Page 40 - Newcom

Electrical Systems
drive times, it might allow the depth of
discharge to get to 50%. That deeper dis-
charge could take a year off [the battery]
life.”
Lead acid batteries don’t respond
as well to deep discharging because of
the makeup of their lead plates. To get
a high-cranking-amp battery, you need
a lot of surface area where the lead is
exposed to the battery’s electrolyte (acid).
“To get the higher cranking-amp
rating, you either make very porous
plates or you put [in] a lot of thin plates
just to get that surface area,” says Larry
Rambeaux, a sales application engi-
neer at Purkeys Electric in Lowell, Ark.
“There’s just not enough material there
to handle that deep discharge/recharge
cycling over and over.”
The CCA myth
The prevailing thinking is that Canadian
trucks need batteries with a high CCA
rating (cold cranking amps). A high CCA
rating ensures there’s enough juice there
to turn the engine over on a cold winter
morning.
That’s true to some extent. But, as
Rambeaux points out, to get that high
rating – maybe 950 to 1,150 CCA – and
keep the battery within the Group 31
form factor, manufacturers use thinner
plates which will degrade faster than the
thicker plates on a lower-CCA battery,
like one rated at 750 to 825 CCA.
“If you could look at a battery cycling
test, you’d see, generally speaking, that
a 700-750 CCA battery will usually
run somewhere around 400 cycles,”
Rambeaux says. “Meanwhile, a 950 CCA
battery might do less than 200 cycles. It
can be a huge difference. And the worst
thing is, you pay more for the 950 than
for the 700-750.”
Starting concerns notwithstanding,
if you run high CCA lead-acid batter-
ies and use an inverter to support hotel
loads, you’re going to see reduced battery
life. There are always trade-offs.
Deep discharge & hotel loads
There are other options, too. AGM
(absorbed glass mat) batteries can handle
deep-discharge conditions much more
readily than standard lead-acid batteries.
They also do just fine with normal start-
ing demands, even after cooking dinner in
the truck and watching a Godzilla double
feature before bed. This makes them ideal
for over-the-road trucks.
There are also dual-purpose AGM
batteries that deliver high current for
starting.
While AGM batteries won’t suffer as
much deep discharging as lead acid bat-
teries, they still need adequate driving
time to sufficiently recharge. Again, the
over-the-road truck is a good candidate
Corrosion on battery terminals restricts the flow of electrons into and out of the battery.
This can result in poor charging capability, which shortens battery life. (Photo: Jim Park)
24 TODAY’S TRUCKING
for AGMs. But as any refrigerated hauler
who has spent a few days in Phoenix
or Laredo waiting on a load will tell
you, even the AGMs won’t have enough
reserve to run the hotel loads and start
the truck without some driving time to
recharge them.
The perceived problem with AGM
batteries is the cost. They can be really
expensive – like three to four times the
price of standard battery.
A systems approach
Technically, batteries do not need a lot
of tender loving care. It’s the rest of the
electrical ecosystem on the truck that
needs your attention – especially cables
and connections.
Corrosion in cables (usually seen as a
green or yellow powder on exposed wire)
chokes the flow of electrons through the
cable. This is called voltage drop, and it
happens in both directions. It affects the
flow of current from the alternator to the
battery, and from the battery to the start-
er and other systems.
“You can buy the best batteries in the
world and the most powerful alternator,
but if you have crappy, damaged, or
corroded cables, you won’t get the ener-
gy needed to recharge your batteries,”
Rambeaux explains.
Brian Thompson, national fleet man-
ager at Delco Remy, warns corrosion is
a battery killer. “We see more of it in the
northern regions where de-icing chemi-
cals are used extensively. Catch it early,
before it has a chance to do some real
damage.”
You can check for voltage drop if you
have the equipment and skill to do it, but
visual inspections are almost as effective,
if they are diligent.
“Watch for any exposed wire or
connections that are not coated with
anti-corrosion compound, or at least
dielectric grease,” he suggests, adding,
“wire chaffing allows moisture and cor-
rosive compounds to get into the cable
itself. Make sure the wire harnesses are
tight tucked up out of harm’s way and
not rubbing against the chassis or any-
thing else.”
Obviously, the battery terminals
need to be cleaned periodically and the
­ corrosion removed from the posts, but