pages Operating the FT-817
from various types of batteries
A Front-panel view of my
Lithium-Ion (Li-Ion,) NiCd, and NiMH cells and battery
potentially dangerous! Very specific precautions must be
to assure cell longevity as well as safety of personnel and equipment!
Do not use a Li-Ion cell or battery pack in any
than specifically stated by the manufacturer without first fully
the factors involved in their usage.
What follows are general guidelines and it is up
user to do his/her own research to determine how best to (safely)
These warnings can also be applied to Lead-Acid,
and other cell types as well. You have been warned!
Comment: Apparently, not all versions of the FT-817
are supplied with an Alkaline battery holder: Some versions (e.g.
European) are reportedly supplied with a rechargeable battery pack.
For information about operating the FT-817
Lithium-Ion cells, go here.
More conventional rechargeable batteries (such as NiCd and NiMH)
the rather unique property that they maintain a fairly constant voltage
over their discharge cycle - around 1.2 volts - although they start out
in the vicinity of 1.5 volts when "fresh out of the charger" and very
quickly settle down to a lower voltage in the vicinity of 1.25
They maintain their voltage fairly well (within 0.1 volts, more or
depending on load and battery condition) until their charge is nearly
- and then the voltage suddenly nosedives.
This property makes them fairly easy to use. It would be safe
to use, say, 10 NiCd or NiMH cells to operate the FT-817: When freshly
charged, this battery would put out 16 volts (the maximum upper voltage
for the FT-817) or less, and quickly settle down to 11-12 volts - a
Why would you want to use alkaline cells in
When I was originally putting this page together, it occurred
that if you could cram, say, 2 more AA cells into the radio, you could
probably get more usable lifetime out of them - maybe even run
down before the radio shut itself off! Because I
had the Li-Ion packs and the Radio Shack NiMH pack (see
I didn't think about it much. Until recently.
Paul, AA1LL, recently read this page and dropped me an email
the same thing - but he went a step further than I did: He ran
numbers. As it turns out, adding 2 more AA cells (and making it a
ten cell pack instead of an 8) added significantly
able to extract more useful life out of a set of cells. Paul's
Assuming 9 volts = end of life:
9 volts = 8 x 1.125v = 8 x Vbatt after 1.3hr at
9 volts = 10 x 0.9 v =10 x Vbatt after 3.3hr at 0.5A
10 batteries last 2.54 times as long as 8
or, at 1 amp:
1.125 v = vbatt after 0.3hr
0.9 v = vbatt after 0.9hr
10 batteries last 3 times as long as 8
Using Duracell Ultra (one of the newer so-called "High Drain"
of cells with lower internal resistance:
1.125 v = v (2 hr, 0.5A)
0.9 v = v (3.7 hr, 0.5A)
10 last 1.85 times as long as 8
1.125 v = v(0.5hr, 1.0A)
0.9 v = v(1.5hr, 1.0A)
10 last 3 times as long as 8
In reality, the '817 "dies" at about 7.5 volts or so.
The question comes up again, "Why would you want
the '817 with Alkaline cells, anyway - especially if you wanted to use
10 of them, you'd need to put them in an external
Paul's answers are as good as any:
1. You can get them anywhere, probably
even in Afghanistan
2. You are 99.9% sure they are not "half empty" when you put
new ones in a radio, as opposed to recharged NiCd's.
One obvious advantage of Alkalines over NiCd or NiMH cells is
could keep them in your "Emergency Radio Kit" for several years - and
still have most of their charge - whereas NiCd (and, especially) NiMH
to suffer from self-discharge.
Another thing: After your '817 is "done" with them,
still run an LED flashlight for quite a while.
Has anyone actually done the "10 cell thing?" Paul is
up for trying it and we'll (hopefully) have some results before too
First off, if you get an '817, don't bother with putting
cells in the supplied holder. You may ask "Why did they
it with just an alkaline holder if it works so badly?" My
A battery holder is very cheap - and people would complain if they didn't
include something. Should they have increased the price
the radio by $50-$60 and included a NiCd or NiMH pack? 'Dunno...
maybe... Anyway, after you have "run down" the alkaline
in your '817 there is going to be enough life left in them that they
probably be used in something that doesn't consume nearly as much
or care so much about the cell voltage - like a flashlight or your
We think of alkaline cells as operating at 1.5 volts per cell, but
reality is that this "nominal" voltage only occurs when the cell is
new and unloaded. Typically, a type "AA" alkaline battery has
2.8 amp-hours of capacity. What may not be so obvious is that
rating is based on a fairly low current consumption (something that the
FT-817 only does when it is turned off...) and it is measured to a
voltage of 0.9 volts per cell (90 percent discharge) - a voltage at
the FT-817 will not properly function. In other
the usable capacity is much less that the cell's
ratings would imply!
