choosing between Winston LiFeYPO4 vs. Headway 38120S cells

[markmm]

I’m trying to use lifepo4 cells to create a 12V40Ah battery pack, to power a 62lb thurst boat trolling motor.

Users here have been *VERY* helpful in getting me this far.

my new question is this, I have been working with Headway 38120S 10Ah LiFePO4 cells (~$15.50 each), but as I was about to order 16 of them (from http://evcomponents.com), I noticed this battery too: Winston LiFeYPO4(LiFePO4) 3.2V 40Ah Cell - $55.00 each.

1) advantages and disadvantages of each type?
2) are both the same in terms of safety?
2) how many of the "Winston LiFeYPO4(LiFePO4)’s" would I need to end up with a battery pack of 12V40Ah? (four?)

thanks very much in advance!

 

[wesnewell]

1 only need 4 40ah cells for a 40ah pack. Makes assembly much easier and more reliable.
2 Same chemistry, so yes.
3 Yes 4.
I don't know much about either, but if cycle life is accurate, the Winstons should last longer. I've read that the Headways are over rated at 10C and arer only good for 3C continuous. Personally, I'd go with the Winstons. IIRC your controller draws a max 60A. That's just a 1.5C load on a 40ah pack at max. During normal use, you will probably draw a lot less than that most of the time.

 

[markmm]

Thx for chiming in again, Wes. Good stuff. So get to my desired 12v40Ah, would i wire those 4 winstons in series or parallal?

and the same balancing charger (link below) would work w/o any probs, right? Thank YOU!

https://www.amazon.com/gp/product/B00ZGZZ40K/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1

 

[dustNbone]

Wire 4 in series for 12V (3.3V each so actually more like 13.2V nominal) and any 4S balance charger that can be set for LiFePo4 charging. That's a big pack and a small charger though, so it's going to take a long time to charge 40Ah.

 

[wesnewell]

Yes. 4 in series. That's a 50W charger to charge a pack with over 500Wh, so it will take more than 10 hours to fully charge an empty 40ah pack. When you're not using the motor don't store it fully charged like you would with a lead battery pack. Charge to no more than ~70% soc when not in use. The charger should have a storage setting that will do this for you.

 

[markmm]

thank you dustNbone and wesnewell. you guys are tops, no matter what they say. haha, jk. thank you!