CZ-7 12AA's to 2, 9v Conversion

As I posted on Find's forum does anyone see a fault in converting my CZ-7 from 12 AA's to 2 9V's? Maybe less life? It seems to be working fine for the last 4 hours but I will need to leave it on all night to see it's new stamina.

Merry CHRISTmas

Yukonbuck

CZ-70, C$, CZ-7, 1270, 1212, GM3, GOLDBUG 2.

The CZ7A Pro is a newer version of the CZ7 and it (CZ7A) runs on two 9 volt batteries. I suspect that the only differences will be shorter run times between battery changes/charges and the CZ7A may feel a little more front heavy without having the 12 AA's on the opposite end to offset the coil weight.

=====

(edited)
After rereading your post I returned to this message to add that the CZ7 (not the CZ7A) had an issue with battery usage when turned off. This issue may result in your CZ7 draining your two 9 volt batteries even when the detector is shut off?



Edited 1 time(s). Last edit at 12/23/2011 05:16AM by NEBeachcomber.

message deleted



Edited 1 time(s). Last edit at 08/10/2012 03:30PM by Tri.

You can get PP3 9V batteries with 280/300 mAh capacity now. Makes the project more viable.

Well what is the difference in current draw between the 7 and 7A I cant see these two machines being that different in draw especially when the 7A had a speaker added and they both are essentially the same. I will be happy to get 20 hours out of this test heck even 15...the savings of buying two 9s vs 12 AA's has to either equal out or put me ahead. 8 hours and counting...will keep you posted. Thx for all the advice! Keep it coming!

There should be no problems in doing such; yet, keep in mind....... the original issue of 'battery drain' (even when the unit is turned off) still exists. If you remove the batteries after each use, you should have no problem.

CZ7 and CZ7A had the best weighting and ergonomics of any CZ ever made even though it was a rodmount only and decreasing the weight under the armcup will alter this ergomomics and should be taken into consideration.
With the price of nine volts and many sales on AA batteries and 80-90 hrs on the AA's versus perhaps 18-20 hrs on the two 9 volts one wonders if you are saving money on batteries.
Your call of course but personally take out one 6 battery holder while not using and get used to the slow pinpoint of the CZ7. Unfortunately the CZ7 did have a battery drain when turned off and had a slow pinpoint but was corrected by the CZ7A. Seems like consumers wanted hipmount capabilities and the CZ7 and 7A just didn't sell and went the way of the Dodo bird. Actually these models are heavier than 2 nine volt CZ's but well the ergonomics makes them feel lighter and don't fix what ain't broke comes to mind.

See my recent post to dbsky regarding the 9.6v batteries I use. They have the capacity of a alkaline in my opinion. Good luck and congrats on the engineering feat.

Well the reason I'm doing this is because my son dropped the battery holder for the AA's and I figured since I have 10 years of electronics experience in the USAF I figured why not... So here we are on hour 18.5 and still two out of three battery bars showing, still getting the depth, light etc... I can still put the old battery packs in should I run into one, so it's not a permanent mod but it's a solid one. I just went to radio shack, bought two 9v leads and two metal 9v clip style holders. Soldered the leads onto the power tabs, used a small screw for the clip/holder and Bobs your uncle. I'm happy so far...I will do more research on battery Mah in the 9V realm. I still like the balance too. My next project? Gonna wire a large coil with proper frequency to one of my many fishers and see what the after market world holds on 12" or larger coils.

CZ-70, C$, CZ-7, 1270, 1212, GM3, GOLDBUG 2.

Always remember my Red Big Bud pro(circa 1988) ate nine volt batteries and the company actually made a buddy box attachment to use two holders of 6 AA units and they lasted much longer and imagine that was the reason the old
Fisher came up with new battery configuration for superior battery life along with better weighting and ergonomics. Years ago when I owned a CZ7A needed a replacement battery pack and although Fisher did not have any they gave me the name of the distributor and was able to buy several ( same pack) without the pull out strap that was attached to stock packs.Don't think radio shack has them but might google for info on a replacement pack and honestly doubt if the new Fisher could help you but only takes a tel. call.
Whatever works is my motto and good luck with your venture....as should work fine....

Well I tried this today. I am using 4 9v batteries now instead of two. I reckon I will get much more life now. I already achieved my goal of 20 hours with two....I expect 30 to 40 now.

CZ-70, C$, CZ-7, 1270, 1212, GM3, GOLDBUG 2.

message deleted



Edited 1 time(s). Last edit at 08/10/2012 03:31PM by Tri.