One possibility that offers better Alkaline performance are the
types of "high capacity" cells. These have only (relatively)
appeared on the market - and they are usually market especially for
cameras and "high load devices." While the actual
of these cells may or may not be much higher than traditional cells,
do offer much lower internal resistance than their
- a factor that may contribute to much longer usable life. Even
with these types of cells, however, don't expect to be able to get very
good operating lifetime from a set of these (rather expensive) cells.
"Why is alkaline
life so poor in the FT-817?"
Many users of the FT-817 have complained that they get very poor
out of a set of AA alkaline cells installed in the FT-817. If you
look at the nature of alkaline cells and the current consumption of the
'817, you'll understand why:
The voltage across an alkaline cell drops as it is discharged:
By the time it gets to 50% discharge, it is already down to about 1.2
When it is 80% discharged, it is at 1.0 volts, and it is down to 0.9
when it is 90% discharged.
The nominal capacity of typical AA alkaline cells (down to 0.9 volts
per cell - 90% discharge) is about 2.8 amp hours at room temperature
70 degrees F - approximately 21 degrees C) when subject to a rather
load (much lower than drawn by the '817, by the way.)
What is worse is that the internal resistance of an
cell increases as it is discharged. When it is new, the
is in the area of 0.15 ohms per cell (1.2 ohms for 8 cells in series,)
increasing to 0.3 ohms per cell when it is 50% discharged (2.4 ohms for
an 8 cell pack) and up to 0.6 ohms per cell at the 80% discharge point
(i.e. 4.8 ohms in an 8 cell pack.)
Translating this to actual receive use in the FT-817 is as follows
are approximate and extrapolated from actual test data published by
manufacturers - see the links near the bottom of the page) Note
data is for "traditional" Alkaline cells and not the
"high output" cells. (See elsewhere for a note on
New cells: 11.6 volts
25% discharge: 9.2 volts
50% discharge: 8.8 volts
60% discharge: 7.8 volts
80% discharge: 7.4 volts (Note that the radio may shut off
Translating this to transmit use (on the 1 watt power setting) results
in the following:
New cells: 10.9 volts
25% discharge: 8.25 volts
50% discharge: 7.75 volts
60% discharge: 6.8 volts (The radio will shut off above
As you can see, in receive, the radio will function down to the 80%
point. This (theoretically) translates to about 10 hours of "on"
time if the radio is always squelched and no transmitting is ever
If one were to put a brick on the key (at the 1 watt level) the FT-817
will consume about 1.1 amps or so. This would mean that
a continuous transmission of about 1.25 hours is possible before
the radio shut off. The situation gets worse when operating on
New cells: 9.6 volts
25% discharge: 7.8 volts
50% discharge: 7.0 volts (If the radio will shut off at
Thus, on high power, a continuous transmission is possible for
about 25 minutes before the radio shuts down. This would also
with transmitting after having the receiver on for about 3 hours (with
the volume all of the way down.)
The upshot of all of this? Alkaline batteries really aren't
suitable for operating a "high drain" device like the "transmitting"
If you do use alkaline cells in the FT-817, do
expect it to work very well when transmitting on high power!
Finally, the battery holder and its connecting wires have a few
of an ohm resistance - further contributing to voltage drop and
reduced battery life.
(Note: These numbers are based solely on calculations based
on data obtained from a battery manufacturer's web site for AA alkaline
cells. Actual reports indicate that operational lifetime
worse than this. Let me know what your
Why can't I charge
rechargeable) alkaline cells in the FT-817's battery holder?
First of all, the "rechargeable" alkaline cells do
as advertised - but they are not advertised to work well in "high
devices. The FT-817 is definitely a "high drain" device. If
you insist on using them in the AA alkaline battery holder, their
will be noticeably worse than that of "normal" alkaline
due to their higher internal resistance (as compared to "traditional"
The FT-817 is designed to prevent "accidental" charging of Alkaline
batteries in the supplied holder: To do so without very precise
and monitoring can result in cell rupture and possible damage to the
(or the operator!)
Note: Technical info (curves, charging, etc.) for
rechargeable alkaline types may be found at the Ray O Vac web site at
link near the bottom of the page.
