For Longest Battery Life, Charge Slow And Build A Detector Jacket, If Cold Do This

[John-Edmonton]

I have always been told, the overall life of a Ni-MH will be extended with a charging a low mAh/rating. I would go with 200 mAh, unless you need to recharge quickly for emergency use. I am on my second year using Enloops, they work fine, except when the temperature drops quickly down to around zero degrees, in which case they discharge very quickly, in about an hour, typically of all Ni-MH type batteries. The only make that will in fact stand up to extremely cold temperatures are the Energizer Ultra Lithium.I have tried rechargeable alkalines, alkalines, Ni-cads and Ni-MH with all discharging quickly in cold temperatures. My normal cut off for cold hunting is with an ambient temperature of -15C/5F but I have been known to go out at -25 with the wind chill factor.

That's why I have built covers for all my detectors. It extends battery life considerably in cold temperatures when you also add one of those hot pacs. I have not tried it water, although I have no doubt that if you put one or two hot pacs in a water proof bag and compressed the bag against the wall separating the batteries from the outside, you would also get more time out of a set of batteries.

Metal detectors with knobs don't always work very well. The values of shrinkage in the different components sometimes causes the knobs to seize up and un-usable. I couldn't use my First Texas or Minelab detector under extreme cold. Push button controls are much superior under these conditions.

All these machines below had hot pacs in them. Hotpacs stay usable for about 7 hours on average.

 

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[Hookedondetecting]

Tenergy also make rechargeable Ni-MH batteries too. They have two classes, standard and low discharge.
If you are using AA then Lithium's would last the longest, then Ni-MH but keep two sets, one in you pocket - in the long run that will be less expensive.
AA Ni-MH only have 2500 mAh compared to D size at 10,000 mAh. so AA never do much for me.
Alkaline power depends on a chemical reaction to provide power and the chemical reaction slows down with drop in the temperature.
Invent a plug in power pack for D mAh batteries and you will have something that lasts 4 x as long

 

[WaterWalker]

I agree that the slow charge is best for the NiMH cells. However, some chargers many not sense the "full charge" state when charging below the one tenth of the cells capacity that is needed to change the charging current to a trickle charge so as not to over charge a cell. .1C or C/10 is one tenth the CAPACITY (mAH rating) of a cell, therefore, any cell with a CAPACITY of over 2000mAH should be charged with a current over 200mA. A 2500mAH cell should be charged with at least 250mA. This has more to do with the charger than the cells you use. .1C-.5C is the safe charging rate for NiMH cells, check your charger for what it will charge at.

I have never noticed a reduced run time in the winter, HOWEVER, I do not experience the temps that John does. If it is below 30F (air) and 35F (water) temps I hibernate and wait for warmer temps. I do a fair amount of detecting in temps well below 40 and speak on that experience.

One problem I see about puting AIR-AVCTIVATED hot pack in to a waterproof bag...NO AIR, NO HEAT. I have tried the air-activated packs on the back side of my hands at the end of my 31" waterproof gloves. The pack produce heat for about 20-30 minutes then go cold. When I take the gloves off and the packs out the pack begin to get warm again. If you use the supersaturated solution heat packs they probably will work OK, they do not rely on air also some are reusable unlike the air-activated ones.

The blizzard of yesterday is over, there is bright sun shine and little wind, but no parking lots at the beach are cleared, let alone the streets. The temps are headed above freezing...maybe I will be in the ocean within the next two days.

John: don't loose your camo detector in the woods, how about a winter white camo? Next we will be seeing bunny ears! They would be a nice touch next to the tight leathers we have seen... A NEOPERNE suit for underwater use!

 

[John-Edmonton]

I agree that the slow charge is best for the NiMH cells. However, some chargers many not sense the "full charge" state when charging below the one tenth of the cells capacity that is needed to change the charging current to a trickle charge so as not to over charge a cell. .1C or C/10 is one tenth the CAPACITY (mAH rating) of a cell, therefore, any cell with a CAPACITY of over 2000mAH should be charged with a current over 200mA. A 2500mAH cell should be charged with at least 250mA. This has more to do with the charger than the cells you use. .1C-.5C is the safe charging rate for NiMH cells, check your charger for what it will charge at.



I have never noticed a reduced run time in the winter, HOWEVER, I do not experience the temps that John does. If it is below 30F (air) and 35F (water) temps I hibernate and wait for warmer temps. I do a fair amount of detecting in temps well below 40 and speak on that experience.

One problem I see about puting AIR-AVCTIVATED hot pack in to a waterproof bag...NO AIR, NO HEAT. I have tried the air-activated packs on the back side of my hands at the end of my 31" waterproof gloves. The pack produce heat for about 20-30 minutes then go cold. When I take the gloves off and the packs out the pack begin to get warm again. If you use the supersaturated solution heat packs they probably will work OK, they do not rely on air also some are reusable unlike the air-activated ones.

The blizzard of yesterday is over, there is bright sun shine and little wind, but no parking lots at the beach are cleared, let alone the streets. The temps are headed above freezing...maybe I will be in the ocean within the next two days.

John: don't loose your camo detector in the woods, how about a winter white camo? Next we will be seeing bunny ears! They would be a nice touch next to the tight leathers we have seen... A NEOPERNE suit for underwater use!

You know....you are so full of interesting ideas, You got me thinking....