Using LED Driver as a 12s Charger

ducktaperules · June 3, 2019, 1:35pm

PROBLEM:
After recently finishing my new board with 12s4p 30Q pack (12Ah). I plugged in my old 1.5A charger, only to find that it takes around 8 hours to charge my board This is simply not be acceptable during group rides. My goal is to be able to charge at the same mins per mile rate as my boosted friends.

I started looking for a 50.4V charger that would give me >4A and will ship to the UK before a group ride this weekend but im not having much luck finding anything more than about 2A (still 6 hour charge)

HOW MANY AMPS?
According to the 30q data sheet (https://eu.nkon.nl/sk/k/30q-specs.pdf) each cell’s standard charge is 1.5A or fast charge is up to 4A. In a 4p configuration this means i could happily charge at 6A or fast charge at up to 16A

4A charger would still take just over 3 hours to get a full charge in and 6A would be ~2 hours.

POSSIBLE SOLOUTION - 48V LED DRIVER

After discussing the problem with a guy from work he suggested i buy a 48V led driver.

These drivers are a CCCV power supply usually used for led lighting but might be perfect for esk8 charging.

They are available in a range of voltages to suit any number of series cells.
The output voltage is adjustable (with a screw driver). The data sheet says that the “48V” models can actually have an output Voltage between 44.8V and 51.2V (perfect for the 50.4V needed for a 12s pack).
They are available in many different output currents up to 12.5A.

Output current is also adjustable (with a screw driver). This means that you could crank it up for fast charge at events and group ride but then dial it back for overnight charging when you not concerned about your charge time. Im thinking this could easily be wired to a few position switch for easy current switching.

you could also mod output voltage to be set with a switch if you wanted a “only charge to 80%” type mode which puts less wear on your batteries if your doing charge cycles every day commuting or plan on not using your board for while and not want to store it at 100%.

BUT WHATS THE COST?
48V - 150W - 3.2A costs £39.
48V - 185W - 3.9A costs £43.
48V - 240W - 5A costs £52.
48V - 320W - 6.7A costs £69.
48V - 480W - 10A costs £104.
48V - 600W - 12.5A costs £151.

All are available with free next day delivery from Farnell.

Im considering ordering either the 240W or 320W version.
The 240W version would give me just over 2 hour fast charge or 5 hour slow charge.
£70 is not cheep for a charger but 320W version would give me just over 1.5 hour fast charge (faster than a boosted extended range pack) or 3.5 hour slow charge. This would still be less than half the “fast charge” current given in the 30q data sheet.

WHAT DO YOU GUYS THINK?
Has anyone ever used one of these before?
Do you think it could work?
Is there a better option that i have missed?

EDIT:
So it seems like, as with most things, im not the first to think of this idea.
On .builders there are quite a few posts about using MeanWell LED drivers as chargers so i have committed and ordered the 48V 320W charger. found them on amazon so it should be here tomorrow

taz · June 3, 2019, 1:48pm

Most esk8 chargers have some sort of charge termination.
Although the power supplies you mention are not just CC or CV as is usually the case with most led drivers, they will continue charging if for some reason your BMS does not stop the charge.

Andy87 · June 3, 2019, 1:51pm

https://s.click.aliexpress.com/e/c3Wxbdlo

If you use a 5.5/2.1 or 2.5 barrel plug as charge port be aware that the plug might handle only 5-7a before getting hot or meld.

ducktaperules · June 3, 2019, 1:55pm

My understanding (which may be wrong) is that If the voltage is set to 50.4V then it wont be able to charge the pack to more than 50.4V.

In the rare cast that this fails and starts charging to a higher voltage then your BMS should cut off charging at 51V anyway right?

Andy87 · June 3, 2019, 1:56pm

If I remember right the boosted charger is a 2a charger, so than get a 4a charger and you even charge faster than your friends

ducktaperules · June 3, 2019, 1:57pm

This link doesn’t seem to be working for me. What is it?

Andy87 · June 3, 2019, 1:59pm

Link to a charger. 12s 6-10a from 55$.
I don’t know why but the link is working for me perfectly. Had this issue before already in an other thread.

Maybe AliExpress links are blocked? @mmaner could that be?

taz · June 3, 2019, 2:02pm

Normally the BMS should stop the charge.
The problem is what happens if it does not?
Does it continue float charging at a smaller current until the voltage reaches 50.4V and then shuts off?
I honestly don’t know. I am not saying not to go for , just that we need to search a bit more how these power supplies operate before using them as chargers.

As far as quality goes, I would take a Meanwell power supply over any esk8 charger.

mmaner · June 3, 2019, 2:15pm

Not that I know of.

taz · June 3, 2019, 2:23pm

@andy87 It is not me it is you

hummieee · June 3, 2019, 2:43pm

An ideal power supply. Robust as apposed to others. Should be fine. No noisy fan. Regardless of if it terminates the charge or floats at top voltage that’s ok. If u don’t like the idea of sitting at such high voltage maybe lower the max it will go to.

ducktaperules · June 3, 2019, 2:47pm

@Andy87 this makes sense however does not account for the fact that an AT board with pneumatic tyres has significantly worse Wh/mile is than boosted street wheels.

