getting 48V? 13s or 12s battery packs?

[ken1645]

I've been reading the forums various FAQ and newb shopping lists but have one question for the more experienced.

For LiPo, how many in series do I want to get in order to run a 48V controller and rear hub?
http://www.yescomusa.com/Brushless_Electric_Bicycle_Engine-_48v_1000w_Rear_Wheel_Hub_Motor_Kit.html

I understand to not discharge past 3.7V and to not charge more than 4.1V. So I was thinking I would need 13S to get 48.1V at the low discharge point of 3.7V.

Problem is finding matching 5S, 5S and 3S battery packs in stock at Hobby King. I'm looking at the Turnigy 5000mAh 25C packs.

Should I just get 12S and hope the lower than 48V to the controller doesn't shut it down?
4 of these http://www.hobbyking.com/hobbyking/store/__14845__Turnigy_5000mAh_6S_25C_Lipo_Pack_USA_Warehouse_.html?strSearch=Turnigy%205000mAh%206s
make that easy. 2 in parallel with 2 in series.

Thanks for any help.

Also I'm planning to get 2 http://hobbyking.com/hobbyking/store/__10328__Hobby_King_Battery_Medic_System_6S.html?strSearch=hobby%20king%20battery%20medic
to balance charge..
Along with http://www.hobbypartz.com/75p-1220-charger.html?gclid=CNa3z9_N57ICFayPPAod10MAPw
and http://www.ebay.com/itm/Precision-Variable-30V-5A-110V-DC-Power-Supply-w-Clip-Cable-Digital-Adjustable-/290809940607?pt=LH_DefaultDomain_0&hash=item43b59f8a7f

 

[SamTexas]

Most 48V controllers support up to 63V. So 14s should work too. I use 14s on my 36V controller.

 

[migueralliart]

Like you said 12S is NOT 48V but it is pretty close. The problem is in order to do 13S then you have to bulkcharge and have one 6S and one 7S pack which is not an ideal setup.

That charges works pretty well and your plan sounds solid. The only thing you need to consider is that you won't get the TOP speed with that kit on 12S.

 

[dnmun]

you can use 15S and there are 15S BMSs available for cheap. i am gonna buy some of these so the lipo pack will work under the 36v or 48V controller specs. they may need a change of the input power resistor in front of the voltage regulator when you get to 63V. this one is $19 before shipping costs.

http://www.bestekpower.com/555v15spcmbmspcbforli-ionli-polymerbatterypack/PCM-D126.html

 

[ken1645]

awesome thanks for the help.

 

[Ykick]

12S RC Lipo is perfect replacement for SLA 48v systems imo. LVC is usually around 41-42v IIRC. Bulk of Lipo discharge will take place between 46-48v. Plenty room for LVC.

 

[mvly]

I use 14s lipo giving me 51.8V nominal and 57.4V hot off the charger if I charge up to 4.1V. 12s isn't really 48V IMO. If you buy a 48V LiFePo4 battery, it will be 16s which is 51.2V nominal and 58.4V hot off the charger. So for lipo, it is really 14s to be true 48V.

 

[dogman dan]

12s works fine if you aren't after every mph of speed. It's pretty simple and easy for noobs to go for 12s. 14s is what I'm running, but 15s is possible. (with typical 48v controllers)

Typical 48v controller low voltage cutoff is perfect for 12s at 42v. But many will be 36-48v and then will lvc low enough to wreck lipos.

I call 12s lico 44v.

 

[999zip999]

12s as it is easy to buy a 12s balance charger and power supply. You didn't say what charger you are thinking of using ?

 

[lifepo4ever]

buy a lyen controller so you can use the voltage you want and ajust the parameter with the software

 

[dogman dan]

He can run anything from 12s to 15s just fine with the controller he's got.

 

[circuit]

I prefer 12S, because 12*4.2=50.4V, which is below 48V+10% (52.8V). I target to be just below 52.8V because most 48V PSUs (such as meanwell, etc) can be adjusted up to +10% output. Some of them have active current limiting, so can be easily used as quality charger in 12S system.

Also, don't believe your controller will hold 63V if it is stated on caps inside. During driving, caps ant wire from battery make a quite good LC contour and resonates badly in some setups, for example 48V ±15V.

