OPENING COMMENTS
The world of electric RC trucks and cars has come a long way over the
past few years. The introduction of longer lasting, more powerful batteries
has given electric enthusiasts more run time per charge and the prices
have remained pretty reasonable. Put simply, the days of having to buy
a nitro powered truck to experience high performance driving are long
gone.
Lithium batteries have been around for some time. Just check your cell
phone or almost any other electronic device that requires lots of power
in a lightweight package. The key here is lightweight. This trait is
one of the reasons why lithium batteries have been coveted by the RC
airplane crowd. Apogee, a long time power supplier to the RC airplane
market has been charging (sorry for the bad pun) their way into the
RC ground scene. Up until recently, most of the lithium batteries
for the dirt and pavement eating vehicles have been limited to 10C.
That kept LiPo batteries stuck in 1/18 scale stuff as it could not handle
the weight and power demands of larger, heavier 1/10 scale applications.
All of that is about to change!
Apogee has introduced a Magnum Series 20C Lithium battery, 3800mah,
LiMN (Lithium Manganese) that is built for 1/10 scale applications.
The Apogee Magnum series of batteries provide the same power and run-time
of sub-C Nickel Cadmium and Metal Hydride technology at about half the
weight.
WEIGHT
Yes, you read that right. Almost half the weight! To compare, we tossed
the LiMn 3800mah pack and IB 3800mah NiMh packs on our scale.
Here is a weight comparison:
- Apogee LiMn 3800mah pack (ready to run): 236
Grams (8.35 Oz)
- IB NiMh 3800mah (ready to run): 428 Grams
(15.15 Oz)
What does less weight mean to the average RC Basher Joe? It means less
strain on your drive train. What does this mean to the average RC Racer
Joe? Well, if your track allows these packs, it means a significant
advantage over your competition via an increased power to weight ratio!
Less weight means getting up to speed faster, less wear and tear on
the drive train which could lead to fewer failures during a heat. In
this case, the Apogee LiMn pack is almost 1/2 pound lighter
than the NiMh pack!
Lithium batteries offer another distinct run advantage over NiMh and
we will get to that in a moment. Now, onto our test vehicle!
 OUR
TEST VEHICLE
We chose our faithful Losi XXX-T as our test vehicle for this review.
It is setup with a Trinity Chameleon 19 turn motor, stock receiver,
stock ESC and Deans plugs. The truck itself is loaded with graphite.
In fact we are pretty sure it has every factory graphite part installed
on it at this point. A machined motor plate helps to keep the motor
cool and we are running stock gearing.
CHARGING
Obviously before we can start tearing things up, we need to get the
battery at full charge. And of course, we are dealing with lithium so
you will need a charger specifically setup to handle lithium. DO
NOT use a NiCD or NiMH charger on a Li battery!
Here are a couple of great links that talk about lithium battery guidelines
and safety:
http://www.pfmdistribution.com/guidelines.htm
http://www.pfmdistribution.com/files/ApogeeGuidelines.pdf
We grabbed our DuraTrax ICE charger and put it to work. Here are the
specifications on the Magnum 3800mah LiMN:
* Maximum Charged Voltage: 8.4V
* Minimum Discharged Voltage: 6.0V
* Maximum Charge Amperage: 3.8A (1C)
* Maximum Continuous Discharge Amperage: 76A (20C)
* Maximum Operating Temperature: 60C (140F)
It charged up like a champ, never even getting remotely warm during
the charging process. The battery seemed to come from PFM about 80%
charged so it did not take long to get it up to 100%. We would find
out later, during our testing, that a fully drained pack took about
7000 seconds (just under two hours) to get back to a full charge.
A note about lithium discharging:
It is VERY important that lithium cells are not discharged below 3 volts
per cell (check with the battery manufacturer for exact numbers). To
prevent over-discharge, a low voltage cut-off (LVC) is required. Some
speed controllers have the ability to do this for you (the MAMBA ESC
is a perfect example). If you do not have a LVC, invest in one like
the Apogee
LOA. They are only $20 and will save your battery from being damaged,
or worse! Ok, enough chit chat, time to bolt it in.
BATTERY FIT, FINISH AND DIMENSIONS
This pack is specifically made for 1/10 scale vehicles and we can confirm
with certainty that it fits into the XXX-T nice and snug. We have heard
of other “competitive” lithium packs on the market that
will not fit into certain trucks and that does not seem to be the case
with the Apogee pack. Here are the dimensions; be sure to double check
your vehicle before ordering: 19mm (3/4") thick x 42mm (1-11/16")
wide x 139mm (5-5/8") long.
