Nexus & Batteries

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R2T2
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Nexus & Batteries

Post by R2T2 » Fri Oct 05, 2018 6:45 pm

You may have heard or read that Nexus Machines 'eat' Batteries .
I thought I would give my experiences as I have a Mk2 and a MP V2.
The Mk2 does use more Battery power than the MP, and for this Machine I use 2700 mAh Nimh rechargeables. These will last for a seven and a half hour day's detecting. I have never bought a spare set as I have never needed one.
For the MP, I use 2400mAh Nimh rechargeables, and again these are fine for a seven and a half hour day's detecting.
Neither Detector has ever used up it's Batteries in the Field in this time.
Why seven and a half hours ? , well by that time I'm about to expire, even if the Batteries aren't !!.

Perhaps I should add that I use a Radio Link (Quest), to my Headphones.
Possibly this uses a bit less power than if driving Headphones direct.... ?

HH Tim.



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Re: Nexus & Batteries

Post by toni » Sat Oct 06, 2018 3:06 pm

Hello Tim,
What AA 1.2v do you use? (GP, Energizer ……….?)
And what earphones?


R2T2 wrote:
Fri Oct 05, 2018 6:45 pm
You may have heard or read that Nexus Machines 'eat' Batteries .
I thought I would give my experiences as I have a Mk2 and a MP V2.
The Mk2 does use more Battery power than the MP, and for this Machine I use 2700 mAh Nimh rechargeables. These will last for a seven and a half hour day's detecting. I have never bought a spare set as I have never needed one.
For the MP, I use 2400mAh Nimh rechargeables, and again these are fine for a seven and a half hour day's detecting.
Neither Detector has ever used up it's Batteries in the Field in this time.
Why seven and a half hours ? , well by that time I'm about to expire, even if the Batteries aren't !!.

Perhaps I should add that I use a Radio Link (Quest), to my Headphones.
Possibly this uses a bit less power than if driving Headphones direct.... ?

HH Tim.

R2T2
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Re: Nexus & Batteries

Post by R2T2 » Sat Oct 06, 2018 7:11 pm

Hello Toni.
The 2700mAh Batteries I use are Lloytrons, and the 2400mAh ones are Duracells.
I tend to use small XP Blue Backphones most of the time, which although very cheap, have a very good quality sound, while being extremely light.
I also use the 'Quest' Wireless link Transmitter / Receiver with all my Detectors.
HH, Tim.

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Re: Nexus & Batteries

Post by AuGold » Mon Feb 04, 2019 6:17 am

Is there a reason why Lithium-ion batteries are not used in the Nexus since you need less of them to attain the voltage, therefore less weight and a quicker recharge time, compared to NiMH?

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Re: Nexus & Batteries

Post by Nexus » Wed Feb 06, 2019 9:59 am

AuGold wrote:
Mon Feb 04, 2019 6:17 am
Is there a reason why Lithium-ion batteries are not used in the Nexus since you need less of them to attain the voltage, therefore less weight and a quicker recharge time, compared to NiMH?
The only reason is because they don't fit in the battery holders available for AA batteries. No other reason.

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Re: Nexus & Batteries

Post by AuGold » Wed Feb 06, 2019 11:29 am

Thanks however surely it would be worthwhile to update the battery holder to hold Li-ion due to the benefits of Li-ion over AAs and NiMHs. For example the detector I use was released using 6 AAs then updated to operate using 6 NiMHs and finally to operate using only 2 Li-ions. Anyway food for thought for the Nexus in my opinion.

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Re: Nexus & Batteries

Post by Fusion » Wed Feb 06, 2019 1:26 pm

AuGold:
While you correctly observe that Li cells have a much higher voltage per cell than NiMH (3.6V to 4.2V depending on type, vs. 1.25V ) you have not realised that the capacity of the Li cell is significantly lower. For example the AA size cell: the highest capacity NiMH's are about 2700 mAh, whereas Li cells seem to be available up to 850mAh ... it's not a popular size for Li cells, I suspect the manufacturers could do a lot better if they tried -( 18650 Li cells are much better for their volume).
Here's a selection of Li AA cells: Ignore the xxxxxFire ones, their 900mAh claims are 'untrustworthy', the rest have a capacity of 800mAh or below. I've read the Sanyo/Panasonic 800mAh is typically 840mAh, that's about as good as they get, at present:
https://www.batteryjunction.com/14500-category.html

So to replace 6 NiMh AA cells with Li , you would need 4 cells ( two paralled-up cells, connected in series), and you would still have lower run-times. It would probably make more sense to use completely different sized cells, such as flat foil-pouch LiPo.

