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Paralling up LifePo4 packs?


#1

Seeing this post in another thread:

I am thinking paralleling up my batteries would give me some useful benefits.
Firstly it will drain some from each (hopefully) rather than all from one, and of course offer me an increased operating time (I plan to use the battery power for doing some backpacking contesting too, which will be more current demanding than SOTA)

Assuming same age and capacity batteries like I have both fully charged, is it acceptable to just parallel them up?
I’ve had a mooch around the web and people seem to be doing it (as is @OE9HRV of course).
Normally when I have paralleled stuff up I have used balance resistors, or in PSUs, diode sharing. Clearly I don’t want to throw away power if it is not needed to.


#2

Try it, see what happens :wink:


#3

I use the parallel method all the time. I have 2 X 5Ah, 11.1V LiFePO4. These batteries were purchased at the same time and will now have been charged 20 times. This allows me to operated for 2 hrs with some reserve capacity. I have 20Amp automotive spade fuses fitted in the positive line at each battery for protection. I parallel up immediately prior to use and charge up individually. The charging power supplied to each battery by the Turnigy battery charger suggests that the batteries share the load very well. I use the X60 connectors for the power connections and Y piece.

Regards

David
G0EVV


#4

Regularly used in radio control model boats where there is significant current drain from the motors. I use a dual Schottky diode (and individual fuses) which makes a very minimal difference to the available voltage at the output and prevents one battery being charged by the other if the terminal voltages vary


#5

Hi,
Pse correct if wrong but aren’t these batteries capable of 30 A individually with minimal voltage sag. I doubt you need more than 20 -22 A so better to use individually and switch over to the next one when drained? That would give you the max Ah with minimal extra bits.

73
Ron
VK3AFW


#6

Ron,
my 4.2AH LiFePO4 is labelled 30C which suggests 4.2 x 30 amps peak current, or over 120. Quite sufficient for voice or cw peaks of 20amps.
Battery power worries a lot of people and I think 2m FM experiences are the cause of many concerns. But ssb and cw are much kinder to batteries than FM.
I also prefer to keep the batteries separate as I believe they will inevitably age differently and one will end up always charging the other, at perhaps rather large and damaging currents.
73
Andrew
vk1da