Well for four 9v...Energizer was $9 and some change and Duracell was $11 and some change. This is very close to AA's so really the only thing I'm gaining is the deletion of a hard to find battery holder. I can live with the cost of disposable batteries knowing that I have a 40 hour machine that my wife and kids can enjoy while I work my C$ and CZ-70. Mission accomplished. Thanks for all the advice...You guys rock.

Merry Christmas,

Yukonbuck

CZ-70, C$, CZ-7, 1270, 1212, GM3, GOLDBUG 2.

Imagine CZ's have a voltage regulator but seems like with 4 nine volt batteries you are using double what you need.
Perhaps someone with electrical savy could jump in the discussion to give us knowlegable info.
Do remember the digital CZ7A pro and CZ70 which followed the CZ7 only needed two nine volt batteries and honestly don't know if this is adviseable or not rel damage to your unit or less battery efficiency...

I've had my CZ7A for over 10 years, and about 6 years ago I thought about making the same battery conversion. My backup detector (1225 ) takes 2 nine volts, and I thought it would be more practical to buy only one size battery for the detectors I was using. But in each case I was getting great battery life from each unit based on the actual hours I was using them, so I decided to leave things alone. One of these days I might make a temporary switch to see what the CZ would do. Good luck on your conversion.

Merry Christmas

Dan

When I wired up the 4 9 volts I ensured that each two (two on each side) were wired in a fashion where they still only put out 9v...just more amps for the CZ to pull from. Like I said I am an electronics tech for the USAF so I kind of know whats up...plus just to be safe I used my volt meter lol :-)

Yukonbuck

CZ-70, C$, CZ-7, 1270, 1212, GM3, GOLDBUG 2.

Well can't argue with that that and just a precaution and glad unit was modded in experienced hands...

If I can come up with the supplier of that battery pack will let you know as not a run of the mill pack to buy.

Just taking a wrapping presents break and you and yours have a happy and safe holiday season...

yukonbuck Wrote:
-------------------------------------------------------
> When I wired up the 4 9 volts I ensured that each
> two (two on each side) were wired in a fashion
> where they still only put out 9v...just more amps
> for the CZ to pull from. Like I said I am an
> electronics tech for the USAF so I kind of know
> whats up...plus just to be safe I used my volt
> meter lol :-)
>
> Yukonbuck
Hi all, any chance you can PM me the details of how you did this, im a mech engineer not elec but pretty clued up, lol i have just been given an cz7a with no batt pods and i wish to convert it to PP9 9v batteries,
cheers
Lee, uk

12 AA - 2450 mah will give you a 2450mha battery. Sorry that's how it works. That's because they are in series. Now the
4 - 9v batteries with 2 sets of 2 - 9v wired in parallel will double the mah of 2 - 9v batteries.

We know the CZ needs 12v to operate so I know it takes a minimum of 2 - 9v in series. I know guys are using the 9.6 rechargeable batteries but the initial charge is a lot higher than 19.2v. Iwish I knew the same maximum voltage.

Any voltage above 12v and less than the safe maximium voltage will work. What's important is the mah rating, how long they will run. Mah is the bigger that is better.

PP3 9V alkaline batteries have about 700mAh capacity, so Buck's 4-battery arrangement has 1400mAh capacity. It sounds like the current draw of the detector is in the region of 50mA, based on his run-time tests. So even if you used 4 x NiMH rechargeable batteries of decent capacity (250mAh plus) you should still get well over a day's detecting on a charge. (Edited: I was a bit generous with the alkaline capacity originally)



Edited 1 time(s). Last edit at 08/10/2012 06:19PM by Pimento.

Heres my thoughts on a rainy morning in Pa.

Too much or too little juice may or may not hurt the performance.

Untrained hands reading this post could damage his unit.

Weighting may be altered a tad as the 7 and 7A were the best ergonomic CZ's ever made.

Having owned and used both the 7 and 7A the batteries seemed to last forever.

Is the cost factor worth it if there is really much difference anyway.

Why fix what ain't broke.

Last but not least...your unit ..your call....

Robert,

I stand corrected...you are absolutely right......I got too tied up with the math...and forgot the basics of series and parallel dc circuits.

With the basic precept that all batteries being used in the circuit ARE the same then:


Series......voltage is multiplied (by number of batteries in circuit)....and mAh rating stays the same.

Parallel...mAh rating is multiplied (by number of batteries in circuit) and voltage stays the same.

Since all 12 batteries are indeed in series.....2450 mAh is the total mAh rating.......

Thanks for the correction........