 

[jonescg]

I call 14s for any non LiFePO4 chemistry (such as LiCo, LiMn, LiNiMnCo). This way any off-the-shelf lithium based "48 V" charger can be used to charge your pack in bulk, as these tend to stop at about 58 V.

The equivalent in LiFePO4 is 16s, but the final voltage is about the same.

 

[circuit]

I call 14s for any non LiFePO4 chemistry (such as LiCo, LiMn, LiNiMnCo). This way any off-the-shelf lithium based "48 V" charger can be used to charge your pack in bulk, as these tend to stop at about 58 V.

I have a couple of chinese "48V" chargers that stop at 54.6V, which is exactly 13S at 4.2V.

 

[Ykick]

Point I was trying to make is that most SLA 48V controller LVC works very well with 12S. A perfectly balanced RC Lipo 12S pack will then hit LVC around 3.5V/cell. If you're not running a BMS or alarms or Methods Boards, etc. This is an excellent fallback to have.

13S - 3.2V/cell, 14S - 3V/cell, 15S - 2.8V/cell = all bad territory for this chemistry. And, no RC Lipo pack is perfectly balanced during discharge curve.

I've ran both 12S and 15S RC Lipo for years. Sure, I like the speed of 15S but it requires more parts/connectors to assemble and different charging parameters, etc.

Trust me, 12S is perfect replacement for most SLA 48V setups. Listen to the people who have actually used it with stock Chinese 48V SLA eBike systems.

 

[dogman dan]

Yes 12s is a good choice when you have a controller with 42v LVC.


My LVC happens to be lower on my longtail, so I don't get pack level lvc that does me any good. I decided to go to 14s, making my 48v kinpan charger work OK as a bulk charger. I tweaked it to 47.8 or something like that. I get 4.12v per cell charges now with it. So for me I happen to get the most benefit from a 14s setup. I don't need the speed, but occasionally it is fun to hit 32 mph on the longtail. Makes the pack 80 wh bigger too. So 3-4 more miles range.

 

[ken1645]

Ok another question for the hive mind. I ended up getting a 72v controller and 8 x 5s 20C 5Ah Turnigy battery packs to run 20s2p. This would be 82V high side (4.1V per cell).

Question is how would I charge this? I already purchased one of the Thunder 1220 chargers ( http://www.hobbypartz.com/75p-1220-charger.html?gclid=CNXG5LOrgrcCFVSVMgodyjgAfA ) which looks pretty sweet but can only do 12s. So I'll have to unplug my battery packs into groups of 10 in series and charge 4 times to charge all my batteries

Is there a better way to use this Thunder charger? or should I get a beefy charger to go up to 80+V like this guy ( http://em3ev.com/store/index.php?route=product/product&path=37&product_id=127 ) ?

 

[mvly]

Do what I do. Keep your 2x Thunder charger. You will need to break up the 20s2p into 2x 10s2p. Charge each 10s2p separately and put it back together when you are done.

 

[ken1645]

Do what I do. Keep your 2x Thunder charger. You will need to break up the 20s2p into 2x 10s2p. Charge each 10s2p separately and put it back together when you are done.

Good idea. Could it do 10s4p?

 

[bgoates]

I am sure this is a dumb questions...but what is the preferable discharge rate
for ebike usage of a lipo

 

[wesnewell]

Good idea. Could it do 10s4p?

Of course. I've charged 4s12p many times.

 

[wesnewell]

I am sure this is a dumb questions...but what is the preferable discharge rate
for ebike usage of a lipo

1/2 C rate or less.For a 10ah 20C pack that would be 100A or less. That's for any usage.

 

[ken1645]

Good idea. Could it do 10s4p?

Of course. I've charged 4s12p many times.

Awesome. Thanks

 

[dogman dan]

I agree, discharge at half the stated c rate or less for better results. But even better results happen when you discharge at even lower c rates. Better as in less voltage sag, and hopefully longer lifespan.


Good performance is had when you run 40 amps controllers on 10 ah of 20c RC lipo. That's potentially 200 amps, half the c rate is 100 amps. But it still sags less at 40 amps, less than 1/4 the c rate. Generally, if you keep the discharge rate low relative to the max amps of any battery, it lasts longer.