By
Jason Jordan
(JAy jordan2) 3/2/03
As many of you know, Jetpack Batteries have been gaining
popularity among both the basher and the racing MT world.
Typically when it comes to batteries, many bashers prefer
to go the economy route and save some money buying bulk
unmatched packs or cells and the racers go for the high
dollar and expensive matched cells. Jetpack has a way for
everyone to get good quality packs that are racer quality
and come at a great price to suit all levels of the R/C
community!
In this
post-race review, a racer review and the proper care will
be illustrated for the Jetpack Sanyo 3000 HV packs. Many
have read on the forums of how well these packs increase
performance for the basher as well as runtime. This review
will give some quantitative results as to how Jetpacks perform
in a high-level race scenario.
Jetpack
Batteries are some of the most well constructed packs in
the business. A 7 cell hump Sanyo 3000 mAH HV pack is shown
in the following picture. The cells are perfectly matched
by runtime and voltage and weak cells are sorted out by
a rigorous 30 amp cycling method. What this means for the
consumer is that there are no dead cells in their packs
and the pack will run with all cells equally during a run.
Remember that a pack is only as strong as its weakest cell
and Jetpacks have no weak cells!
The
cells are individually shrink-wrapped and glued with silicone
and have quality Deans Bars soldered on solidly. To further
increase the physical durability of the packs, another outer
layer of shrink-wrap is added to the whole pack. I don?
know anyone in the industry who puts this much time and
effort to make a pack bulletproof with all the extras. Plus,
you can have your packs custom built in any side by side
configuration with any number of cells and already wired
with your choice of battery connector!
The best part is, you don? pay any more for all the extras
involved.
Typically
only some seasoned veterans in racing go the extra mile
to strengthen their packs by silicone gluing their cells
and adding extra shrink wrap or novices aren? experienced
enough or have the proper equipment to solder their own
packs. Jetpack eliminates the difficult steps and does all
the grunt work for you all at no extra cost!
Nowhere in the industry will you find such dedication to
the customer. All you have to do is order your cells and
tell Jerry what configuration you need for your application.
As recommended
bt Jerry of Jetpack Batteries, it is best to cycle through
a new 3000 HV several times before running them. One cycle
is one discharge and one discharge on the pack. Cycling
the cells helps ?rain?the cells and get them ready to run
properly.
I received
my Jetpacks just before the Winter Monster Bash at Bradenville,
PA. Several weeks before the race, I cycled my packs using
both my Novak Millenium v.1.2 and Tekin 112A v. H28.
I?e
been using these chargers consistently for several years
and both charge cells equally. On both chargers I used a
5.0 amp charge rate, the Millenium was set for a delta peak
of 8 mV per cell and linear charge with no trickle charge.
The Tekin used the P2 mode with the power flex off and no
trickle charge. After the initial charge, one repeak charge
was used before measuring the discharge characteristics.
For
the initial 6 cycles, I used an Astroflight Super Whatt
meter to measure mAH and time to discharge as I was discharging
the pack. I used my Integy Reactor 20 as the discharge load.
A string of lightbulbs with a cutoff box can also be used
as the discharge load. The Reactor 20 has a 4.9V cutoff
voltage which is 0.7 V per cell. This falls safely within
the .7-.9 V per cell cutoff recommended for these packs.
Once
the pack had discharged, the cells were equalized on an
Integy Octane 2 discharge tray. Holes were cut out in the
shrink wrap so the pins in the tray could contact the cells.
The
use of a discharge tray is vital for maintaining top performance
for your side by side packs. It allows the racer to have
all the cells discharged individually and equalized. Over
time, you can see when your cells need rematched by the
difference in time each cell takes to discharge. Cells will
also need to be rematched over time if you notice a significant
increase in peak voltage. Since the tray can only equalize
6 cells at a time, you need to do 6 cells first, then flip
the pack to equalize the 7th cell. For the 3000 HV packs,
you only want to keep the cells on the tray until the bulbs
go out. Once they are finished, remove the pack and let
it cool before the next charge.
On average,
the 3000 HV packs peaked at 11.28 ?11.30 V and took in just
over 3300 mAH. Approximate charge time from fully discharged
was 37-40 minutes at 5 amps.
Using the Whatt meter, the packs discharged down to 4.9V
in 8.5 minutes with an average of 2916 mAH. Remember, this
was a continuous load and actual vehicle runtime will be
longer due to being off throttle and modulating your speed.
On the bench, these are very good results. The next test
will really put this pack through the grinder? Racing at
the Winter Monster Bash!
My test
vehicle was my Xtreme Racing XC2 clod fitted with (a Power
Hungry) Hitec HS-5625 MG digital servo, (even more power
hungry) Big Jim Reedy Ti 12X3 mod motors all controlled
by a GM V12 ESC and Novak XXL receiver and M8 Transmitter.
Only
one 7 cell 3000 HV pack was run during the 2 day race weekend
including all the practice and qualifying runs and the main.
This would surely test the consistency and durability of
the 3000 HV cells under hard racing conditions.
I charged
the cells exactly as I did during bench testing. Shortly
before each race, I repeaked the pack. I would race the
qualifiers and after the qualifier, unplug the battery and
let it cool to room temp between races. Since there was
a large number of racers, there was more then ample time
to let the pack cool before recharging.
If time was short, a small cooling fan was used to bring
the pack temp to room temperature.
After several minutes of cooling, I plugged in the charger
and just repeaked the cells. Everything was peaked and repeaked
before each race. These NiMH cells perform better each time
you run them. Remember to let the pack cool properly before
recharging.
In the
end, how did Jetpacks do??
3 Jetpack powered trucks made it to the extremely difficult
4WD A main. How difficult?? The 4WD A main consisted of
many world class drivers (In no particular order):
Bill
Herzog (Team Tweaked)
Dan Wyatt (Team Tweaked)
Tim Powers (Team Tweaked)
Mike Eckenrode (Dev2K)
Jay Jordan (JAy jordan2)
This
was no easy feat to accomplish with such world caliber driving
talent in the A main!!!!
I would
like to thank Jerry of Jetpack Batteries for all his excellent
customer support and a chance to run some of the best cells
in the business!!! If Jetpacks can make it to the A main
in one of MT racing? most difficult classes, they have what
it takes for the most demanding R/Cer!!!
For
more information check out Jetpack Batteries here:
Jetpack
Batteries
If you
haven't tried Jetpacks yet, it's time to "Feel the
Thrust!"
JAy
