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Old Jul 04, 2011, 05:50 PM
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Charging Without Balancing

Yes, this idea probably scares the crap out of most here, it scares me a little too. The fact is I am running a 12s 2p setup on my electric bike and I have been using a 350watt 48 volt Meanwell regulated power supply to quick charge my Turnigy 20C lipos at work. So far it has worked great, all cells are behaving well and staying within .02 volts of each other. I am not deep discharging and I only charge up to 4.18 volts per cell. I have checked each 6s pack every 5th charge or so and run some low voltage alarms that buzz if any cell gets too low or too high.

Well recenty my Meanwell supply bonked out on a 100 degree day and I like to charge outside. So my question for the lipo experimenters:

Are all regulated power supplies the same i.e. Do the all operate with CC/CV? What I like about the Meanwell is that it will charge at 9 amps for the majority of the cycle and then tapers off at the end until it reaches 50 volts and then just sits there until I unplug it.

Is this how you the majority of power supply modders charge or are you guys powering your chargers with the power supply?

Thanks for any help guys, this forum rocks and many on our small electric bike forum come here to learn much about motor theory, battery chemistry and charging methods. Also, I use a tiny little HV110 to power my bike quite briskly about at 30 mph. You guys have really blazed the trail for EV technology.
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Old Jul 04, 2011, 06:03 PM
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Are you using a proper battery charger designed for LIPO. For a moment I had this crazy idea that you were just hooking the batteries up to PSU
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Old Jul 04, 2011, 06:10 PM
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I rarely balance my 12S LiPo 4200mAh.
Only once in about 10-15 flight, so far they have 250 cycles and still healthy.
They usually do not need it, but when there is a time for it, i do it.
But i check them with CellLog8 about every 2nd charge, just to be sure.

Some MeanWell PS are CC/CV, some shut down on too much load, Meanwell have it in specs for every type.

I had been warned this is protection method and should not be used for this purpose, the PS will not "like it".

So i have 2x iCharger 3010B, mainly because i charge from 12/24V in the field, so PS is useless.

I have now 1x 1200W and 3x 800W server power supplies for charging in all locations i go to.
Always 2 units 400/600W connected in series for 25-26V and now i am working on some fanless models.
They will need a box with a fan, so bit more work then the ones with fans.
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Old Jul 04, 2011, 06:15 PM
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BTW i know why you have this solution - there are no 12S reasonably priced chargers, and if, you still need the PS to power them.

I believe it is working, but i would add some diode to it, to be sure the voltage from the charged pack will not go into the PS in case you loose power for the PS.

That might damage the PS (or not) depending how it is done internally.
I blown some 13.8V/40A PS for RC use when i tried to charge 12V LiFeYPO4 with it...
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Old Jul 04, 2011, 06:24 PM
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Originally Posted by lipoflyer View Post
Are you using a proper battery charger designed for LIPO. For a moment I had this crazy idea that you were just hooking the batteries up to PSU
Yes, I am going directly from the PS into the battery pack. The Meanwell has an adjustment pot right on the front that I can fine tune the voltage that the PS will terminate the voltage at. It does sound crazy but has worked quite flawlessly for about a month now.
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Old Jul 04, 2011, 06:29 PM
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Originally Posted by savant77 View Post
It does sound crazy but has worked quite flawlessly for about a month now.
What you should have said is that it worked for about a month and then the PSU failed.

I would look into getting a proper lipo charger. If you are running two 6S packs in series you could set them up with a jumper to parrallel them and then charge them with an off the shelf charger and you would also gain the ability to balance them.
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Old Jul 04, 2011, 06:36 PM
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Jointer,
Thanks for the post, that is all very usefull. Have you found other PS that are CC/CV?? That is not something the eBay seller usually lists in the specs. I have the S350-48 volt model that many on my forum have used with great success. There is one that sells a current limiter board which allows the current output to be dialed in.

