Dry Charge Plate Drying

Plate Drying Considerations

The Tiegel SmartDry™ Dry Charge machine are able to dry individual plates whereby the baskets which are normally used to dry elements have no partitions and are thereby able to take the same formation cassettes in which the plates have been formed. The cassettes have no bottom, allowing them to be used in the wash as well as the drying cycle. Additional information on tackless formation, as well as formation cassettes and tanks is available from MAC Engineering on request.

The drying of plates materially enhances the production of any given machine because only negative plates need to be dried in an inert atmosphere. No separators are present to reduce the flow of drying gases and it is possible to dry double panels stood vertically on end, whereas when drying elements only, a single panel depth is dried at a time.

The cycle time of plate drying varies between eighteen minutes to half an hour. Test results are excellent – the same as those obtained from element drying.

Production of Dry Charge Negative Plates

Form battery plates in open tanks in the usual manner.
Remove plates from tanks.
Wash positive plates lightly and dry them in a recirculating air dryer not exceeding 180ºF temperature.
1. Wash positive plates lightly and dry them in a recirculating air dryer not exceeding 180°F temperature.
2. Wash negative plates thoroughly until overflowing wash water is neutral.
Preheat Negative Plate Processor by turning on heat for approximately 10 minutes. Adjust thermostat to a platen temperature of 350ºF.
After testing one or two batches for the correct processing time, set timer for repeating the process.
If desired, after washing the plates, the negative plates can be dipped into a PROTECTO solution for a few minutes. After processing the plates will have a minute paraffin oil coating which will protect the dry plates against atmospheric humidity during storage.
Caution: the charged wet negative plates should be exposed to the air a minimum of time to prevent oxidation of the sponge lead. All operations should be planned so that the time from the washing tank to the inside of the processor is a minimum.
It is important that the processing of formed plates be started immediately at the end of the formation, but not later than one to one-and-a-half hours maximum. If for any reason the formed plates have remained in the forming acid without charging for a longer time, a two-hour boost should be given these plate.

Test Data for Available Free Lead

In Typical Dry Charge Negative Plate Processed in Tiegel SmartDry™ Oven

Assumptions

Molecular weight of lead carbonate	267.22 grams
Density of CO₂ gas	1.977 g/l or .001977 g/ml (cc)
Molecular weight CO₂	44 grams
Plate Weight	Positive Double Panel 184 grams, (wet) 162 grams (dry) Negative Double Panel 180 grams (wet) 160 grams (dry)
Plate Dimensions	.061” x 4.5” wide x 4.85 high (without lug) 1.55mm x 114.3mm x 123.2mm (without lug)

Test Data

(Based on the volume of CO₂ evolved from Dry Charge negative plates upon the addition of acid.)

Sample #1	1.02 cc	CO₂ per square inch of .061” thick negative plate
Sample #2	1.20 cc	CO₂ per square inch of .061” thick negative plate
Sample #3	0.93 cc	CO₂ per square inch of .061” thick negative plate
Sample #4	1.02 cc	CO₂ per square inch of .061” thick negative plate
Average	1.04 cc	CO₂ per square inch of .061” thick negative plate

Calculations

Average volume of CO₂ per square inch x Density of CO₂ gas = Amount of CO₂ gas\1.04 cc CO₂ per square inch x .001977 grams CO₂ gas/ml = .002056 grams CO₂
.002056 grams CO₂÷ 44 grams CO₂/mole = .000046 moles CO₂.000046 moles CO₂ x 267.22 grams lead carbonate/mole = .012292 grams of lead carbonate

Assuming the weight of 1 square inch of .061” thick negative plate @ 7 grams;
.012292 grams of lead carbonate ÷ 7 grams total weight
=.001756 grams available free lead per square inch of negative plate
1.000000 – .001756 grams free lead ¸ 100
= 99.824% available free lead