That, or your meter is not very accurate in measuring the voltages.
The voltage of all 66 series cells (plus cable losses) should add up
to the voltage that the charger is supplying.
It has been said before that charging to 3.45V is sufficient, so about
but make sure that all cells (esp the lowest and highest) do charge to
the same voltage.
Do you use a BMS to make sure all cells are at the same limit and stay
below 3.5V each?

Cor van de Water
Chief Scientist
Proxim Wireless Corporation
Email: Private:
Skype: cor_van_de_water Tel: +1 408 383 7626

-----Original Message-----
From: EV [] On Behalf Of John Lindsay
via EV
Sent: Thursday, September 25, 2014 6:29 PM
To: Buddy Mills; Electric Vehicle Discussion List
Subject: Re: [EVDL] LiFePO4Charging

Read the voltage drop across the cables connecting the batteries.

The missing volts equal the charge current multiplied by the total
resistance in the connections and cables. Otherwise known as Ohms Law. 

You may have some bad connections. 

John Lindsay

> On 26 Sep 2014, at 10:50 am, Buddy Mills via EV <>
> I thought I understood how to charge my 9 month old LiFeP04 but know I
> doubting my process.  So I will lay it out and see what feedback the
> gurus here can suggest.
> I have 132 60AH batteries in 2P66S.  So I am going to call this 66
> at 120AH.  Specs call for 3.6 volts max,  so 66 in serial is 237.7
volts.  I
> don't want to push them so I set the max voltage at 231volts charge
> brings me to approx 3.5 volts per battery.  Now in real life once it
is at
> this 231 volts for the string each individual battery voltage is
approx 3.34
> volts +/- 0.10 volt.  Even at the plus side of that each battery would
> 3.44 volts or 227.04 volts for the string.  So how is it that my
> string voltage is reading 334 - 335 volts while each battery is
> 3.34?  Does it matter if the total voltage is over the max (66 X 231)
> long as the individual voltage is less 3.5 volts?  Should I set my BMS
> charge voltage cutoff higher and just leave each cell set at the 3.5
> max.   Hope I am making sense.
> Thanks in advance for any feedback,
> Buddy Mills
> <>
> Look mom, no gas.  <>
> Disclaimer:  No animals were harmed or killed in the process of
writing this
> email.  Any stories to the contrary are, for the most part, either
> or greatly exaggerated. 
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