IEC TR 61044:2002 pdf download

IEC TR 61044:2002 pdf download.Opportunity charging of lead-acidtraction batteries.
The object of this report is to lay down rules or recommendations for the use of opportunity- charging of lead-acid traction batteries of vented and valve-regulated types, when the battery manufacturer has not recommended the required operating procedures. When the battery manufacturerts recommendations are available, they take precedence over these rules and guidelines.
2 Definitions
For the purpose of this report the following definitions apply.
opportunity charging
use of periods of inactivity of a partially discharged battery (i.e. state of charge lower than 80 % of the nominal capacity) to increase its state of charge
2.2
regular charge
charge of a battery necessary to attain the state of maximum storage of electric energy
[see 3.3 of IEC 60254-1]
2.3
self-compensating charger
charger which continuously monitors the state of charge of the battery and terminates the charge when the correct amount of electric energy has been supplied, and which will provide only minimal overcharging if a fully charged battery is connected to the charger
2.4
vented (secondary) cell
secondary cell having a cover provided with an opening through which gaseous products may escape.
[1EV 486-01-18, modified]
2.5
valve-regulated (secondary) cell
secondary cell which is closed under normal conditions but has an arrangement which allows the escape of gas if the internal pressure exceeds a predetermined value. The cell cannot normally receive addition to the electrolyte.
[see 1EV 486-01 -20]
2.6
excessive discharge
vented battery: discharge >80 % of the nominal capacity
valve-regulated battery: discharge >60 % of the nominal capacity or other limit indicated by the manufacturer.
NOTE Definitions 3.1 and 3.6 are illustrated graphical’y in Figures la, ib, 2a and 2b.
3 Planning
The following points should be considered when planning to introduce opportunity-charging:
• Indications that opportunity-charging may be beneficial
a) When the maximum permissible size of the battery for the vehicle does not have enough capacity to do the work required.
b) When the operational requirements of the vehicle are such that it is impossible to predict when it will be next released for a complete recharge (for example, places such as airports where 24 h working is a rule).
c) When a battery is close to the end of its life and the use of opportunity charging can be shown to be maintaining its work period.
NOTE 1 If the periods available for charging are of short duration and infrequent, then opportunity-charging will be of little benefit.
NOTE 2 When opportunity-charging enables the user to discharge substantially more than the recommended percentage of the nominal capacity each day, battery-life measured in terms of cumulative ampere-hours should remain about the same. In consequence, the battery-life measured in years can be reduced.
Opportunity-charging may result in higher working temperatures; this may further reduce battery life. It is essential, therefore, to discuss the proposed operation with the battery manufacturer as modification of his normal guarantee may be necessary.
4 Operational procedures
The following points should be considered when operational procedures are being generated.
4.1 Self-compensating chargers shall be preferred for use with opportunity-charging.
A correctly sized battery/charger combination is essential for all batteries. For opportunity-
charging of valve-regulated batteries it is of utmost importance that only chargers with
a characteristic in accordance with the battery manufacturer’s recommendation are used.
In order to maximize the efficiency of opportunity-charging, it should preferably be applied only if the battery has been discharged by at least 30 % of its nominal capacity (vented type) or 20 % of its nominal capacity (valve-regulated type). Should a non-self-compensating charger be used for opportunity-charging, which would be permissible with vented batteries only, the 30 % pre-discharge limit is of great importance.
NOTE Where a known duty cycle exists, a calculation of the energy or ampere-hour balance is recommended. It should be established that adequate charging periods are available for opportunity-charging.
4.2 The frequency of regular charge, whereby the battery is allowed to complete its charging cycle to prevent deterioration of the battery, should be
— for standard vented batteries, 1 period of regular charge in every working day;
— for vented batteries with acid agitation system, a longer interval between complete recharges may be allowed;
— for valve-regulated traction batteries, a complete recharge at least every 3 working days.