Simple DIY 16V 18650 battery for Whites TDI SL

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XLOOX

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Folks, Here is a 16V 18650 battery holder for the TDI SL that you can make at home in about an hour.

You will need a set of 4 decent 18650 batteries such as Panasonic NRC18650B (PCB protected 3400mhr) ~AUD$40 and a Whites #802-7150 8 AA battery holder AUD$30.

1) Take your battery holder and with the holder closed and empty slowly & carefully drill thru the embossed Whites symbol on the slide lid using a drill bit 10mm or so, the size is not too critcal. This will remove the little plastic protusion on the underside of the lid which prevents the lid being fully removed.

2) Slide the lid off.

3)All the metal fittings in the case are simply held by friction & if you use a scribe or similar to slightly bend up those little tangs you will easily pull off all fittings with a pair of long nose pliers.

4) Lay your 4 x 18650 batteries as shown in the photo. Take a dremel & cutoff knife and cut out all the reinforcing ribs etc that prevent you laying the batteries neatly in position. Dont cut more than needed.

5) Using the dremel with a cutoff wheel cut a 15mm wide slot thru the case bottom. The slot is centred on the centreline of each pair of batteries. These slots are needed to allow the batteries to sit low enough to slide the cover back on. They also act to hold the batteries laterally once the lid is in place.

Now we need some terminals.

6) For the back end of the battery where we need to join the 2 strings of batteries together just cut a rectangular piece of thin copper strip to fit across the whole back and solder a couple of ~3 x 3mm pieces of copper strip onto the main strip to raise the surface enough to contact the battery terminals.

7) For the front terminals I used the existing Whites +ve & -ve terminals but cut the sides off & bent them to fit and hold the batteries firmly. WARNING. The terminals are made of the most brittle metal I have ever seen. Cold bending is totally out . All bending to be done after heating with a mini gas torch. If you break the Whites terminal a simple U shaped piece of ~3mm wide springy steel or brassy strip wil work just as well.

8) Load the batteries & slide the lid on. If the lid wont go on then check where the batteries are sitting high & cut another mm out of the base slot(s).

9 Once assembled check continuity ie should have 16V at the terminals. Shake the battery around and recheck voltage. If all good you can superglue the back terminal in place. If not then one or more batteries are not touching their terminal. Issue can only be either battery being obstructed by some plastic or insufficient pressure from the front terminal, which acts as the spring. A bit more dremmeling or bending and all will be sorted.

I get 5 hrs runtime from this pack down to 13.8V. Note that you CANNOT rely on the Whites battery light as that is set for 8.5V.

Using a NF Sadie & compared to the Whites NiMH battery pack, depth on a 1 grain 24k ingot goes from 45mm to 60 mm and depth on a 1/2oz 30mm dia 24k coin goes from 220mm to 250mm. Max depth on massive iron goes from 400 to 500mm.

Ok its not a Minelab but its probably the next best thing.

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XLOOX what a great and simple low cost design, I'll look at sacrificing a spare battery holder since I've got everything needed for this project.
Those Panasonic NCR18650B cells that you use are the type without the nipple? I've got a variety of cells and my nipple variety probably won't fit, need the flat ones for a still reasonably tight fit.. I've been carefully measuring everything so I thought I'd mention that some protective 18650 cells with nipples may not fit. I'm looking forward to having a good go at this project, thank you XLOOK.

All the best,
Karelian
 
Thanks you again XLOOX, I am almost finished. When the postie delivers my ultra thin carbon fibre I'll complete the project. Just cosmetic changes on my project, got the slide lid off without drilling and just cut the notch off. Will post again when 100% finished.
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Must heat the connectors so they don't break, as stated, you have been warned.. Use quality copper not too thin or thick. I went with .4mm. Used a punch on the soft copper for better connections at contact points. Lots of tension so the flat cells have good connections. 16.48 volts using not fresh cells, they have been sitting for a while. I'll go again when I'm finished with hot off the charger cells..
Got to be happy with the voltage. Full credit to XLOOX for a quick and simple solution.