Tri

The slightly less voltage of nimhs will NOT decrease performance. Modern detectors use a voltage regulator. For example...Let's say the regulator has an operating window of an input voltage of between 9 and 12 volts. Regardless of how high or low that voltage is in that window, the circuit board is only going to see a static input voltage of say 8V for an example. They have to have this in order keep in tune and operate with stability. Otherwise as the voltage dropped as the battery drained the machine would constantly be drifting out of tune.

Nimhs may have a lower starting voltage than store bought non-rechargeables, but the reality is that a good 2500ma or higher capacity nimh will maintain and hold it's voltage "flat lined" for a much longer period of time during the drain cycle. What that means is that even if the store bought non-rechargeable starts out at say 12V, it's voltage drops faster while draining and will soon be at or below that of the nimh during dicharge. Modern 2500ma or higher nimhs will often give 1 to 3 times longer run times than store bought non-rechargeables these days.

Personaly I am running a 3 cell series lipo in my GT to replace the 8AA alkalines. This provides a starting voltage of 12.6V volts and the voltage is held high until near depletion of the battery. What this means is that even with a somewhat lower capacity pack often you'll get longer run times than a higher capacity non-lipo due to the voltage being held higher for a longer period of time and thus not tripping the low battery alarm as quick. Lipos have many advantages, like being much smaller/light/and with more capacitity than other batteries, 1 hour charge times without pushing the pack and shortening it's life, and not self-discharging on the shelf (although there are now low self-discharge nimhs on the market these days that maintain their charge for months while sitting). Many people complain about nimhs not giving them as long of run times. That's usually because they either A) Bought low capacity cells, or Charged the pack weeks or months ago and it has self drained on the shelf.

I'm using a 3 cell Rhino 750ma series lipo in my GT from a place called Hobby City/King. They are big in the RC world and you can buy lipos of this type for around $7. A 1450ma pack would have still saved me weight and only costs around $14, but I was shooting for max weight savings here in a light weight custom machine and shaft. You can also get lipo chargers from them for around $5 to charge it, although I bought their Accucel 6, which is a $20 computer screen charger that will do things not seen on chargers costing over $100 from other sources. It will charge nimhs, nicads, lipos, lithium ion, and several other battery types. Be warned though, a charger like this takes knowledge to safely set and use. You'll need to read up on it. Otherwise just shoot for one of the simple plug-n-charge lipo chargers.

Lipos got a bad rap early on because they didn't feature balance ports and would overcharge a cell while charging and thus could cause a fire. These days with balance ports on the chargers they monitor each cell and so in some ways are even safer when charging than nimhs or nicads or other batteries due to know way to monitor each cell on those. Just be sure if you decide to go lipo conversion on a machine that you read up on the proper care and feeding of lipos. They IMO are no more dangerous to handle than any other battery type these days, but that's only if you know how to care for them. Just like any other battery, because ANY battery can pose fire or explosion risks if treated wrongly.

If you've got 4 9V batteries with two pairs wired in parallel and then wired in series to the other, then the capacity is double that of one cell (the sum of two in parallel) and the voltage is double that of the two pairs wired in series= 18V. Two cells wired in series only increase the voltage and not the capacity, but two cells wired in parallel increase the capacity and not the voltage.

Should you consider lipos, a 4 cell series pack will output 16.8 volts. That's only 1.2V lower than the target voltage of a fresh pack meant for your machine. Lipos hold their voltage very high until the end of discharge, so very soon during the discharge you'll probably find that 12AAs or 2 9Vs used (no matter if they are non-rechargeables or nimhs) will have a lower voltage than the lipo as they drain. The other advantage is that the lipo would be much lighter (even than 2 9Vs) and still have a higher capacity depending on which size pack you decide to buy. They re-charge in an hour without pushing them, and an easy plug-n-charge lipo charger can be had for about $5 at Hobby City/King. The lipo would probably cost you around $10 to $20, depending on how big of a capacity you decide to buy.

The alternative option might be a 5 cell series lipo, which will output a voltage of 21V. That's 3V higher than your target starting voltage the machine is designed for. This might be risky, because I don't know what the operating input voltage window range of the regulator in that machine is. Often a regulator designed for say a 12V source voltage will operate in a design window of say 9 to 13 or perhaps 14.5V or so. The regulator in your machine *might* have a upper operating range of 21Vs or so, but without opening the machine, writing down the regulator's part #, and looking up it's specs on the web, you'd be taking a huge risk by trying to run a 5 cell series lipo in it.

I suspect all metal detectors use a linear regulator, because not only is it cheaper than a switching voltage regulator, but it is also much less noisy, which is essential to the stable operation of a metal detector's electronics. Switching regulators put out a varied pulse to control the output voltage and keep it at static level to the circuit board, and is why they tend to be noisy and also require extra components on the circuit board in an attempt to cancel out that noise.

