[UnknownVT]

since the SANYO Eneloop charger uses 250 mA I would not go over that
I charge mine Eneloops in BC-900 @ 200 mA and they are okay for 400 raw shots in cold at least

Well .. how much was that eneloop charger - that probably came with the batteries?

It is unfortunately a cheap charger (and I hate that old phrase "you get what you pay for") - and although it "works" - it is just not optimum - please see below for a fuller answer.

what I think is, that the less the charging current is, the less damage (memory effect) to the cells occurs (and charging takes more time of course)

Sorry that's not strictly true -
it may seem logical -
but it is a kind of myth.

There are many strategies for detecting end of charge
- ie: when the battery is Full.

This is important because charging beyond that will over-heat the battery and therefore damage it.

Most chargers (except for the cheapest ones) now use chips for controllers, and those mainly use -dV (delta V or NDV) end of charge detection - and according to the experts and all that I have read - -dV is difficult to detect below about 1/2C - and the ideal detection is between 1/2 to 1C.

quote from BatteryUniversity.com (about 1/2 way down that page)-
" Nickel-metal-hydride chargers require more complex electronics than nickel-cadmium systems. To begin with, nickel-metal-hydride produces a very small voltage drop at full charge and the NDV is almost non-existent at charge rates below 0.5C and elevated temperatures. Aging and degenerating cell match diminish the already minute voltage delta further. This makes full charge detection difficult.

A nickel-metal-hydride charger must respond to a voltage drop of 8-16mV per cell. Making the charger too sensitive may terminate the fast charge halfway through the charge due to voltage fluctuations and electrical noise. Most of today's nickel-metal-hydride chargers use a combination of NDV, rate-of-temperature-increase (dT/dt), temperature sensing and timeout timers. The charger utilizes whatever comes first to terminate the fast-charge. "

So the optimum charging current is the oft mentioned 0.5 or 1/2C - in the case of eneloops where typical C=2000mA - this is 1000mA = 1Amp - this is NOT by any means a low current - and better chargers have temperature sensors.

Batteries should be pretty warm (close to hot) toward the end of charge - they should not be too hot to hold in a tightly closed hand - it that is the case, then the battery is likely to have been damaged.

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Last edited by UnknownVT; 01-31-2011 at 10:24 AM.

[stanic]

Well .. how much was that eneloop charger - that probably came with the batteries?

no idea on price mate, I did not get the charger just looked at specs on web

So the optimum charging current is the oft mentioned 0.5 or 1/2C - in the case of eneloops where typical C=2000mA - this is 1000mA = 1Amp - this is NOT by any means a low current - and better chargers have temperature sensors.

Batteries should be pretty warm (close to hot) toward the end of charge - they should not be too hot to hold in a tightly closed hand - it that is the case, then the battery is likely to have been damaged.

I am not going to argue on this since I am not an electrician...everybody to their taste, I am happy with 200 mA/cell

[UnknownVT]

no idea on price mate, I did not get the charger just looked at specs on web

I am not going to argue on this since I am not an electrician...everybody to their taste, I am happy with 200 mA/cell

Just to be clear I did not intend this to be in any way antagonistic -

200mA for a 2000mAh battery is the standard "forming" charge and should take about 14-16 hours - it is indeed "good" for the battery - but not necessarily "better" than at 1/2C - which is 1000mA.

Although what you said - over charging at a low current of 200mA is much less likely to damage the battery than over-charging at 1000mA - this of course is dependent on the charger -

A good charger should have stopped charging when the end of charge is detected (-dV) -
which unfortunately is non-existent at 200mA -
so that charger is likely to be based on a timer -
the trouble is if one charges a partially charged battery ie: not empty/fully discharged - then a charge at 14-16 hours at 200mA is much more likely to lead to over-charge/heat than a good charger that detects the end of charge signal (-dV)

Anyway if you would be kind enough to please give the model number of that eneloop charger (they make several models) we can then look more closely at its features.

[stanic]

Anyway if you would be kind enough to please give the model number of that eneloop charger (they make several models) we can then look more closely at its features.

now I see, I was looking only at MQN04, the others differ
also, the 2500 mAh xx eneloop looks promising

[UnknownVT]

now I see, I was looking only at MQN04, the others differ
also, the 2500 mAh xx eneloop looks promising

This thread may be helpful:

Sanyo Eneloop Battery Chargers - Spec Sheets

230V Chargers

NC-MQN04
http://www.eneloop.info/uploads/medi...ICATION_01.pdf
4 position Battery Charger
2 Channels - Must charge batteries 2 or 4 at a time
Input: 230V AC 50 Hz
AA 250mA x 2/4
AAA 150mA x 2/4

From that spec sheet:

" d Charging control method Timer cut"

which means the charging is by timer only at ~16 hours
- there is no other end of charge method mentioned in the spec sheet.

This theoretically means that even if one put in a fully charged eneloop
- that charger will still charge at 250mA for 16 hours
- this obviously will be grossly over charged.

I hope you can see that although 200-250mA may well be "kind" to the battery - the charger strategy is not, and can potentially lead to gross over-charge.

Just to be clear again this is not meant to be a personal put-down -
but simply explaining why a low current may seem to be kind to the battery
- that most chargers using lower currents are cheap timer chargers (if they actually have a timer)
if used without knowledge can potentially lead to over-charge - damaging the batteries.

[stanic]

This theoretically means that even if one put in a fully charged eneloop
- that charger will still charge at 250mA for 16 hours
- this obviously will be grossly over charged.

