10s 41v charger, where to find?

[mighty82]

Hello. Long time reader and builder, but never registered before now.

Last year I built a e-bike for my mother with a bafang bbs01 250w and a 36v bottle battery. Thing is, i´m trying to get a hold of a charger with a end voltage of around 41V to be a little more gentle on the cells and maybe get some more time out of the battery as it gets charged every day and a LOT of use.

I know about the satiator and various diy solutions, which is fine for me and my builds, but I need something simple and not too expensive for my mother. Last year em3ev sold a 10s charger with variable termination voltage, but I can't find that one anymore.

Any idea where I can buy a 2-5A charger that charges to 41v or that can be adjusted internally to get the voltage that i want? Preferably a proper cc/cv charger.

Thanks

 

[dogman dan]

You should be able to adjust most better chargers internaly. The very cheap plastic ones tend to not have the pot to adjust voltage.

But not balancing your battery ever can't be very good for it. If it's used that often, it will spend very little time at full voltage. Cycling it often is less damaging than sitting around full.

 

[kdog]

Most of the standard 4-5a chargers ( not the small ones with no fan) have a few trimpots in them to control current, cc-cv point and voltage. Buy one, open it up find the V adj, wind it down a notch and you'll be good to go. Depending on the charger you get, a photo of the internals should suffice for some help here.
Otherwise careful trial and error can do the trick ( to find the V adj trimpot)
Got a DMM? Happy to work on a live device? Keep away from the bitey end!
K

 

[mighty82]

I know I will have to charge it to a full 42v once in a while for balancing, but since it rarely get drained to more than 40% I don't believe there will be a problem. In my experience, it will take quite many cycles for a pack of identical cells to go significantly out of balance.

One problem that comes to mind; is the bms buildt into the chinese frame battery able to handle a charge rate of 4-5A? It is supplied with a 2A charger.


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[DrkAngel]

MeanWell S-150-48 is often found on eBay for ~$20.
Mods to 41V ≤3.65A

Full instructions on voltage and current mods - MeanWell S-150-48
41-42V mod requires 1 resistor or 1 pot replacement
3.6A regulation requires adding pot or replacing 2 resistors with 1 resistor or pot
Oops - sorry!
Never finished amp mod table (just now factored regulations - not tested)
Lowering r33-r38 resistance to 330ohm should regulate at ~3.56A
recommend pot in parallel and test with amp meter (most basic multimeters will meter amps <10A)

Deluxe mod
I never speced 48V amp mods because I built in pot with 0-5.4A adjustable with Amp meter

 

[mighty82]

That is very interesting. I see that the s-150-48 you tested had a low voltage limit of 40.X volts unmodded. Is it really necessary to mod the voltage range if this is correct?

It seems the sp series is easier to get my hands on these days. Are they moddable in the same way or are they completely different?

 

[DrkAngel]

Low voltage limit varies by unit.
SP series Amps not modable.

S-150 series and s-350 series have documented mods.

Good mod documentation on cheap 400w MeanWell clone
110/220V to DC 48V 8.3A 400W Switch Power Supply

Should be able to amp adjust below 5A

 

[mighty82]

I ended up ordering the clone you suggested. Hopefully I can mod it to output from 40 to 60v so I can use it both to charge the 36v pack and my 16s lifepo4 packs. Will it do this with a 2k adjustable pot?

I also have a dc-dc boost converter and a 48v psu on the way. Just to test that route also.

 

[dogman dan]

Yes, under discharges that light, you won't get unbalanced very fast. Or see the battery wear out fast.

Just have her get in the habit of not charging it till she wakes up, and most of the time the battery will be sitting around 40% discharged. If she needs it right away,, she's got 60% in there for another ride. Plus whatever gets in there in 30 min or so, while she gets dressed.

 

[999zip999]

Make sure it isn't charging at to high of amp rate for the bms or batteries.

 

[sannder]

The easiest way I find for making a 41V voltage is either by using 2 laptop power bricks at 20.5V each or by using a power supply (or the existing charger) with an efficient DC-DC converter with current and voltage control (modern 80+ PC power supplies are working this way).

I have used the ZXY6005S module to monitor the charging - you can program even the frequency and cutoff current - however these modules are rather fragile (mine stopped working)

 

[wez]

It should also be possible to connect one or several high current diodes in series to lower the voltage by 0.7V/diode. There vill be some loss of charging power, but it is not that much (0.7W/ampere).
Then you have the possibility to charge to 42V by disconnecting the diodes.