Where as linear regulators waste off excess input voltage as heat to maintain the proper output static voltage to the electronics they are feeding. Linear regulators have a heat sink to which they expell the excess voltage in the form of heat. Should the input voltage get be too high, there reaches a point where the regulator can not get rid of the heat anymore and the regulator will *usually* shut down on a thermal overload switch.

Should that happen the machine will just appear to shut it's self off. If you are lucky, once the regulator cools back down the thermal overload will reset and the machine will work again, but thermal overloads have a limited life, so there is no gurantee it will ever cool down and re-make the internal connection.

As a side note, switching regulators are much more efficient than linear ones since instead of burning off excess voltage as heat, switching regulators never waste away the excess input voltage but instead control the output voltage to the circuit board by varying the rate of pulsing power to it. That's how a dimmer switch for a light works. As you turn the dial it uses something that I think is called pulse width modulation, in which it increases those pulses as you turn the brightness of the light up, and decreases those pulses as you turn the dial down.

Either way, if you do decide to look into converting over to a lipo to run a detector, a 3 cell series lipo should be perfect for all 8AA series running machines that I'm aware of. It only has a .6V (point six volt) higher starting voltage than 8AA non-rechargeables, which *should* be well within the tolerance range of most regulators, but as with all things in life use at your own risk of burning up your machine.

Lipos also require some knowledge as to how to care and feed them. They should only be charged on chargers featuring a balance port that plugs into the balance plug on the lipo (all lipo chargers I'm aware of these days do feature this), and a lipo should never be drained lower than 3V per cell (or 9V total in a 3 cell series pack) or it may ruin the battery. For that reason, you need to be aware of the cut off point on a detector as to when it's low battery alarm begins to sound. If it doesn't sound above 9V, then you'd have to time your usage to prevent over draining, or monitor the voltage display on your detector, or plug a little 9V alarm buzzer into your lipo while in use to tell you when it's approaching 9V. Hobby King/City sells these little buggers for a couple of dollars. Only string attached is that should you forget to unplug that little thing and throw your detector into storage, over a long period of time (probably weeks if not months) the little alarm will eventually drain the lipo past 9V and there might not be anybody around to hear it.

One other perk to lipos- They don't really self discharge on the shelf. Charge a pack and a year later it's still ready to rumble.

And a final little tip- Should you decide for some odd reason you want to change the plug on a lipo, do not cut both wires at once as that can cause a split second short and might cause it to go nuclear. If you do decide to change a plug on one, only remove one wire at a time, solder it to the new plug and heat shrink it to isolate, and only then remove the next wire to hook up to the new plug. Far better idea to just buy the little JST male plug that will fit the lipo (most smaller lipos have a female JST on them) and solder that to your battery holder in your machine. I have one in my GT's 9V akaline battery holder and it's so small I can move it out of the way and still install 8AAs should I ever want to do that for some crazy reason again.

By the way, the little 750ma 3 cell series lipo I use is about the size of two 9V batteries sitting side by side roughly, but much lighter due to the chemsitry make up of lipos and also due to the fact that they don't require a hard outer metal shell like nimhs or non-rechargeables and other battery types do.

FINAL WARNING: Don't follow my advice or it could lead to destruction of your machine, a fire, personal injury, or burning your house down or something. Always confirm and verify from other sources, and never mess with any battery type, lipo or not, unless you educate yourself and know what you are doing!



Edited 1 time(s). Last edit at 08/14/2012 03:21PM by critterhunter.

Surprisingly, not all PP3 9V NiMH batteries are heavy these days. I have a few (Varta and RS Components brand) that you would swear they were cheap 'lookalikes', (something like those D-cells that are actually a Sub-C/RR cell in a big D-cell plastic box.) they have a plastic outer case, and weigh only 30 grams each. But they are more than full-spec on capacity.

I believe there are also lithium based rechargeable 9Vs on the market that retain the proper voltage for devices that use 9V. Only caught wind of that while skimming for other things so not sure if I have the details right. I'd look into it, because if true that might be your perfect solution.

When running ML Sovereigns , I took Critters advise and went the Lipo route and never looked back ........They are light weight , powerfull , quick to charge , and inexpensive if bought thru Hobby King as he mentions ....A little adapting is involved but nothing major .....Make sure you read up on all the warnings of using Lipos as Critter also mentions ...... Used with care , they are the cat's pajama's !!.......Critter also knows how to properly set up the inexpensive charger needed for these batteries which will charge very quickly and carrying spares is much eaisier than AA's or a bunch of 9V's .... ..... Jim