4.6 EXCESSIVELY DISCHARGED BATTERIES
NOTICE: Your Tomberlin dealer will have the equipment and experience to perform the following battery
inspections.
The on-board charger will not charge dead batteries. First establish that none of the batteries have an
internal fault or bad cell. If a battery has remained too long in a discharged state (i.e. 2-4 volts each), it
may be internally damaged and not capable of accepting a charge and must be replaced.
If the electrolyte specific gravity is low (less than 1.1098 SG) or individual battery voltage is less than 5.25
volts for three cells (10.5 volts for six cells), recharge each battery with an ordinary 6 volt external trickle
charger at a rate of 3 to 6 amps.
It is not necessary to disconnect the battery cables, as the alligator style clips can be connected to each
positive and negative battery post. Follow specific charger instructions.
To prevent a spark from igniting the gas emitted from the batteries, always disconnect the Charger AC power
cord first when moving the positive/negative alligator clips.
Be sure to charge all of the batteries in the set. Each battery may require two to three hours of charging
to bring it back to serviceable condition. After all batteries have been individually charged, remove the
external charger and restart charging with the on-board charger (Section 4.5.1). It may require several 8-
12 hour cycles to restore severely discharged batteries back to 100% charged condition. If again the on-
board charger has the RED FAULT LED (Fig. 4.5A No. 6) flashing there is a problem with one or more of the
batteries.
4.7 SPECIFIC GRAVITY TEST
It is possible to determine a battery's ability to perform by measuring the specific gravity (sp. gr.) of each
cell with a hydrometer. This is the best method to determine a defective battery.
The hydrometer readings indicate two things:
State of Charge - The amount of electrical power stored in the battery.
Condition - The ability of battery to store and deliver power.
NOTICE: Batteries should be fully charged before performing specific gravity tests to determine battery condition.
Hydrometer tests of batteries not fully charged are misleading and inconclusive.
There are different type hydrometers. Carefully read and follow the instructions supplied with your
hydrometer
.
NOTICE: Specific gravity readings are at 80
0
F. Values need adjustment for electrolyte temperature. Reduce .004
for every 10
0
F below 80
0
F. Increase by that amount for every 10
0
F above.