Then there's the expense: a Li cell is more expensive than a NiMH, the pack needs protection circuitry ( over-charge/over-discharge/over-current/overheat/fuse etc etc ), and a seperate charging connector. And then a dedicated Li charger is needed.
Last edited by Fusion on Thu Feb 07, 2019 1:16 pm, edited 1 time in total.
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Re: Nexus & Batteries

Post by Nexus » Wed Feb 06, 2019 4:14 pm

Fusion wrote:
Wed Feb 06, 2019 1:26 pm
AuGold:
While you correctly observe that Li cells have a much higher voltage per cell than NiMH (3.6V to 4.2V depending on type, vs. 1.25V ) you have not realised that the capacity of the Li cell is significantly lower. For example the AA size cell: the highest capacity NiMH's are about 2700 mAh, whereas Li cells seem to be available up to 850mAh ... it's not a popular size for Li cells, I suspect the manufacturers could do a lot better if they tried -( 18650 Li cells are much better for their volume).

So to replace 6 NiMh AA cells with Li , you would need 4 cells ( two paralled-up cells, connected in series), and you would still have lower run-times. It would probably make more sense to use completely different sized cells, such as flat foil-pouch LiPo.

Then there's the expense: a Li cell is more expensive than a NiMH, the pack needs protection circuitry ( over-charge/over-discharge/over-current/overheat/fuse etc etc ), and a seperate charging connector. And then a dedicated Li charger is needed.
I am not going to pounder much on the possibility of thermal run off for Lithium-ion batteries, but it is also one of my concerns.
There is no benefit of using these batteries other than may be a bit longer running time. These batteries will not make Nexus deeper or a better performer in any way.

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Re: Nexus & Batteries

Post by AuGold » Thu Feb 07, 2019 1:22 am

Thanks Nexus for your reply and from what you say then you know what is best for your detectors.

Just in regards to replace 6 NiMh AA cells which was used previously in the detector I have then they were replaced with 2 18650 2000mAh Li cells.

There are much higher mAh 18650 Li cells for extra run time but of course at extra expense.

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Re: Nexus & Batteries

Post by Fusion » Thu Feb 07, 2019 10:29 am

The shape of the original battery pack plays a big part in what choices are available for replacements.
If you had the 'brick' shaped 6-cell pack, ie. the 2x3 array, one cell long, then you definitely have more possibilities than if it were a long 'stick' three cells long, 2 cell-diameters wide, something like some MineLab machines use.
Another thing worth considering is detector balance. Some machines place the heavy battery pack under the elbow cup, where it's weight helps counter-balance the coil. Replacing this with a lighter pack may actually leave the machine feeling just as heavy.

The success of this 'two cell' replacement depends on how well the detector works on lower voltages, and what Lithium chemistry batteries are available. Many of them are 4.2 Volts when fully-charged, and about 3.5V when run down, so they will produce a voltage comparable to the original pack. But Li cells with a charged voltage of 3.6V or 3.7V are quite common, for example the MineLab Equinox uses a single 26650 cell of this type. And a two-cell pack is more likely to give inadequate voltage to many machines, with short run-times.
Last edited by Fusion on Thu Feb 07, 2019 1:09 pm, edited 1 time in total.
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Bors
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Re: Nexus & Batteries

Post by Bors » Thu Feb 07, 2019 10:49 am

Quote nexus,....
" There is no benefit of using these batteries other than may be a bit longer running time. These batteries will not make Nexus deeper or a better performer in any way."

From the way I interpreted R2T2 `s initial post , that is why he fitted the NiMh rechargeables AND, he can just keep re-charging them rather than keep buying new batteries.
It was more of a cost related change rather than a performance one in as far as making the detector go deeper related change .
Maybe I`m wrong but thats what I thought he was stating.

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Re: Nexus & Batteries

Post by AuGold » Thu Feb 07, 2019 12:12 pm

Fusion wrote:
Thu Feb 07, 2019 10:29 am
Another thing worth considering is detector balance. Some machines place the heavy battery pack under the elbow cup, where it's weight help counter-balance the coil. Replacing this with a lighter pack may actually leave the machine feeling just as heavy.
Yes you are right in regards to extra weight to counter balance the coil as the designer of my detector did in a further update add and extra 6 NiMH batteries in parallel inside the battery compartment under the armrest not only for extra Amp hour capacity but it also acted as a counter balance when larger coils were attached. However the 2 Li-ion batteries instead of the 12 NiMH batteries has produced a much lighter detector to detect with which I assume was the aim of the designer.

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Re: Nexus & Batteries

Post by R2T2 » Thu Feb 07, 2019 12:39 pm

Bors you are right. My post was only concerned with the cost of standard AA Batteries.
Regards, Tim.

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