Looking for lithium cells for a particular application? Check out this
handy spec chart:
http://www.pfmdistribution.com/specs.htm
The Apogee battery is wrapped nicely with a protective coating to prevent
damage from rubbing or handling scratches. The wrapper is great for
us as our chassis is graphite and graphite conducts electricity. We
have to be careful when mounting conventional batteries into our XXX-T
so that we do not cause a short. The Apogee makes this easy and it is
a direct drop in unit.
The pack comes standard with a Tamiya style plug installed which is
what most RTR 1/10 scale trucks are equipped with. Our XXX-T (and most
other electric rides in the BYT fleet) uses a Deans Plug so we did a
quick plug swap. Remember to cut and solder one wire at a time to prevent
a short while chopping off the plug and also, the female plug should
ALWAYS be used on the battery. We like Deans Plugs as they offer an
excellent, low resistance connection. They are inexpensive, have a tight
fit and work extremely well. We highly recommend these for use with
all battery packs, especially big power packs like lithium.
TEST DRIVE / PERFORMANCE
Time to light 'em up! We took our XXX-T out to our test track for some
hot laps. Quickly, we realized that a slipper pad adjustment was needed.
It needed to be tightened up slightly to handle the power. Once the
slipper was dialed in, it was time for some fun. Lap after lap, the
truck seemed to have the same “snappy” juice level as it
did when we first started our test.
This is the beautiful thing about lithium power. It does not “step
down” like NiCd or NiMh does. What do we mean by “step down”?
On a typical NiCd or NiMh pack, about half to two-thirds of the way
through the pack, some of the power “punch” is gone. There
is significant battery life left but the “snappiness” that
the freshly charged pack had is absent. With the lithium packs, this
“step down” is just not there. If it is, it is so slight
that it is almost unnoticeable. Why is this important or significant?
Well, if you are a racer, it is huge. When your competitors have lost
that little “zip” half way through the race, your truck
will still be going as fast as the first lap. Advantage lithium! A lithium
pack will drop off rapidly when it has discharged just like any other
battery (be sure you are using a LVC).
The Apogee LiMN delivered solid power at all times. It seemed to shrug
off any high load situations like blasting through the grass or up big
dirt piles. There was always plenty of power on tap for whatever our
trigger finger desired.
RUN TIMES
We found the run time of the 3800mah LiMn to be very comparable to the
3800mah NiMh pack we were running previously. When conquering big dirt
piles with lots of traction and heavy loads, we would get about 14-16
minutes per pack. This is all out 100% trigger pull during most of the
driving. Pretty impressive. We took the XXX-T out to the parking lot
for high speed asphalt runs and experienced slightly better run times
at 15-18 minutes per pack.
Again, the beautiful thing is that even towards the end of a run, the
pack felt like brand new. Simply amazing! We are dying to try this battery
with a brushless motor. The extra efficiency of a brushless motor should
drastically increase the battery life, dare we say it could
even double it?! BYT has a 1/10 scale brushless motor on tap for a review
this summer and we will of course be reporting our results. In short,
the battery life is impressive and the power delivered throughout the
runs was excellent.
VERDICT
We love lithium power and have been using it in our little trucks for
years. It is a treat to now have a lithium pack that we can use in our
1/10 scales. If you do not have a lithium battery charger, there is
good news. There are a few inexpensive
chargers out there right now. If you can afford it, we recommend
using something like a Duratrax
ICE that will not only charge your Li packs, but your NiCd and NiMH
as well. If you have been thinking about making the plunge into lithium,
there is no better time. The technology is growing fast and Apogee is
at the head of the pack. We have been using their batteries for years
and have never had a problem with any of their products. The guys at
PFM DIstribution
(Apogee battery distributor) really know their stuff and
are always happy to help with questions about the right pack, charging
or anything related to their products.
At a retail price of about $99, they are more expensive than a comparable
3800mah NiMH pack. However at almost half the weight and with the extra
performance they deliver, we feel the value is there without a doubt.
Lightweight, powerful, long lasting, what more can you ask for? We
could not find a single fault with this battery pack. Treat
yourself! Treat your truck! Spank your competition! Check out PFM
distribution for the best Apogee products and customer service in
the RC world.
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APOGEE LIMN 3800MAH BATTERY PACKS 
