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4-12
A SIMPLE, EFFECTIVE AND PROVEN SYSTEM
The J&J electric bumper boat utilizes four Trojan T-105, 6V Batteries rated at 225AH, and connected in series. This battery
pack was chosen to provide the best performance-to-weight ratio and has proven, since its introduction in 1996, to have
an excellent record of performance and durability.
INSPECTION
One of the top
fi
ve service call questions is: “The relay clicks, but motor does not turn or turns slowly”. Another is: “Why
won’t my boats last all day?” Or: “They start out
fi
ne, but quickly start getting slower.”
THE MOST COMMON CAUSE OF THESE TOP ISSUES ARE RELATED TO THE BATTERY PACK.
LEARNING TO TEST BATTERIES WILL SAVE YOU A LOT OF HEADACHE.
This test assumes that battery
fl
uid levels have been maintained; note that adding water prior to testing will result in
bogus readings. If possible, charge the boat overnight prior to testing; batteries that have bad plates will still take a
“surface” charge and appear to be good, so let the pack sit for an hour after disconnecting the charger, then put a load on
the system by turning on the motor and taping the plunger down for 15 minutes (while in the water).
Shortcut Tip: At this point, back probe the charger lead with your DVOM and read the DC volts. Compare with chart (page
5-149), to give you a quick check of the overall charge condition of the battery pack. If “charged voltage” is not good, you
can proceed with the speci
fi
c gravity testing to determine which battery(ies) are causing the poor performance.
A battery cell’s speci
fi
c gravity is a great way of measuring a battery’s state of charge. This is because during a discharge,
the speci
fi
c gravity decreases relative to the ampere-hours discharged. The speci
fi
c gravity also increases as the battery
is recharged.
Use a hydrometer to measure the speci
fi
c gravity of the electrolyte solution in each cell. A hydrometer is a tool used to
measure the density or weight of a liquid compared to the density of an equal amount of water. A lead acid battery cell
is fully charged with a speci
fi
c gravity of 1.265 at 80° F. For temperature adjustments, get a speci
fi
c gravity reading and
adjust to temperature by adding .004 for every ten degrees above 80° F and subtracting .004 for every 10 degrees below
80° F.
Draw up
fl
uid to
fi
ll line.
Tap lightly to remove any air bubbles.
Top pointer must be vertical. Large
pointer shows speci
fi
c gravity.
Check every cell recharge if reading
is less than 1.210 speci
fi
c gravity.
Battery replacement indicated if more
than 30 point di
ff
erence between cells.
Flush with hot soapy water to clean
and rise with clean, warm water.
HYDROMETER BATTERY TESTER
