Jump to content

Charging


Guest

Recommended Posts

Would this work?

A small solar panel plugged into the 12V cigarette lighter outlet in the cockpit, leave the appropriate switch on and the house battery switch on. Will this feed the battery?

Link to post
Share on other sites

You would be better to wire it directly to the Battery. Solar panels can produce quite high voltages that can damage electronics. If you were to accidentally switch off the house battery isolation switch, any other electrical equipment on the same circuit could get damaged as the voltage spikes (assuming you didn't have a regulator).

Link to post
Share on other sites

They sell small panels that come with plugs to do just what BM wants to do. They put out bugger all, but do keep the battery from self dishcharge of periods of little use. Of course there are better options, but are there simpler or cheaper ones? Probably not.

Link to post
Share on other sites

Hey Clipper I'm not saying it can't be done, just be careful. I have a small solar panel wired to my start battery for exactly that purpose. No regulator required because it is quite small. Personally I wouldn't every put it on the other side of my isolation switches, but that's me.

 

Solar panels can create voltages > 18V, especially when no or limited current is drawn from them. When the battery is connected it acts as a sink and regulates to something more reasonable.

Link to post
Share on other sites

There is a slight draw, the LED on the panel which will glow brightly when it's sunny. Of course this will also draw at night but I think it's pretty negligible. I guess it would be better through a regulator but this seems pretty easy. I'll know next time I'm on the boat as last time I got a low battery warning from the instruments after not using the panel. It's only on the house at the moment as I was worried that it might make matters worse with the panel light on all night and I wouldn't be able to start the engine. But if it works I'll link them.

Link to post
Share on other sites

I have a 5W small one to keep the battery up, which it did nicely. Wired direct to battery.

 

Then I dropped on a 40W for extra juice while cruising so had to add a tiny MMP controller, so I didn't fry the batteries. So I wired the 5W up to run thru the controller as well. Now the small panel will put a fair, knot large but noticeable, charge into the battery.

 

Last week came home with the meter reading 12.3V. Small panel on all week and yesterday the meter was reading 'chocker full'. Knot too shabby and far better now it runs thru the (cheap and real easy to fit) controller.

 

Mine are wired direct to the battery via the controller. The battery has a isolator switch which means nothing can get out but the panel can get in. Nothing out means I know nothing can start, run, leak and the likes. That includes trying to remove body parts from any unsuspecting person working on the bow when they bump the winch switch only to find the anchor winch all powered up :?

 

The 5W I have is a BP and I have seem 23.something Volts coming out of it on a good day. Watch for that as 23 is well above 12 so as mentioned by F above, unless that is controlled you could easily feck something. Some fittings these days have minimal wire size. Thinking heat, melt, short and I'm sure 23V is more than enough to start a FIRE!!!!!

 

And don't forget all panels are rated at the World Standard of 1000 Sun bugs hitting a square metre. In NZ we actually run an average of 1250 sun bugs per sq/mt. That means a panel rated at 100W when used in NZ is actually more a 125W. So the output we get is higher here meaning if your wiring and bits are rated to the same as the panel the wiring and bits are actually undersized.

 

Having done a lot with 12V over the last year or so I would always run a controller now. The potential damage and battery life shortening costs are a lot higher than the cost of a decent controller.

 

The MMP (MMPT??) ones are the go. D1's micro dwelling panel was still pumping 14.4 volts into her bank at 8.15pm the other evening, no way you can sneeze at that.

Link to post
Share on other sites

Most small controllers seem OK. You can get a simple one that will take upto 70W worth of panels for $40 odd. Goes upwards from there depending on how fancy you want.

 

If it's just a float charge to keep the batteries up, you don't need to go fancy. D1's dwelling was running thru this http://www.dse.co.nz/dse.shop/4d0557bf011202bc273fc0a87f3b0632/Product/View/O3356 Dicky Smith one for 6 months, it worked well. It's a low level fancy one that has a full charge and a float charge (automatic). Now upping the input to allow for mission critical hair dryers so have gone fancy.

Link to post
Share on other sites

KnotMe deals with an importer that supplies regs and panels and you name it. He can gets stuff cheap, so give him a yell. He has a bit of experience, so should be able to source the right size for you. But if he isn't sure, I have can advise and he can order. Just need to know panel wattage.

Unfortunately the reg for the Alt won't work for the Solar panel.

 

Do be aware that the wee baby solar panels will work OK at keeping a battery trickle charged. But never let the battery deeply discharge and expect the baby panel to pull it back up. The deeper the bank discharges, the greater the load on the panel becomes and it gets to a tipping point of where the panel will not lift it. The new generation Calcium/Lead batteries are very bad. New Generation does not mean a good battery. Calcium is being added to the lead in many Batteries today, to make the lead go further and thus make a cheaper battery. It doesn't make a better battery though. And in fact a Dead flat battery can actually be very difficult to charge with anything. Some require special Mains Chargers. But that is getting side tracked from the discussion.

