Chargers. They are a necessary part of our radio control lives these days. With LiPo batteries becoming the standard for R/C cars and trucks, much as they already have for airplanes, helicopters and drones, more people are finding themselves with advanced multi-chargers, capable of much more than the average user will ever need. Yet these chargers are, like the LiPo batteries commonly used on them, increasingly complicated and sometimes downright hard to use. And most of the manuals furnished by the manufacturers (if one is even included at all) leave much to the imagination.

I’ve had customers complaining about this for years now – so much so that we routinely sit down with a customer immediately after he or she purchases one of these chargers in an effort to explain how to do the specific things needed for their purposes, whether it’s balance charging a LiPo battery, put a LiPo at storage voltage, or simply charge a NiMH battery. Inevitably, that customer will call again with questions, because these chargers are so complicated that it takes multiple attempts to use it fluidly.

So in this guide, I’m going to go through a few of the standard things that beginners should know about the chargers, as well as present walkthroughs for standard uses for them. This guide is based around the Hitec X1 AC+, Hitec X4 AC+, Venom Pro Chargers, and others.

Multi-Chargers, Defined

What is a multi-charger, you ask? I will define it as a charger capable of charging multiple chemistries of batteries, including Lithium-Polymer (LiPo), Lithium-Ion (Li-ION), Lithium-Iron Phosphate (Li-FE), Nickel Cadmium (NiCd), Nickel-Metal Hydride (NiMH), and Lead-Acid (Pb) Batteries. Most modern multi-chargers also have the built-in ability to balance LiPo cells, and the better chargers also have a LiPo storage function. Additionally, they should all be capable of minute adjustments in charge current, ideally in increments of 0.1 Amps.

There are various other attributes that some multi-chargers have that are not necessary for most users. Some are AC and DC powered, meaning they can plug into the wall or hook up to any 12V source and be used. Some are DC-only, and require a 12V power supply for use at home. Some charge more than one battery, and some don’t. Some of these attributes are nice to have, but not necessary to fit my definition of ‘multi-charger’.

Breakdown of the Charging Screen

This is the screen that you will eventually get to when the battery is charging.

  • Battery Type: This indicates the type of battery you are charging. In this specific case, we’re charging a two-cell Lithium-Polymer battery, otherwise known as a “2S” LiPo.
  • Charge Rate: This indicates the current charge rate. Even though you might set it to a specific number, it will change over time, depending on the battery you are charging.
  • Battery Voltage: This shows the current battery voltage. This is not necessarily indicative of the voltage upon unplugging the battery from the charger, since there is almost always a tiny amount of current flowing into the battery, which may inflate the value slightly.
  • Function: This shows whether you are charging, balance charging, discharging, or storing your battery.
  • Time Elapsed: Shows the time elapsed since the charge began.
  • Capacity Charged: This value is the total amount of mAh the charger has put out. It does not accurately indicate the amount of mAh the battery has retained, so this is just gives the user a ballpark idea of the charge level.

Before We Go Further

Make sure you have the correct charge lead plugged into the charger. Otherwise you won’t be able to charge your battery. Most chargers don’t come with a wide variety of charge leads – usually just one or two. Be sure to buy the proper charge lead from your local hobby shop, whether you use Traxxas plugs, Deans Plugs, EC3 Connectors, XT60s, Power Poles, or anything else.

LiPo balancing (which we will get more into later) requires the use of a balancing board for most chargers. Any charger with a built-in balancer will usually come with at least one. You can see a battery plugged into the balance board here. If the balance lead on your battery is too short, you may need to pick up a balance extension from your local hobby shop.

Make sure that your charge lead is plugged into the charger, and verify that the polarity is correct. Red should be plugged into red, and black into black. Also make sure the charger end of the balance board is plugged in to the charger, if you’re charging LiPo batteries. Also, plug in your battery to the charge lead.

NEVER CHARGE A BATTERY UNATTENDED!

While these chargers are very advanced, there are still many things that can go wrong. Following all the proper protocols will prevent most accidents. But just as being a safe driver doesn’t prevent 100% of accidents from occurring, following the proper instructions won’t prevent a fire or some other unfortunate incident. Be close enough to react to any hazard that may crop up. Have a fire extinguisher nearby. For LiPo batteries, charge them in a fireproof container, whether it’s a LiPo Sack or a ceramic pot – anything that will contain a fire. These safety tips aren’t meant to scare, but it’s better to be safe than sorry.

