Are NiMH 2200 mAh rated batteries too powerful to use?

[kschae4]

I'm looking to switch over from alkaline to NiMH. I saw Thunderbolt NiMH 2200 mAh re-chargeable AA batteries for sale at Harbor Freight. The manual seems to note that just 1600 &1800 mAh are suggested. Andy's "Mastering The Quattro " suggests minimum 1600 mAh rating. Are 2200 mAh too powerful to use?

 

[Mtnmn]

All my rechargeable AA batteries for the Safari are rated between 2,000 and 2,500 mAH's and work just fine in it. Although I'm not very happy with their battery life as generally it is only possible to get one day's hunt out of them before they'll need recharged. Even in Andy's book on pg. 94, he say's he just recently purchased an 8 pack of 2500 mAH AA batteries to use in place of Minelab's rechargeable battery pack. Would highly recommend that you buy as highly rated mAH rated batteries as you can find just so as to have them last as long as possible before needing recharged. Just be sure to not use Lithium Ion rechargeables as Minelab says their voltage is too high and will damage their detectors. One last note, don't use a charger on your batteries which recharges them in under an hour's time as it will shorten your battery life if you do. What I do sometimes is unplug the charger for a few minutes once the batteries are charged and then plug the charger back in with the batteries still in it to give them a little fuller charge.

 

[DaugBiscuit]

I can't help you concerning 2200 mAh but I do use the 1800 mAh. The only downside with the 1800 is what Mtnmn said, it is good for a days hunt and then will require an overnight recharge, but still, I think it is better than using AA batteries only.

 

[Johnny Quattro]

Hello kschae,

The 2200 mah rating only pertains to the storage capacity of the battery. It won't deliver any more power , it will just last longer. It won't hurt your detector. each cell is still only 1.2 volt for a rechargeable AA cell and 1.5 volts for an alkaline cell. the important thing with NIMH batteries is not to overcharge them or charge them too fast, It's good to have a charger that will charge all 8 cells together and shut itself off once charging is complete. What I do is get an 8 cell battery holder from a "hobby-shop" which usually has like a 9-volt style terminal on the end ( 2-buttons) like a 9-volt battery has, and get an adapter at a hobby-shop to fit which ever charger you use. then install all 8 NIMH rchargable cells in the holder and charge them all together. It's really worth investing in a quality battery charger, again "hobby-shop", one that has adjustable charging rates so you can charge your NIMH cells slowly, this will greatly increase the lifetime of your cells. So, they make the 8-cell holder I use for most radio-control transmitters, they're only $4-$5 . Otherwise, most chargers they make for AA size re-chargeables , only charge 4 cells at a time, so you really need two of those to charge all 8 cells. Anyway, hope this info helps, Johnny Quattro

 

[Birdseed]

kschae4

What Johnny Quattro says is spot on in regards to (milli-amp-hour) ratings, They only refer to the storage capacity. I have seen this topic discussed on other forums, so it may be timely for a re-cap.

Nicad and NiMH re-chargeable batteries only have a cell voltage of 1.2 Volts, AA alkaline batteries have a cell voltage of 1.5 Volts. So when you have eight rechargeable batteries in your alkaline battery pack the total voltage available to run your detector is only 9.6 Volts. Your detector is designed to run from 12 Volts, but will operate down to about 9.5 Volts in a pinch. Using rechargeable batteries means that at best you start with 9.6 Volts and as soon as the terminal voltage drops a little you get symptoms of a flat battery. To run your detector efficiently from rechargeable batteries you need to have a 10 cell pack (10 x 1.2 Volts =12 Volts), Minelab do supply rechargeable batteries for the Safari, I am not sure about the Quattro. I get about 20 hours with the rechargeable battery pack on my Safari. (not cheap though). If you could devise a method to add extra cells in series with your alkaline pack you will get the same benefit. If you are not sure how to do this, get help from someone with the relevant experience as you could destroy your batteries or worse, you may damage your detector.

Hope this helps

Peter downunder.

 

[kschae4]

Hey Folks- Appreciate all the great feedback. I did pick up 2 four packs of the 2200 mAh re-chargeables.

 

[edjcox]

Interested to know the source of the Minelab comment on Lithium Ion batteries?

As a electronics engineer it's a bit surprising as most of these systems include voltage regulation and as such they can deal with over and under voltage in the batteries well. Would be most intereted to read their comments. Thanks...

The average AA cell will range from 1.8volts to 1.2volts brand new and a fast curve down as time and current are pulled from the cell. Thus a fresh pack of ne alkalines will overvoltage for a bit during first use. If their gear is that sensitive they would be losing detectrs all the time... Just very curious...

 

[Mtnmn]

Ed: The source of Minelab's comment on Lithium batteries comes directly from the Safari manual, pg. 11 that states rechargeable lithium "ion" batteries have a combined voltage of above 13 volts which may damage your detector. As a retired high tech journeyman industrial electrician, you and others are right on all counts. The Safari does come with a built-in voltage regulator and I know of at least one Safari owner who does use lithium rechargeable batteries in his Safari with no ill effects, but I'm not about to risk it. Regular rechargeable AA batteries may be rated 1.2 volts, but they recharge to well above that and the 3 brands I checked all read about 1.36 volts after having been recharged and setting on my shelf for about a week. If I remember correctly they will charge up to about 1.6 volts or slightly higher when first out of the charger. Hope this helps clear things up a little.

 

[kschae4]

I had also posed the same question to Minelab and here is the direct reply from Kevin Hoagland/Director of Partner Development.
Ken,
mah is an expression of battery capacity. It is the product of current in
milliamps and time in hours, or mah = ma X hr...

It is not recommended that you exceed the manufacture rating for mah as damage
could result. Minelab developed the battery systems to offer you the best power
and longevity possible.

I hope this helped.

Regards,
Kevin D. Hoagland
Director of Partner Development

He didn't specify what damage could result when I sent him a return email query, this past Monday. Hope that he does.

 

[Mtnmn]

I am curious as to why if Minelab's battery packs are only rated 16-1800 mAH, they supposedly will last up to 12-14 hrs. and yet the average 22-2500 mAH rechargeables you buy in the store will only get about half that many hrs. I have no doubt what-so-ever that Minelab's batteries are built of much better materials than our store bought rechargeables, but when you figure in the cost: do you want pay up for two day's use or a fraction of that for one day's use out of your rechargeables.