Nimh Battehries...How long do they Last?

[chimera_h]

<p>I'm trying rechargeable batteries for the first time and am wondering how long they last.</p>

<p>Thanks</p>

[phule]

<p>That would depend entirely on the capacity of the battery. A 2700 mAH battery is going to last longer than a 2100 mAH battery.</p>

<p>You might try searching for information on your particular flash with NiMH batteries. Certainly someone has reported usage numbers already.</p>

<p> </p>

[ejder]

<p>Longer than alkalines.</p>

[howard_m]

<p>+1 depends on what battery you've chosen and how much power the flash is producing and when the last time you charged it was. </p>

[JAPster]

<p>Check the owners manual of the equipment these re-chargeables will be used in, to get a baseline idea of how long they will last under 'typical' conditions. There should be a page or two in the manual to specifies ballpark figures for different types of batteries. Battery life *per session* is dependant on many things like: a) the ambient temperature, b) the state of battery voltage level at start of session, c) how often the flash is used, d) how much you use the auto-focus, e) how long of an interval between pictures, f) how much you use Live-view, etc, etc.</p>

[picturesque]

<p>I assume you are talking about rechargeable AAs--NiMh or hybrid? All the people above are correct--it depends on usage--how you use your flash and the venues involved. Most people these days (with usage of higher ISOs) 'may' go for a complete 5 or 6 hour wedding. At the very least, a change out mid way. Of course, one should have more than enough change out sets, just in case. For instance, I use more flash during the winter months at weddings, so I plan to bring more batteries/battery power. Depletion isn't the only concern--recycling can slow so much as to cause you to lose shots.</p>

[at]

<p>Some additional input: Best nimh battery at the moment seems to be the Sanyo Eneloops.<br>

Best chargers: MAHA, Lacrosse, Annsmann. Dont be fooled by ratings alone. My 2000 mah batteries<br>

outlasted another well known brand that claimed 2700 mah. Google Sanyo Eneloops and you<br>

will see the overwhelming positive ratings. My personal charger is an older duracell power gauge<br>

with 4 individual charging channels.....on ebay now for $15.00 shipped...works great.</p>

[pete_s.]

<p>Check your flash user manual, it may have information in it.<br /> Below is data for the Nikon SB900 flash.</p>

<p>PS. As the batteries get older and older their capacity will diminish. High capacity NiMh are suppose to have a service life of about 500 recharge cycles in theory. When using the batteries in a flash I think it's less than that in real life.</p><div></div>

[matthew_newton]

<p>Alkaline AA batteries tend to be 1,700mAh at 1.5v (2.55w/hr), but also have higher internal resistances, so there is going to be a bit more power loss in charging a flash or other device, the impact is less the lower the current draw is (so a wall clock isn't going to see much loss in efficiency because of the high internal resistance, but a flash is).<br>

Eneloop which I use are 2,000mAh at 1.2v (2.4w/hr), Eneloop also have extremely low internal resistance, which makes then better suited for high draw applications such as flashes (there is less efficiency loss because of the low internal resistance). Eneloop are also hybrid NiMh in that they self discharge very slowly, about 30-40% in 1 year based on user tests.<br>

High capacity (non-hybrid) NiMh batteries tend to have slightly higher internal resistances then hybrid NiMh batteries, so they don't charge things quite as fast and only have slightly higher real use capacities in things like flashes (look at the chart above), they range from around 2,000mAh to around 2,700mAh for regular NiMh batteries. They self discharge at about 1% per day, so completely exhausted without having used them once in about 3 months and would then need to be recharged (heck even just a week of sitting will see close to 10% of their power lost through self discharge).<br>

Anyway look at the chart Pete posted for an idea of relative real use capacities for a high discharge application, the Alkaline are very much the lowest and the Eneloop are up there, as well as having very low self discharge. Just takes a week or so in a camera bag and they have the same capacity as the 2,600mAh NiMh batteries do discharging for a week.</p>