A boosted extended range pack (199Wh) gives about 12 miles range. This means they are using <15Wh per mile. It takes 1h45m to charge the extended range pack so they need ~9 mins of charge time for 1 extra mile range.

I seem to be using around 30Wh per mile so my 12Ah/520Wh pack is giving me around 15 miles range. At 4 amps the 12Ah pack would take 3 hours to charge meaning that i need ~12 mins for 1 extra mile range. Even 4A charge current wont allow me to keep up in the long run.

once the pack voltage equals the charger voltage there is no voltage diffrence to push more current into the battery. the charger wont “shut off” as its still outputting 50.4V but it will be outputting 0A current so wont “overfill” the cells. I think this is how most eskate chargers work, the led just goes green once the charge current is very small.

ducktaperules · June 3, 2019, 2:51pm

Whilst i have no doubts that the AliExpress one will work and is probably cheaper, it wont be here before the boosted & evolve group rides in London on the weekend

Additionally i like the idea of having a charger which i can switch between charge currents depending on my needs.

hummieee · June 3, 2019, 2:53pm

I have doubts the cheap one will last. I have a pile

ducktaperules · June 3, 2019, 3:06pm

So you think this could be a good option?

I might just order one and see how it turns out as i cant find anything else that looks acceptable in uk.

I might have to change my charge socket to something more substantial than a 5.5 barrel jack . . . .

. . . hmmmmmm . . . . . guess if its rated to 5A then 6.9A might still be within its safety factor right? Im not that bothered if it runs a little warm so long as nothing gets melty.

deucesdown · June 3, 2019, 3:12pm

The HLG series are great for charging. Make sure the model you choose has the “A” suffix (adjustable). They are psus not changers, so they will not terminate charge. Nor will your BMS unless you hit cell ovp (likely for moments during balancing stage) or pack ovp (not likely at all unless you misconfigured). So you will be float charging your pack until you unplug.

For charge rates, sometimes it’s helpful to think in terms of “C”. A 1C charge should take 1hour. 1.5a for a 3Ah cell is .5C, so .5hours.

The CC portion happens at full speed but the CV portion will be slower. I think total time 150% of the rated current is typical. So for a 1C charger it should take about 1.5hr. Assuming cells are in balance.

The balance portion can take days.

But for your situation I think it’ll charge at max speed the majority of the time.

You might eventualy want to consider getting a DPH5005 to put in front of it. 5A max but it’s buck/boost and you can control/monitor via bluetooth or serial. There are high amp versions like DPS5015 (15A) but it’s buck only.

If you search buiders for meanwell you’ll find a bunch of hits.

The PDF data sheets list the limits of adjustability for each sub model.

hummieee · June 3, 2019, 3:13pm

I’d get the meanwell over the alibaba stuff. Maybe double or even triple the price but worth it and will actually last. Not smell. No noise. No surprise snap that ends it. There’s mods u can do to them too

ducktaperules · June 3, 2019, 3:20pm

This Should not cause a problem tho should it? (eg if left over night)

Im guessing that in the group ride scenario you will mostly say in the CC portion anyway as you frequently do many short charges then move on the the next place. i cant imagine spending over 2 hours somewhere.

good tip, hadn’t thought to do this but i will go check it out now

deucesdown · June 3, 2019, 3:22pm

If you print an enclosure that houses a ruideng psu and something like this

It’s a reall nice setup. You can see total watthours charged, time duration. Some meters forget the total wh when shut down but others accumulate and need to be manually cleared (not sure which I like better).

Most of the meters are slightly off and cannot be calibrated. The reading will be off anyway because of the resistance of the charge leads (unless you do a 4wire setup)

But, I put some kind of power meter inline when I charge, every time.

deucesdown · June 3, 2019, 3:40pm

Another thing I do is put a wall socket timer switch inline, so no matter what, charging shuts down at the appointed interval.

Some photos

DPH5005 with VAC1030 (remembers WH total when shutdown, not able to calibrate)

This guy is set up for XLR charging. I like it a lot but no calibration, and the WH reset button is recessed

This guy is tiny! 3 digits precision (only some models have this, and it’s dammed hard to find) but it’s not that accurate. No calibration. Because it’s tiny it’s always facing the same way. This one would be better in a small enclosure with hardmounted DC barrel jacks like @b642 does with pack voltmeters. Remebers WH.

This one I put in a big ole enclosure. Forgets WH, which is nicer sometimes, but if you have AC power on a timer and the meter powered off the AC side and not the battery side, you won’t see how many WH went in.

Oh all the meters can power off the DC feed, but most can also be powered with an independent DC source, so you don’t drain the battery pack when charging is complete.