Choosing a power supply for your new, big arse charger


The situation we find ourselves in
The RC world is exploding with big arse chargers. That in itself is a good thing but as cool as it is to have these big arse chargers, they are far from simple to use. Who would have thought that a charger would get to the point where it could strain a normal 15A household circuit! Well here we are, a place where tons of guys just know they want a 1000W charger but are simply lost as to what they really need to pull it off.

Skip all the boring stuff
At this point I would usually delve into the math behind why you need what you need but I find that most people could care less. Instead most people just want answers and for once I will just give them what they want. But not to worry, I will put some math at the end of this article for those who are interested.

Grouping chargers
I have decided to group all the the current big arse chargers into three groups, 600 ~ 800W, 1000W and 1344W, and some of the chargers will appear in 2 groups, one for their max output on 6s lipos and another for their overall max output. I will cover any specific charger bits later on. Also only 24V or higher voltage power supplies will be shown, as all the the chargers require at least 24V to achieve full output power.

An important concept: Just because these big arse chargers can output 600-1344W does not mean you have to use them at their full output. In fact many people will never use the full output of these chargers. So when choosing a power supply for your charger, consider your actual charging needs and not the maximum charger requirements for full output. Of course covering the needs for full output is not a bad thing but it can be wasteful if you don't need it.

Not all power supplies are the same
There will be a broad range of power supplies shown below. I will talk about each specific unit below but I want to cover some general info first.

Different styles of power supplies
I am going to say there are 4 different styles of power supplies, and each will have its own benefits and drawbacks.
  • Bench top units. These units are made to be used in a work/lab area. They are usually the most expensive type but are housed in a proper case with a wired input lead and output terminals. They often have integrated meters and adjustable outputs. Example: Mastech units
  • Bare unit, closed terminal. These units are made to be used by people but are more single purpose designed. The metal enclosure is the power supply case and all connections are covered. Since they are designed to be used directly by people, they are likely to be quiet units with temperature controlled fans. Example: Iota units
  • Bare unit, exposed terminals. These are usually industrial grade units and are designed to be installed in equipment. Since they are made for industrial use, no efforts are made to make the power supply friendly for the RC hobbyist. They are housed in basic, purpose built cases, have exposed terminals for both AC input and DC output, and have aggressive cooling designs that often make them very loud. All connections need to be made by the user and care needs to be taken to shield the bare terminals. Example: Meanwell units
  • Repurposed units. These are the server power units that are similar to the bare, exposed terminal units except that they must be modified for use. In this case each effective power supply will be made up of 2 units wired in series. These units offer the best bang for the buck but are also the least safe of the 4 types. 
Noise
Many of the units below are noisy. This is because no switching power supply is 100% efficient. They all create heat as they function and with these being such large units, they can create a lot of heat. So they must have good cooling to function properly and that cooling is usually not the friendly type. I will attempt to estimate the noise of each unit, rating it from 1 to 10, where 1 is barely audible and 10 is near unacceptable.

Active Power Factor Correction (APFC)
This is a term that is becoming more and more known in the RC world because it can limit how you can charge when using weaker power sources like a generator. Without going into a long explaination of what power factor is, let me just say it decides how much current a power supply can use off an AC source. The better the PF, the more current it can use and the less that is effectively unusable. A power supply with a poor PF can draw 40% more current than it can use. This puts added strain on a household AC circuit and severely limited the useful output of generator. When it comes down to it, if you are planning to use one of these big chargers at a high output, make sure your power supply has APFC.

For those who are curious is their power supply has APFC, look into getting a Kill-A-Watt at your local hardware store or online at places like Amazon.


600 ~ 800W charger output
This groups includes the Hyperion Duo3+, 306B (756W max when charging 6s lipos), 3010B (756W max when charging 6s lipos), and the Thunder Power 820CD.