I would bite the bullet and just buy the Hyperion that charges up to 14s lipo but my other ebike runs at 18s which as you can imagine is a real PITA to switch back to 12s for charging. So my plan was to get the S350-24 Meanwell in series with my S350-48 to make an 18s charger.
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Old Jul 04, 2011, 07:11 PM
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So how about some unit from here?
http://www.mastechpowersupply.com/dc...ply/cat_7.html

I was considering getting one year ago, but the shipping to Europe is half the price, then the VAT and import tax...
If you are US, it could be the solution.

The only issue is balancing, it could happen some cell will go mad (especially Turnigy, that never lasted over 70 cycles in my case) but the PS will stay charging...

I do not charge in some very safe enviroment, but in you case, it is more dangerous then usual, so you should charge somewhere where is nothing flamable.

9A at 50V is 450W, so you stress the unit over limit.
Did i understood correctly it switched off due to overheating?

Meanwell specs are here:
http://www.meanwell.com/webnet/search/seriessearch.html
The S-series does not have PFC (not allowed in Europe), so it probably take much more power from the power socket then what is needed.

If there is current limiting board, it would be nice to use it, to prevent overloading the PS.
That is for that S350 model?

Not sure how 24+48V PS in series will work.
You will probably need to unground one (should be possible to do on DC side).
I would get a Mastech PS, if you are really decided to charge like this.
75V model should be fine and the EX line should have no problems directly charging.
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Old Jul 04, 2011, 07:17 PM
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Originally Posted by savant77 View Post
Yes, I am going directly from the PS into the battery pack. The Meanwell has an adjustment pot right on the front that I can fine tune the voltage that the PS will terminate the voltage at. It does sound crazy but has worked quite flawlessly for about a month now.
It does sound crazy and it is crazy. if this thing fails for what ever reason its going to be very uncomfortable at work whilst they repare the fire damage etc.

Chargers are cheap
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Old Jul 04, 2011, 07:59 PM
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Thanks Jointer!

Check these links for some common PSU charging solutions that a few of the guys are using:

http://www.recumbents.com/wisil/e-be...ll/default.htm

Here is the current limiter board, I should have bought this and now I will. I guess the PS was working overtime at 9 amps when it should have been running around 7.

http://endless-sphere.com/forums/vie...urrent+limiter

BTW, I charge in a bunker like structure outside at work so the only embarrassment would be a charred bicycle. Again I have overvoltage alarms that I can hear while it charges, so I do have some firewalls in place. I am probably as safe in my methods as your average indoor lipo charging member. So please, let's not turn this into yet another lipo charging safety thread.
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Old Jul 04, 2011, 08:17 PM
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Here is some more interesting topics

This one uses DC to DC converter to get more voltage from PSU:

http://endless-sphere.com/forums/vie...anwell#p421975

This one shows some pics of Meanwells in series:

http://endless-sphere.com/forums/vie...Cheap+meanwell

And here is a very long thread on modding these supplies:

http://endless-sphere.com/forums/viewforum.php?f=20
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Old Jul 04, 2011, 08:20 PM
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Originally Posted by lipoflyer View Post
Chargers are cheap
Please show me this cheap charger that puts out 350 watts at 50 volts.
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Old Jul 05, 2011, 05:25 AM
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Czech Republic, Hlavní město Praha, Prague
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Nice modifications!
I shared all the PS-related knowledge i gained over 4 years of RC flying, so it is up to you what to do next.
I know many members here will not like this solution.
I think it could be fine, since i basically use my chargers as CC/CV PS and do not balance (especially in the field).
So they will not save my day if any cell decide to go mad...
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Old Jul 05, 2011, 09:12 AM
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Originally Posted by savant77 View Post
Please show me this cheap charger that puts out 350 watts at 50 volts.
Use 6s packs.

My old Hyperion Duo 0610i (250 watts a side) can balance charge the two 6s packs as one 12s (50.4v) pack. It doesnt cost much at all.

The later ones are as you say are 14s (2x7s) capable. They are also very well priced.

Anyway, your not bothered about balancing so just charge a few packs with a proper lipo charger and plug them together...
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