Tricopers for RC newbies: what do I need to charge my batteries?

By combining my readings of rcgroups.com and my personal experience, I try to outline what you need to know about battery charging in order to power your tricopter.

A lot of the discussions around tricopters are focused on the tricopter itself: how to make the best yaw mechanism, how to calibrate your kk board, what type of ESC should you use etc...  When it comes to batteries, Chad Kapper wrote a great article about choosing a LiPo battery and charging best practices.  I’m going to go more novice on this article and try to give an overview of what equipment is needed for charging.

One thing that surprised me is that most of the chargers in the market (if not all) do not actually come with the power circuitry built-in.  In my opinion that’s seems like a significant drawback to the hobby but I digress.  This means that if you need to charge fast (less than 20 mins) you’ll need to buy a power supply that can deliver the necessary amperage (for example my charger and my batteries can charge at a maximum 10A).  

In order to deliver that power, I purchased a power supply rated at 10A.  Now the consensus in the hobby is that it’s better to charge all batteries slow (at 1 AMP) so if you want to save money and you’re handy soldering iron (you’ll have to be if you’re building a tricopter), then you can commandeer one of those laptop power supplies (they can generally output 3.5A to 5A at 12V), they’re cheap and they’ll do the trick.  Some folks modified their ATX power supplies found in an old computer to provide the output that they need.

Warning: Modifying these types of high power electronics comes with risks.  Some of these power supplies contain capacitors that can discharge and cause real harm to someone that is new to high power electronics.

Connected to the power supply is your charger: you can find on cheap online. Make sure you buy one that can draw the necessary amps for fast charging and that also has a built-in balancer.  By the way, balancing is also an important step in the charging process that you should know about. I can configure my charger to balance the LiPo cells automatically as it charges my batteries or balance after they’ve been charged.  Make sure your charger comes with a balancing port (insert photo) and an adapter to accommodate different battery types (mine supports 1 cell to 6 cells).

Connected to the charger is the battery: one connection is the balancing port (as stated above) and the other connection is the power connection.  Now if you look at this flitetest article on soldering connectors, you’ll see that there doesn’t seem to be a real standard for the power connectors in the RC hobby industry.  There are MANY connectors, some are more prevalent than others.  I suggest that you standardise to one connector and stick with it.  The Joshes really like the XT60 as it’s quite robust. If it’s not back ordered at Hobby King go with that.  Standardising to one power connector also means that you’ll probably have to change your input connector for your charger.

Tip: When changing and soldering new connectors on your battery, follow the instructions on the flitetest video.  One thing I would add is only snip off and solder one lead at time this way you always leave a connector protecting one of the leads and reduce the chances of a short circuit.  Covering your battery leads temporarily during this process with electrical tape is also a good idea.

Finally, during charging, your battery should be placed in a LiPo bag.  Makes sure that all your connections from the charger to the battery are long enough to center the battery in the bag while charging.  The reason for a LiPo bag is simple: safety.  You’ll crash your tricopter and during this crash your battery may strike something hard and get some invisible internal damage.  While charging, a damaged LiPo battery can fail catastrophically, so better be safe than sorry and place it in a fireproof LiPo bag.

Another thing you need to think about is that the electronics involved here require a lot of precision in order to charge all of your cells to the right voltage. I realised very quickly that my crappy electronic voltmeter wasn’t actually calibrated correctly to measure voltage on both my power supply and batteries. So from the start I’ve trusted that these things come well calibrated out of the factory.

About me: After watching David Windestål and “the Joshes” on flitetest fly a tricopter, I was sold and I decided to jump into the hobby.  I have never flown an RC plane before and never owned any RC equipment, so these are my learnings from getting into the hobby from scratch.  

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