What controller and motor to use with a 15S lipo pack?

[coolbreezz17]

What's up guys how's it going.I could use some help with one of my e bike builds .I'm trying to figure out what motor volt 48v or 60v and controller to use with a 15s battery pack I'm running.Its normal volt is 55.5v .It is three 18.5 v packs run in series and one parallel .Fresh off charger I no the volts will be more like 63v and there is where my predicament lies.Most 48v controllers will cutout at 60v for a high and cutout at 42v for low. If I go 60v controller with my battery I'm guessing I will cutout at 54v so you can see my confusion lol .Anyone have a recommendation for this battery setup?I'm going with a mid drive system because hub motors will not fit on my bike.I am experienced with RC and LiPo batteries .I thought about a voltage regulator but don't know how well that would work.I also thought about only charging to pack to 59v but would limit My range .Any help or advice guys would greatly be appreciated.Thanks

 

[Ykick]

As someone who’s used 12S, 15S and now 16S RC Lipo for years on daily commuters I strongly suggest 16S on a 60-72V controller and install a BMS on your pack for LVC/HVC.

I use 20C 5Ah Turnigy 4S hardcase bricks for easy assembly and protection stuffing into bags and similar. 4qty of those bricks in series brings you to 67V off a bulk charger.

Here’s one of my 16S1P packs with 315Wh capacity before installing the BMS which allows me to safely utilize ALL of it's capacity:

A very good cell count, operating voltage IMO…

48V controllers generally handle 15S RC Lipo but that’s operating very close to max component specs. And as you mentioned LVC can be a conundrum. We’re really better off having a BMS help to keep an active eye on individual cells or series strings during discharge use. Makes charging much more plug & play as well.

 

[coolbreezz17]

THANKS for the info I do have a buzzer alarm set to monitor and alert me if the batteries drop below 3.4v .As far as a 16s vs 15s Yeah it would be nice but I already built the pack out of 3 5s battery's in series and The forth one in parallel.so I have a 15s 20ah battery already .I have over 1800 in this build already and still have to buy motor and controller and don't want to buy more battery's and connectors and sit for another hour soldering.Probably purchased a Lifepo4 next year so I just need the pack to last for now.if you have any ideas that would cost less than a hundred bucks I Could swing that.Thanks

 

[Ykick]

I hear you brother. I was in the same boat for a few years but file it way for 16S using 4S hardcase as future replacement/upgrade.

You can use these BMS in 16S on 15S, merely leave the #16 channel disconnected:

http://www.bestechpower.com/592v16spcmbmspcbforli-ionli-polymerbatterypack/PCB-D167.html

That way if/when you replace and move up to 16S you can reuse the same BMS. Ordering from that company can be frustrating but maybe somebody would go in with you or you might wanna 2nd pack and/or spare BMS? They only sell 2 MOQ (minimum order quantity) to us peons.

You're doing okay. I'm not dissing anything but rather sharing "shit from shinola" I've "learned" over 5 years running these things on a daily basis. LifePo4 sucks by comparison, IMO...

EDIT - meant to advise if you can buy a controller good up to 72V and programmable you'll be in much better position to upgrade at a later date.

 

[dogman dan]

1s more always feels better, especially toward the slower tail end of the ride. I settled in nice at 14s, liking the ability to use 48v chargers I had already.

But for you, I'd say a controller with a wide range of voltages would be good. 36-72v ones are out there, (Grin) but 48v -72v will be enough for your needs.

16s is a really handy size, for building out of the 4s batteries. That's for the many others reading. You have 15s now.

One option is a cheap generic 48v controller, and charge your 15s pack to less than 4.2v. Charging to 4.1v said to make them last longer, and that would get you 61.5v fully charged. No problem to start out at that voltage with any 48v controller. for most 48v controllers, the upper limit is the 63v capacitors inside. As your packs age, they will drop a bit, leaving you with only about 62v once you take it off the charger set to 4.2v.

 

[coolbreezz17]

48v to 72v controller sounds like the plan ykick.Yeah I'll just charge the batteries partially so they stay under.I was thinking that to Dogman just didn't no how well it would work.Thanks guys .Do you have any recommendations for a mid drive motor?I know which ones are the best rated I'm just wondering what your guys's opinions are.It will be mounted to a trek top fuel 8 full suspension mountain bike.Motor needs to perform well off road.Thanks for all your help.
Here's the kit I ended up going with.
Update 3/16/15
http://www.ebay.com/itm/191489810595?_trksid=p2059210.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT