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Battery compartment preventive maintenance

Battery compartment preventive maintenance

Common cause of the sonde’s failure is contact oxidation in the battery compartment. It is not a big deal but it may break contact between electronic components and the battery inside the sonde’s body. Oxidation can be eliminated only at complete disassembly of the sonde.

To avoid failure follow the 3 simple rules:

  • monitor
  • clean
  • lubricate
Contact oxidation can result in damage and repair of the complete sonde

Battery compartment oxidation affects the contact between the battery and the electronic board

Cause of oxidation — penetration of the drilling fluid

The drilling fluid blocks all possible gaps. With poor contact of the cap to the body drilling fluid enters inside the compartment which leads to electrical corrosion of the spring and to the full or partial loss of contact between the sonde and the battery. For example, with 100 mA consumption current and 4 Ohm parasitic resistance the contact will ineffectively lose 0,4V. Having fresh batteries with the voltage of 3,2V, the contact will let sonde electronics have only 2,8V. But electronics demands constant power from the battery, thus proportionally increasing the consumption current, which will again increase parasitic drop in contact voltage. Basically, your batteries operating capacity will be at least 30% less — the sonde is “eating” the batteries as we call it.

Basic task of the sonde maintenance is to insure the battery compartment tightness.

What if the drilling fluid penetrates the battery compartment

In case the drilling fluid penetrates the battery compartment, clean the thread, body and the spring using the paper napkin or cloth, dry or impregnated with commercial alcohol. In the field environment use the dry cloth and the cane which fits inside the body, it may be a swiss file or a screwdriver. In theory, the inner surface of the battery compartment must be shiny.

Cleaning transmitter

If the drilling fluid is inside the battery compartment — immediately clean it with materials at hand

DO NOT let the drilling fluid inside — check the seal ring

During operation and improper sonde maintenance the cap seal ring can be worn out. At wear-out or loss of the seal ring tightness of the battery compartment is broken.

Ring for sondes

The right seal ring can be thrown away

Extend the life of the seal ring — lubricate it with specific sealing grease. In the field environment you may use white petrolatum(vaseline), for example.

In case the seal ring is broken or lost — use adhesive PVC tape. Wind up 3-4 layers instead of the seal ring. Screw the cap tightly and cut off tape residue.

PVC for beacons

Use PVC tape instead of the seal ring

We recommend to keep a couple of seal rings with the location container. Seal rings are sold in tool shops. Seal ring inner diameter is 24 mm., cross section — 2.5 mm.

Check the thread of the cap

The thread of the battery compartment and the cap must be clean. In case of the dirty thread, it is possible to have incomplete contact of the cap and the sonde, you may have marks of oxidation (which again leads to parasitic transition resistance!). It is easy for the drilling fluid to enter the body if the cap of the battery compartment is dirty and oxidized.

You have to carefully clean the thread with a sharp tool: with the fine screwdriver, for example. After cleaning, wipe out the thread with the cloth soaked in alcohol. If possible, grease it with specific conductive lubricant or vaseline.

Another problem is compression

When after boring the cap is stuck or the batteries will not come out — then you may have deformation of the body. With compression you may also have latent faults, damages to the electronic unit components, including the damage to the ferrite antenna. The only way out is repair of the sonde.

Failed sondes HDD

You failed to unscrew the cap as the sonde was was pressed in the boring head

The main thing — it is preventive maintenance

One of the causes for the sonde failure — it is the loss of battery compartment tightness and, as a result, penetration of the drilling fluid into the battery compartment with all the possible enumerated consequences. To prevent depressurization take care that the thread is clean and the seal ring is not damaged. In case of drilling fluid penetration, follow the above said recommendations.

Hopefully, our recommendations will help you to preserve operational performance of your sonde. Please, share your observations and questions in commentary.

Author`s articles:

Nagovitsyn Aleksandr Leonidovich
Founder and Leading Engineer in repair, modernization and development of HDD location systems
My e-mail: repair@hdd-electronics.com

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