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Forum Index : Solar : Plasmatronics

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SnowT
Newbie

Joined: 14/12/2013
Location: Australia
Posts: 3
Posted: 11:38pm 13 Dec 2013
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Hi all My first post..

I about to rig a Coaster bus to be independent.

I have been relearning a heap of information in the Last few week's..

One of the issue that has Popped up is that a few of the people are using the Plasmatronics DINGO 20 Solar Regulator.. for system up to 1k+. and I'm trying to get my head around it..

Can I use Dingo 20 to handle a 600-1000w panel system safely..?

To output to a 24v 300Ah LFP battery..?

Juergen
 
fillm

Guru

Joined: 10/02/2007
Location: Australia
Posts: 730
Posted: 11:56pm 13 Dec 2013
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Hi,

Welcome to the forum , a PL20 or Dingo20 will control 20A of solar so if you are running 24V then approx 24 x 20 = 480 ~ 550W of solar , but 20A @ 48V is 1000W .

You need to get a Pl40 or different controller for 1000W @ 24v . Stay with Plasamatronics as they are the best battery management money can buy .




PhillM ...Oz Wind Engineering..Wind Turbine Kits 500W - 5000W ~ F&P Dual Kits ~ GOE222Blades- Voltage Control Parts ------- Tower kits
 
SnowT
Newbie

Joined: 14/12/2013
Location: Australia
Posts: 3
Posted: 12:49am 14 Dec 2013
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ok.. I sort of got that..

but if I'm reading the spec's then..

- Max voltage SOL+ to BAT - 100v
- max charge 20A --

The way it sort of Look's that it's pointing to a Max of 2000w, But I not 100% sure I need to know if that is the fact..

Juergen
 
Downwind

Guru

Joined: 09/09/2009
Location: Australia
Posts: 2333
Posted: 01:34am 14 Dec 2013
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  Quote  ok.. I sort of got that..



All calculations are based on Ohm's Law, as Phill implied above.

Volts x Amps = Watts (24 x 20 = 480w)

This also works backwards 2000W / 24V = 83 amp

So its rather easy to calculate what size solar regulator you require if you know two of the factors .. Volts.. Amps ..or Watts.

Pete.
Sometimes it just works
 
SnowT
Newbie

Joined: 14/12/2013
Location: Australia
Posts: 3
Posted: 05:18am 29 Dec 2013
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Ok.. here goes..




So If I'm correct I should be able to do this..

Has anyone done so..?

Juergen
 
norcold

Guru

Joined: 06/02/2011
Location: Australia
Posts: 670
Posted: 10:54am 29 Dec 2013
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Now your talking, using relays so as the Dingo can handle more then 20 amps solar. But then I`m reading a very fuzzy diagram.

Plasmatronics manuals are tops you`ll get all you need from them, just a matter of getting your head round them. I assume from your diagram that is what you`ve done.

Now you can look to the load side of things you`ll find the Dingo will do that ensuring your battery does not get drained too low, once again using relays if your load is in excess of 20amps.

Would suggest if you wish to also charge from your vehicles alternator you wire it through a manual switched relay direct to your battery. The Dingo will sense your batteries charge and control the solar input. The KISS principle, for reliability.Edited by norcold 2013-12-30
We come from the land downunder.
Vic
 
yahoo2

Guru

Joined: 05/04/2011
Location: Australia
Posts: 1166
Posted: 06:52am 30 Dec 2013
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Hi Juergen,

the error in your logic is that you are looking at the panel voltage and assuming that the controller will convert all this energy to usable power.

if you are not using a mppt controller that can step down the higher voltage (like the midnight solar classic)then any voltage that is beyond the battery voltage at the time is technically a loss.

for example
with a 12 volt system and grid spec 72 cell panels 45 volt open circuit 35 volt max power 8 amps short circuit at 1000w/m2 (sunshine)



The graph shows a fairly flat amps curve so the amps output from the panel only changes with the amount of light that is hitting the panel.

Here is the tricky bit, max watts will be at the point that the controller starts to pulse modulate the solar input. so if the end point for LFP's is set at 14.3 volts then,
14.3v x 8A = 114 watts from a 280 watt panel. if the cost of the panel and fittings was less than two 12 volt 70 watt panels it might be viable but it would only work with a plasmatronic controller, most other controllers have a lot tighter limits on the max panel volts for different battery voltage ranges.

I admit this is a ludicrously extreme example, besides which a panel this size would flex and crack on a camper.
The other thing to consider is that every tree within 500 metres will sprint across to where you park and hang a branch over your van and cast a shadow over a single cell and restrict the power on that series just to drive you nuts. They are vindictive like that, especially the Norfolk Island pines.

system looks good, you are well under 0.2 C charge rate so the batteries should last well, although that's a lot of capacity for a bus.

One question, is float charge a problem for LFP batteries? can that be disabled or set low in the custom menu?
I'm confused, no wait... maybe I'm not...
 
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