Hi Woolly,

               300watts is a good sized system. A 30amp mppt regulator is the way to go. Depending on what equipment you are running, you should not have any problems. You have the basics of a good system there. I personally would not worry about the tug charge to the house batteries, I would rather install another battery as the 3 panels will keep 3 batteries happy. Of cause, it depends on whether you have room to install it, I assume you do.

Wooly, if you really wish to get a decent charge into a second battery from the alternator, then you need a DCDC charger.

A direct alternator charge will simply not give you a decent input to a second battery.

There are a number of reasons for this which I will go into if you really want to know, but get the popcorn ready.

You can get something like the Redarc BCDC 1240 which has an inbuilt MPPT solar regulator as well.

Be aware that the similar Ctek unit is not suitable for some vehicles due to their low alternator voltage.

This is the one I have on my Coach, I have 270 Watts of Solar panels,

30 Amp MPPT controller, $40-00 from China,

It puts out more than I can use, It works perfectly, Its connected to the House Battery, The Coach battery doesnt need any thing, 

The main motor pumps out 120 Amps on the alternater, So its allways fully charged, and it also pumps it into the Coach battery as well,

All my Stuff is Chinese, I have had no problems with any of it, It all works, Perfectly,

I have no Genny, No Battery charger, No Invertor as I am going full 12  volt, 

I do have a Pure Sine 5000 Watt Invertor with a 10000 Watt surge cover, With all the Bells and Whistles, Its totally unnecesary now, 

Waste of $500-00, It wont be going in, I dont need it, 

My complete system is 4 Solar Panels, 270 Watts, One 30 amp MPPT Controller, and a 200 amp hour lead acid Battery,

I havent got round to putting a fuse in it yet, 

Its Fully Self Contained Electrically, 

I dont need any external power whatso ever, Ever, 

Its simple, It works, Thats it,

And it wont over cook my Batterys, 

Woolly wrote:

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Now my question is - My batteries currently charge from the alternator & I would like that to continue as well as off the solar, do I need to buy a redarc charger or similar with inbuilt regulator or can I use the current system to charge the batteries while traveling and then when I stop will the regulator pick up that the batteries are not receiving charge and take over.

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One concern I would have with this system is that with your solar panels exposed to the sun at the same time as the motor is running, you'll have both the motor-driven alternator/charger and the solar regulator trying to manage the batteries at the same time. Solar regulators can get confused by the presence of another regulator connected to the same battery, and this can result in the battery being over or undercharged. I'm no expert, but my guess is that it would be fine if it was just the alternator doing the charging, but there would be potential for conflict if a smartish high-current DC-DC charger was trying to charge the batteries at the same time as the solar regulator. @brian probably knows the answer to this.

As to whether you need to go to the expense of a DC-DC charger, that would depend on whether your batteries were charging sufficiently from your panels and alternator and whether you were driving enough for the device to make much difference. 300W is plenty enough to charge 200Ah, so it will come down to what the load is.

Woolly wrote:

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Also what are the differences between regulators, for there seems to be a very very large price range & nearly all claiming to do the same thing.

I am willing to pay more for better quality as I really want a system that I can install and basically forget.

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My response to that last sentence is not to get a $30 regulator from China off eBay. I have a couple of 10A ones and one of them misbehaves (it randomly decides to shut off the load when the sum of the input and output is pushing 10A, e.g. 5A each). To run a small compressor through it I need to disconnect the solar input first, and needless to say I only connect my fridge to it when my other system is offline. I didn't discover this issue until I'd had it for several months, so I don't know if it shipped with the problem or has developed it.

So one thing you should get for a higher price is a (local) warranty, and hopefully more assurance that it will work to specification in the first place. Some of the fancier ones have digital readouts and collect and store data. Some are more waterproof than others. Some are made outside China.

Separating the Solar input from the Alternator input to your house batteries, while driving, is easily achieved by use of a changeover relay that is energised by a connection to your ignition switch. The solar is connected to the normally closed contacts, and the alternator to the normally open. Once the ignition switch is turned to "ON", the relay cuts off the solar and connects the alternator. The user manual for the Redarc DC-DC chargers show a schematic on how this is done.

moblet wrote:

 Some respondents here have assumed that the charge from the vehicle will be routed through your solar regulator, while others (myself included) have assumed that it won't.

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 HI Moblet

YOUR assuption is correct

If using both alternator direct charging  & solar charging , the Alternator reg controls the ALTERNATOR output

and the SOLAR reg controls the SOLAR output

BOTH will do their own thing!!

That may mean that one reg may cut back it's sources output before the other

Usually it is the Alternator reg which cuts back FIRST as the battery approachs fully charged voltage

DC >DC chargers [with solar inputs ]  select one or the other  but not both @the same time[often  the alternator may the" one" source selected while the engine is running]

PeterQ

-- Edited by oldtrack123 on Saturday 1st of February 2014 01:11:20 PM

-- Edited by oldtrack123 on Saturday 1st of February 2014 01:15:56 PM

Shakes head..

