D9 Transmitter, Battery Polarity Reversed

[mddolson]

I can't believe that it doesn't have reverse polarity protection in it. That's just ridiculous.

I agree

MikeD

 

[marcushall]

I can't believe that it doesn't have reverse polarity protection in it. That's just ridiculous.

Do we know that the OP's transmitter is dead now? Chicken SCUBA said that he did the same thing with no ill effects.

There are two primary ways to go about protection, a forward biased diode in series with the battery, which lowers the voltage by the forward drop (1.2V for most diodes, but I believe that some can be had with less drop), or a parallel reverse biased diode. The reverse biased diode would not incur a voltage drop in normal operation, but would essentially short out a reversed battery. If that was what was done, it could produce a little magic smoke and is probably not good for the battery, but might be harmless for the transmitter circuit (for a short period of time, at least).

 

[mddolson]

Do we know that the OP's transmitter is dead now? Chicken SCUBA said that he did the same thing with no ill effects.

I haven't had a chance to try it out again. It's been a low priority since I've switched to sidemount & have 2 spg's.
I have to order a new battery for it.

Mike D

 

[DIVEWATCHDOCTOR]

What Marcushall said is correct. The diode in series is not feasible because the intrinsic voltage drop of the juncture would be considerable, given that the battery has only 3V. A reverse biased diode in parallel with the battery is another reverse polarity protection option. The smoke suggests that it could be what Suunto chose to protect the transmitter circuits. Probably the diode burned and you lost the protection. But the electronics inside shouldn't be damaged. The only way to know, other than having access to Suunto's circuit diagram, is installing a new battery and seeing if the transmitter links up with the computer.