Hi Gerry,
LiFePO4 Rechargeable Batteries
High Performance —High capacity as high as 165mah/g - light weight for
capacity
Long Cycle Life: up to 2000 cycles (8x of Lead Acid and 3-4x of Li-ion)
Extremely Safe/Stable Chemistry: will not explode or catch fire under
collision over charged or short circuit; hi thermal stability of phases
up to 500C
3.2V per cell, thus 4 cell pack nominal voltage 13.2V
LiPo Rechargeable Batteries
Even higher performance, 210mah/g - very light weight for capacity
Shorter Cycle Life: up to 500 recharges.
Unstable Chemistry: can explode or catch fire during charging. Can only
use with specialized chargers
Used extensively with RC vehicles requiring light weight - high current
discharge
3.7V per cell, thus 4 cell pack nominal voltage 14.8V
Both are possibilities for portable operation with KX3 (LiPo need a
little voltage reduction circuitry to keep it under 15V at full
charge). Both much lighter an equivalent Sealed Lead Acid battery.
See this page for further details -
http://www.batteryspace.com/hi-powerli-popacks.aspx.
Hope this helps,
Gary
On 12/15/2013 3:32 PM, Gerry leary wrote:
Can anyone tell me the differences between the two types of batteries mentioned
in this email?
Sent from my iPhone this time
On Dec 15, 2013, at 3:50 PM, Gary Hawkins <g...@hawkins-zhu.com> wrote:
Hi Mark,
Thanks, this seems to be the best explanation as to why the Hi Cur warning is
happening.
I'm now trying to decide whether to go for LifePo or LiPo. I like fact LiPo
have higher voltage per cell thus creating a nominal working voltage around
14.8V but I will likely go for LifePo (nominal working voltage 13.2V) since
they seem a lot safer during charging process.
Gary
KK6GXD
On 12/13/2013 10:01 AM, Mark Petiford wrote:
Gary,
I didn't find the table, but I did find two relevant posts:
This was the problem reported by one poster:
During xmit at modest power 8 - 9 watts, I occasionally see a msg flash on the display
that shows "hi curr". It seems that when that happens, the xmit power gets
reset to 5.0 watts. I have the battery charger option installed and NiMH batteries in the
unit, but have been running from an external 12v gel cell.
Sounds quite similar to your experience. There was a response from Myron, WV0H,
who has done considerable testing on his KX3:
8-9V will allow you 3W on any band.
9-11V will allow you 5W on any band.
11-13V will allow you 10W on 160-15m, 8W on 12-6m, and HI CURR if you exceed
2.5A.
13-15V will allow you 12W on 160-15m and HI CURR if you exceed 3.0A, or if on
12-6m HI CURR
if you exceed 2.5A.
If the HI CURR warning shows up, expect to see the power setting throttled back.
I have tested some of these data points and my results are very similar to
Myron's. In addition, I took a look at some SLA datasheets, and would be very
surprised if the voltage at the KX3 during transmit stays above 11v for long.
The discharge curve (NOT the same thing as the resting curve, or the charge
curve) for SLA's is pretty steep. Combine that with the relatively high
internal resistance of the cells, cable/connector drop, and the KX3's reverse
polarity protection, and the voltage at the KX3's Power Amplifier tends to get
knocked down a lot. I ran successfully ran SLA's for a while after receiving my
KX3, but only at 5w and below.
I suspect your decision to move to Lifepo/Lipo cells is the right answer if you
want to stay in the 8-10 watt range. There are lots of folks using them
successfully for that reason.
Mark
KE6BB
From: Gary hawkinsg...@hawkins-zhu.com>
Sent: Fri, Dec 13, 2013 at 9:04 AM
To: Mark Petiford rv6am...@yahoo.com>; elecraft@mailman.qth.net
elecraft@mailman.qth.net>
Subject: Re: [Elecraft] [KX3] Hi Curr Warning
Hi Mark,
I have revision C2 of the manual and, if I remember correctly, theimportant power
voltage setting is >11V for full power. Thatbeing said, if 13.8V is what is
required this may explain what'sgoing on. The SLA nominal voltage is marginal. I'm
going topurchase some Lifepo/Lipo batteries to both reduce weight in packand
provide a slightly higher nominal voltage.
I'm not a member of the Yahoo KX3 user group - perhaps I shouldjoin. If you do
find the table you referenced I'd love to see it.
Best regards,
Gary
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