Finding, buying, and using your first RC charger

Finding, buying, and using your first RC charger

Now that you have a few batteries for your race quad, you should learn how to charge and fly them properly. That's what I'll teach you in this blog!

In this blog, I'll be talking about what type of charging setup to get, briefly about why, then how to use it with your batteries. I had better also talk about draining the battery while flying too.

Before we start, I should tell you that battery capacity (mAh) is linked to battery voltage.Think of mAh as water, and voltage as the water pressure. A tank full of water is 4.2v, tank empty is 3.7v. This also means that there's less power in the water pressure when voltage gets low. You can judge how much mAh (Water) there is in your battery (Tank) by looking at the voltage (Water pressure).

Also, chargers will vary in power, and will be labelled with a wattage. 100w, 250w, 500w for example. I'll get to that later, but keep it in the back of your mind for now.

--------------------------------------------------------------------------------------------------------------------------------------------------------

If you're still yet to buy a charger, you need one that will charge the type of battery you have.

Most RC chargers will do a huge variety of batteries, but we want one that will do Lithium based batteries. Here's a list of battery types you'll want to look for when choosing a charger: 

-LiPo (definitely need this one)

-LiIon (Lithium-Ion. For some goggle batteries, but not totally necessary)

-LiHv (High voltage LiPo, each cell goes to 4.35v, also not a necessity unless you want to run High Voltage later down the line) 

Choosing these options in the charger will determine the voltage that it charges each cell to, so it's extremely important. 95% of the time I only use the LiPo setting.

--------------------------------------------------------------------------------------------------------------------------------------------------------

Next, your charger has to have a balance charge setting. This means it will charge each cell of each battery individually so that they're all the same voltage. You need to balance charge racing batteries because there's 3 or 4 (or more) cells in each one, and since they all discharge at the same rate, you don't want one cell much lower than the others, or else you will drain that one too far while flying.

Look for something like "2S - 6S balance charging" in the features list. That's what you want.

So now you know to look for a charger that can charge 2S to 6S (or 4S, whatever S you need really) LiPo batteries. But there's more to look for than just that! 

--------------------------------------------------------------------------------------------------------------------------------------------------------

You now need to check what amperage it can charge at. When you fly, you're drawing amps, and when you charge, you're putting amps in. The more amps a charger can charge at, the faster you can charge your batteries, within reason.

This is where C rating for batteries comes in. I would never recommend charging at a rate above 5C. For example, if charging a 1300mAh (1.3Ah) battery at 1C, you charge at 1.3Amps and it will take about an hour. You could charge at 2C which would be 2.6A, 3C which is 3.9A etc etc all the way to 5C.

The reason you never charge above 5C is because batteries don't take amps as well as they give them. So if your battery says it's 95C, that's only referring to discharging. Don't charge at 95C!

1C charge rate is mAh divided by 1000. So a 1500mAh battery at 1C is 1.5A. 1800mAh is 1.8A. I don't know why more batteries are labelled as Ah (amp hours) instead of mAh to make this simpler, but that's the way it is.

Anyway, look for a charger that can deliver at least 10A, because it's also possible to use a board to charge multiple batteries at once!

--------------------------------------------------------------------------------------------------------------------------------------------------------

Once you have gotten your head around all those features you need, there's another on you need to consider. a DC or AC charger? An AC charger has the advantage of just plugging right into the wall, but may lack power to push the amps into your batteries. A DC charger is usually more powerful, but you also require a power supply for it.

When choosing a power supply, things will get complicated, so I'll try explain it in a fairly easy way... The power of your power supply (PSU) needs to match, or best your charger. So if you have a 500w charger, you should get at least a 500w PSU if you want the max performance our of your charger.

To go a little deeper into that, you also need to check the output amps and voltage of the PSU. For example, if you want to charge at 20A, your PSU needs to be able to deliver at least 20A as well as be the same voltage as your charger input, or battery you want to charge. If your charger only takes power from a 12v source, your PSU needs to be 12v. Some chargers can take up to 30v, and that's when you can take into consideration higher voltage PSU's. You want your PSU voltage to match or best the highest voltage of the batteries you want to charge. A bunch of 4S batteries at 15A will need a PSU that outputs at least 16.8v and 15A. But if you had a 12v PSU that can pump 30A, that will work too. 

PSU's were the hardest part for me to figure out. So I'll be nice and leave links to what to buy, as well as charger links of course!

--------------------------------------------------------------------------------------------------------------------------------------------------------

I'll leave the charger links for the end of the blog. Now it's about how to charge!

There are two methods I use to charge. One battery at a time, or parallel charging. Parallel charging uses a board that connects all the batteries, and basically makes the charger think they're all one battery.

I recommend charging one at a time until you understand how to use your charger, and what C to charge at.

