I want to safely power an Arduino project with an 11.1V 3S LiPo battery. The battery will be disconnected prior to charging.
Should my main concern be preventing an overdischarge of the battery while it is powering the project?
What is the best and simplest way to do that?
Main concern? Hard to say without more information about your project. A concern? Yes.
Battery protection boards are cheaply available on eBay/Amazon etc, but it must be one designed for use with your type/voltage of battery.
Main concern as far as battery safety concerned. The battery will power a single 12V motor and an Arduino (likely Pro Mini) through a buck converter.
I have seen a few battery protection boards like the on below. Not sure if this is appropriate for a hobby 3S battery? I am confused as to how these should be wired. Once these are wired to a battery, is the charging and discharging done through the same connection (P+/P-)?
Def a concern, one of several to keep in mind with lipos.
If you have a spare analog input, you should monitor the battery voltage and provide for an alarm or action of some kind through the software when the voltage goes below…
below wherever you think it shouldn't.
3.3 volts per cell under load is a conservative figure. So look for 9.9 volts and start screaming about impending doom.
Please go to
batteryuniversity.com
and read up on lipos.
Great source of power, not so great in terms of their need for care and handling, physical as well as electrical.
You could also use a battery monitor. They can be set to beep rather loudly when the voltage goes too low on any cell.
If you keep,your battery in good condition, the cells shouldn't get unbalanced, so measuring them all, or just one, can be a proxy for checking every cell. But as a battery ages, the cells may start getting their own idea of things, and even though you balance charge them, they can discharge non-uniform ly, so either scrap old batteries that no longer maintain balance under discharge, or carefully monitor each cell.
These are cheap - I have several, a few of which are more or less a permanent part of deployed, lipo-powered devices.
a7
Thank you. Monitoring the voltage seems the best approach with the battery monitor as a backup for an audible alarm. Is it possible to read the state of one of those alarms using Arduino? That would be handy.
For my project, I am now thinking of using a Li-Ion 18650 battery pack with protections already built in. I have found some with the voltage and capacity I need. They have much lower C ratings but they will be just fine for my application.
It isn't something provided for by the device, but they def can be hacked to do.
But yes, if massive C current is not an issue, it is much easier to off-the-shelf the entire power subsystem or as much of it as possible.
Probably a bit safer, too. Just don't cheap out on it…
a7
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