A Minor Adjustment Before We Start

Most chargers that run this firmware have a Capacity Cut-Off enabled from the factory. This is a safety mechanism that will shut the charger off when the battery reaches a certain capacity charged. This cap is usually 5,000mAh. Depending on the battery you’re charging, this can be problematic.

In the instance that we are charging a well used 5000mAh LiPo, it’s certainly possible for the charger to need to put out 5000mAh  – 5500mAh to fully charge the battery.  This is because nothing is 100% efficient. The charger can only measure what it puts out, not what the battery actually absorbs. The rest of that energy is released from the battery as heat, which is why batteries heat up when being charged.

If the charger cuts off at 5000mAh, but the battery requires a bit more energy to fully charge, you’ll never get a full charge on your battery. But there is a way to fix this, and raise the cap up to a manageable level. Let’s do that now, so we don’t have to worry about it in the future.

Step 1 

UserSetProgram_Step1.jpg

Press the [BATT TYPE] button enough times to see this screen. Go ahead and press the [START] button to enter the next screen.

 

Step 2 

UserSetProgram_Step2.jpg

You should see the “LiPo V.Type” screen. At this screen, press the [DEC.] button three (3) times.

 

Step 3 

This is the Capacity Cut-Off screen. We want to leave the cut-off on, but raise the limit. Let’s start by pressing the [START] Button. The “ON” will begin to blink. Press [START] again to move on to the capacity.

 

Step 4 

UserSetProgram_Step4.jpg

Now that the “5000mAh” is blinking, press the [INC.] button to increase the capacity. Let’s set it to 6000mAh. Once you’re there, press [START] once more, and the change saves.

You can now press [BATT TYPE] to get back to the main menu.

 

How to Charge a Ni-Cd Battery

NiCd and NiMH batteries are probably the easiest type of batteries to charge on a multi-charger, since the charger will auto-detect the number of cells, and the only variable is the rate of charge. For this walkthrough, we’ll assume the battery is a 6-cell (7.2V), 1800mAh NiCd battery.

 

Step 1

Press the [BATT TYPE] button enough times to see this screen.

You should have the battery plugged in at this point.

 

Step 2

Press the [START} button. This screen should show up, in some variation. The number followed by the “A” could be anything from 0.1A to 6.0A.

Press the [START] button again. The 0.1A will start to blink.

 

Step 3

For this 6-cell 1800mAh battery, I usually charge at a 3.0A rate. Check your battery to see if it requires a specific charge rate.

Use the [INC.] or [DEC.] buttons to select your charge rate. It will go up or down in increments of 0.1A. Once you’re at the correct charge rate, press and hold the [START] button.

 

Step 4

When you press and hold [START], the charger will beep and flash this message to you. Then it will proceed to the next screen.

 

Step 5

You’re charging! The charger will beep when it detects a full charge on the battery.

 

How to Charge a NiMH Battery

NiMH batteries are what most beginners in the R/C car or truck will use at first, and come stock in almost every vehicle that includes a battery. For this walkthrough, we’ll assume the battery is a 7-cell (8.4v), 3000mAh NiMH battery (such as a stock Traxxas battery).

Step 1

Press the [BATT TYPE] button enough times to see this screen.

You should have the battery plugged in at this point.

 

Step 2

Press the [START] button. This screen should show up, in some variation. The number followed by the “A” could be anything from 0.1A to 6.0A.

Press the [START] button again. The 0.1A will start to blink.

 

Step 3

For this 7-cell 3000mAh battery, I usually recommend a charge rate of 4.0A; you can charge it slower, but I wouldn't charge it any faster than that. Check your battery to see if it requires a specific charge rate.

Use the [INC.] or [DEC.] buttons to select your charge rate. It will go up or down in increments of 0.1A. Once you’re at the correct charge rate, press and hold the [START] button.

 

Step 4

When you press and hold [START], the charger will beep and flash this message to you. Then it will proceed to the next screen.

 

Step 5

You’re charging! The charger will beep when it detects a full charge on the battery. Remember, never charge a battery when you aren't around; it's not safe!


LiPo Batteries Are Different

LiPo batteries require more care and attention than their older brethren. I do cover this in much more detail in my article, A Guide to LiPo Batteries, but I want to cover a few of the details relevant to charging, balancing, and storing the batteries in this article as well.

