A realtively good cost for the 20Ah LiFE cells can be found at 
http://www.batteryspace.com/LiFePO4-Prismatic-Box-Battery-12.8V-20Ah-256Wh-10C-rate-without-PCM.aspx.
  The plastic case contains four 20Ah cells and does not come with a battery 
management system.   Many guys in the model warship world are using these cells 
with a simple balancer found at 
http://www.batteryspace.com/Smart-LED-Balance-Module-for-3.2V-LFP-Cell-with-250mA-Balance-Current.aspx.
  One balancer across each cell helps keep the cells balanced to each other 
without limiting the output current.  The cells themselves are good for a 
continuous 200 amp draw.
 
 I switched my combat ships to these cells (and the Headway cylindrical 10ah 
cells for smaller ships) a couple years ago and have never looked back.  Half 
the weight and more capacity than a similir sized SLA, longer cycle life, and 
they don't dump voltage under load.  My ships can battle all day on one charge 
... heck, I don't even take a charger out to the pond anymore.  
 
 Wish I could make it up for the upcoming battle.   T81 is still awaiting its 
time on the building schedule to get remotered.  SV15 is even further down on 
the schedule requiring a total rebuild from the suspension up.  Lastly the 
semi-secrete tank project is stalled as other higher priority projects compete 
for time.  Still, the goal is to have all three assets operational by the 2014 
Spring Battle.  :) 
 
Mike M

From: Derek Engelhaupt <[email protected]>
To: [email protected] 
Sent: Friday, September 20, 2013 9:12 AM
Subject: Re: [TANKS] Re: Battery find



Under normal conditions the motors don't pull 30 amps, but I have blown a 30 
amp fuse on the Sturmtiger using the same motors.  18AH batteries are 
sufficient using SLAs for most tanks.  I'm just really not sure about what size 
LIFEPO4 battery pack I should use.  I was demonstrating the KV-2 to some people 
that visited us and the two 7AH batteries got really hot.  One was so hot that 
it started to bulge so I really need to find a sufficient battery pack for this 
beast.  I was thinking that the 20AH packs would be sufficient to power it.  
Problem with going over 20AH is price. 

Derek



On Fri, Sep 20, 2013 at 7:30 AM, isaac goldman <[email protected]> wrote:

Max discharging current : 30 Amps. 
>
>
>If you happen to pull more than 30 amps total the battery will shut down on 
>you. Your going to want to make sure running both drive motors doesnt pull 
>more than that...
>
>
>
>On Fri, Sep 20, 2013 at 7:56 AM, TyngTech <[email protected]> wrote:
>
>I would say that on this unit, the BMS is integral to the case.  I don't see 
>any connectors or wiring that would indicate an external BMS unlike this 
>sellers 15AH solution. 
>>
>>
>>http://www.ebay.com/itm/24V-15AH-LiFePo4-battery-Lithium-Electric-Bicycle-Scooter-Rechargeable-Battery-/221280643607?pt=US_Rechargeable_Batteries&hash=item33855aaa17
>>
>>Steve
>>
>>
>>On Friday, September 20, 2013 4:52:59 AM UTC-4, Neil Rochford wrote: 
>>Cant grumble at the price, I`ve been looking at something like this for my 
>>e-bike that I can also use in my tank. Im just a little concerned about 
>>reliability of a technology I dont understand, Does the BMS come part of the 
>>battery box ( integrity built in ) or does it require finding a home in the 
>>tank somewhere ?. 
>>>Think how much weight would 2 X 12v SLA  20AH be ? compare that to 4.8kg
>>>wonderful stuff imo.but remember I know nothing 8)
>>>
>>>
>>>Neil
>>>
>>>
>>>
>>>
>>>
>>>On Thursday, September 19, 2013 8:59:16 PM UTC-7, [email protected] wrote: 
>>>What do you guys think of this one?  Kind of a nice setup with a voltmeter, 
>>>on/off switch, quick disconnects, charging port, and a charger.  All in a 
>>>nice neat package.  I'm looking at it for the KV-2 so it will fit in that 
>>>tank.  It's about 7"x3"x10" from my quick calculations. 
>>>>
>>>>
>>>>http://www.ebay.com/itm/321207262810?ssPageName=STRK:MEWAX:VRI&_trksid=p3984.m1423.l2661
>>>>
>>>>
>>>>
>>>>Derek
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>
>
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>5142334423
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