Link to post
Share on other sites

Hi ya,

for what its worth....

I have A seperate engine start battery and a set of house batteries. The engine alternator and solar panel feed into the engine battery. Solar panels have a regulator. The engine battery is connected to the house battery with a combiner/isolator. This lovely bit of gear allows the engine battery to fully charge before then connecting to the house battery. It will not allow the house battery to draw down on the engine battery. My wind genny (Jenny to all on board) delivers the bulk of our needs straight into the house batteries. (also regulated).

You can get solar panel regulators that will run up to 15 amps very cheeply. Dead simple to wire up solar panel in / battery out. Led light on means charge coming in. I have a 10 watter, on my neglected other boat that keeps the battery topped up so that the bilge pump stays in operation. Has been doing this for ten years.

Link to post
Share on other sites

It's only a 10W panel but it's pretty sunny these days. Now I'm a bit concerned that I really do need a controller. As you say, I'm not expecting it to charge from flat. Ran the motor for 40 minutes then hooked it up and crossed fingers.

Link to post
Share on other sites
AA0348 12V 5A Battery Charging Regulator for Solar Panels

Designed for efficiently charging 12V batteries using solar cells rated up to 5 amps. It is easy to wire up, prevents battery discharge during low ...more

 

RRP: $29.95

 

just as an example...about $18 Oz wholesale...

Link to post
Share on other sites

I think my setup is similar to idlerboat. I've an engine and house battery, wired to a BEP panel with VSR, engine start and emergency parellel switches. I guess that if I ran a solar set up to the engine battery that once it was full the VSR would switch the charging across to the house battery???

Link to post
Share on other sites
KnotMe deals with an importer that supplies regs and panels and you name it. He can gets stuff cheap, so give him a yell. He has a bit of experience, so should be able to source the right size for you. But if he isn't sure, I have can advise and he can order. Just need to know panel wattage.

Unfortunately the reg for the Alt won't work for the Solar panel.

The stuff we have is pretty serious and priced accordingly even if sharp for serious stuff. BM doesn't need so serious in this application hence Dicky Smiths, JayCar or most marine shops probably, will have small and cheap.

 

A 10W panel should be controlled from everything I've seen. On a good day in NZ sun it could be running at 13W, maybe a smidgen more and be banging out 21-24Volts or in other words banging out enough to cause bad things to happen, maybe knot short term but longer term for sure. Generally 99% of the 'experts' I've seen and spoken to say about 7W is the largest you should run without some sort of control. So in NZ speak that's a 5 Watt panel max. That is assuming zero drain on the batteries while unattended on the panel/s for a while.

 

Don't forget a un-controlled panel will just keep pumping juice into the battery even if they are 100% charged, over charging isn't a good thing. A 10W panel probably doesn't have the grunt to boil a battery but I'm sure the batteries will be starting to bitch hard all the same. A controller will sense the battery state and adjust the charge to suit i.e. when they are full it'll shut the input down, when the battery drains a little it'll turn back on to top them up. Just think of a controller as the same thing as the fuel nozzle on the diesel pump when filling the tanks. If that nozzle is locked on and has no one watching, what's the outcome? A nasty expensive mess with the possibility rising very fast towards BANG.

 

Most controllers also sense what type the batteries are and will adjust between the 2 most usual charging rates, being 14.4 and 13.8 volts. Knot all batteries like 14.4 volt input rate but some do to get full charge. Some like only 13.8 and pouring it in at 14.4 will hurt their longevity.

 

I don't think I've seen any controller so small it couldn't run a 10W panel.

 

The one on my beast is a Sunguard 4.5Amp. That will run the 5 and the 40W panels at the same time even if it only ever has once. NZ cost around $60 ish I think.

 

As mentioned earlier my 5W panel now puts more back into the battery thru the controller than it did without the controller. What's more is my 120aHr battery is 4 years old and gets drained and refilled a lot due to our dodgy and part time charging systems. Checked it last week and it's saying it's still at 100% capacity, which is pretty bloody good these days of knot so flash batteries. The battery is a Amptech as recommended by and purchased from Sailors Corner. By joves they were right, it has proved tuff enough to handle me :) :)

 

Yes if all batteries are linked (properly) they should all charge at the same time. By 'properly' I mean all are the same type. If you have a mix and match it still will but may knot be quite so effective but will still work. The 2 input leads connect to the terminals the 2 output leads attach to.

