All about the batteries.

Using the Right Batteries

The DTD uses three 3-volt lithium batteries, BA-5123/U, NSN 6135-01351-1131.

Before you insert the batteries, make sure they are fresh. Meter them. Good batteries will meter out between 9.25 and 9.50 volts.

Don't use batteries that rail below this range of your DTD might soon become erratic, intermittent of even lock up.

Don't substitute look-alike batteries like the BA-5372/U for the BA-5123/U.

The last guys who did that are buying new DTDs to replace the ones that were destroyed by the high heat produced by the BA-5372/Us.

A future alternative to the BA-5123/U is the rechargeable 9-volt NiCad, NSN 5810-01-501-5401. Right now, only Navy folks can order it, but check FED LOG in the future, because the move is toward using rechargeable batteries whenever possible.

One final option is "for emergency use only" and that is a 9-volt battery. A 9-volt lithium, NSN 613501-369-9792, or alkaline, NSN 6135-00-900-2139, can be used, but neither one will last as long as the BA-5123/Us. However, the lithium will last longer than the alkaline.

Also, they will not sit as well in your battery compartment. You may need some "stuffing" to keep the batteries snug in the compartment.

Installing Them Right

First, you will get a low battery indicator message readout: LOW BAT. This message will be displayed continuously after a low battery is detected and will give you enough time, in most cases, to complete your current operation.

Don't depend entirely on the low battery indicator light, though. Batteries have been known to creep well below 9 volts without the light coming on. Do your best to keep track of how long a battery has been in the DTD.

When time has almost run out. the low voltage detector (LVD) will activate, sounding an alarm. You will have enough lime to shut down the DTD in an orderly and secure manner, but not much more.

"To replace batteries, first remove the battery cover, NSN 5810-01347-9668, by loosening the four screws.

Carefully insert a flat-tip screwdriver under the extension lip and pry up the battery housing, NSN 5810-01-348-3147.

Once the battery housing is disconnected from the DTD, you've got 2 minutes to replace the batteries and reconnect the battery housing. After 2 minutes, data is lost and the DTD must be initialized again.

Don't try to save money on batteries; replace all three each time. Make sure the polarity is correct as you install each new battery, It's important to do it right the first time, because you might not have the time to do it a second time.

Put the housing back into the DTD with the positive contacts going in the slot first. The housing will not fit if you put the non-contact end in first.

Tighten down the four battery cover screws, but don't overtighten them. You'll crack the cover if you do.

Turn on the DTD to make sure the batteries are working.

Keeping Good Contacts

As you install the battery housing, take a look at the positive and negative contacts on the DTD. Are they loose? Any burn marks?

Do the burn marks limit the electrical contact? Good electrical contact is a must.

Unit maintenance can replace both the negative contact, NSN 5810-01-350-8388, and the positive contact. NSN 5810-01-3508387.

They will use a 1/16-in hex head screwdriver to remove the screws that hold the contacts. Then they will replace the contacts, making sure to get them in the right positions.

They will tighten the screws without over-tightening of they could crack the case.

One strong word of caution: 40,000 battery housings were replaced in 2003 because contacts were shorted! Never touch the contacts with your hand or any other material that may conduct. The fuse in the battery holder will blow. Since the fuse is not replaceable, a new battery housing will be needed.