• Balancing

Balancing is a term we use to describe the act of equalizing the voltage of each cell in a battery pack. We balance LiPo batteries to ensure each cell discharges the same amount. This helps with the performance of the battery and helps maintain the battery’s health. Since all of the chargers this article is about have a built-in balancer, it would be silly to not use it. I recommend balancing your LiPo battery every time you charge – not because you have to, but because it makes sense to get in the habit. That way you never have to worry about forgetting when you last balanced the battery.

• Charging

Most LiPo batteries need to be charged rather slowly, compared to NiMH or NiCd batteries. While we just charged a 3000mAh NiMH battery at four amps, a LiPo battery of the same capacity should be charged at no more than three amps. For the vast majority of LiPos, the Charge Rate is 1C. The equation works like this:

3000mAh = 3A = "C"
Charge Rate = 1 x "C" =3A

 

So, for a 3000mAh battery, we would want to charge at 3A, for a 5000mAh LiPo, we should set the charger at 5A, and for a 4500mAh pack, 4.5A is the correct charge rate.

Some batteries like the Dynamite Reaction line we carry here in our store, can be charged faster than 1C. Always make sure your battery is capable of being charged at a higher C-rating before doing so — you could have a fire on your hands if you don't! If your battery doesn't specify the proper charge rate, always assume it can only be charged at 1C.

• Storage

In the old days, we used to run our cars or airplanes until the batteries died, then just set the batteries on the shelf at home, waiting for the next time we could use them. We just stored them dead. But you should not do that with LiPo batteries. Nor should LiPo batteries be stored at full charge, either. For the longest life of the batteries, LiPos should be stored at room temperature at 3.8V per cell. All of the chargers discussed in this article have a LiPo Storage function that will either charge the batteries up to that voltage, or discharge them down to that voltage, whichever is necessary.

I recommend to our customers that they put their LiPo batteries in storage mode after every run. This isn't necessary per se, but it does build up good habits. If this is done every time, you don't have to worry about whether or not you remembered to put it in storage. I have had many customers come to me with batteries that died because they charged it up, intending to use it, but life got in the way and they never remembered to put it back to storage voltage. Lithium-Polymer batteries can be damaged by sitting fully charged in as little as a week. So don't forget to put your LiPos at storage voltage when you're done using them.

Now that we have that out of the way, let’s get on to how to charge and store our LiPo batteries.


How to Balance Charge a LiPo Battery

LiPo batteries require a bit more work to charge and balance, so this is going to take a few more steps than NiMHs or Ni-Cds, so let’s get to work. In this example, I will use a common battery we sell, a 5000mAh, 2S (2-cell) LiPo. You should have both of your battery's leads plugged into the charger at this point.

Step 1

Press the [BATT TYPE] button enough times to see this screen.

Again, you should have the battery plugged in at this point, both to the main charge lead and also to the balance board.

Press [START].

 

Step 2

This screen should show up, in some variation. The number followed by the “A” could be anything from 0.1A to 6.0A. 
 
Unlike the last couple batteries, we don’t want to use this screen. Press the [INC.] button.

 

Step 3

LiPo_Step3.jpg

This screen, whatever the numbers, should come up. This is the screen that we want. Instead of simply charging, we want to balance the LiPo as well. 
 
Press the [START] button. The "0.1A" will start to blink.

 

Step 4

For this 2-cell 5,000mAh LiPo, according to the formula in the previous section, the charge rate should be 5.0A. Remember: Capacity multiplied by the charge rate indicator (i.e. 1C charge rate, 3C charge rate) will give you the correct charge rate.

Use the [INC.] or [DEC.] buttons to select your charge rate. It will go up or down in increments of 0.1A. Once you're at the correct charge rate for your battery, press [START]. The "3.7V(1S)" will start to blink.

 

Step 5

Now we need to select the correct cell count. Match the voltage up to the battery you have. In this case, we’ll select 7.4V(2S). 
 
Use the [INC.] or [DEC.] buttons to select your cell count.  It will go up or down in increments of 3.7V. Once you’re at the correct cell count, press and hold the [START] button.

 

Step 6

When you press and hold [START] as instructed above, the charger will beep and flash this message to you. Then it will proceed to the next screen.

 

Step 7

This screen is trying to make sure that you entered everything correctly. It’s saying you submitted 2 cells in series and it reads 2 cells in series. When you are charging LiPos, both of these values have to match. If they do, press the [START] button once more. If the values don’t match, press the [BATT TYPE] button and fix your mistake. Then repeat back to this point.