Power supply
DC output voltageMax DC outputAC input voltage
Max AC current
APFC
Noise
Cost est.
Meanwell SE-1000-24
24V
1000W
110V - 240V
17.5A
no
?
$220
Meanwell RSP-1000-24/27
24V/27V
1000W
110V - 240V12A
 yes4-5
$320
Iota DLS-27-40
27V1000W110V
20A
no
1-2
$330
Mastech HY3030E
0-30V
900W
110V
est.12A
 yes
?
$260
2x HP 575W server PS
24V
1130W
110V - 240V
17.2A
 yes6-7
$30 - $100

Meanwell SE-1000-24
This is a bare unit, exposed terminal type of power supply that has a max output of 1000W at 24V. This unit does not have APFC, making it cheaper than the RSP models below.

Meanwell RSP-1000-24 & RSP-1000-27
These two are bare unit, exposed terminal type of power supplies that has a max output of 1000W at 24V or 27V. The output voltage is adjustable from 22-28V on the 24V unit and 24-30V for the 27V unit. The drawback to these units is their high cost.

Iota DLS-27-40
This is a bare unit, closed terminal type of power supplies designed to charge RV deep cycle batteries but it also functions as normal power supply. They do not have APFC.

Mastech HY3030E
This is a bench top, lab grade power supply that is fully adjustable. It also has a full set of gauges. This power supply will work fine for most of the chargers in this group but it might come up a bit short for the TP820CD.

Custom series connected server power supplies (HP DPS-600PB units)
There are one of the many repurposed server power supplies that can easily be converted to power chargers. They are all 12V units and so two units must be placed in series to achieve 24V. There are many benefits to using these power supplies but they are have drawbacks. For the purposes of this group, I will use the HP DPS-600PB series units for the example and they are APFC units.


1000W charger output
This group contains the Hyperion 720i Super Duo3, iCharger 3010B and the FMA PL8 v2 (1000W max when charging 6s lipos).

Power supply
DC output voltage
Max DC output
AC input voltage
Max AC current
APFC
Noise
Cost est.
Meanwell RSP-1500-24/27
24V/27V
1500W
110V - 240V
17A
yes
5-6
$430
Mastech HY3050E
0-30V
1500W
110V, 240V
18A est.
yes
?
$420
2x Dell NSP-700AB server PS
24V
1400W
110V - 240V
20.2A
yes
9-10
$30 - $100

Meanwell RSP-1500-24 & RSP-1500-27
These two are bare unit, exposed terminal type of power supplies that has a max output of 1500W at 24V or 27V. They do not have a simple voltage adjustment like the 1000W units.

Mastech HY3050E
This is a bench top, lab grade power supply that is fully adjustable. It also has a full set of gauges.

Custom series connected server power supplies (Dell NSP-700AB units)
There are one of the many repurposed server power supplies that can easily be converted to power chargers. They are all 12V units and so two units must be placed in series to achieve 24V. There are many benefits to using these power supplies but there are also drawbacks. For the purposes of this group, I will use the Dell NSP-700AB units for the example and they are APFC units.


1344W charger output
There is only one charger in this group, the FMA PL8 v2.

Power supply
DC output voltage
Max DC wattage
AC input voltage
Max AC current
APFC
Noise
Cost est.
Meanwell RSP-2400-24
24V
2400W
240V
15.5A
yes
?
$650
Meanwell RSP-3000-24
24V
3000W
240V
20A
yes
?
$580
Mastech HY3080EX
0-30V
2400W
240V
15.5A
yes
?
$550

Meanwell RSP-2400-24 & RSP-3000-24
These two are bare unit, exposed terminal type of power supplies that have an output of 24V and either 2400W or 3000W. Both are only available for 240VAC and are APFC units. There are no 27V units of this size, so if the full 1344W is needed, the power supplies will need to be adjusted to raise the voltage to 27V. Using one of these units to achieve the full output of the PL8 should draw roughly 11A off a 240V circuit.

Mastech HY3080EX
This is a bench top, lab grade power supply that is fully adjustable. It also has a full set of gauges. Using one of these units to achieve full output should draw roughly 11A off a 240V circuit.

Custom series connected server power supplies
There are one of the many repurposed server power supplies that can easily be converted to power chargers. They are all 12V units and so two units must be placed in series to achieve 24V. There are many benefits to using these power supplies but there are also drawbacks. For the purpose of needing an effective 1700W unit, look for HP Proliant DL580 units.


