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Old 01-26-2022, 04:54 PM
mh9162013 mh9162013 is offline
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Default E-Trac Battery Discharge Curves

Here's a post some of you might find interesting.

I recently acquired an E-trac and it cames with 1600, 1800 and alkaline battery packs. All of these have been used, some more than others (presumably), but I have no idea as to their life. Anyways, I decided to charge them up using the stock Minelab "trickle" charger and test their capacity and performance under load.

Below is a chart where I have the alkaline pack, except it's loaded with eight AA 4th generation Eneloop (Panasonic) cells. The picture makes it clear that it's performance is amazing. Not only does it exceed the rating capacity of 2,000 mah per cell, but it has a pretty flat discharge curve.

As for the 1800 E-Trac pack by Minelab, it did ok. Assuming it's at least a few years old, it still has plenty of life left.

A few notes about the testing.

1. All discharge tests were at 200mah. This exceeds what the E-trac will pull on a consistent basis during normal operations.

2. The discharge test ended when the pack had an overall voltage of 8.4 volts. The E-Trac manual implies that 8.4v is some sort of important point in the pack's discharge cycle. I've concluded that this is when the battery bar starts to blink or when the automatic shutdown kicks in.

3. The Eneloop test used 4 cells that were about 4-5 hours off the charger and 4 cells that were abour 5 minutes off the charger. This charger was a single channel charger and charged the cells at 300mah (per cell).

4. The 1800 pack was about 55 hours off the charger before discharge testing began. In case you're wondering that had an effect on the overall capacity, but not by much.

5. When the cells in the 1800 mah pack dumped...they DUMPED. I iniitially suspected it had some sort of auto-cut off. But I don't think that's the case because the cut off is so high voltage-wise (about 9.5 volts) and the 1600 pack (also an OEM product from Minelab) did not have a discharge curve that had such asn abrupt termination. Instead, the 1600 discharge curve looked similar to the Eneloop curve in SHAPE only, ie the curve as it approached the 8.4v cutoff point was gradual, not abrupt. Anyways, I suspect that this 1800 pack is an accidentally created matched pack. Or, there could be 1 or 2 cells that are dumping fairly early, but the overall discharge curve of the 1800 is fairly close to the Eneloop pack. So I'm not 100% sure what's going on here.

6. So how does this data relate to run times? Well, the E-Trac manual says the 1800 pack should get 16 hours of run time. That equates to about a 112.5mah current draw. Assuming Minelab is being generous here (which they probably are), let's assume an actual current draw (during normal use) of 135mah (a 20% current draw "adjustment"). Assuming that's the case, then this 1800 pack I tested should get about 10 hours and 20 minutes of run time and the Eneloop pack would get about a 14 hours and 45 minutes of run time. If we used Minelab's numbers, then the run times are 12 hours 20 minutes and 17 hours and 35 minutes, respectively.

7. These discharge tests were completed using the CBA III (which is no longer in production and has been replaced by the CBA V).

P.S. In no way am I affiliated with West Mountain Radio.
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Last edited by mh9162013; 01-26-2022 at 09:54 PM.
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Old 01-26-2022, 05:14 PM
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Good to know MH. Thanks!

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Old 01-26-2022, 09:27 PM
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Cool tests. So clearly the fresh Eneloop "1600" is the winner, and I'm guessing since the Minelab "1600" doesn't take that dump, it outlasts Minelab"1800" ? Either way, now you know any of them should get you through a long day.
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Old 01-26-2022, 09:49 PM
mh9162013 mh9162013 is offline
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Originally Posted by TorqueMaster View post
Cool tests. So clearly the fresh Eneloop "1600" is the winner, and I'm guessing since the Minelab "1600" doesn't take that dump, it outlasts Minelab"1800" ? Either way, now you know any of them should get you through a long day.
Yes, the Eneloops are clearly the winner and probably the best bang for your buck. The RNB lithium pack might be an option (or the 3D printed adapter that lets you run your FBS machine off of three 18650s), but those are very specialized (or expensive) options. With 8 AA cells, you can use it in almost any device that uses a AA battery, whether it's a smoke detector, toys (adults or kids), Garrett AT Pro, etc.

