[Elecraft] KX1 LiPo Batteries

[Alan WB6ZQZ]

Lithium Polymer batteries for the KX1? A couple of possibilities:

I just measured the battery space on my KX1.

I get about 2.3 by 1.8 by 0.7 inches on the smaller side, and about 2.4 by 
1.8 by 0.7 on the larger side by measuring the existing battery packs. 
There may be a smidge more space available, but it is pretty tight in there.

Looking at the LiPo batteries from the batteriesamerica.com RC web page, I 
see several possibilities:

In the individual cell category:

P610 3.7v  1200mAh  1.9"L x 1.3"W x 0.3" thick  24 gms (0.85 oz)   $10.95
   This appears to be the best fit. Can easily fit four of these in the 
KX1. This would yield 7.4v at 2400 mah or 14.8 at 1200 mah. Since lipo 
batteries don't mind high current drain you'll get close to the full 
milliampere-hours unlike some other batteries. Another possibility is to 
use 3 cells in series for 11.1 volts at 1200 mah.

P611 3.7v  1600mAh  2.35"L x 1.3"W x 0.33" thick  34 gms (1.2 oz)   $12.95
   This appears to be awfully tight in length, which is a problem for 
attaching leads, and two stacked is tight vertically as well. This is what 
I used in the K2, two stacks of three cells fit easily on the battery tray 
in the K2 with room to spare. Testing still underway on that project... (K2 
works great but charging testing has not been completed)

In the prepackaged battery category:

2LP610 7.4v 1200mAh  1.9"L x 1.3"W x 0.62" thick  48 gms (1.7 oz)  $ 26.95
   This is probably the way to go. You can fit one of these 2-cell packs on 
each side. They can be paralleled if the charge states are similar, and 
charged and discharged in the parallel configuration. In series the voltage 
is a bit high, but that might work also. How would the KX1 like 16 volts 
when fully charged???

A single one of these 2-cell packs would also work quite nicely, and it 
comes with cables attached. That may be the best deal. Premade packs with 
leads are very easy to work with. You could get a mating connector and make 
an adapter to fit the KX1 battery jack and do NO soldering on the LiPo 
pack, or you could change the connector to fit the KX1. At 34 ma the pack 
would power the KX1 on receive for 30 hours, or about 8 hours of transceive 
operation. Rechargeable, good for a day's operation, and lighter than the 
existing battery pack.

Provisions for charging would need to be made as well. I will leave that up 
to your imagination.

2LP611 7.4v 1600mAh  2.35"L x 1.3"W x 0.68" thick  68 gms (2.4 oz)  $ 32.95
   This one is really tight but might work, especially on the slightly 
larger side. Just using one of these on the larger side should work out 
pretty well. It is going to be a tight fit, if in fact it will fit. This 
would leave lots of room on the other side to put an inverter to make 
higher voltage.....

If you decide to work with Lithium Polymer batteries make sure and read 
instructions and work carefully. They can deliver tremendous short circuit 
current and you must insure that never happens. Use only an appropriate 
charger.

-- Alan WB6ZQZ