Andreas

 

[cal3thousand]

I have a limited number of Mean Wells that I am selling; will do 10S to 14S (adjustable) Potted and rugged (IP65) so they are bike mountable in all weather. I just sold the only one I had made up, but I can whip up another by Tuesday. I'll be posting them in the for sale section.

If you want to make your own, get a CLG-150-48A and solder your own AC and DC plugs. Done.

EDIT: removed Sale-like terms to adhere to forum rules.

 

[amberwolf]

Not sure if you've read the rules, but ads of any kind are not allowed outside the Online Market area.

 

[Chalo]

It should also be possible to connect one or several high current diodes in series to lower the voltage by 0.7V/diode. There vill be some loss of charging power, but it is not that much (0.7W/ampere).

That's what I was thinking.

According to my research, single power diodes can have forward voltage drops from approximately 0.5V up to about 1.1V. Since the point of a diode in this case isn't to block reverse current but only to bleed off a little bit of voltage, leakage current and breakdown voltage are irrelevant; you can just choose one according to its VF and its current capacity. Zener, Schottky, whatever.

 

[parabellum]

Dunono, but the market is flooded with balance scooter chargers, most are 10S with 42V CV. They do ~2A in CC, make no noise (passive cooling) and start at ~10USD with all sort of approval marks. I use 2 diodes to get my 41V on 10S LiPo pack.
Works well by now, even 5USD unit without approval marks works fine.

 

[mighty82]

Since my understanding of electronic circuits is pretty basic. Could anyone tell me what kind of diode I would need to lower the voltage and where/how to connect them in a charging circuit?

 

[parabellum]

Since my understanding of electronic circuits is pretty basic. Could anyone tell me what kind of diode I would need to lower the voltage and where/how to connect them in a charging circuit?

Use any 1N5400 for 2A (they are 3A max, but you need some room) and connect in series between battery and charger positive or negative, it will droop .5 to .7V, use 2 to droop double of that. For higher amps I would take cheap bridge rectifier, they have 4 diodes inside and you can use 1 or 2 at once.
Ring on the 1N5400 points in positive flow direction, so must be pointing battery positive (on + leads) or chargers negative (on - leads). Ex. Charger + to back of the diode and Battery + to ring side of the diode. Negatives just stay in normal connection.

Bridge rectifier has +(Pos),- (Neg and two ~(Alternate), + wolud be same as ring, pointing battery positive (on + leads) or chargers negative (on - leads). Ex. Charger + to ~(alternate) pin of rectifier and Battery + to + pin of the rectifier. In this case you have droop over 1 diode or ~ 0.5-.7V
Or Ex.2 Charger + to -(negative) pin of rectifier and Battery + to + pin of the rectifier. In this case you have droop over 2 diodes or 1-1.4V.

Hope it helps.

P.S.Bridge rectifier example (Note "AC" is other name for ~): http://img1.exportersindia.com/product_images/bc-small/dir_98/2920418/electrical-rectifier-2151971.jpg

 

[mighty82]

Thanks very much guys. I got the mean well clone mentioned here, did the modifications and it works great. Adjustable from around 30v to 60v and charges my 16s lifepo4 pack beautifully at 6A. The fan running constantly is a bit noisy though.

I still think I am going to keep it to bulk charge my own packs as it´s a bit overkill and diy-ish for my mother with the exposed 220v connections and all. She also charges her battery outdoor on the bike, and although its under roof (carport) it does get a bit too humid for this "open" fan cooled power supply.

So next thing will be to try and add a diode or 2 to her existing charger. Will these emit any heat during use? Can i just wrap them in think tubing?

 

[Chalo]

Yes, the diodes will heat up. Charging current in amps times the diode's Vf equals the number of watts of heat each diode will emit. You might need to heat sink them.

 

[mighty82]

At 2 amps it shouldn't be more than 1.4w of heat or so for 2 diodes?

 

[Chalo]

At 2 amps it shouldn't be more than 1.4w of heat or so for 2 diodes?

Right, probably about that much per diode. The power diodes I've used before have Vf values from about half a volt to just over one volt. So 2A through a diode with a 0.5 Vf drop would make 1W of heat. 5A through a diode with 1.1 Vf drop would make 5.5W of heat. Whether you need heat sinking depends on both the power being dissipated and the thermal mass/physical size of the diode.