and it's all very close to my heart. If I added a fridge I am sure I'd need a bit more solar capacity. However if I was further north (than Melbourne) and sailing during summer I might not need to.

Most small yachts will typically have something like a 80 - 120 Ah house battery. Whilst battery Ah capacity is important, it must be accompanied by adequate charging capacity and over a few days (versus day sailing), the latter is the more critical factor. Measure the current of each your loads in all their various operating modes with your multimeter, then you can compute how many Ah you will use per day (and night), both sailing and anchored, and then will be able to determine how much solar you need. I have found that my panels put out on average about 1/3 their nominal capacity in cloudy weather - ie something like 20Ah per day. This pretty much copes with the load. But when the sun shines the panels provide much more and win hands down.

I am a huge fan of the sealed second-hand UPS batteries that you can find on Gumtree or eBay fairly regularly - Google something like "used 80Ah battery". I have had a few of these and they last for 5 years or more with normal use (including not being run down below about 50% rated Ah). Although they are not designed for engine starting they will cope fine with starting your small diesel and hence can be used for both house and starting. I did manage to kill one by running it flat with the anchor winch (end of long solo passage, exhaustion, brain-dead, should have had engine running with batteries paralleled, but s%#t happens). They sell for about $1 per Ah and are terrific value compared with new batteries.

Make sure you get an MPPT regulator as they will pass about 30% more charge than the cheap PWM ones. You can pay hundreds, but I bought a Tracer brand 10A one over eBay, complete with display, for about $130 and it has served me admirably for 4 years now. I use a cheap PWM one on the 5W starter battery panel, which gives me a spare should the MPPT one cark it.

Your panels need to be "on" all the time during daylight hours, so forget about using folding ones at anchor (especially as the sun sets!). My panels are mounted on a 32mm SS tube, which is fixed to the pushpit and has a tee cross-piece at the top. Simple and cheap, has survived 50kn gusts, and has the benefit of being able to swivel and tilt the panels for best efficiency depending on relative sun/boat angle.

Your hardest task might be to assess the actual daily Ah load of a fridge under the various operating conditions you will encounter. But wtf as my kids say, just start the engine if you have to!
Hope this is of use, good luck with it all,

Graeme

Graeme you've given me a days work in that post! I've been scouring gumtree for a decent house battery.. Plenty there just need to decide what I need. $120 for 120AH and $130 for a new 100W solar panel is looking good! I'll chec my regulator is MPPT.. Seems to do the trick!

Jode5 as much as I'd love an Engel and top of the line matching batteries... Maybe next year $$$$$

I have been using the Century marine range battery from Super cheap auto and found them excellent value and reliable. I have a combination of a deep cycle and starter, both Century. I read a million posts on lead acid vs gel vs lithium vs blah blah blah and just decided the lead acid was (for my needs) the way to go. SCA regularly has them on sale for up to 30% off. You probably pay a bit more for the 'marine' brand because they are blue rather than black.

I do not know or particularly understand the science but different batteries require different types of charge cycles. Might be worth reading up on this before you decide on your battery choice.

Ed

I've done what Datawiz has [power consumption chart] in the past after converting all lights to LED.

We were then surprised to find that the highest consumer was the lights on the switch boards [ex WW]
So we made up a new one without lights! Saved heaps!

I had pretty much decided on a Dometic CFX40 from researching, but the cheapies are interesting & with a $500 saving as a bonus.
Can you plug it in to 240v to test it?
cheers

Both fully charged. I run the diesel weekly so that'll keep then topped up nicely.

Any thoughts on a 100W solar panel? I was thinking about leaving the 20watt panel in place over the Stern and getting a flexible panel for use when cruising.. I'd throw it on the cabin top and only use it for short periods... Any links to proven cheapies?