One of the common 'mods is to cut the green wire: This will
charging of the batteries in the holder - no matter what kind they
But is this a good idea?
The answer is no - especially for any
types. Charging these types of cells (even when charging is
is best done under strictly controlled conditions. This involves
analyzing the cell's current state of charge, carefully monitoring the
cell's charge progress, and then terminating the charge (or changing
charge rate) in response to the way the cells charge is
This cannot be effectively done with series-wired cells without
the proper monitoring/control circuitry.
What about NiCd or
rechargeable batteries in the battery holder, then?
Again, no. But, since I suspect that you will try anyway, I
as well explain why:
One of the main reasons why the supplied alkaline battery holder is
a poor candidate for truly efficient rechargeable battery use is that
spring contacts have noticeable resistance of their own. When a
amps of transmit current are pulled, you are losing a few tenths of a
due to resistance. This is simply wasted power, and as the
wear with use, this will only get worse. Finally, if the pack
shorted (and unfused) those springs may melt, and wiring and components
within the FT-817 itself may be damaged - possibly making a mess and
causing a safety hazard.
Why is there this problem, then?
First, one should understand how a "normal" NiCd or NiMH pack is
A good quality pack will have overcurrent protection and maybe even
protection as well. Why? NiCd/NiMH packs have a very low
resistance when they are new and fully charged: A new, freshly
AA NiCd cell can easily put out 30 amps (or more) when shorted - enough
to melt tools or burn holes in shorting objects - including the cell
If it happens to be the radio that is doing the shorting, then you can
expect damage (i.e. burned components, wires, and circuit-board traces)
from the current. In addition to the heat generated, a cell can
(i.e. explode) and cause damage to equipment and people.
Another "safety feature" of a battery pack often overlooked is the
of the insulation over the cells: Individual NiCd/NiMH cells
have a single layer of rather thin "heat shrink" plastic over
This insulation can be scraped off (especially if you have an
with sharp edges around its battery compartment) allowing the
to short to the case of the radio. A battery pack, on the other
typically has rather thick insulation over the entire pack (in addition
to the insulation over the cells themselves) preventing this sort of
How do you make it safe, then? I can't recommend that you
use the supplied alkaline holder and modify it to allow use and
of NiCd/NiMH cells - but I know that some of you will.
some recommendations as to how one can make it safer. You
responsible for any damage you may cause to you or your
radio if you do this, however:
Put a fuse in the negative lead of the battery
- If a cell touches the case, the short will send the most
through the negative lead. The so-called "pico" fuses work well
they are very small) but one can quickly solder the miniature glass
inline if one is adequately skilled. (You can put a fuse in the
side as well, but that may be contribute unnecessary resistive losses.)
Put some insulating material between the exposed cells and the
case. This will prevent accidental shorting of the batteries to
case and prevent chafing of the (already thin) insulation on the
This insulation could be "fish paper" (a very tough, reinforced
paper) or plastic sheeting.
Monitoring the charge of the cells. The charge rate of the
(when supplied with 13.8 volts on the rear panel connector) is
between 160 and 200 milliamps - depending upon the charge
How long should you charge the cells with the '817? When the
are discharged, they should be charged such that about 1.2-1.4 times as
many amp-hours are put into the cells as was taken out. If you
a 1.4 amp hour pack, this would mean that you should put at most 2 amp
hours (or so) into the pack. At 200 milliamps, this would mean
you should charge the pack for 10 hours. When NiCd or NiMH
cells are fully charged, additional charge (i.e. overcharging) will
them to become warm. If the cells become warm when
at the sort of current that the '817 charges, they are probably already
Finally, a bit of soapbox: I don't believe in the
- at least not under normal "human" usage. This affect has been
documented (and misdocumented) and it occurs only when
cells are fully charged and then discharged to precisely the
level repeatedly. Such precise charge/discharge
is not likely to happen in everyday usage with most
operating habits. What is most often mistaken for the "memory"
is actually permanent damage resulting from cell reversal.
For more information on the "memory effect" as well as the care
feeding of NiCd and NiMH cells, go to the The
Making your own NiMH
What is the best use for the supplied alkaline holder? Well,
connector is useful! Here's one suggestion. (Note:
that you know how to solder and that you have at least a
of common sense when it comes to electronics. You take full
for your actions and the results.):
The completed 1.6 aH NiMH battery
Note the fuse in the negative lead.
Remove the battery connector and its wires from the supplied
(Maybe you can find something useful to do with the holder...)
