APPENDIX
BATTERIES
As a result of radical changes in vehicle battery design and performance that have taken
place over the last 18 months it is essential that the correct type are specified on new
vehicles that will include an electric winch or other high electrical power consumer. Heavy
Duty ED3/VB3 rated should be specified as these are vibration proof and have 2.5mm
thick plates compared to the standard 1.5mm. They also have glass wool separators which
reduces the leeching problem. Thee operating duty cycle for this class of battery is 14
compared to only 6 on a standard battery.
For extra heavy duty applications where high start up surges are required Holchstrom Gel
filled batteries should be specified which have a flat instead of declining rate of discharge.
These offer up to a 40% increase of cold start performance for a battery of the same
physical size.
Incorrect type will cause problems for vehicles using equipment requiring high DC Power
consumption such as an electric winch, flashing beacons and work lights.
A standard amp hour rating is used for all batteries and this indicates the amperage
available when a constant discharge is achieved over 20 hours. As an example a battery
with an amp hour rating of 75 means the battery can carry a load of 3.75 amps for 20
hours. Vehicle manufacturers’ requirements have changed due to improved engine
efficiency and many now require hundreds of amps for a few seconds for starting and to
save space they demand small lightweight batteries. These batteries are designed to
discharge around 15% of their total capacity and then recharge quickly from the alternator.
The duty cycle design criteria for vehicle batteries is to crank a cold engine for 10 seconds
and then rest for 1 minute allowing the battery to recover and the starter motor to cool
down. The engine would normally have started consuming equipment like a DC winch is
operated for much longer periods of time with only short breaks and then recharged this is
referred to as deep cycling. In winching applications the battery is continuously subjected
to deep cycling and recharging this will result in premature loss of battery capacity.
The new generation of starter batteries are now light duty designed to retain 75% - 85%
charge throughout their working life with a maximum duty cycle of 6 – 7.
If they are used for winch or similar applications and the voltage falls to 12.2v soft lead
sulphate deposits on the plates and separators.
If left discharged for a period of around 70 hours the lead sulphate hardens and
crystallises forming an insulation barrier preventing it from accepting a charge and
effectively causing irreparable damage.
All popular traditional batteries leech between the plates when not in use particularly in
warmer weather causing a self discharge. In poor quality batteries this problem is worse.
24v systems using two 12v batteries of this type:- If one battery deteriorates and becomes
weak it will resist charging and the stronger battery will take precedence. A voltage reading
of 25-26v may be measured but under the very high load during winching this will reduce
dramatically putting excessive strain on the good battery causing it to fail prematurely.
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Summary of Contents for DCY200
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