All the best,
Karelian
 
Carbon fibre had arrived and apart from cosmetic changes this is the XLOOX design, thanks to him for making it easy. Final images of the finished product. Carbon fibre covers the channels cut out for the batteries and is used for a new cover replacing the White's original. Karelian
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Hi Karelian,

I am so happy to have been able to help you as I have been reading your TDI posts since 2017 and your comprehensive coil tests is the reason I got a Sadie ( which I think is perfect for the SL both in terms of weight and performance).

As you know by now the Panasonic NCR18650B has nipples but still fits in the adapted case.

BTW your case is a MUCH more professional job than mine - Nice !

Would you be able to post the depth you get with the TDI SL + Sadie+16V battery for the 1 grain ingot, 1/2gram coin & AUS penny ? That would really be appreciated.

Break/Break

Before I adapted the AA case I wanted to see if the 16V battery delivered a benefit so I made up a "temporary" 16V system which actually worked quite well so for those who want to try out a 16V pack without totally butchering their AA case then see the attached photos.

The dowel is 14mm ( same dia as AA battery) and is cut to be as long as 2 AA batteries. I soldered a piece of copper on to the wires and glued them to the dowel but frankly stripping the wire bare and holding in on the dowel with a wrap of tape would be just as good. The wires are 20cm long which is just enough without having any loose to snag branches. A strip of duct tape over the wire after loading ensure all remains intact during a hard day bush bashing.

The 4 cell 18650 case is from Ebay - $7. The batteries are held quite firmly by the case but I added a strip of velcro tape to be sure.

The case held to the detector just with a screw thru the stand strap. You do need to make sure that you slightly undersize the hole so the screw cuts its own thread.

You do need to cut a small groove in the back of the AA case so the wires can feed out with the lid on and also need a small slit in the middle of the battery compartment door as far as the right angle, again to allow the wires to pass thru.

have fun !

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Hey guys, will this 16v mod still charge via the supplied whites charger or are they a pull out and charge.
 
Pull out and charge, major advantage in choice of 18650 cells and the ability to carry spares to swap out in the field. Karelian
 
Gidday Karelian, I am not understanding the contact points in this picture, is it just the + & - at one end that are the contacts or is it both ends? I see there is a long piece of copper running across both ends of the batteries, do they make contact? Running a piece of metal across negative and positive dont make sence to me, I am a little naive wen it comes to this stuff.

Cheers mate
Len
 
I'll include better images and one with a diagram. The copper at one end just bridges the batteries over to the other end. Hopefully the images make it much clearer. Karelian.
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karelian65, thanks so much man, that really helps out, I can make one 2day now. Bloody rippa.
Do you gold detect, have you noticed a difference with depth and signal? I only search for nuggets with mine, no biggies yet, largest being under a gram, smallest being 0.1g.
 
Hard pressed to do much better than an OPUS BT-3100. Loads of features including diagnostics & capacity tests. $65-75 but worth it.

They run on a 12v 3A 240VAC plug pack so easy enough to run them off your car 12V to to recharge stuff when on trips away, just need to get/make a standard 12V cable.

Checkout this indepth review

https://lygte-info.dk/review/Review Charger Opus BT-C3100 UK.html

BTW that guy does the most detailed reviews for all types of Li batteries etc.
 
Edit: as per above :Y: XLOOX posted while I was typing. :)
IMAX B6 are well regarded if you want to charge as a pack of 4 cells?
There are a lot of fakes on eBay so make sure you get one from a reputable retailer.

There's a lot of good 18650 li ion chargers for doing single cells if you want to remove them from the pack for charging. Like these: https://www.liteshop.com.au/content/nitecore-q4-li-on-imr-4-slot-quick-battery-charger/
https://www.liteshop.com.au/content/nitecore-intellicharger-i4-smart-charger/
I use a Nitecore charger (not the linked model, basically the same but 8 slots) & it is good.
 
I use the OPUS BT-3100, allows me to control the voltage of each cell. The advantage of this is maximum cell life, keeps the 4 x 18650 pack at just on or just under 16v. 16v is generally accepted as the safe maximum voltage, better for the batteries and for the detector as well. We all draw a line in the sand somewhere, so 16 volts is it for me and the OPUS charger allows me to do this easily. Make sure it is genuine etc but in my view highly recommended..
All the best, Karelian.
 

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