Go to Radio Shack and buy a 23-331 Battery Pack. There
of this pack, and the "23-331C" is a 1.6 amp
NiMH pack used for R/C toys that is almost exactly the correct shape
the radio's battery compartment. It costs between $25 and
You may have to ask at the counter for it, as the stock of this item is
often kept in the back room. The "B" version is, I have
told, a 1.4 amp-hour version of the same pack and may be mixed in with
the stock of "C" versions.
While you are at Radio Shack, buy some heat-shrink tubing and use
insulate the connections you are about to make. Also buy a
of those tiny (4x20mm) 4 amp glass fuses if you don't already have some
Pico fuses. Since we are guarding against a ground fault, either
the slow-blow or fast-acting are adequate.
Cut and strip the wires on the original '817 connector and
and connect the red (positive) wires from the connector together
- remembering to slip the heat-shrink tubing over the wire before you
Allow the connection to cool before sliding the shrink tubing over it
else you'll shrink the tubing before you can get it into place.
a match or heat gun to (carefully) shrink the
It is important that you insulate the conductor at this point as the
will have enough of a charge on it to cause problems if it is
Make a note of how long the black wire will need to be
the length of the fuse) so that both sets of wires will be
the same length. Cut and strip the wires, taking the appropriate
lead length into account.
THE MOST IMPORTANT STEP - INSTALLING A FUSE IN THE
LEAD!!! Get a piece of heat-shrink tubing that will slide over
and put it the negative lead. Scrape the ends of
fuse (if you using a glass fuse) and quickly solder it
the negative lead of the pack, and then to the two black wires of the
Soldering these glass fuses is tricky as the link itself can melt at
temperatures and the glass caps can come off. If you aren't good
at soldering, you may not be able to do this. After soldering, do
a continuity check of the fuse to make sure you haven't "blown" it with
the heat from soldering. DO NOT EVEN THINK OF USING THIS
WITHOUT A FUSE IN THE NEGATIVE LEAD IF YOU VALUE YOUR RADIO! You
have been warned! It isn't really necessary to put a fuse
in the positive lead as any "cell-to-radio" faults will cause current
flow in the negative lead and an extra fuse would simply result in a
of extra voltage drop.
Allow the fuse/connection to cool to room temperature, verify
of the fuse, and slide the heat-shrink tubing into place. Using a
match or heat gun, carefully shrink the tubing over the
Using too much heat during soldering and shrinking will not only wreck
the insulation or heat-shrink tubing, but it could unsolder/melt the
VERIFY that you have soldered the POSITIVE
the red wire on the '817 connector and NEGATIVE lead to the
At this point (or any other time) make sure you either insulate
wire, or remove it from the connector entirely.
When installing the battery pack in the radio, I added a piece of
foam to the bottom of the pack to take up a bit of space and prevent
pack from sliding around. I was also able to route the wires/fuse
along the top of the pack in the radio.
Before using the pack, make sure you charge it.
packs have a "surface" charge on them - that is, a slight
of charge present when they were made. In actuality, the pack is
really nearly dead when it is brand new and has never been used.
When 12-13.8 volts is supplied from the back of the radio, the '817
charge a completely discharged pack of this capacity in two consecutive
6 hour charge cycles when it is supplied with a 13.8-15 volt source.
It should be noted that the best life/performance can be had from
cells when they are charged in a charger specifically designed for NiMH
cells. The '817's built-in charger won't do this perfectly, but
the built-in timer and the modest charging current, one can at least
gross overcharging and damage to the cells.
What about the thermal protector? Many NiCd
battery packs have a thermal protecting device. This opens the
if the pack's temperature gets too high - as can be the case when the
is charged or discharged at high current. The Radio Shack has
no thermal protection device, but is it necessary? If you are
going to using it only in the '817 and use the radio to charge
pack, then I'd say "probably not." The '817 cannot overcharge the
battery pack to the point where it is likely to be able to ever trigger
the thermal switch. What about overheating due to
If you installed the fuse in the pack, it is unlikely that you will be
able to overheat the pack from a high discharge current without blowing
the fuse. If you charge the pack on a "quick charger" you may
to keep a close eye on the pack's temperature if the charger doesn't to
this for you.
Comments on an
external NiMH battery pack:
Just as adding one or two alkaline cells can greatly increase
operational lifetime by keeping the "end of charge" voltage up, the
same can be said for adding another cell or two to a NiMH battery
pack. Using the same cell size, this can't be done using an
internal battery pack so you must resort to an external one.
