Lightweight battery

Hi Folks - has anyone had experience / recommendations for a lightweight alternative battery to the ML battery for GPX machines? Ones like the Docs GoldScreamer type, LT, Reeds etc. that can be attached to the control box. I'd like to get the weight off my back and be rid of the curly cord. Thanks.

G'day 1981, Welcome, I am sure if you trawl through the archive here for past threads you will get some good alternatives, there have been a few, I am unsure myself who does or doesn't produce a system at this time, have you thought of using the standard battery on the side, short leads can be made to customer requirements, adds about a Kg, not too harsh, depending on the individual and what you do of course.

Wayne.

Thanks, digginerup. I have trawled through all the forums but info is sketchy. Ismael doesn't do them any more (sadly) and I can't get any current info on what's available and how good they are. I reckon putting the ML battery on the control box might be a bit too heavy - I would really like to reduce the overall weight - but especially on the harness - gives my back grief as it is now.

HI since1981
Welcome on board..

Ok... hopefully Mechanic will see your post or someone else who may know..

Thanks Jen. Mechanic has given me a teaser about one he has on the boil, so that would be great. Still interested in anything others are using or have used though.

Hi Since1981

Not personal experience - but - a couple of local guys are using model car batteries (~<$100 ?). Each pack lasts a day of detecting (they say) and they are certainly much lighter than the standard ML "box". They just tuck the battery in the detector cover.

However, they require a suitable charger and the unit I saw was a 12/240V version (~<$50 ?). A 5-pin connector (~<$20 from ML ?) and suitable cable is required to link the battery to the detector and allow the headphones/booster/wirelessTx to be connected etc. (assumes the output level & impedance of the detector can drive headphones direct ?)

Cheers

Thanks, Auger. Seems to be a few variations around the place - haven't heard of that one. I think I'm leaning toward the Reeds EQ Spirit as I'm not sure something I put together will be reliable enough for me out in the bush!

Since1981
A "ready to go" package is a good idea and one that includes a wireless link is even better. Building your own can get "messy" with some techo dramas to sort. However, I'm going to give a "model" battery a go because I have the skills and I'm curious etc. I plan to extend the h-phone cable and unplug it when needed - without having to switch the detector off.
BTW - I've been experimenting with the ML battery and have tried "lashing" it to the control box with a short cable between them. The extra weight is noticeable and for that configuration I need to use the bungy-cord for ALL coils.
Cheers

Keep us informed Auger, previous information suggests that a voltage regulator is needed just for insurance.

Hi llanbric
I don't plan to incorp any regulation at this stage. I intend to use a two-cell Lithium pack which has is a nominal 7.4V as per the ML pack. In that way the control box will still show-levels/give-warnings as per normal. If I use a regulator (eg using higher than ~8V battery) the control box would simply "fall over" without warning when the battery was flat etc.
Cheers

Auger wrote:Hi llanbric  
I don't plan to incorp any regulation at this stage.  I intend to use a two-cell Lithium pack which has is a nominal 7.4V as per the ML pack.  In that way the control box will still show-levels/give-warnings as per normal.  If I use a regulator (eg using higher than ~8V battery) the control box would simply "fall over" without warning when the battery was flat etc.  
Cheers

Keep us posted.

I dived into the ML 5000 "battery box" and can see where the audio arrives at the circuit board.  The input circuitry looks BALANCED to me, which sounds like a good idea.  It also "agrees" with the circuit used by the Lucky-Lark which shows a balanced input to their audio chip. I got that info from a L-L review by Ishmael Jones.  The circuit that Ishmael provided does not show a terminating resistor across the balanced input and I wonder if the ML "box" uses one ?  I'm being lazy here and want to avoid the process of tracing the ML circuit etc.  
Can anyone help ?  
Cheers

BTW - it's the presence and value I'm interested in - or maybe the natural input impedance of the ML chip is sufficient ?

Have you seen this Auger?

https://www.reedsprospecting.com.au/shop/detail/eq-spirit-li-ion-battery/

Robert

goldnomad  --
Thanks for that.  I had heard of that gear but I have not seen it "in the flesh" yet. It looks/sounds like it solves a couple of problems elegantly.  

llanbric  --
I bought a couple of batteries and a charger recently.  They were $45 each and the charger (240/12V) was $90.  (I got those figures back to front in a previous post)
The batteries are very light and compact but have only half (4Ah) the capacity of the ML pack (9Ah).  I have since seen a 6Ah Li-pol (PowerGrunt Hobbies, Bendigo) that is not noticeably heavier/bigger for about $100.  

I now have to "package" the battery/audio stuff in such a way that it is reliable when out in the bush and easy to charge etc.  

Cheers

Update etc

A while ago on this topic I was chasing techo detail for the audio circuitry in the 5000 battery box. It's no surprise that I did not get a bite and so recently I dived into the box and have now traced most of the audio path.

The main problem was the "bogus" (MLAB GB3 etc) numbering on the audio chip. After about 4 hours on the InterWeb (!!!) I discoveredd it is a NCP4894 (OnSemi) which is a dual/differential amplifier listed as delivering 1 Watt into an 8 Ohm speaker with <0.1% distortion.

The balanced audio from the control box either drives headphones direct through a pair of analog switches (1 Ohm each path) OR through the amplifier and the "other side" of the same switches (1 Ohm each path) to a speaker etc. The analog switches and the amplifier enable/inhibit are controlled by the action of the headphone socket (that WE are familiar with ?) via a yet unidentified active device (u106 ?).

I've now got most of the detail I need to make a lightweight 5000 battery (box ?). I will have a look inside the control box and might get a clue as to what audio chip used to drive the headphones directly, however, I am told that there is "crapp" sprayed over the components etc. Eventually, I plan to post a tidy diagram of my version of the audio circuitry.

Cheers

Good work Auger, keep us informed.

Good work, I personally do not possess the skills to utilise your research but I am sure there will be value to those that can, good to see a follow up from you, keep it up , thanks for sharing that

Wayne.