Cheapest way to replace 4 D Cell batteries with higher watt-hour optio

[palmernet]

I work for a Conservation Organization which is looking to extend the battery life on its digital camera traps. In short, our camera traps use 4 D Cell batteries and we want to attach an external power pack that would provide the equivalent of 50-100 watt hours or highers.

Does anyone have any suggestions?

Best Regards

Jonathan

 

[itsmoked]

Nothing beats a 6V lead acid battery when weight, and (to a small extent) size, don't matter.

Are these traps for humans? Or animals? That is, can you use a solar panel?

If you can then find a small solar panel with charger built in or a small solar panel and a separate charger. Whatever charger you get IT MUST be a good one that either CUTS OFF or drops to trickle charge. This would allow several years before needing a battery change.

Alternatively just get the LA battery of size ~20Ahrs and manually retrieve and charge it twice a year(depending on what your system draws).

Perhaps you can better describe the system.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[waross]

I agree with itsmoked.
I googled "batteries 6 volt sealed lead acid", and the first hit I got out of about 424,000 lead to

http://www.mdsbattery.com/shop/productprofile.asp?ProductGroupID=1050

It looks like 72 watt/hours for 19 volts. It should be compatible with the solar charging panels that itsmoked mentioned.
respectfully

 

[itsmoked]

He meant $19.

A lead acid battery will self discharge enough that you will want to charge it about every 6 months even if it is never used.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[palmernet]

The traps are for animals but there are people in the area so theft can be a risk. The cameras are in locked Pelican cases so are secure.

If we need a lighter weight solution, what options are there instead of a LA battery?

 

[itsmoked]

Much, much, lighter Li-ion battery technology. But it is much, much, more expensive and is a more problematic battery in that over discharge or over charging both lead to explosion and fire.

Do you have a link to the device you are using? Maybe we can give you better specifics.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[palmernet]

We are testing a range of products - including:

http://www.bushnell.com/products/sport_image/specs/11-9930.cfm

http://secure.yisi.net/trailsense/product.asp?dept_id=10&pf_id=TM-DIG-06

 

[IRstuff]

You'd be hard pressed to beat alkaline batteries. A Duracell D-cell is rated at over 10 Ah, which for 4 cells is over 44 Wh.

A comparable 70 Wh laptop battery costs over $60, with little, if any, gain in volume or weight.



TTFN

 

[itsmoked]

Ah I see..
Are you complaining about the battery expense or do you need a longer run time?

They have different solutions.

If you just want to save on the battery expense by all means switch to NiMH batteries. They are a much better fit for that service in the first place. Pick up a charger and just cycle the batteries through in rotation. Your battery costs would probably be about (guesstimating) about a 1/10 of alkaline. The down side of NIMH is they self-discharge fairly quickly. That's why it's important to understand your problem in detail. If you visit your cameras monthly NiMH! If you visit them every other month they still make the most sense. Every three months? Not such a great improvement...

If you just need more capacity, then just add another 4- battery pack in parallel to the existing one. Using either type of battery, (But they must be the same types!)

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[IRstuff]

I think that you'll be very disappointed in the NiMH battery capacity. The Eveready NiMH D cell is specified for 2500 mAh, while all the alkaline D cells are specified around 20000 mAh, i.e., at least 8 times the capacity:

http://data.energizer.com/SearchResult.aspx

http://data.energizer.com/PDFs/E95.pdf

http://data.energizer.com/PDFs/NH50-2500.pdf

When coupled with the lower voltage on the NiMH battery, the apparent life is quite short.

There's less of drastic difference in AA batteries, with ampacities roughly comparable. But even then, the lower voltage still makes the them appear to have shorter lives.

Makes you wonder why have NiMH D cell, when the AA has the same capacity...

TTFN

 

[davidbeach]

'cause AA batteries won't fit where a D in needed.

 

[ScottyUK]

Some high capacity lithium cells and batteries are listed by SAFT, among some of their more exotic cells. This company has a long-standing reputation for high quality.

http://www.saftbatteries.com/120-Techno/20-10_Lithium_system.asp

There are very high capacity NiMH cells on this website too, although the Li-SO₂ based cells are probably a better fit to the application.

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I don't suffer from insanity. I enjoy it...

 

[itsmoked]

For reference the Panasonic D NiHM is rated at 8250mA. And not a a bogus 25mA load that the Eveready touts. At half an amp they are the same rating. The Alkaline can act dead before the NiMH because they have higher internal resistance.

Alkaline 300 milliohms
NiMH 3.2milliohms

This is important to charging flash units.

If I drop a set of new alkalies in my camera I can snap about 8 shots before I get a dead battery signal. I can snap 30 shots using NiMH before giving up on the comparison.

But alas, it would be nice to understand palmernet's needs better.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[ScottyUK]

SAFT's snappily named 'Long Fat DD' Li-SO₂ cell - ain't that politically correct? - is a 34000mAH 3V cell. The 'D'-cell is a 7750mAH 3V cell. The higher voltage is significant: greater energy storage for cells of equivalent mAH rating.

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I don't suffer from insanity. I enjoy it...

 

[tsgelectric]

If you go with a sealed lead acid battery you may need to completely drain the battery and recharge it at least every six months.

 

[itsmoked]

Oops tsgelectric; You never want to completely drain any Lead Acid battery. You may be thinking of NiCd batteries.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com