 

Step 8

Assuming both values matched and you pressed the [START] button, you will see some variation of this screen. The battery is now officially charging! It will beep when it’s done.

If you want to check the status of the individual cells, press the [INC.] button, and it will display the screen below.

 

Step 9

If you pressed the [INC.] button at the previous screen, you’ll see this screen. The values will probably be different, but what you see is the individual voltages for each cell in the battery.

Here, the voltages read 3.81V and 3.81V; the LiPo is pretty well balanced. Since this is only a 2-cell battery, we're only seeing two values and everything else is just "0.00V". With a higher-cell count battery, you would see more of those zero values populate.

You can press [INC.] again at any time to view the previous screen, and if you want to stop charging for any reason, press the [BATT TYPE] button before unplugging the battery, except in an emergency.

 

That is how to balance charge a LiPo battery. Next we will look at another important aspect of owning a LiPo battery: storing them properly with the LiPo Storage function on your multi-charger.

How to Storage Charge / Discharge a LiPo Battery

Storage mode works just like charging. We set the numbers, make sure everything is plugged in, and the charger will beep when it’s done. You do not need to leave the battery plugged in until you use it again, nor should you. It’s best to unplug the battery as soon as the charger lets you know the battery is done.

Let’s get to work. In this example, I will use the same 5000mAh, 7.4V (2-cell) LiPo as before.

Step 1

Press the [BATT TYPE] button enough times to see this screen.

Again, you should have the battery plugged in at this point, both to the main charge lead and also to the balance board.

Press [START].

Step 2

This is the LiPo Charge screen, like we saw above. Since we're working on LiPo Storage, however, this isn't the screen that we want. Press the [INC.] button three times.

 

Step 3

It you pushed the [INC.] button three times in the previous step, you should see this screen. Again, the numbers may be different – that’s fine. We will change them to suit our needs anyway.

Press [START]. The "0.1A" should start blinking.

 

Step 4

Press the [INC.] button enough to get the charge/discharge rate up to the correct charge rate of the battery, in our case, 5A. 
 
However, on most chargers, the max you can go on storage is 1.0A, because the charger discharges at 1.0A max. If that’s the case on your charger, just max it out at 1.0A. That is what we will do here as well, since the charger we’re using maxes out at 1.0A. If yours goes higher, just make sure not to go above the safe charging rate for your battery.

Press the [START] button. The "3.7V(1S)" will start blinking.

 

Step 5

Just like when we balanced charged the battery, we need to select the correct voltage and cell count.

Our example battery is a 2-cell LiPo, so that means we're setting it for 7.4V(2S) using the [INC.] or [DEC.] buttons to increase or decrease the value, respectively.

Once everything is correct for your battery, press and hold the [START] button.

 

Step 6

When you press and hold [START], the charger will beep and flash this message to you. Then it will proceed to the next screen.

 

Step 7

For whatever reason, it won't ask you to confirm cell counts on storage mode. Instead, it takes you to the main charge screen. As with balance charging, hit the [INC.] button to view the individual cell voltages.

The charger is now putting your battery into storage mode, either charging or discharging as needed – it will figure out what needs to be done. It will beep when it’s finished, just like when charging.

And that’s Storage mode on your multi-charger. Nothing mystical, just a great feature that you now know how to use.

 

Now Go Have Fun

We’ve gone over the most basic functions of these multi-chargers. Now that you know how these basic mechanics work, you should be able to easily figure out the rest of them as needed. Your new charger does many, many things – most of them you will never use, and going through all of them would probably be a waste of time for most people.

But do explore all the menus in the charger, and familiarize yourself with where they are should you ever need to get to them for something.

But more importantly, get that battery charged and go have fun! Don’t forget to talk to your local hobby shop with questions, or contact us. We’ll be happy to help!


Change Log

  • October 23, 2012 - Guide published.
  • May 12, 2016 - Gude removed for updating.
  • May 28, 2016 - Guide split into two guides, for two different charger UIs. This change log now only reflects this guide.
  • May 28, 2016 - Guide back up at new URL.
Brian Schneider / Brian is the manager, webmaster, & social media guru for Roger's Hobby Center. He's been in the hobby industry over a decade, teaching people the essentials of the R/C world. He's written a number of helpful guides, including A Guide to LiPo Batteries.