LiFePo4 Vs. LiPo w/ safety

[Bitmaximus]

Ok, So I bought my first ebike... made by a brand named velec...

Its got a rear 350W motor with a 9AH 36V LiFePo4 battery comes with a 36V 2A charger, no idea what controller is on it...

I want to add running time to it.

I want to start off by buying 2-4 of the below battery to get 4.2AH to 8.4AH at 33V additional power when my 9AH one runs out.

The LiFePO4 Option
http://www.hobbyking.com/hobbyking/store/__14071__ZIPPY_Flightmax_4200mAh_5S1P_30C_LiFePo4_Pack.html

Or with the below lipo 5.8AH to 11.6AH at 37V
The LiPo Option
http://www.hobbyking.com/hobbyking/store/__21388__ZIPPY_Compact_5800mAh_10S_25C_Long_Lipo_Pack.html

I want to know about how to protect these cells from puncture (boom) (casings) and how to protect from charging issues (boom)
Which charger, bms?, balance? bulk? etc....

Can someone give me some advice?

 

[dnmun]

don't

 

[dogman dan]

The lifepo4 from HK has not turned out to work as well as the advertized c rate, so on that pack, indeed don't.

RC Lipo is as safe or dangerous as you make it. But yes indeed, I don't agree with folks that just tape some packs to the frame, or throw em in a bag kinda loose and ride around. Hard shell packs are one good approach, and lately they've been fairly cheap. Seem to only come in 4s though.

My approach is one of two methods. On the dirt bike and the racing bike, I made a nice box to protect the packs while riding out of wood and 1/8 aluminum sheets. The packs fit tight enough to flip the bike and none fall out or get damaged. By now there are some nice dings in the metal sheets, but no damage to the packs. On other bikes, I may carry a bit of RC lipo in the pannier bag for a range extender. If I do that, the packs are put into a tight fitting custom box cut and folded out of coroplast sign material. So a bit of bouncing around in the bag never punctures a cell, or a crash won't leave naked packs vulnerable.

With RC lipo, you are usually the bms. It can be as simple as a voltmeter monitoring the whole pack voltage, or you can get voltage monitors for each pack, or even monitors that warn if any single cell gets low. There are lipo bms's out there, for instance this one is highly recomended. http://www.methtek.com/2012/02/05/complete-hobby-king-lipo-protection-kit/

What you are advised to do depends on lots of things. Where and how you charge, particularly if safe charging while you work is needed. How often you cycle it, do you need long range every day, do you just want to go further on weekend adventures, and of course if you have any money.

You could add 5 ah of range with RC lipo and a cheap slow charger quite cheaply. But if you need more range everyday, 5 days or more a week, I tend to advise people to just get a 36v 20 ah or 48v 15 ah pingbattery. With a big ping, you get lots of range, and a long expected lifespan with little risk while charging it.

 

[ksw9915]

If you decide on lipo, I suggest two 5s packs.
They're cheaper packs than one 10s and the balance/charging equipment is cheaper too.