Homemade Battery For Impulse AQ Ltd

[PimentoUK]

One of the reasons 18650 size is favoured is because that size has had a lot of development put into it, firstly in laptop computers, then electric vehicles. Other sizes, both larger and smaller, seem to have lower capacity than what you would expect, based on 18650 specifications.
The internals of these cells are basically rolled up sheets of aluminium & plastic, so any technical improvements should immediately be applicable to smaller/larger cells. It just doesn't seem to have happened.
I have just tried a 'math comparison' with 26650 size , and I would expect a capacity of over 7000 mAh should be attainable. But so far, 5500mAh is the best claim I recall seeing for one. [this is the 'ShockLi' brand, which sound awful and dodgy, but seemingly are not, and are also sold under other names, particularly when re-packaged as 'protected' types. At low-drain 0.2C rate ( ie. about 5 hours discharge time ), they test at near 5800 mAh]

In practice, energy per unit volume is not always the important characteristic, energy per gram weight may be more relevant. If the cells are lighter as a result of being under-capacity, they will meet this requirement.
Does a detector battery need to be small? Or is there an optimum weight range, for example?

[Steve Herschbach]

41 minutes ago, PimentoUK said:

Does a detector battery need to be small? Or is there an optimum weight range, for example?

As far as I am concerned the optimum weight in an under elbow configuration is that which properly balances the detector. I get that the 18650 is “more proven” but the 26650 certainly does not seem “unproven” either.

Well, I’m no battery expert, but I like the form factor, nice for fumble fingered types.

 

[PimentoUK]

It would certainly be worth experimenting with added weights, to see how much the battery pack could weigh. Then use that data to influence the design of a homebrew battery pack.
Going by its appearance, and my familiarity with the F75, I expect it could be quite a substantial battery. 12 x 18650, 8 x 26650 may be practical. Or 11/12 x A-size NiMH.

[Skull diver]

I'd love to try this 26650 beasts to modify with only 4 of them my battery pack for the Tdi.

Assuming a 535mAh / hour consumption this will last sooo long in it!

At least 8 hours at full gain.

[Elbert]

Good to hear that you now have a AQ and the Tarsacci. It will be interesting to see how they compare in the extremely black sand conditions in Tahoe. Maybe on your next trip.

El.

[Steve Herschbach]

2 hours ago, Elbert said:

Good to hear that you now have a AQ and the Tarsacci. It will be interesting to see how they compare in the extremely black sand conditions in Tahoe. Maybe on your next trip.

El.

It’s not a pressing concern for me. I got the Tarsacci to try as a nugget detecting machine, and hopefully will be doing that in the next couple weeks. I plan to get up to Tahoe again tomorrow to hunt with the AQ but my plan is to go detecting, not testing. I did enough of that to satisfy myself on the last trip. When I next get to a nugget location I will be using both the Impulse and Tarsacci looking for gold nuggets, and will be comparing the Tarsacci to my other VLFs, so I may gain some insight at that time.

[dewcon4414]

3.17 ozs each.   I’ve used mine hard for nearly 17 mos.  stared out at 4.1 charged... both are still charging at 4.1.  They have larger mah capacity but Dimatar said these were a better longer lasting ones

[Carolina]

27 minutes ago, dewcon4414 said:

3.17 ozs each.   I’ve used mine hard for nearly 17 mos.  stared out at 4.1 charged... both are still charging at 4.1.  They have larger mah capacity but Dimatar said these were a better longer lasting ones

Gave Joe all the info last week. He ordered four to build a set. Mine charged 4.2 and now 4.0 after 16 months of hard use. Really nice battery.

[Joe Beechnut OBN]

5 hours ago, Carolina said:

Gave Joe all the info last week. He ordered four to build a set. Mine charged 4.2 and now 4.0 after 16 months of hard use. Really nice battery.

Thanks Carolina...I think these maybe the ticket..going for a cheap battery pack..maybe 50 dollars total? Don't want to use 1 inch PVC pipe but may.... I want to have it so anyone can make one without having to much trouble finding parts..