I hope you can see that although 200-250mA may well be "kind" to the battery - the charger strategy is not, and can potentially lead to gross over-charge.

when I put "depleted" Eneloops into the BC 900, their voltage is usually around 1 V
and after around 3,5 hours charging with 200 mA current they are good to go at 1,46 - 1,5 V and automatically switched to trickle charge

[UnknownVT]

when I put "depleted" Eneloops into the BC 900, their voltage is usually around 1 V
and after around 3,5 hours charging with 200 mA current they are good to go at 1,46 - 1,5 V and automatically switched to trickle charge

The LaCrosse BC-900 is a very good charger (except for a few cases of melting chargers)
- its end of charge strategies are very good
- using more than one type of detection for multiple safe end of charge.

So none of the over-charge by cheap timer chargers comments apply
- since it is/was a $50-60 charger at one time - hardly cheap.

Although 3.5 hours at 200mA does not sound like those eneloops are anywhere near depleted
even though the 1V sounds about right -
maths: 200mA x 3.5 hours = 700mAh - this is only just over 1/3 the eneloop capacity of 2000mAh.

When I charge my eneloops (I use them until camera shutdown) they still measure over 1V like 1.15V but only have about 30mAh when discharged at 400mA to 0.9V - and after an overnight rest I get about 1800mA for about a 2 hour charge at 1000mA (about 90% full) using a Maha C9000.

[raider]

Should I go get the Maha C9000 charger? or there is another alternative just as good.

[UnknownVT]

Should I go get the Maha C9000 charger? or there is another alternative just as good.

The Maha C9000 is a very fine charger - a bit complicated -
but if one wants a good analyzer/charger - it is just about the best for a normal consumer grade charger.

However your existing Sony BCG-34HRMF charger
- is every bit as good at charging eneloops -
esp if one charges just 2 at a time.

[raider]

So with my Sony charger do I have to press the refresh button to refresh the eneloops before charging them? How do I know if my eneloops are still in good shape?

[UnknownVT]

So with my Sony charger do I have to press the refresh button to refresh the eneloops before charging them? How do I know if my eneloops are still in good shape?

from the Sony BCG-34HRMF instructions:



Since you appear to suspect your eneloops of being under-par
it probably is worthwhile to doing refresh cycle.

There is a note on the refresh in the same instructions:

" If the batteries are stored without use for 6 months or longer,
it is recommended to charge the batteries before using the Refresh Function. "

So it's probably better to fully charge the eneloops first, before using the Refresh cycle.

A single sub-par battery can bring a whole set down.

Mark your eneloops individually for identity and try different combinations for your shot count and see if it make any difference - that way you may be able to figure out if any are sub-par.

You can also buy another set of eneloops charge them fully before use and see if your shot count is significantly higher.

Of course with an analyzing charger like the Maha C9000 on can actually discharge a fully charged set and see their capacity - they should be around 1800-2000mAh and at least over 1700mAh minimum -
unless of course somehow they were not charged fully -
but a Maha C9000 is at least US$52 in the USA -
for that price you could have bought another 5 sets of eneloops
and be happy.

[KxBlaze]

I just recently found out (first hand) that chargers matter. For the first 8-10 cycles or so I used the stock charger that came with it and got about 300-350 photos out of a full charge (most of the time with no flash or burst shooting). For the last 3 cycles I used a charger with individual charge slots and now I get close to 500 shots per full charge (again, mostly with no flash and no burst shooting). The stock charger will completely stop charging when one cell is full even if the other cells are not, whereas the individual slot charger will fully charge each individual cell so you can get the maximum amount of power out of every single cell. So a good charger us highly suggested.

[UnknownVT]

I just recently found out (first hand) that chargers matter. For the first 8-10 cycles or so I used the stock charger that came with it and got about 300-350 photos out of a full charge (most of the time with no flash or burst shooting). For the last 3 cycles I used a charger with individual charge slots and now I get close to 500 shots per full charge (again, mostly with no flash and no burst shooting).

It's good that you now have a better charger -
but your description is not necessarily attributed to the charger -
all NiMH including LSDs (like eneloops) take a few cycles to attain full capacity -
so lower shot counts in the first few cycles is actually to be expected.

The stock charger will completely stop charging when one cell is full even if the other cells are not, whereas the individual slot charger will fully charge each individual cell so you can get the maximum amount of power out of every single cell. So a good charger us highly suggested.

This is true, but only partially -
chargers that have to charge in pairs can leave a cell under-charged -
if the pair was unbalanced - ie: at significantly different levels of charge.

However the OP's Sony BCG-34HRMF charger does have independent charging channels -
if one reads this thread it has been mentioned that the Sony BCG-34HRMF charger can charge 1-2 AAs at 1050mA, or 3-4 at 525mA.

So the Sony BCG-34HRMF charger is a very good lower priced charger that gives very little away even when compared to the Maha C9000 for charging - it merely lacks the analyzing functions and when used with 3-4 batteries the charge current is only so-so/OK at 525mA.

[lectrolink]

I have Sanyo Eneloops; shoot RAW, 3-second review with every shot. I also perform a couple of review and deleting sessions on each charge. Getting about 350 shots per charge with 40% flash. I had hoped for better. My charger (Lacrosse BC-700) tells me on test cycle that all four batteries are taking a full charge with matched terminal voltages. I dont understand how some people are getting over 1000 shots on their rechargeables.

[raider]

Okay. That is an incredible piece of info. Thanks! Someone should make this a sticky or something.

When I use the Sony charger sometimes the battery gets very hot and I do mean hot not warm. Is this normal? What sort of temp should I be expecting?