# 100Ah x2 or 200Ah Does it matter



## wessss77 (Jan 4, 2013)

So in looking at making my battery purchase, does it make a difference if i go with 36 or 45 200Ah batteries or with 72 - 90 100Ah? either way i get the same pack size but is there a difference when it comes to charging is it healthier on the batteries to use twice as many to fuel the car based on the discharge rate? I think I just answered my own question which is scary cause I may actually be catching on. :S


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## dougingraham (Jul 26, 2011)

wessss77 said:


> So in looking at making my battery purchase, does it make a difference if i go with 36 or 45 200Ah batteries or with 72 - 90 100Ah? either way i get the same pack size but is there a difference when it comes to charging is it healthier on the batteries to use twice as many to fuel the car based on the discharge rate? I think I just answered my own question which is scary cause I may actually be catching on. :S


No real difference in operation between a 200AH cell and a pair of 100AH cells paralleled. Probably the 100AH pair will weigh more than the 200AH cell and you will have more issues with battery interconnects. On the flip side you might be able to fit the paired 100AH cells better than the larger 200AH cell. You can also test every cell and pair them to make cells that all have nearly equal capacity. The advantage to having matched cells is a greater tolerance for issues because your system would have the characteristics of both bottom and top balanced packs. Bottom balance is tolerant of an over discharge and a top balance has a more pronounced end of charge voltage rise.

If you are doing a DC setup you should also consider a 90S 100AH pack and a motor controller that will limit the motor voltage to what ever you need. The Soliton, Netgain and Zilla controllers can do this.

Good luck with your build!


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## Ziggythewiz (May 16, 2010)

Even though buddy pair matching would make the pack more consistent, he still has to balance at the top or the bottom. You can't magically get the benefits of both.

A 2P pack would be prohibitively difficult to do in pairs anyway, I would just do two strings if the 100 AH cells happened to fit better. For simplicity maximizing the voltage the controller can handle is the way to go.


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## wessss77 (Jan 4, 2013)

Thanks...I figured its cheaper for shipping to get the 36ea 200Ah with only half the cells and reduced weight, fewer connections, less hardware. Next year I can go for the remaining cells to get me up to 144v and if I wanted to go past that later, I can update to a new controller to control the motor volts. What I wasn't sure of is if it was faster to charge or something else.


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