By David L. Hough
I normally plug my machines into
automatic chargers when they aren't being ridden. Each machine normally stays on
the charger until I take it out for a ride—sometimes months later. I haven't
been very critical about my chargers. I just picked up different ones over the
years, without much research.
But at the end of the riding
season I had a brain fart
and forgot to plug a charger into Sparky's
battery. After two months the Cycletron Plus was flatter than a pancake, and
none of my chargers would bring it back to life. A quick trip to the dealer
determined the charging system was fine and the Cycletron battery was OK, just
The experience was another
reminder of the need to keep my motorcycle batteries charged. But the big
eye-opener was that none of my automatic chargers could bring a discharged AGM
battery back to life.
If you're a battery guru, you can
skip the rest of this. But if you're a rider like me—who hasn't been paying much
attention to battery and charger technology, perhaps you're ready for a jolt of
reality. First, for those who aren't "gearheads", let's do a little battery
review. There are two basic types of lead/acid motorcycle batteries on the
market, "flooded" and "sealed".
The old flooded lead acid battery
(FLA) has lead plates suspended in liquid battery acid. A 12 Volt battery has
six separate 2V cells, wired together. The flooded battery has removable caps on
the cells to allow checking the electrolyte and topping up when needed. Flooded
motorcycle batteries usually have a small vent tube plugged into the top
chamber, extending down underneath the bike to allow any acid droplets to bypass
any delicate motorcycle parts. One advantage of an FLA battery is that you can
top up the electrolyte as needed, with distilled water. FLA batteries also have
a slightly lower resting voltage.
The most common battery today is
"sealed lead/acid" (SLA) that seals the acid electrolyte inside the case, which
is a huge advantage for reducing corrosion. Since the acid is sealed inside, an
SLA battery can be shipped through the mail, and installed in any position. You
can even lay the bike on its side, without fear of battery acid dribbling out.
The best news is that SLA batteries can hold a charge for long periods of
time—assuming no parasitic loads such as a clock or security alarm. The downside
of an SLA is that there is no way to replace the electrolyte as it slowly
Batteries tend to heat up and
generate gas when being charged, and that creates pressure inside a sealed
battery case. To prevent a nasty explosion, there are tiny relief valves in the
case. That's why sealed batteries are sometimes called "valve regulated lead
The most common type of SLA
battery is Absorbed Glass Mat (AGM), in which the battery acid is entirely
absorbed into dense fiberglass mats, so it can't leak out. AGMs typically have a
higher resting voltage than other types. Another type of sealed battery is
"gel", where the battery acid is chemically treated to make it about the
consistency of pudding.
Did you ignore the hoopla,
Now, I admit that I pretty much
ignored the hoopla when AGM and Gel batteries came out about 20 years ago. There
were all sorts of rumors about AGMs and Gels needing special battery chargers,
but, like most riders, I naively assumed that 12 volts is 12 volts, and any
suggestions about buying pricey special chargers was just sales hype.
My little experience with Sparky
demonstrated that it's a bit more complex than that. First, although we might
call a battery a "12-Volt", different types of 12V batteries prefer slightly
different charging voltages, maybe 12.9V or 13.7V. Why does this matter? Well,
if a battery isn't fully charged, it loses some life. My old FLA batteries liked
to rest at about 12.5V. My fleet now uses various AGM batteries, which if
disconnected will "rest" somewhere between 12.7V and 13.1V.
What's more, SLAs have different
chemistry that responds differently to charging rates. The old way of charging a
flooded motorcycle battery was to wire up a trickle charger (say, 1.5 or 2 Amps)
for several hours, and then disconnect it when the battery acid started to
bubble and boil.
Yeah, but doesn't the bike
charge the battery?
Of course, the battery is
recharged when the engine is running. And, after a ride, the battery will be at
whatever voltage the bike's voltage regulator has been supplying. The important
point here is that if you install a new AGM battery in an old machine that was
originally designed for a flooded battery, the charging system could be working
perfectly, but never keeping the AGM battery fully charged. And if the battery
isn't fully charged, it loses some life. If you run the bike every week or two
you'll keep the battery alive, but not necessarily fully charged. Contemporary
machines regulate at a slightly higher voltage—more in line with SLA batteries.
The problem comes when you let
the bike sit for a month or two without running—as I did. Today's machines have
various parasitic loads, such as clocks and security systems that slowly draw
down the battery even when the key is off. When Sparky's Cycletron battery went
flat, I tried all my old chargers, but none would bring it back to life. One
charger flashed a light indicating a bad battery. The reality was that none of
my chargers were capable of bringing a discharged AGM battery back to life. What
I needed was not only a smarter charger to make up for my less powerful memory,
but a more powerful charger with the amperage capacity to wake the dead, and a
charging sequence (algorithm) suitable for an AGM battery.