 

My starting bank is actually powered by Stieny Pure amongst others or Mt Gay rather than lead and acid. So I don't have to worry about switching between house and start banks :thumbup:

 

Why knot wire in a dedicated plug, could be a ciggy plug, somewhere in the cockpit and wire it direct to a controller then on to the batteries. Panel out and plug into that socket, easy clean neat and can be tweaked to make sure the wiring is up to it with minimal loses or increased side-effect risks. Doesn't have to be a huge plug or wiring for 10W or even 40W. When my cockpit change happens that's what I'll be doing.

 

And in Auckland all panels will produce the best output if faced North (around 350 degrees really) and angled at 36 degrees. Panel tilt is usually the same as the latitude at which it is sitting.

Link to post
Share on other sites
BM doesn't need so serious in this application hence Dicky Smiths, JayCar or most marine shops probably, will have small and cheap.

No they don't. That's why I suggested you KM. What you can supply is better quality, and at the very least, the same price if not cheaper. Trust me, I have looked.

A 10W panel should be controlled from everything I've seen.

Yes, although it does depend on the battery bank size. 10w unregulated will happily run 400Ahr, but would boil a 200Ahr bank. However that is not the real reason why a regulator should be used.

 

24V seen on the output of a panel is ONLY the Open Circuit voltage. That voltage drops off very quickly as a load is connected. The load in our case of course is a Battery bank. A Battery is a hefty load to a Solar panel. In fact the Battery is seen as almost a dead short to a panel. As the battery itself drops in charge level, that load also becomes greater to the Panel. Now this is where a Panel differs from all other charging devices and why we have to have a special Charge regulator for a Panel as against a wind gen for instance. The result is that the voltage is dragged way down on the panel and even in the bright Sun on the Longest Day in the Sahara desert, the Panel will be producing nowhere near its rated power. The load has to be just right for the Voltage and Current to be the highest it can and thus produce the greatest output it can.

The regulator isolates that panel from the battery and provides a far more respectable load to the Panel to work into. But there is one other issue with a Panel output. The current and the Voltage is not linear. In fact the two vary wildly. Just because it gets sunnier, does not mean the Voltage increases or the Current increases. The two waver, although independantly of one another. The Current output will remain resonably linear. But that is no help to a battery. I have said this before in a similar discussion we recently had, this is where the MPPT regs come into their own. "Multi Power Point Tracking" and what those clever little devices do is use the Voltage and the Current to produce a linear Current at a set Voltage. Don't get me wrong, Pulse Width Modulation also works very well and is quite adiquate in most situations. But the MPPT will take your panel that next step in getting the most out of it. Which ever though, either reg isolates that dead short the battery represents and provides a much better load to the panels so as they will be far more efficient in producing a charge current.

So realisticaly, a Panel with no reg will struggle to get a battery up high enough to be in any danger of damaging electronics. If the panels are big enough to do so, then the first thing that happens is that you batteries are Boiled or Gassed which ever hemisphere you come from. This results in the Liquid disappearing all the time and no liquid over plates is not good for them.

 

Now the batteries. Right, first thing to understand, a Battery does NOT store electricity. It stores Chemical energy. I will come back to that further down.

Knot Me was very correct in his comment about different types of batteries require different Voltages. In fact it is far more complex than even just that.In this instance, I am talking about FLA (Flooded Lead Acid). In a Car, Alternators are set to 13.8V. This is fine for Cars and the manufacturer considers that a battery lasting 5yrs is ideal. 13.8V will never fully charge a battery. FLA batteries provide some difficulties as there storage charge increases. This is because the Energy being stored is infact Chemical energy. As I said above, Batteries do NOT store electricity. A chemical reaction produces a flow of electrons. As the chemicals are converted, the Electrons keep flowing till all the reaction has used up the availabe Chemicals. But connecting a charger and putting electrons back into the battery, we reverse that chemical reaction and the Chemicals are changed back again.

But like all things of this world, nothing is ever simple. Nothing ever happens for nothing. Nothing is ever perfect. There are always losses in everything. The Battery losses a little of itself each time it discharges and charges. But the main point we all a concerned with, is that the Chemical reaction is not straight forward and linear. Hence why Multi Step charging is all the rage these days.

3 Stage charging is a must if you want to get the most form you bank and also keep that bank for as many years as possible.

The first stage in these devices is "Bulk" charging. This is where 80% of the batteries charge is Kicked back into it. The next stage is "Top up". To get the chemicals to continue to react, the Voltage must be increased. It can sometimes be increased to 15V or more. This is done to get that last 20% back in, then the charge current is dropped to a "Float" charge. The float charge is normally 14.2 to 14.4 V depending on the battery type.

Link to post
Share on other sites

Archived

This topic is now archived and is closed to further replies.

×
×
  • Create New...