Rebuilding the Minelab/Etrac Battery Pack

I’ve virtually closeted my well-used Etrac the last few years due to erratic performance and an OEM rechargeable battery pack that would run no longer than 30 minutes before losing power. I never seem to have 8xAA batteries lying around so the machine was replaced by my upgraded F75 for general hunting.

All the Nox Talk has got me wanting to swing the Minelab again so I decided to get a new rechargeable battery pack. The Li-ion RnB ML-3400 looks to be a fine replacement but $140 is more than I wanted to spend. So I decided to rebuild my OEM pack and replace the old rechargeables with the newest, highest capacity name-brand NiMh rechargeable batteries that are reasonably priced.

After researching the web I found this vid and generally followed it to the letter: [m.youtube.com] Two 4xAA rechargeable 2500 mAhr Duracell packs set me back $25: [rover.ebay.com] The batteries are rated at >400 charges. A pack of #9 compression springs from Lowe’s (P/N 422419) cost $2.63. The job took me twenty minutes start to finish.

The batteries are supposed to be partially charged so after the rebuild I dropped them in and powered up. Nothing but a small audio chirp! I check the voltage on the two circular contacts on the pack and I measure 9.44V. The batteries are nominally rated for 1.2V each so the pack should be 8x1.2V = 9.6V. Still the detector should power up. I crack open a fresh pack of standard Energizer AA batteries and drop them into the extra AA pack to test the machine. Nothing again! The Etrac won't power up. Now I’m thinking I just wasted $30 and the Etrac needs to be sent in for repair. I hadn’t used the AA pack in years.

I look into the Etrac battery cavity and the springs look clean and fine. The AA battery pack contacts have a light grey toning to them, unlike the shiny look when new. I lightly abraded the contacts with a green plastic abrasive pad, replace the pack and the Etrac fires up with four bars. I clean the contacts on the newly rebuilt pack, install them and the unit turns on with three bars. I never knew this minor level of tarnishing would create such an insulator. Lesson learned: clean those contacts occasionally.

I charge the rebuilt NiMh pack overnight and measure voltage to be 11.82V. After a one hour hunt w/headphones the Etrac still showed four bars. Leaving the unit on two hours later the display still had four bars. At four hours total time the battery gage dropped to three bars. I’ll check again later tonight and the morning.

Hopefully this is of value to the Explorer/Etrac owner that has a weak rechargeable battery.

Very interesting to know.
Please keep us posted on how this works out. Thanks.

Up to my ____ in Pulltabs, Grant

This is excellent news! I appreciate the link posting, and your parts list. Mine is on its way out. I can charge all night and hunt for about 3 hours and it’s down to one bar.
I’ll be doing this soon!

XP Deus
Minelab Etrac
Minelab Equinox 800
Garrett Carrot
22 silvers, 2 silver rings, 1 Gold Ring -YTD 2018


Some of my random digs: [www.youtube.com]

Oh I forgot to add.. did you cut the tension springs, elongate them then sauder them?

XP Deus
Minelab Etrac
Minelab Equinox 800
Garrett Carrot
22 silvers, 2 silver rings, 1 Gold Ring -YTD 2018


Some of my random digs: [www.youtube.com]

I did this to a couple of my old packs, too. One, I was too chicken and had Interstate do it for me, cost about $35 and worked like a charm. Then, I did two myself. Again, worked like a charm. I

Steve

Quote
Gannon
Oh I forgot to add.. did you cut the tension springs, elongate them then sauder them?

Yes, I cut one spring into thirds, threw away the middle and soldered the ends to a cut down picture hanger as was done in the video. These are compression springs, so do not need to be stretched.

I just terminated the test as I’m going to work now and won’t return home for another 15 hours.

So after leaving the detector ‘on’ overnight (total time = 12.5 hr) the battery gage dropped to two bars and the battery voltage measured 10.03 V.



Edited 1 time(s). Last edit at 03/29/2018 10:15AM by go-rebels.

Remember that Duracells are the "BMW" option for rechargeables. Here’s a set of eight for those on a budget: [rover.ebay.com]

Total cost = $4.36.

