What is this warning tone?

Just bought a second hand 4500 and last saturday night charged the battery and went out sunday but after a couple of hours detecting I got this tone which came thru the speaker and the best way for me to describe it would be a ding-dong, ding-dong sound. I checked the battery and it was at 7.9 and after another half hour it did it again followed once more 5 minutes later before I turned the machine off (it was then at 7.4) After 10 minutes I switched it back on and did fifteen minutes detecting and it did not happen again and the battery when I checked it was back up to 7.8.
Paulf

The sound you describe is the warning of the battery about to go flat, the voltage fluctuations are a bit strange

Thanks for that. Will go for a detect on Saturday (weather permitting) and if it does it again then back to the shop it goes. The detector is only 8 mths old.
Paulf

A low battery warning will sound at every one minute interval, this will start when the battery falls to 7.3volts and will shutdown at 7.1volt. the sound you describe does sound like a flat battery to me, give it a full charge and if it continues then your battery might be stuffed, I think you said it was second hand? you don't know how old the battery is and if was looked after.

Regards Johnny

G'day Paulf

When you say you "charged the battery and went out sunday" are you sure it went through all its full cycle, read the manual and it will tell you what each stage is, it shouls end up with a solid green light. When hookek up to the detector it should read at 8+ volts.

Goldstalker is right the dingdong sound is a warning sound for a battery going flat, and it will switch of a about 7.1v I think, but the warning starts a round the 7.4v. Why you were getting a fluctation in the readings I have no idea.

I do know that with a fully charged battery (8+v) I have got up to 10 hours detecting and you should have no trouble getting 8 or so hours. As the battery gets older it will get less efficent, as in not running the machine as long, but this should not be until it battery is quite a few years old.

cheers dave

The battery was charged correct and I checked when I first switched on the machine. The battery should only be 8 mths old unless it has been swapped at some stage.
Paulf

Gday Paul
I've got a 4500 and recently had a similar problem. Contacted Nenad at ML and he suggested that I run the battery right down and then recharge. Ran the detector in the back yard on Cancel with headphones attached till the machine shut down automatically, then stuck the battery on charge. I've done a couple of trips bush since then without any dramas.
I think it's just lack of consistent use that causes this sort of thing.
Good luck.
cheers
Brett

Thanks Brett, will give that a try.
Paulf

I've only had it happen once, went detecting on a Saturday then forgot to charge the battery for the Sunday session

Brett is right, (and I know it sounds stupid) you need to train your rechargable batteries how to work.

I thought with these batteries they did not have a memory. Is that right or am I mistaken. Anyway the detector is running the battery down now so tomorrow I will recharge and hopefully get out on the weekend to try it out. Thanks for all the advice guys, appreciated.
Paulf

paulf wrote:I thought with these batteries they did not have a memory. Paulf

By my statement I was referring to all rechargable batteries, by this (maybe just myth) I mean that even before use one should charge then flatten batteries a few times before use to let them know what thier purpose is.

C'mon who really does this having said that I have had dud rechargables, don't the 'experts' do this when they revive cordless tool batteries? (flatten-trickle charge-flatten-trickle charge-flatten-charge=new again )

Let us know how you get on Paul.

Cheers

Yer battery is flat or stuffed.
Give it a full recharge cycle.
NiMh batts do not have a memory effect and it is much better for these batteries to be recharged before running right down, they will last longer, unlike NiCads that needed to be discarged fully before recharging.

When the battery is almost flat according to the tones and you then switch the detector off for a while say an hour or two, the battery will rejuvenate itself a bit and when you switch on again your detector may give a better battery condition tone and you may get a few minutes detecting before the machine again gives the low battery warning.

Adrian SS