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HomeRC & Power✈️Aircraft🚁Helicoptere-Electric Battery-Charger-pSupply › help with wattage calculations
03-21-2016 02:36 AM  4 years ago
Topic Vote0Post 1


Anchorage, AK

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help with wattage calculations
So I have a 406Duo with a 4 port para board on each side.
I am charging 8 6s 5000mah packs at 1C so 20 amps per side.

How many watts is this total? I have a meanwell 1000W powersupply and it wont last very long before it cuts out. If I only do one side at a time and 5amps on the other it is fine.

I want to be able to charge all 8 at once and curious what Power supply to shop for.

03-21-2016 09:33 AM  4 years ago

rrElite Veteran

Meridian, Mississippi

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Hello skytrekin.

Volt x Amps= Watts.

Your charger will be pulling maximum wattage just as your batteries reach 4.2 volts per cell and before your charger begins to reduce the current to hold that voltage.

Soo.. A 6s battery will reach a max voltage of 25.2V (6c x 4.2V). You said you are charging at 20 amps per side for a total current of 40 amps. So 25.2V x 40A yields a max power of 1,008 watts.

This is just the power being pumped into the cells. There will be further power required for losses along the way - such as powering the charger. So it looks like you are at the extreme limit of what our power supply will keep up with.

Others will have more complete suggestions for home based power supplies but I personally have been using an eFuel 1,200 watt power supply with my 4010 Duo for a while now. I'm very happy with it. I will confess I don't charge at the limits of it's abilities so I don't know how it will perform for you. Pulling 1,000 or more watts from a 1,200 watt power supply might work but I personally would like more "head room". With that said, notice the power supply is rated as an output of 30 volts and 50 amps for a calculated 1,500 watts (30V x 50A). It is sold as a 1,200 watt power supply suggesting there may already be some headroom in the product.

Again, others will have more information about various power supplies.


"Well, nothing bad can happen now."
03-21-2016 12:08 PM  4 years ago



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skytrekin, that looks like a great charger....up to 40A.

As wj mentioned, you must have a DC power supply that is "robust".

The 40A max charge current can only be achieved by using a PS that can supply > 40A @ 30V....according to the specs.

Your Meanwell PS is capable of 1000W(your claim, no reason to doubt that).....but you didn't mention the PS max output voltage that your particular Meanwell is capable of.

To the details of your situation...

"I am charging 8 6s 5000mah packs at 1C so 20 amps per side."

I don't understand what you mean by "per side"...but....

At a 1C charge rate....using two(I think) 4-port paraboards(perhaps that's what you meant by per side) charge eight(4/per side) 6S, 5000mah(5 Ahr) batts at a rate of 1C requires the following......for best results.

Charging at a 1C rate, 8-6S(22V), 5 AHr batts requires from the charger...

8(total batts) * 5A(at 1C) * 22V(6S batts) = 40 * 22 = 880W.....minimum.

Your Duo charger has a max input voltage of 30V.....which means that your PS should have a 24V output(Meanwell does have 48V output PS's but that would exceed the input voltage of your Duo charger.

So a 24V Meanwell PS output voltage(at 1000W output current) would just barely be your requirements for charging your 8, 6S batts simultaneously at 1C.

If your Meanwell PS has only a 12V output...that will be a problem.

Another thing to consider, is the paraboard capable of handling the current required....

The way to check this is to use a DVM to measure the input voltage to your Duo charger when you charge.

If the charge current(at 1C) demanded by your total parallel 6S batts is such as described above....and your PS is not capable of supplying that power to your Duo when in its charge mode....the PS voltage output will be "low", as measured by your DVM.

From your description of you PS "cutting out", it sounds like your PS needs to be more "robust".

Meanwell has the RSP and RST series PS's that will meet your requirements.

If your Meanwell is a 12V, you might be able to "parallel" another 12V Meanwell....but that presents some other issues.

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03-26-2016 01:55 AM  4 years ago


Anchorage, AK

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Thank you for your comments!

I will be on the look out for the efuel 1200W one.
The meanwell worked pretty good for a little while till I started pushing it. The input cord would get hot, I changed that for some 10 gauge heavy duty wire. Then the PS itself would get hot, so I got a harbor freight case and a couple of computer fans to draw out more heat. It helps, but when its already 115 degrees outside in the summer I just need to take it easy on them.

The 110v cord you buy with it comes with very small wire inside. Thats what was getting hot. The 2000w Yamaha is up to the task, although it does rev up a bit under load.
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