I built a 3 stage PWM solar charger using an arduino

[Jamesr]

I am an electrical engineering student. I have been on summer break for a few weeks now and I had time to work on my project. This is not a school project but something I had wanted to complete for a while. I haven’t decided what I am going to do with it yet. I just built it for the fun of it. Please tell me what you guys think and ask questions. The link --> http://jr.120v.ac/pwm_charger_project/pwm_charger.php

 

[Windadct]

Hello James - Looks very good! -- Keep this documented well, as employers look for what you can DO as much as what you know! -- I would add web accessible data log, let the arduino report energy converted, battery condition etc - so you can show it off !

 

[meBigGuy]

Looks pretty cool. I'm assuming Rsc is effectively your current limit.

I'll assume you always stay below the gassing voltage, and that lead Acid batteries do OK with the current pulses during topping and float.

If you float for too long you may have issues. (but maybe it is being used a lot so that is not an issue)

 

[dlgoff]

Please tell me what you guys think and ask questions.

From meBigGuy's comment

... and that lead Acid batteries do OK...

are you interested in charging other battery types? There's a lot more to batteries than most would think. Battery University has excellent information that may interest you.

 

[Jeff Rosenbury]

Nice.

 

[Jamesr]

Looks pretty cool. I'm assuming Rsc is effectively your current limit.

I'll assume you always stay below the gassing voltage, and that lead Acid batteries do OK with the current pulses during topping and float.

If you float for too long you may have issues. (but maybe it is being used a lot so that is not an issue)

I have read a lot of different experiments that were performed on lead acid batteries. UPS sealed lead acid batteries for alarm systems are kept at a constant float voltage for most of their lifespan and they can last for up to 8-10years without damage. The float voltage is precisely controlled according to the temperature to prevent any form of gassing. I have also read that the small pulses to keep the battery at float is good for the battery because it provides desulphation.

This charger was designed to have lighting run off the battery at night so floating will hopefully not be an issue. If I find that it is an issue, a quick change to the code will fix it.

From meBigGuy's comment

are you interested in charging other battery types? There's a lot more to batteries than most would think. Battery University has excellent information that may interest you.

I chose lead acid just because they are the cheapest and most tolerant of abuse. Most off grid solar systems use lead acid batteries for energy storage. I would probably have to redesign a new charger to work with other battery types. The charger shown in this thread does not have any way to sense current. I would be uncomfortable trying to charge other batteries such as lithium type without current sensing.

This charger was designed to have lighting run off the battery at night so floating will hopefully not be an issue. If I find that it is an issue, a quick change to the code will fix it.