USB/DC LiPo battery charger questions

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Mcmoody1472
 
Posts: 9
Joined: Fri Nov 16, 2012 5:42 pm

Re: USB/DC LiPo battery charger questions

Post by Mcmoody1472 »

It is not possible to charge the battery and run it at the same time. The current will bypass the battery and power the load directly. What we ended up doing was creating a circuit that powered the load with the solar cells when the voltage was high enough and when it dropped below the voltage of the battery, the battery would take over. If the battery was discharged at all, 1.2A from the solar cells would be routed through the charger while the rest would power the load. We used a Schottky diode to control what powered the load depending on voltage and a parallel branch from the solar cells to the charger to recharge the batteries. Make sure your solar set up has a significant margin between the expected voltage and the needed 8.4V for charging because you will have more losses than you think. Changing the chip was simple for the lady we had do it. She was an assembler so she worked with parts like that every day. We didn't have experience to do that. It appeared to be a simple removal and solder. The led light on the board will indicate when it is charging and it will cut off when max charge is reached to prevent over charging. Balancing only comes into play in the long term. If you only need it to work for a couple months, it will be fine. You can go charge it with a regular lipo charger once in a while to balance the cells. Some people only do this a few times a year because balancing isn't always necessary and it takes longer to do. You should have one charger for each 2S battery for the charging and indicating to work properly. I also did a lot of research on all this because I was not comfortable with the electrical side of the project. As a request, if you use this info for your project, could you please site me as a reference? My name is Michelle Moody. If you have any other questions you can email me directly at [email protected]

chrisc123
 
Posts: 9
Joined: Tue Oct 22, 2013 7:53 pm

Re: USB/DC LiPo battery charger questions

Post by chrisc123 »

Thanks for the reply! If I use any of that information, I will definitely cite you as a reference. It seems like your group's capabilities are higher than mine though. I am basically doing this project alone, and I don't think I'll be able to switch the chip or build a circuit like that. I am hoping to figure out something simple soon. If only I had a micro rc car that used a 1 cell lipo, things would be much easier!

Mcmoody1472
 
Posts: 9
Joined: Fri Nov 16, 2012 5:42 pm

Re: USB/DC LiPo battery charger questions

Post by Mcmoody1472 »

The circuit is pretty simple in itself. Solar panels connected to both the diode and the charge controller. Charge controller to the batteries and the batteries also to the diode. And the diode to the load. As for changing the chip, your best bet is to seek an electrical engineering major to do it for you in a lab with proper soldering equipment. Research Schottky diodes and solar panels. You'll find some good info.

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