Random notes on chargers, power supplies, etc.
  • The power supply input needed to power a PL8 charger at full output will require greater than 15A on a 110VAC circuit, meaning you can not use it off a standard US household outlet. A 20A 110VAC or 240VAC output will be needed.
  • If planning to use any of these chargers off a generator, an APFC power supply is highly suggested. This lowers the current draw of the power supply and will increase the usable generator output. 
  • All these chargers can be run off a pair of deep cycle lead acid batteries but most can exceed the output rating of the deep cycles. They also have the ability to drain even large deep cycles in very few charge cycles. 
  • The iCharger 3010B and 306B can output their full 30A output on 6s lipos using 17V input but will require 50A to do so. It is recommended that a 24V power supply is used. This lowers the input amps to about 38A.
  • Many power supplies can be connected in series or parallel in order to increase the output, some are even designed for it including the Meanwell and Iota units. 
  • The iCharger 3010B and 306B will accept up to a 38V input. This means that 3x 12V power supplies can be connected in series to power these chargers.

In case you wanted to see the math
There are 3 numbers that are important when looking at the power requirements of these big chargers, the charger output, the charger input / power supply output and the power supply input. I cover how to get all these numbers in other places on this site but let me quickly explain them once again, as this is an important thing that must be understood.

1) Calculating charger output in watts. As mentioned above, just because a charger can output 1000W, does not mean you have to use 1000W. We start with a well known equation

Watts = Volts * Amps

Now lets do the math for charging a 6s lipo at 30A, the maximum output of the first 1000W chargers.

Watts(out) = 6s * 30A = (25.2V) * 30A = 756W

It will take a maximum of 756W of charger output to charge a 6s lipo at 30A.

2) Estimating charger input watts needed for 756W of charger output. For this calculation we need to make an assumption, we will assume that the charger is 80% efficient. Now some of these chargers are more efficient than this but it is good to be safe, so 80% it is.

Watts(ps) = Watts(out) / .8

Watts(ps) = 756W / .8 = 945W

It will take approximately 945W of power on the charger's input, from power supply output, for it to output 756W.

3) Estimate power supply input AC power needed for it to output 945W. Again we need to make an assumption, we need to assume that the power supply is 80% efficient. This number may be high or low for power supplies in general but I will assume that most 1000W or greater units will have an efficiency of 80% or greater. So once again we need to add that in.

Watts(AC) = Watts(out) / .8 = 945W / .8 = 1181W

It will take approximately 1181W of power on the power supply's AC input for it to output 945W.

Now to put it all together. In order to charge a 6s lipo at 30A, it will take 756W of charger output, requiring roughly 945W of input power from the power supply. In order for the power supply to output 945W, it will require roughly 1181W of input power from an AC wall outlet.

Quickly let me do the same math for the full output of the largest charger, the PL8. The PL8 is rated at 1344W of output, so how much input does it need?

Watts(ps) = Watts(out) / .8 = (1344W) / .8 = 1680W

Now for the power supply input needed to output 1680W

Watts(AC) = Watts(ps) / .8 = (1680W) / .8 = 2100W

A quick note: Some might notice that 2100W is greater than 1800W, or the maximum wattage available at a US 120V 15A wall outlet. These are important notes to keep in mind.

Volts and amps
Now that we have some power (wattage) numbers, lets talk volts and amps. If we rearrange the equation above, we can get both

Volts = Watts / Amps
and
Amps = Watts / Volts

Once you calculate the needed input wattage to cover a charger's output, you can use the above equations to help make decide on a power supply. For example there are both 24V and 27V versions of the Meanwell RSP 1500W series power supplies, so which is better for a iCharger 3010B charging 10s packs at 1000W? First we know that to output 1000W, the charger will need approx. 1200W on the input. Now we plug in some numbers

Amps = 1200W / 24V = 50A
or
Amps = 1200W / 27V = 44.4A

Given the option, choose the 27V model because it will lower the input amps. This will lessen the strain on both the charger's input leads and the charger itself.

Why 24V?
Now that I have covered watts, volts and amps, I can answer a question I see a lot on the forum, "Why do the new chargers need 24V for full output?". The answer is that they all have a specific input amperage limit. In order to raise the output wattage, the input voltage must be raised, allowing the input amperage to remain the same.