Just to confirm... Meanwell s-350-24 to charge 7s lipo

T

tostino

10 kW
Joined
Mar 24, 2008
Messages
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Location
New Port Richey, FL
Well I got to work today, and I go to charge my battery on my bike... power supply is dead. Now I have a nice 27 mile ride home on 50mph roads, with only like 5ah usable in my battery, since I can't charge while i'm here =/.

Anyways, I want to get a meanwell to charge my pack up with, and i'd like to order it like...right now :p.

I have a 14s 28ah pack that is broken in two for charging (in parallel). So I when charging, the pack is 7s 56ah. Will a Meanwell s-350-24 be good for charging it? Do I need to do any mods to get it to work properly? Please let me know your thoughts asap :p

Thanks,
Adam

P.S.
This is the route i've gotta ride home with VERY limited power now =/.
http://maps.google.com/maps?f=d&sou...798,-82.614441&spn=0.419857,0.727158&t=h&z=11
 
Actually, I just found a 400w ps at the same ebay store...
http://cgi.ebay.com/24V-DC-16A-400W-Switching-Power-Supply-S-400-24-/170397697770?cmd=ViewItem&pt=LH_DefaultDomain_0&hash=item27ac7e86ea#ht_4038wt_1195

Is this the same type of PS? Will it work as well the 350

This is the 350 I was looking at:
http://cgi.ebay.com/24V-DC-14-6A-350W-Switching-Power-Supply-New-S-350-24-/170457097168?cmd=ViewItem&pt=LH_DefaultDomain_0&hash=item27b008e3d0#ht_2329wt_911

Edit: I would also like to note...I don't use a bms. So are there any other considerations i'll need to make?
 
These look like nice inexpensive supplies- Do you charge through a balancer that 'throttles' the charge down as the pack voltage comes up? I think things to concider are: (1) avoiding overcharging cells (explosions and fire), ({2) preventing over discharge during discharging (pack life and risk of fire/explsion if try to charge an over-discharged cell) and (3) balance each cell during charging- only need be done occasionally and not a concern if you need a top- off at work.

I have only experience with SLA and LiFePO4. I have one "factory built" Headway 48V pack with a mystery BMS that seems to be working fine, and a self-built 36V Headway pack with a signal lab BMS that melted down and destroyed half of my cells during break-in. so I am not an expert by any means. Right now I have a cheep 48V LiFPO4 charger that I am using with 2 8s "cell-logs" to monitor balancing (since I am now wary of BMS systems that come with no specifications, instructions, or any indication that they are actually functioning). The cell logs give me some confidence that my pack seems to be functioning normally and is staying in balance. I have been reluctant to run it down more than 25-30%, so have kept rides short.

I want to use this system for a long commute (22mi one way) but I will either need more capacity or to charge up at work. I do not want to carry my flimsy but functional charger with me, since it would be destroyed by vibration (we have some really crappy roads in Seattle). I wonder if Meanwell power supplies are appropriate charging solution and durable enough to carry around on the bike?

I have seen charge/balancers that run off 12V for RC use. Could a 12V power supply drive one of these to charge Lipo through the balance taps? forgive me if this is a stupid question, I am still a noob.
 
That is my current setup actually. The power supply that died was a PC power supply I was using to power a RC lipo charger to charge my pack. But I would like to move away from that if at all possible for faster charging. That charger is limited to 7a... That is a slow charge for a 56ah pack.

The meanwell I am hoping will be a better solution... I am just waiting on one of the many experts with them to comment :p
 
I think the 400W model will work fine. The specs mention Constant Current protection, specifically, so I'd think this might be fine. The only issue is like the Meanwells, it probably has the constant current limit set at 135% of its rated 16A, or about 21-22A. These supplies are really meant for applications that may have an average current usage under the 16A limit, but may hit some brief peaks that are higher. To be used as a battery charger, the current needs to be delivered continuously, so if the CC limit of the supply is really at 21A, that's what it is going to try and supply. Sometimes that's okay, and it works anyway, or it might be too much and it might go into its "hiccup" mode, which basically shuts the current off, waits a bit and turns it back on. What many of us have done is modify the S-350 models, to lower the CC limit, back down to the 100% level. The good news is that this is a 5 minute mod, piggybacking a resistor to an existing one. The bad news is that there are several different versions of the PCBs used in the S-350 series, so there's now standard mod that will work for all of them.

Finally, since you have a 7s setup, you should probably go for the 27V version. To charge 7s at 4.15V per cell, you'll need about 29V, and I think that is a bit higher than the adjustment on the 24V model will allow.

-- Gary
 
Hmm, I don't see a 27v version. How easy is it to modify the voltage adjustment to get that 29v out of the 24v supply?

And that is good that the mod to change the CC limit is not too big of an ordeal! That will be needed for sure.
Edit: I see the 27v model on ebay now... I suppose that is the better solution for me.

What do you think? Should I buy it?
http://cgi.ebay.com/350W-27V-DC-13A-Regulated-Switching-Power-Supply-K007-/170431332887?cmd=ViewItem&pt=LH_DefaultDomain_0&hash=item27ae7fc217#ht_5780wt_1372
 
tostino said:
Hmm, I don't see a 27v version. How easy is it to modify the voltage adjustment to get that 29v out of the 24v supply?

