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Topic: Arduino Solar MPPT battery charger (Read 11 times) previous topic - next topic

GreenMart

#5
Dec 26, 2012, 11:36 pm Last Edit: Dec 26, 2012, 11:38 pm by GreenMart Reason: 1
Yeh, I could easily go out and buy one, but where is the fun in that!?

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I made a charger using a TI BQ2031 IC


Funny you should say that. I've actually got a free sample in the post as we speak. I also came across it in my research and it looks really neat! I'm planning on testing it too, however, I really wanted to be able to control everything through the Arduino rather than using R-C networks to configure the IC. Nevertheless, I'd love to see the schematic from your charger!
It was my hope that I could use the Arduino to basically mimic that same charging algorithm that the BQ2031 uses.


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First, read this:  http://handybobsolar.wordpress.com/the-rv-battery-charging-puzzle-2/


Thanks kev_rm, that link was really useful and informative too!

mauried

Ive made a number of MPPT solar chargers, and you have the right idea with the various voltages and charge currents.
The practical problem that arises is that the input power to the charger varies over the course of the day and may vary
rapidly as clouds move over the solar panels so the tracker will be trying to maximise the power into the battery all the time.
Its quite possible that there simply wont be enough power available to provide the bulk charging and equalizing currents
when you want them, so you have to keep track of how much power was available to provide the required charging when you wanted it.
Is the battery that is being charged also being drained by some load, or is the Solar Charger just to keep a battery fully charged by trickle charging it.


GreenMart

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Is the battery that is being charged also being drained by some load, or is the Solar Charger just to keep a battery fully charged by trickle charging it.


Potentially both, but most of the load will generally be on during the evening.

mauried

OK, so whats the relative drain caused by the load , compared to the size of the Solar Panels.
ie how much is the DOD of the battery overnite.

kev_rm


...
Its quite possible that there simply wont be enough power available to provide the bulk charging and equalizing currents
when you want them..


I think that's a question of do you have enough panel, not how to charge. 

PS: "When you need them" does not apply to equalizing... this can be done every 2-6 months as time & energy allows.  (less frequently the better behaved your system is on your batteries)



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