Now, when you charge, you plug both the discharge lead and balance lead into the charger (or parallel board). You'll have options on the charger for what you're charging. You need to pick LiPo Balance Charge. That will charge the battery by charging each cell individually. Some chargers will automatically sense the voltage, and what "S" the battery is, but you should check that it says the right cell count. If it doesn't, you need to choose it yourself.

Now you pick the amperage. 1C-5C. Charging a 1300mAh at 1C will be 1.3A. 2C is double the amps, so half the time, 3C and 4C make it even faster to charge, but can be risky if your battery doesn't like taking amps that fast.

Let's recap into a simple list

- Plug in both battery leads

- LiPo Balance Charge

- Pick the right cell count if the charger doesn't do it

- Pick the amperage to charge at (I usually go for around 2A per battery, which is just under 2C)

- CHARGE!

While charging, you should never leave your batteries unattended. Strange things can happen with these little power packs, so keep an eye on them in case something happens!

 (Discharge Lead on left, Balance Lead on right)

 --------------------------------------------------------------------------------------------------------------------------------------------------------

If you want to parallel charge your batteries, you get a parallel charging board! You plug the board into where your single batteries go, then plug multiple batteries into the board. Before you parallel charge you MUST be sure of the following things:

- All the batteries are the same cell count (NEVER charge a 3S and 4S on the same board. NEVER!)

- All batteries are at least fairly close to the same voltage PER CELL (Don't charge your 3.7v per cell battery with you battery that is 4.2v per cell). They should only really have 0.1v difference, so 3.7v and 3.8v together is fine.

- All batteries are about the same capacity. You can charge a 1300mAh and 1500mAh together, but not a 1000mAh and 1800mAh.

Once all those boxes are checked, you plug the batteries into the board, making sure the plugs are all the right way. The plugs are all keyed, so it's hard to plug in wrong.

From there, you choose all the same options as charging a single battery. The cell count remains the same, so if you're charging six 4S batteries together, the charger should say 4S. The capacity changes though, the charger will see all your batteries as one big 4S battery, so to determine that "C" to charge at, you need to add all the batteries Ah together, then you'll get your 1C value.

Six 1300mAh batteries will be charged at 7.8A so that each battery is charged at 1C. 6 x 1.3Ah packs = 7.8A charge rate.

--------------------------------------------------------------------------------------------------------------------------------------------------------

When flying, it's best to never discharge lower than 3.7v per cell, or below 20% of the batteries full capacity. I like to fly to 3.8v per cell, because that is the voltage you store batteries for over longer periods of no flying. You can monitor this by either using an OSD that tells you battery voltage and mAh on screen or setting a timer on your controller. I recommend a 2 minute timer, then check your battery voltage after a chill flight, and you can adjust from there.

If you use an OSD, fly until it's just below the voltage you want it to be when you land. While the quad is sucking power, the battery voltage can sag (Remember the water pressure example?), but when you land, and there's no strain on the battery, the voltage will recover to a resting voltage, and that's the voltage you aim to have at 3.7v or 3.8v per cell. It all sounds really complicated to judge, but you'll learn your batteries just by going out and flying them.

--------------------------------------------------------------------------------------------------------------------------------------------------------

After your flight session, if you're not going to be flying for a few days, charge your batteries to storage voltage which is 3.8v per cell. Use your charger if your packs aren't already at 3.8v. 

Using your charger for storage voltage is the same as normal charging, except you would choose LiPo Storage rather than LiPo Balance Charge.

--------------------------------------------------------------------------------------------------------------------------------------------------------

Great chargers that run off AC:

ISDT D2 (Has two battery outputs)

SkyRC D200 (Two battery outputs, plus one can be used as a soldering iron)

Great chargers that run off DC (require a PSU): 

ISDT SC-620 (Can pump 20A)

ISDT Q6 (Can do 14A)

SkyRC iMax B6 (Can run off a laptop charger) 

SkyRC B6AC V2 (Can run off AC or a laptop charger) 

Power supplies:

ISDT Power Adapter (I wouldn't use this with very powerful chargers, and it outputs 27v, so keep that in mind)

- Since we don't have other PSUs in stock, I have to link out of the store, but this 13.8v 40 Amp 550 Watt PSU is probably one of the best options.

There are tonnes of PSU options out there, so if you do some research specifically on power supplies, you'll find something to fit your charger.

Parallel Charging boards:

ISDT Safe Parallel Charging board

General Parallel Board

-------------------------------------------------------------------------------------------------------------------------------------------------------- 

That brings us to the end of this blog! I hope I've been able to help some of you beginners out there. Batteries were one of the big hurdles for me when I was new, so I hope I can help other new pilots with what I've learnt.

Thanks for reading!

Jax

Posted: Wednesday 14 March 2018