Lab Power Supply as a Charger


#1

All,

While a dedicated charger intended for RC use is a great option, one should also consider that a lab power supply with adjustable current limit can also be used. This is appealing as there are few 1000W+ chargers available.

For example, this should work or come close (50V limit): https://www.amazon.com/Volteq-Variable-HY5020EX-Voltage-Protection/dp/B00PXJHRKO

To charge a lithium based battery, just set the voltage to the desired final voltage (50.4V for 12S setup) and the current limit to something safe (in this case all the way up since it has limited capability). This is identical to the constant current - constant voltage charge that any Lipo charger does.

You could charge the whole pack as a 12S setup, which makes things simpler.

The downside here is that there is no cell balancing. Extreme care must be taken to ensure cells to not get mismatched as it could result in overcharge. I would recommend that they be monitored externally. An smaller RC charger could be used from time to time to do balancing if required.


#2

Why? If it doesn’t have cell balancing, why would anyone pay for an extra charger?


#3

For the reasons I mentioned above. I will repeat:

  1. Possible to find >1000W power supplies for modest prices. Options are limited for RC chargers that do that power.
  2. Can charge 12S directly. I am not aware of many RC chargers that do 12S. Having one connection greatly simplifies things. Taking 4-6 packs off the PPG and charging them in parallel is a mild hassle.

With an RC charger, you still need a 1000W+ power supply.

It is relatively rare, at least with high quality cells, to need cell balancing every charge, or even at all.

This solution would allow faster charging than most RC chargers are capable. A slower, cheaper RC charger could be used for the occasional balance charge. Many of us have those sitting around. I have about 5! But none are suited for charging a 2-3kWh pack in a reasonable amount of time!

In the early 2000’s, when RC hobbyists were first experimenting with Lipo batteries, we used a lab power supply to charge them. Worked great so long as you watch balance yourself. There were no dedicated hobby Lipo chargers available at that time.

This is not for everyone, but it is an option for some that are competent with such equipment.


#4

I been testing this one for awhile and haven’t had any problems. https://www.aliexpress.com/item/HTRC-HT700-DUO-AC-DC-1-8s-Lion-LiPo-Battery-Charger-350W-2-20A-2-Dual/32833042846.html

Nice because it doesn’t need any power supply its has it built in.


#5

So the bench supply is a good idea - but balancing is pretty important. I also like the idea of charging without disconnecting to the 2 x 6S packs, but charging is the most dangerous part of all this. I personally wouldn’t attempt this without a cell balancing charger. It will monitor for 99% of the dangerous conditions, which can be detected with cell over voltage (COV) conditions.


#6

I know nothing about RC battery charging so excuse my ignorant question. I was looking into different chargers reading reviews and someone said the the voltage was not quite calibrated (on a completely different charger than the one you linked).
So my question is, because so many battery packs are going to be hooked up together, would it be best practice to charge all batteries from one charger? Which would assure they’re charged the same. Or is it OK to buy 2 of the identical units you linked to charge 4 packs simultaneously and then combine those batteries for flight because the difference should be negligible?
Thanks.


#7

Check out this link for battery charges.

https://www.maxamps.com/products/lipo-battery-charger

I can personally attest to the Hyperion Duo, but you have to split it into 2 x 6S packs (no big deal. Been doing it for years with a big 12S e-bike pack). The other is capable of a 12S charge.
Both will do the 2 Bonka packs (featured in latest video) in just over an hour.
Their Lipo packs are damn expensive but supposed to be pretty good.


#8

Nice. I think that hyperion charger looks like the best option for moderate charging.

My intention with the power supply is to suggest a solution that can come as close to 1C charging as possible. If people are using 2-3kWh of capacity, a charge time that is greater than 3 hours is less than ideal and makes the OpenPPG less accommodating. It forces people to plan the night before they may want to fly.

As I mentioned in my first post, extreme care must be taken to ensure balance, but I am confident that could be achieved with some other external circuitry. Even a lipo monitor could be used. Not a solution for the masses, but maybe one for those that are familiar.

Which kind of brings me to another point: if ePPG gains traction, we need to make sure users know how to handle lithium batteries. What balance means, proper storage, safe charging, over discharge, etc. I suspect that you will get users that don’t understand series and parallel… All things that could lead to them doing something disastrous by mistake. Maybe part of a future guide?

Probably better discussed in a separate topic!


#9

All the guys in the Endless sphere forum will tell you never charge your battery pack while it is attached to your bike. I personally had a cell go bad while I was charging and it almost burnt the whole bike to the ground.

I would never risk charging Lipos on a machine again. I put them outside on the patio in a concrete block container.
Anything you want to know about batteries can be found over there at ES …no need to re-invent the wheel here guys and gals.


#10

Holy shit those batteries are stupid to work with.
And why are those chargers so expensive?