American Motorcycle Dealer AMD 218 September 2017 | Page 59

LESS CURRENT AS THE
VOLTAGE INCREASES CURRENT INCREASES
TO 12.8V
HIGH CURRENT
AT LOW VOLTAGE CURRENT
STARTS LOW
LEAD ACID CHARGER
LITHIUM CHARGER
The "Bermuda Triangle" of battery charging - use the wrong charger
(a lead acid charger) and you can kiss that nice new lithium goodbye!
battery is in an unstable low impedance state, and
with the cells are unequal in impedance/resistance,
it demands a very high current from the vehicle's
charging system and, sometimes, that charging
system cannot cope.
“The voltage regulator may become damaged, and
it becomes an overcharge situation very rapidly. The
high current also damages the weakest cells, which
then becomes a liability when exceeding 14.6V.
“If you want it to live, use a charger that
automatically starts with low current and grows it
whilst automatically monitoring the performance of
the cells against the known LFP charging curve.”
Use the wrong charger
Lithium battery killer method #3? When the battery
is discharged really low, “charge it with a powerful
lead acid battery charger instead of a lithium specific
device.
“Lead acid battery chargers are designed to deliver
high current at low voltage and then taper off,
whereas a lithium battery at low voltage needs a
controlled low current charge so that cells can
receive and retain charge and therefore stabilize
their internal impedance (resistance) BEFORE it can
receive high current charge.
“So, in other words, charging of a low voltage lithium
Battery monitor
is 'inversed' compared to a low voltage (but healthy)
lead acid battery - current starts low and then slowly
increases until the voltage reaches 12.8V and then
it can be charged at full current.
“I've seen pictures of burnt out bikes - most recently
a new Husqvarna that was taken home, and despite
the dealer asking (but not insisting) if the user has a
lithium battery charger, the owner went and
connected a 'supermarket' type lead acid charger,
and by the time he smelt the smoke from his garage,
it was too late. His new bike was burnt - damaged
beyond repair.”
Lack of maintenance
Killer method # 4: don't maintain it. “LFP batteries
are typically 1/3 to 1/4 the Amp-hour of the
equivalent lead acid battery and it will drain 3-4
times faster in a bike with a parasitic draw (most
bikes now have parasitic draw due to always on
circuitry). The result? Terminal low discharge
syndrome – see killer technique #2!
To make it live longer, make sure that your lithium
specific battery charger has a genuinely lithium
specific maintenance program. “What a lot of people
don’t yet realize, is that lithium does not need
maintenance charging if it remains at full charge, so
a genuine lithium charger senses only what is drawn
and makes sure it supports that battery, keeps it at
100% whilst providing power to always on circuitry.
“The other negative of LFP's high CA (cranking
amps) to Amp-hour ratio is that OEMs cannot resist
the temptation to embrace the opportunity to make
their batteries smaller so they fit, which
unfortunately means they sacrifice Ah capacity. That
means that an OEM fitted battery absolutely always
needs to be fully charged to deliver the rated CA. So,
the fact is, lithium batteries place a premium on
having a (suitable) maintenance charger – they need
one more than the lead acid batteries they replaced.”
TECMATE
Tienen, BELGIUM
Tel: [phone]
www.tecmate.com
www.optimate1.com