What type of external battery power could be used with the Promark2? What connectors would be needed? And approximately what cost per unit for something in the range a 20-30 hour battery source?

Just curious.

J.D. Billings

go to a photo store, or online at www.thomas-distributing.com and get some 1600 mah or 1700 mah NiMH AA batteries, I would bet you a large pizza that they'll power that receiver for 25 to 30 hours on one charge. And a set of four (two to charge and two to go) plus a charger will probably run you about $30.

I am referring to the post about Thomas Distributing. You made me look. Then I had to buy.

Thanks for the post. I need to count how many links I have saved to various places referred to from reading post from this sight.

The ProMark2 runs on 2 AA batteries. As you have correctly point out, there are some strong battery compositions out there such as alkaline, NiMH and Li-ion. The strongest batteries will be non-rechargeable. The rechargable NiCad batteries don't last as long as regular alkalines. The ProMark2 also comes with an external "battery pack" that holds 4 more AA's and I think we are spec'ing 30+ hours with alkalines.

until next time,

Rod Johnson,
Ashtech Marketing

Lew,

Thanks for the link. The combo package for the charger, vehicle adapter, and four NiMH 1600 batteries looks good. If the advertisement statements are true concerning the comparison to alkaline batteries and the 1000 cycle recharge life, looks promising. But, being electrically challenged myself, on what do you base your idea of 20+ hours of operating time for a pair of these 1600 NiMH batteries.


Rod,

Thanks for the additional info concerning the external battery pack. I guess I wasn't aware this was included. What is your opinion of the NiMH rechargeable batteries for this application. My reason for asking is that very often we leave a receiver up for continuous 8-10 hours while roving with 1 or 2 others. Being on the very conservative side, and somewhat a pessimist (not unlike the way Locus Processor views data - a good thing) I would consider potential battery life should be at least twice the length of time considered for the application at hand. I've lost too many days work due to ram card battery failures in old hp48sx data collectors, which has made me very "power contious" over the years. I know that the stored gps data in the receiver will not be lost, up to the time the batteries fail. It's the thought of roving a few points late in the day away from that receiver and not being sure the base is still up and running that I want to avoid. Since my September 2000 purchase of 3 Locus units, I have changed batteries 3 times in these units. That's only 36 batteries. I would say that's very inexpensive, and not really that many batteries to dispose of. With the disposable AA batteries, assuming let's say 200 hours of operation of three units, that's 150 batteries to throw away. Still a small expense for "what you get", but quite a bit of disposal.

Just trying to stretch out the power.

Thanks,

J.D.

that's a wild @ss guess.

My camera gets about 30 shots on alkalines, and about 200 shots on the 1600 mah AA's, so I went 4x - 5x the stated time to be conservative.

Again, for the price is costs, it's worth a shot.

J.D.,

Most standard AA alkaline batteries (Duracell, Energizer) are 2700 mah. Two AA alkalines will run the ProMark2 for about 8 hours at room temperature. Based on this, I would guess that the ProMark2 would run for approximately 5 hours per charge on 2 1600 mah NiMH batteries. With the external power pack, this would give you about 15 hours of operation per charge.

Bill

Bill,


Thanks for clearing that up. I thought the alkaline batteries normally had a higher mah rating, but as I said being "electrically challenged", wasn't sure. You did give something to consider though. If a "six pack" of NiMH batteries (rechargeables) could be expected to supply 15 hours operation, then with a trickle charger (reconditioner) capable of handling 6 AA batteries at once, one could safely expect to operate a PM2 for 10 or so hours without fear of power failure on an unattended unit. And, not have to fear the enviro-nazis wrath for disposal of so many depleted AA's.

You can whup me if I'm wrong. (lol)

J.D.


p.s. Had a chance to do any fishin' yet?

JD,

If you're looking for a "long time" solution...an external battery pack can easily be made....

1. Radio Shack experimeter box...$5±
2. 3 volt gel cell 8-10 amp hours..Call it $20 + charger $25. At any local electrical supply type place.
3. Radio shack connector that will mate with the PM 2. Connector for the charger. 10 feet of 16ga. wire... call it $10.

Toatal cost $60± and an hour or so of time.

Replace gel-cell every coupla years.

PM2 uses 675mah± per hour of run time
8 amphours = 11.8 hours run time (+ internal battery time)
10 ah = 14.8 hours run time (+ internal battery time)

Jimbo

Jimbo,

That sounds like a reasonable solution, but......

How would that affect the warranty on the units? My guess is that it could void the warranty in the case of an electrical malfunction. I'm still electrically challenged, so it's still just a guess.

I still like the idea of a rechargeable external power supply. The internal AA's are a good idea for the handheld recon type work, and those short, fast static observations. But those of us planning control networks need the extended power. Don't we?

J.D.

No fishing yet J.D. Too busy getting ready for the move across country. Hope to be able to drown a worm or two before I go though.

Bill

A few assumptions: this unit has the form factor of consumer grade magellan's. If we can assume similar behaviour? I have done some research and experimentation using rechargeable's on Garmin GPS which might relate. So behind two levels of assumptions my experience with this unit but may be of interest as a similar device. The type of device being powered affects greatly the cell dynamics and life.

1) Mnh cells last less time than replaceable Alkalines in this type of application which is voltage dependent. The overall energy in the cell may be greater, but due to the lower initial base voltage (1.2-1.3 vs 1.5-1.6) and the different discharge curve (V vs time) and a fixed cutoff voltage they usually end up powering for less time say 1/2 to 2/3 as long. They simply get to the cut off voltage quicker. If that time is long enough for data collection, they may still be viable.

Costs are much less since rechargeables can be cycles hundreds to thousands of times. Biggest limit in operation is how long you need to run it unattended or single session, otherwise they can be replaced at intervals. Spare charged sets usually have to be maintained and managed carefully. Having an emergency replacement set that is discharged doesn't cut it. Also, overall saving some money on batteries but losing sessions because cells go dead might be a poor bargain.

Another factor to watch is whether the battery life indicators (if there is one) may not reflect the actual life due to being calibrated to the different type of cell and discharge curve. Some units let you set between types. My Garmin's do not so they essentially quit working when battery gauge is just below reading half.

If the electronics cut off at a certain supply voltage, it doesn't matter how much energy is left in the cell. Some uses may not care, such as for a flashlight. It appears from the experience cited that digital cameras are much less sensitive to voltage.

2) the higher capacity MnH cells last longer than regular onces or NiCad's because they raise the whole discharge curve slightly and thus the tail cuttoff is extended in time. These need to be 1600ah or higher. The cells are characterized by a quick initial voltage drop (from the already lower value) and then a long slightly downsloping plateau then a rapid drop at the end. Quick smart chargers are the best way to handle them and prolong their cycles and life and can be had in the $25 range.

Rechargeable alkalines are another type but they have the worst of both worlds, a shorter and quicker discharge curve, overall on a new set about half the running capacity of regular alkalines and they go downhill from there.

3)Premium alkalines only add marginally and not worth the extra cost (such as Energizer Ultra or Titanium).

4) Lithium are of value where extended single session life or cold operating conditions or storage are relevant.

Again these observations may or may not apply to the Promark2 but seem like would be similar and corroborate the information from ashtech as to less life from rechargeables in this application.

- jerry