As is mentioned on the Optimizing
Consumption page, it is wasteful to operate the '817
at higher voltages than necessary for operation. While 8 cells
would seem to be ideal for this purpose, it is, in practicality, not
quite enough: During transmit, the internal resistance of the
cells plus that connectors and wiring can cause excess voltage drop,
causing the voltage to drop far enough below 8 volts to cause the radio
to shut down.
Having, say, a 9 cell battery pack can greatly reduce
this problem without too much increase in wasted energy - an
important factor if you are carrying this for portable use. Let's
take a comparison of the two situations on receive:
An 8 cell battery pack, freshly charged and under minimal load,
will produce just over 10 volts, which corresponds to about 3 watts of
power consumption by the radio in receive.
A 9 cell battery pack, freshly charged and under minimal load
will produce about 11.5 volts, which corresponds to about 3.5 watts of
power consumption by the radio in receive.
The use of 9 cells represents a 15% increase in power consumption - but
since the current consumption by the '817 stays about the same, the
only real penalty is the added size and weight of that extra
cell. For receive, the extra cell won't make too much of a
difference as to how long the radio can operate on a charge, but where
the use of the extra cell really shines is when one is transmitting,
particularly on high power, and taxing the capacity of the cells:
While using an 8-cell NiMH battery pack, the voltage on a battery
pack that has been discharged to 70-80% of capacity will drop to about
8 volts during transmit on high power. As the battery is
discharged more, the voltage drops even more, causing the radio to shut
down at about 7.8 volts or so - usually before the battery pack is even
Using a 9-cellNiMH battery pack, the voltage stays 0.8-1.0 volts
higher, maintaining at least 8.5 volts under the same conditions as
As in the example with alkalines, more of the capacity of the battery
is usable by the radio: The radio will continue to operate much
longer on a charge because the extra cell can supply some of the energy
lost not only as the voltage on the cells drop down, but as their
effective internal resistance increases as they discharge, reducing the
available voltage under a transmit load. In this example, one
could expect to see at least a 30% increase in the usable charge life
of the battery pack (if one transmits using high power) in using a
9-cell pack over using an 8-cell pack - this improvement likely be more
dramatic with older (higher resistance) cells or if one has extra
resistance in interconnect cable.
If you construct (or buy) such a pack, it is imperative that it be
fused - at least in the negative lead - to prevent damage to the radio
should any cell become exposed and touch the radio's chassis. Of
course, one would want to minimize lead length to minimize resistance
losses. It should be noted that little extra capacity is likely
to be gained by using a 10 cell pack (unless the connecting cable is
fairly long) but a pack such as this is more likely to be commercially
available - and the only added penalty is just a little more weight of
the extra cell. It should also be noted that under 11 volts or
so, the FT-817 will not be able to produce the full 5 watts on
all (if any) bands: While a freshly-charged 10-cell battery pack
may produce 12 volts or so, it will very quickly drop down
(especially during highest-power transmit) down below 11 volts, causing
the "high power" icon to flash.
(Thanks to Miikka for pointing out the omission of mentioning the
use of an extra cell or two to extend NiMH pack capacity.)
What kind of connector is used on the FT-817's battery pack?
The battery connector that is used on the FT-817 reportedly mates with a
Molex part: The female housing seems to be part 51021-0500 (5 pole) and the (5
each) female terminals are part
50058-8100. The male connector housing is part 51047-0500 and the
corresponding pins are 50125-8000. One possible source is Digi-Key.
Note that a special crimp tool is required to install the pins terminals/pins properly, but like most crimp-type connectors it may be possible to do some very careful soldering and "manual" crimping to make a reliable electrical and mechanical connection.
If you construct your own FT-817 internal battery pack you are doing so at your own risk! Do not
do this unless/until you know the "ins and outs" of the sorts of safety
circuity required to do this - particularly if you are planning to use
a LiIon, LiPO or any other type of battery technology. You have been warned!
Notice: The information contained on this and
related pages is believed to be accurate, but no guarantees are
or implied. The information on this and related pages should be
to be "as-is" and the user is completely responsible for the way this
is used. If you have questions, additional information, or you
information that you believe to be incorrect, please report it via
For information about operating the FT-817
Lithium-Ion cells, go here, and for
about operating the FT-817 with "other" types of cells, go here.
Another "battery" page:
page- This page describes in
some detail the care and feeding of NiCd and NiMH cells and
This explains how to keep NiCd cells going, and what that "memory"
really is! (Hint: It's not the "memory" effect
all!) This page also has Links
information about various types of cells (NiCd,
Li-Ion, Alkaline, etc.)