And while the 1600 doesn't "dump" like the 1800, it's still not as good. It has lower overall voltages during the discharge curve and maxes out at around 1,100mah. So that's a solid 6-8 hours of run time, even with such a "crappy" pack. The 1600 should get you a solid day's worth of detecting, with little reserve power. The 1800 should handle a full day with plenty of reserve power for some post-dinner night hunting if you wanted.
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Old 01-26-2022, 10:28 PM
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Originally Posted by mh9162013 View post
Yes, the Eneloops are clearly the winner and probably the best bang for your buck. The RNB lithium pack might be an option (or the 3D printed adapter that lets you run your FBS machine off of three 18650s), but those are very specialized (or expensive) options. With 8 AA cells, you can use it in almost any device that uses a AA battery, whether it's a smoke detector, toys (adults or kids), Garrett AT Pro, etc.

And while the 1600 doesn't "dump" like the 1800, it's still not as good. It has lower overall voltages during the discharge curve and maxes out at around 1,100mah. So that's a solid 6-8 hours of run time, even with such a "crappy" pack. The 1600 should get you a solid day's worth of detecting, with little reserve power. The 1800 should handle a full day with plenty of reserve power for some post-dinner night hunting if you wanted.
"(or the 3D printed adapter that lets you run your FBS machine off of three 18650s)"

I bought one of those, came from Ukraine. It is in my dusty Etrac now, and has never been drained. I forgot the cost but it seems like it was a total with 18650 batteries and the 3D printer adapter, was under $50. This was 2 or 3 years ago. It is good to know how much capacity I have at the ready, even though I never used the Etrac enough to even take the top of the charge off. I also set up my V3i with one of them and that battery hasn't been run to charging needs. Those 18650 packs rock over the RNB with the prices, IMPO

Last edited by Martin_V3i; 01-26-2022 at 10:46 PM.
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Old 01-26-2022, 10:33 PM
mh9162013 mh9162013 is offline
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Originally Posted by Martin_V3i View post
"(or the 3D printed adapter that lets you run your FBS machine off of three 18650s)"

I bought one of those, came from Ukraine. It is in my dusty Etrac now, and has never been drained. I forgot the cost but it seems like it was a total with 18650 batteries and the 3D printer adapter, was under $50. It is good to know how much capacity I have at the ready, even though I never used the Etrac enough to even take the top of the charge off. I also set up my V3i with one of them and that battery hasn't been run to charging needs. Those 18650 packs rock over the RNB with the prices, IMPO
That's the impression I've gotten, too.

I have mixed opinions of RNB batteries, but that's another topic for another thread...

Just keep in mind that lithium ion cells HATE being stored with a full charge, and it'll degrade their overall capacity/performance. They're best stored around 50% capacity or so.

LSD NiMH cells like Eneloops are designed to be stored long-term with a full charge...like decades long term.
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Old 01-27-2022, 09:01 AM
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Good information. Thanks
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Old 01-27-2022, 10:44 AM
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Martin_V3i Martin_V3i is offline
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Originally Posted by mh9162013 View post
That's the impression I've gotten, too.

I have mixed opinions of RNB batteries, but that's another topic for another thread...

Just keep in mind that lithium ion cells HATE being stored with a full charge, and it'll degrade their overall capacity/performance. They're best stored around 50% capacity or so.

LSD NiMH cells like Eneloops are designed to be stored long-term with a full charge...like decades long term.
Thanks, I didn't know that about not keeping them stored full charge. Now I need to figure how to discharge them to 50%. The damage must already be done by now anyway.
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Old 01-27-2022, 11:42 AM
mh9162013 mh9162013 is offline
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Originally Posted by Martin_V3i View post
Thanks, I didn't know that about not keeping them stored full charge. Now I need to figure how to discharge them to 50%. The damage must already be done by now anyway.
Besides potential safety risks with lithiums, the inability to store them fully charged over the long term is the single biggest reason why I shy away from rechargeable lithiums and primarily use LSD NiMH cells (AA and AAA mostly, but I have a few 9Vs, too).

For example, I have a chainsaw for the occassional storm cleanup. I considered electric, but after a bad storm, we might not have power. So that means no way to plug in the saw or charge halfway depleted litihum battery packs.

Ok, so I could store the batteries fully charged. But I may only use the saw once ever few years. So when I finally need the fully charged lithium pack, it's probably been damaged from the storage.
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Old 01-28-2022, 09:28 AM
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Great info here! Thanks!

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