The Odyssey battery site
recommended an ACI smart charger, and I got the model 1214CC with a capacity of
7 Amps. And, at the recommendation of several battery gurus, I obtained a 0.8A Optimate 4 for my other machines. With the new chargers in hand, I excitedly
hooked them up and tested the voltages with a new Radio Shack digital voltmeter,
comparing the new chargers against the old ones in my garage.
Photo, ACI 1214CC
Photo, Optimate 4 02
Photo, Battery Companion 01
span style="font-size: 10.0pt; line-height: 150%; color: blue">The Schumacher
Battery Companion can automatically charge either 6 or 12 volt batteries. The
only indications are lights indicating charging or charged. But it has up to 1.5
Amps, it's very reasonably priced, and it comes with a huge selection of
Photo, Battery Doc Port 01
span style="font-size: 10.0pt; line-height: 150%; color: blue">The 1.25A
Battery Doc Portable is small enough to carry on a bike, has a detachable power
cord, and has a column of lights to show more about what its doing. In my tests,
the Doc cranked out just enough voltage to keep an AGM charged. There's also a
sealed version that's waterproof, if you don't mind the extra weight. The
downside is that I had to make up my own adapter to connect the BD output plug
to a standard SAE plug.
The Hough test
My batteries included a Panasonic
AGM, a Westco AGM, an Odyssey AGM, and the Interstate Cycletron Plus AGM. To see
how my different batteries would respond to the different chargers, I connected
each charger to each battery for a minimum of 12 hours, then checked the
voltage, which after that time should have reached the float mode. Then I
disconnected the chargers, allowed the batteries to rest for a minimum of 12
hours, and measured the "resting" voltages. I rotated the chargers and batteries
over several days, with the garage maintained at 65F.
Battery Doc Sealed after 12
Schumacher Battery Companion
Battery Tender Plus
Resting voltage 12 hrs after
disconnecting charger (average)
Note that this wasn't a
comprehensive test of all the latest chargers on the market. I just wanted to
see whether the various chargers in my garage seemed to be working acceptably.
It's clear that my battered old Battery Tender Plus wasn't adequate for my AGM
batteries. I also measured a pair of brand new Battery Tender Juniors, which
produced lower float voltages than the Plus version. I tossed the BT in the
trash, and gave away the BTJs to someone who lives in a warmer climate.
If a charger can't produce float
voltage that's higher than the resting voltage of a battery, it can't charge
until the battery voltage drops to the output of the charger. For example, my
old Battery Tender didn't produce enough voltage for the Panasonic. So, a cheap
charger might maintain a battery at 60% or 70% of full charge - keeping the
battery from completely discharging, but shortening the battery's life by a year
or two. That's why the manufacturer of a battery charger can state "charges all
batteries". They don't say their charger will keep all batteries charged to 100%
of capacity in all climates.
All my AGM batteries seem to
"rest" at right around 13V, which means my other chargers are adequate for
maintaining them. The ACI 1214CC settled on float voltages averaging 0.77V above
the typical "resting" voltage. The Optimate 4 charged an average of 0.56V above
resting voltage. I was pleased that the Battery Doc smart chargers I've been
using are in the ball park.
However, the two high-zoot
smart chargers, the ACI 1214CC and the Optimate 4 are capable of handling more
complex issues, such as reducing plate sulfation, and bringing a discharged AGM
battery back to life. The Optimate 4 has a panel of colorful lights that wink
and blink to show what it's doing, and a handbook to help you decipher what they
mean. Of course you don't Have
to read the lights, since it's all
automatic. The ACI does its job with just a single indicator light, but it
cranks out 13.74V at up to 7 amps. My flat Cycletron battery snapped to
attention after a few hours hooked up to the ACI.
My point in all this is not to
diss any brands, or convince you to buy what I use. But I strongly suggest
laying your hands on one of the new smart chargers, and keeping it hooked up to
your battery whenever the bike is parked. That's really
if you park the bike outside in sub-freezing weather, or park it for months at a
And, if you've been using a
charger, but your battery always seems to be a little flat, I suggest taking a
few voltage measurements with a reliable digital voltmeter to see how your
charger measures up. With the key off, and the charger connected for 12 hours or
so, a "flooded" battery should settle to a float of around 12.5 – 12.6V,
indicating 90% to 100% of full charge. An AGM would prefer at least 12.7V, and
maybe 13.6V depending on temperature.
Battery Doc chargers:
online store. Tel (206) 329-7808
Optimate 4 automatic 0.8A
ACI 1214CC automatic 7A charger:
strong>Schumacher 1.5A Battery
Companion: Wall Mart stores
For additional information on