MiniDv battery life length?

[capman21]

Guys what is normally the length of a minidv battery before you need to get a new one? I have had my mindv for about a year and it seems the battery doesnt charge fully anymore. Than again maybe it does, its just that the minidv lcd use to say 60 min for a fully charged battery now it is saying 30 or 40 min. What you think it might be?

[redwudz]

When I buy a digital camera, I always get a second battery at the same time. They do wear out.

[edDV]

What battery technology?

NiCad declines over two years and has the memory issues.

NiMH decline over ~3-4 years without memory issues

Lithium Ion
Permanent Capacity Loss versus Storage Conditions
Storage Temperature 40% Charge 100% Charge
_0 °C (32 °F) 2% loss after 1 year 6% loss after 1 year
25 °C (77 °F) 4% loss after 1 year 20% loss after 1 year
40 °C (104 °F) 15% loss after 1 year 35% loss after 1 year
60 °C (140 °F) 25% loss after 1 year 40% loss after 3 months
http://en.wikipedia.org/wiki/Lithium_ion_battery#Guidelines_for_prolonging_Li-ion_battery_life

[JohnnyMalaria]

It's worth reading http://www.batteryuniversity.com/ - a whole website dedicated to information about batteries - especially the most common rechargeable formats.

There's debate about whether NiMH do or don't suffer from the memory problem.

I came across this site last week when trying to find out how to revive a 10-cell NiCd battery pack for an underwater video light. The pack had sat in storage for over 6 years. Following the advice on the above site, I have successfully revived the battery pack to an almost as-new condition (saving many $$$ in the process).

The site has a section about Li-Ion longevity:

Prolonged battery life through moderation

Batteries live longer if treated in a gentle manner. High charge voltages, excessive charge rate and extreme load conditions have a negative effect on battery life. The longevity is often a direct result of the environmental stresses applied. The following guidelines suggest ways to prolong battery life.

-The time at which the battery stays at 4.20/cell should be as short as possible. Prolonged high voltage promotes corrosion, especially at elevated temperatures. Spinel is less sensitive to high voltage.

-3.92V/cell is the best upper voltage threshold for cobalt-based lithium-ion. Charging batteries to this voltage level has been shown to double cycle life. Lithium-ion systems for defense applications make use of the lower voltage threshold. The negative is a much lower capacity.

-The charge current of Li-ion should be moderate (0.5C for cobalt-based lithium-ion). The lower charge current reduces the time in which the cell resides at 4.20V. A 0.5C charge only adds marginally to the charge time over 1C because the topping charge will be shorter. A high current charge tends to push the voltage into voltage limit prematurely.

-Do not discharge lithium-ion too deeply. Instead, charge it frequently. Lithium-ion does not have memory problems like nickel-cadmium batteries. No deep discharges are needed for conditioning.

-Do not charge lithium-ion at or below freezing temperature. Although accepting charge, an irreversible plating of metallic lithium will occur that compromises the safety of the pack.

Not only does a lithium-ion battery live longer with a slower charge rate; moderate discharge rates also help. Figure 5 shows the cycle life as a function of charge and discharge rates. Observe the improved laboratory performance on a charge and discharge rate of 1C compared to 2 and 3C.

[capman21]

The battery is a JVC BN-VF707U 1.5 Hour, it says also it is a 700mAh rechargeable lithium-ion cell.

[edDV]

I buy a new camcorder battery every year or so so that I have a mix of fresh and semi depleated stock in the case. Periodically I test the old batteries by playing tapes until the battery goes dead and then mark the battery with minutes.