And that is good that the mod to change the CC limit is not too big of an ordeal! That will be needed for sure.
Click to expand...

Yes, Mike (mkeefer...) has done this a bunch. Again, it's an easy mod, but I'm not sure exactly what is required.

-- Gary
 
It's alright, the 27v model is a good deal cheaper than the 24v one anyways. $33 shipped 0_0!

So i'll get that ordered right away XD. Thank you for your help! I'm sure i'll be asking for more as soon as it comes in and i'm clueless lol :)

Edit: Purchase made!
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=170431332887
 
Alright I got the power supply in last night! I can't find too much info on what resistors to change for the hiccup mode mod... Here are the pictures, of the PCB, if anyone could tell me what they know about changing the resistor.
 

Attachments

  • pcb.jpg
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You rock sir! I just got done with the resistor mod. I can tell by the buzz of the transformer that it is changing the current limit. Rather than a fixed resistor, I used a pot. That way I can adjust it to just what I want.

I do have one more question (at least for now lol) though... How would I be able to have the fan run all the time? It is not kicking on even though it's getting really warm...
 
Fan mod needs to be done before dialing in current since the additional draw the fan presents will lower the mcu/pwm ic chip (tl494cn) in effect raising the current again.

To get your fan on replace the thermistor closest to the fan Jack with a resistor, measure out of circuit impedance of the thermistor the you add resistance to get the fan to come on... More resistance = faster fan speed.

I'm on the phone at the moment but I'll post back more detail later when I can see your pcb clearly.

-Mike
 
Hello All, thanks to this thread, I ordered a S350-15V to feed my LipoCharger...

for 32$ shipped :shock:

It works fine. The fan starts after 10 minutes of usage !
They say that it is very efficient, but at the same time, it becomes very hot before the fan kicks in.

Before I was using a modified PC-PSU and this limited me to charge at a rate of 6 amperes max, for my 5Ah 6s battery pack.
More than that the PSU would stop.

Now I can use the full 10 amperes of my 106B :)

It takes 35 minutes instead of an hour.

Thanks !
Here is my fireproof charging station :)
IMG_0041%20%28Large%29.jpg

IMG_0042%20%28Large%29.jpg
 
Fredo,I also have a 14s pack (2 10p-7s Konion) and have the very same SWP. I like your Idea to add a trimpot.,can you tell me what value trimpot-I got a 1k and mine has 3 legs-which 2 do i use? Also could anyone confirm the location of the shunts i'm assuming they are just right of those 3 big capacitors.I have never soldered anything to a pcb before.
 
wow, I should have done this mod before my first PS blew up !!

Here is my new :
13.5V 25.8A ST-350W Regulated Switching Power Supply
seller pages http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=120585069288
one-900.jpg

Can someone please show me the resistor which is to be modded in parallel ?

AC input range selectable by switch
Protections: Short circuit / Overload / Over voltage
Forced air cooling by built-in DC fan
PWM control and regulated
Built-in cooling Fan ON-OFF control
100% full load burn-in test
Fixed switching frequency at 25KHz

I dont want to use the charger until I get the mod done..
 
still trying to decide on a model
S-350-27V 13A 350W Regulated Switching Power Supply
or
S-350-13.5V - 25.8A 350W Regulated Switching Power Supply
charge 4 cells at one time
seperated by a DPDT switch

Is this a bad idea ?? I would also use the resistor mod..

seems to me a faster charge is at 6A per cell x4 (x2)
.VS.
1.43A or less (11.5A) x 8 cells
 
I think you are looking at that the wrong way...

You have a 8s pack. Lets just say it's 10ah for example.
4s2p = 256WH of energy (splitting your pack in half). 8s1p = 256WH of energy. A 27v PS charging at 12a = 355 watts. A 13.5v ps charging at 24a = 355 watts. Both will charge your pack as fast. I would still use the 27v PS over the lower voltage one though, because why split it in two when you don't have to??
 
I dunno
There is a PDF from A123 showing the newer electrode has 12 minute charge to 80% ability
The fastest way to charge to 80% would be to have a PS output at higher amps ?
 
Okay, think of it this way, if you split your pack in half, you now have half the voltage, and twice the amp hours needed to be charged. So it will take the same amount of time no matter what with a single charger. If you want to charge your pack faster, you will need a 2nd charger, because if you are using those 350w psu's, they will charge the same size pack up in the same amount of time no matter how you decide to hook them up.

I don't know if hooking up multiple PSU's in parallel or series is easier though, so wait for someone knowledgeable to comment on that.
 
Power losses and heat generated are proportional to the current squared. All things being equal, you are better off charging in series than parallel. For instance charging a 24V pack at 10 A can have 1/4 the resistive power losses than charging it as two 12V packs in parallel at 20A. Charging the two 12 v packs independently at 10A each might have twice the losses as the 24V connection (it can depend upon the efficiency of your chargers)
 
That is not necessarily true... If you add the batteries in series, their IR is the sum of every battery added in that series string.

The only part of that that actually is true is for losses in the wires.
 
'Doh! :oops: Left over addled thinking from a previous project involving two power supplies and two capacitor banks... and lots of sparks.
 
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