On LIPO and LFP batteries for the FT-857D

The FT-857D radio requires  13.8 v +- 15% or 2V for a nominal range of 11.8 to 15.8V.  At 100W it should have a 25A power supply though the transmit discharge will be much lower than this.


Above : voltage discharge curve of volts vrs AH showing the very flat 12.8 V discharge at 4.8A for 4 LiFePO4 cells.

There are many battery options for powering the FT857  radio for portable operations  including SLA (sealed lead acid),  Nicad, NiMH, LIPO, and LiFePo4 to name a few.  I decided on the Tenergy 12.8V 10Ah LiFePO4 Rechargeable Battery (DGR-A)  one for about $160 (with charger).

  • designed to be drop in replacements for standard 12V 10 AH SLA batteries
  • built-in protection cicuitry
  • can use the existing SLA charging system as well as it’s own charger.
  • 128 Wh
  • Max discharge (pulse) : 40A
  • Max continuous discharge : 30A
  • Charge V  : 14.4 v
  • Weight : 1.2 kg  (2.6 lbs)
  • 151 x 64 x 95.
  • 1/4″ standard spade terminals
  • very constant discharge voltage. Voltage stays close to 3.2V during discharge until the battery is exhausted  allows the battery to deliver virtually full power until it is discharged.
  • simplify or eliminate the need for voltage regulation circuitry – probably referring to the battery boosters now used for SLA
  • The use of phosphates avoids cobalt’s cost and environmental concerns
  • higher current or peak-power ratings than LiCoO2.[8]
  •  slower rate of capacity loss than other  lithium-ion battery chemistries
  • thermal and chemical stability over other lithium ion chemistries

12.8 V 10Ah  gell cell size. This will definitely jump start the Prius 🙂


Source: All-battery.com

I received my battery in good order.  all-battery.com is not the slickest operation, order tracking and communication weren’t the greatest, but prices were good.   Tenergy is California based, with interesting marketing and branding for Chinese battery technology.  It seems to be a reasonably good brand  – I have other lithium cells from Tenergy and I have no complaints.

Use Case:  I’ve run the radio on batteries now in the shack, portable at the beach, and again today on 9/6/14 have been running the FT857 for nearly nine hours.  V is 12.7V.    0730 9/7Z – 20M QSO PSK 31 with VK4VXX.

Our friend, kh6fm uses a Lithium ferro phosphate (LFP) battery  LiFEPO4  12.8V 13.2 Ah which has a good voltage profile well within the operating voltage specs of the FT-857D radio.  It is based on a 3.2V LFP cell.  3.2v * 4 = 12.8 .  This pack employs 8 cells,  thus 2 12.8 v 6.6 Ah packs wired in parallel to get the 13.2 Ah.  $184.

  • Size:  217mm (9″) x 137mm (5.4″) x 28mm (1.1″)


Another option is the K2 Energy LiFePO4 batteries, similar in form to the Tenergy line.

There are probably many more sources of this chemistry and it will likely become more popular especially if it develops a better safety record than the LiPo.  Time will tell.

Battery junction has 14.8 Tenegy LIPO with protection for about $155.http://www.batteryjunction.com/lithium-packs.html

LIPO Use with the FT 857

There is good info on using for LIPO 3.7v cells with  11.1 and 14.8 packs for the 857D with nobody reporting any issues with either as far as the radio is concerned.   Some use  dropping diodes to keep higher voltages within spec.   Others don’t bother and report no problems due to higher voltages, especially when using fully charged batteries.  See also: http://www.sotawatch.org/reflector.php?topic=4132

~ by marksun on May 7, 2014.

3 Responses to “On LIPO and LFP batteries for the FT-857D”

  1. What kind tx time a certain watts did you fet with the 857 and Tenergy 12.8V 10Ah LiFePO4 Rechargeable set?

    • Sorry I don’t have any real data for you. From a handful of events, the 857 does run for hours on receive with short intermittent transmitting on SSB at 100W so it works for monitoring and occasionally transmitting for the day, maybe more but I’ve never run it down that long. Lifepo4 voltage stays flat above 12.5v when my car battery will run down below 12v in a matter of minutes. Your mileage may vary – depends a lot on your transmitting style – I tend to be brief on the air – others as you know, tend not to be brief 🙂

      • Ok thank you. Wonder if there is a bigger capacity battery with charger that would work?

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