Do you 2 ever stop trying to out do each other with BBB..

Vehicles have been running for years and years with alternators keeping the battery charged..

And as I see it if someones house batteries need a bit of a top up connecting them to the start batteries when the motor is running will bring the house batteries up....

Now you can back at me with all the rubbish about Yatty Yatty Yatty Yatty but it works for me and thats a fact..

HI Brian
NO disagreement from me with your post regarding 100% charge ing of remote batterries with direct systems.
And the usual systems are totally useless ,due inadequate cables[ voltage drop,]' even more so when other loads are on the remote battery or the charging cables

PeterQ '"big smile""

Wooly,

I note that some people are suggesting PWM (traditional old style solar controllers) and some are suggesting MPPT (newer more efficient controllers), both work, and on a 300W system there will not be a huge difference between them.

The only caution I would give is that your solar panels need to be connected differently depending which one you go with. With the PWM they would be connected in parallel (all the +s connected together, and all the negatives connected together), if you go MPPT you would connect in series (+ to -, then + to -). 

There are also a few other considerations (max volts, etc), so please talk to someone who knows this stuff before you buy anything.

oldbobsbus wrote:

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brian wrote:

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No point coming back at you with any more rubbish Bob, you should just keep on believing that your house batteries are actually charging fully from the alternator. 

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 You are both assuming again...

I only want to bring my batteries up not friggen fill them to the brim...

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Sorry Bob, I didn't understand that you really meant keeping the battery only partially charged when you said "Vehicles have been running for years and years with alternators keeping the battery charged".

My interpretation of a battery being classed as charged, is fully charged.

Thank you everybody for the responses,

I think I can purchase the required gear for the install with a little bit of confidence that I won't be purchasing the wrong stuff now.

Plendo wrote:

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There are also a few other considerations (max volts, etc), so please talk to someone who knows this stuff before you buy anything.

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 After seeing the varying opinions on here, I am guessing it would be the same when talking to someone, go to one installer/shop and get 1 opinion, walk down the road to the next installer/shop and get another.

That is 1 thing I have definitely learnt, a lot of people have there own ideas on how things should be done.

Woolly wrote:

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Thank you everybody for the responses,

I think I can purchase the required gear for the install with a little bit of confidence that I won't be purchasing the wrong stuff now.

Plendo wrote:

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There are also a few other considerations (max volts, etc), so please talk to someone who knows this stuff before you buy anything.

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 After seeing the varying opinions on here, I am guessing it would be the same when talking to someone, go to one installer/shop and get 1 opinion, walk down the road to the next installer/shop and get another.

That is 1 thing I have definitely learnt, a lot of people have there own ideas on how things should be done.

 

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 G'day Woolly, I'm no techie or have any qualifications in these fields, but have been using solar and alternative energies since the 1970's and your system is fine for what you intend. 

What ever you do don't connect your batteries positive to negative, or you end up with 100 amps and a 24v battery bank, instead of 200amps x 12v connecting positive to positive. You can have batteries connected in either or both parallel and series at the same time, it will make no big difference to your charging capacity. As you only have two batteries, it's really easy, just connect the positives together and negatives and you'll be right.

As far as solar chargers go, a PWM will pulse charge your battery up to it's maximum and uses the direct input voltage/amp from your panels. On a cloudy day this will mean you may not get much voltage input and charge.

An MPPT will choose the best voltage to ensure there is constant input, even under cloudy conditions, so it may only be putting in a very small amperage, but it will be a constant and balanced voltage as possible.

Some new chargers are MPPT, but have a PWM facility so your battery gets the best of both worlds. Bought a 30amp MPPT/PWM solar solar charger, to see how it went, it was cheap of Ebay and from china. Had it more than a year and it does the job very well, combining the two types of chargers, gives you one which will do a good job under all conditions and keep your LA batteries in good shape. The people to talk to, are those who lived and developed with this technology every day and have done for many years, not school/book learnt experts, sales people or wannabe users.

Chargers come with good instructions and labeled connections, buy or build a small switchboard/ circuit breaker/fuses and that's all you'll need. Make sure you have good size wire for connections, a small voltage/circuit tester or multimeter and go for it. Add LED lights and life will be a breeze. it's always a good feeling to know you've built something which enhances your life and know how to trouble shoot and fix it.

Can someone explain to me when I should expect any batteries to be FULLY charged if they are in service..

I have a boot full of batteries and if they are showing 27 v of an afternoon when they are being used I am very happy..

But according to you blokes that is only 80%

So what!!!!  they are doing the job and are keeping everything working....

AND

I am happy what else can I ask for..