Have you tried those particular cells, GoRebels? Cheap unbranded cells bought online have a bad reputation, and they may be poor quality and/or low capacity. A clue is the quoted capacity value. The most fraudulent types usually print the most exaggerated mAh figures. These cells meet that criterion - 3000mAh is right at the upper limit of what the best brands offer.
The 'budget brand' that seem to offer good performance at more reasonable prices are EBL. It appears their highest capacity AA's are 2800mAh.
And the other 'top brand' that generally get good reviews are Sanyo-Panasonic 'Eneloop' cells, of which there are several varieties, including the low-self-discharge (LSD) type.

It's worth adding: If you are still using the same ML trickle-charger, you will need to leave the pack on charge for twice the time to fully charge it up. It's intended to charge a 1200mAh pack in 12 hrs roughly, so a 2500+ capacity pack will be needing 24+hrs to charge, if it's fully flat.

Pimento Wrote:
-------------------------------------------------------
> Have you tried those particular cells, GoRebels? C
> heap unbranded cells bought online have a bad repu
> tation, and they may be poor quality and/or low ca
> pacity. A clue is the quoted capacity value. The m
> ost fraudulent types usually print the most exagge
> rated mAh figures. These cells meet that criterion
> - 3000mAh is right at the upper limit of what the
> best brands offer.
> The 'budget brand' that seem to offer good perform
> ance at more reasonable prices are EBL. It appears
> their highest capacity AA's are 2800mAh.
> And the other 'top brand' that generally get good
> reviews are Sanyo-Panasonic 'Eneloop' cells, of wh
> ich there are several varieties, including the low
> -self-discharge (LSD) type.
>
> It's worth adding: If you are still using the same
> ML trickle-charger, you will need to leave the pac
> k on charge for twice the time to fully charge it
> up. It's intended to charge a 1200mAh pack in 12 h
> rs roughly, so a 2500+ capacity pack will be needi
> ng 24+hrs to charge, if it's fully flat.

It has been found that Ikea AA and AAA batteries branded as "LADDA" are rebranded Eneloop cells.
I've been using these for many things and they perform as good or better than the standard Eneloop and Eneloop Pro AA's. The price is half of the Eneloops.

Up to my ____ in Pulltabs, Grant

Up to my ____ in Pulltabs, Grant Wrote:
-------------------------------------------------------
> It has been found that Ikea AA and AAA batterie
> s branded as "LADDA" are rebranded Eneloop cells.
> I've been using these for many things and they per
> form as good or better than the standard Eneloop a
> nd Eneloop Pro AA's. The price is half of the Enel
> oops.

I've found the same to be true of AmazonBasics high-capacity AA's (and AAA's).
All those relabeled Eneloops are usually pretty easy to spot as they have a "Made in Japan" label, as opposed to the Chinese mfg ones.

Eneloops consistently test to their rated capacities in my battery tester, and I use them in most of my machines that need AA.

Pimento is absolutely right about the Chinese batteries.
Of the hundreds I've tested, very very few have performed to their ratings...(one notable exception was the excellent black label Powerex)

Any AA from China labeled up to about 1500 mAh is usually OK, but anything labeled higher...such as those 3000mAh labels...are a dead giveaway as being a 'prevarication'. (http://www.dictionary.com/browse/prevarication?s=t)
They are inconsistent, and of absolutely horrible quality...frequently testing as low as 750mAh. Never above 2000.
My guess is they just slap the 3000mAh label on sub-standard 1500mAh batteries.

My recommendation is to stick with the labeled/re-labeled Japanese Eneloops, or possibly the Chinese Powerex...and avoid the others like the plague.
If you're going to take the time to do it...do it right. Otherwise you end up wasting time AND money.

mike

Also, on the subject of Etrac batteries;

You can make a poor-mans RNB Li-ion battery pack with a holder available on eBay.
The seller (from Eastern Europe...Ukraine, I think) 3d prints an orange plastic holder designed to hold 3 of the larger 3.7v 18650 batteries.

The caveats here are:
1. You'll need to remove the batteries from the holder to charge them.
2. You'll need a charger designed to handle 18650s...the AccuPower IQ 338 is a good one.
3. Quality control on the holders can be a little 'iffy'...especially dimension-wise.

If you can live with that, you've got a lightweight eTrac battery that will last far longer than any other...similar to the Rnb.

This same guy makes a similar 18650 holder for the White's detectors (like the TDI-SL, V3i, MXT, DFX, etc)
I use them on my V3i, and DFXs. I can hunt for 6 hours and only uses a fraction of the capacity.
...so it ends up being about an 18 to 50+ hour White's battery...depending on the detector and/or backlight...far longer than I can hunt!