Good rechargeable setup

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Good rechargeable setup

Postby pipewrench » Mar 8, 2013 3:28 pm

So I have finally acquired some decent lights and started doing research on a rechargeable setup. I know a lot of people here talk highly of eneloops. I plan on starting out buying around eight.
Now for the hard part...a good charger. Using the search function I read on a post the charger you can get with the eneloops is not very good. I read on another post that La Crosse may be a good charger. I looked at the BC-700 and it looked pretty fancy.

So my question is: are there other good chargers out there I should look into? Are there pro's/con's to this particular charger?
I have essentially zero experience with rechargeable batteries but will be doing more research here and there before committing. I'd like to spend a week or so reading before making a purchase.

I do have somewhat of a budget for this type of item. However, I don't mind spending extra if I feel like it is something that will last a long time. Would anyone care to chime in?
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Re: Good rechargeable setup

Postby NZcaver » Mar 8, 2013 3:48 pm

Eneloops are good. So are most of the other low self-discharge NiMHs. You are right - the chargers that come with most of these batteries (and most other cheap chargers) are complete crap and will kill your expensive batteries in short order.

I have been using the now-discontinued LaCrosse BC-900 for about 5 years, and it's great. The current version is the LaCrosse BC-1000 and I would recommend going with that. They do make other models like the BC-500 and BC-700, but those are lower current and you are better to charge NiMHs at high current with an intelligent charger.

If you haven't already done so, take a read through the rechargeables in the real world topic.
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Re: Good rechargeable setup

Postby Extremeophile » Mar 8, 2013 5:59 pm

NZcaver wrote:Eneloops are good. So are most of the other low self-discharge NiMHs. You are right - the chargers that come with most of these batteries (and most other cheap chargers) are complete crap and will kill your expensive batteries in short order.

I have been using the now-discontinued LaCrosse BC-900 for about 5 years, and it's great. The current version is the LaCrosse BC-1000 and I would recommend going with that. They do make other models like the BC-500 and BC-700, but those are lower current and you are better to charge NiMHs at high current with an intelligent charger.

If you haven't already done so, take a read through the rechargeables in the real world topic.

I think the BC-700 is great. It will charge at 200, 500 or 700 mA, which I think is plenty for AA and AAA. It has all of the same benefits of the BC-1000, i.e. charges individual cells, smart charges, reconditioning capability, etc., but at 2/3 the cost.
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Re: Good rechargeable setup

Postby NZcaver » Mar 9, 2013 2:51 am

Extremeophile wrote:I think the BC-700 is great. It will charge at 200, 500 or 700 mA, which I think is plenty for AA and AAA. It has all of the same benefits of the BC-1000, i.e. charges individual cells, smart charges, reconditioning capability, etc., but at 2/3 the cost.

The BC-700 is not as ideal for charging high capacity AA NiMH cells. See this previous topic:

Marduke wrote:For NiMH cells, charging at 0.5C-1C is ideal. On the LaCrosse, the best setting for AA cells is 1A, or 1.8A if you are only charging two cells in the #1 and #4 slots. The 500mA or 700mA are ideal charge rates for most AAA cells.

Technical reason:
Charging at the higher current helps make the -dV signal of a fully charged cell more prominent, reducing the chances of a missed termination.

I'm comfortable taking battery/charger advice from Marduke, given that he tinkers with this technology professionally for NASA.
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Re: Good rechargeable setup

Postby Extremeophile » Mar 9, 2013 9:03 am

NZcaver wrote:
Extremeophile wrote:I think the BC-700 is great. It will charge at 200, 500 or 700 mA, which I think is plenty for AA and AAA. It has all of the same benefits of the BC-1000, i.e. charges individual cells, smart charges, reconditioning capability, etc., but at 2/3 the cost.

The BC-700 is not as ideal for charging high capacity AA NiMH cells. See this previous topic:

Marduke wrote:For NiMH cells, charging at 0.5C-1C is ideal. On the LaCrosse, the best setting for AA cells is 1A, or 1.8A if you are only charging two cells in the #1 and #4 slots. The 500mA or 700mA are ideal charge rates for most AAA cells.

Technical reason:
Charging at the higher current helps make the -dV signal of a fully charged cell more prominent, reducing the chances of a missed termination.

I'm comfortable taking battery/charger advice from Marduke, given that he tinkers with this technology professionally for NASA.

I wonder why the LaCrosse default charge current is 200mA then? You'd think they might know something too. And if the cells are charged independently then what's the relevance of the #1 and #4 slots

o.5-1C is pretty cold. I guess I'll put the charger in the frig. :rofl:
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Re: Good rechargeable setup

Postby potholer » Mar 9, 2013 3:21 pm

A deal may depend on how the charger terminates charge - what method is used and how sensitive the charger is.

If the charger is looking for a voltage drop when a cell is full (-dV or negative-delta-V), that drop gets smaller and slower as the charge rate is decreased, and at low relative charge rates might be hard to detect, or even absent.

If the charger is looking for the voltage across a cell to stop rising (0dV or zero-delta-V), that might be a more reliable termination method for low relative charge rates on NiMh cells.
I've had a smart charger which charged at 550mA and two different ones that charged at 700mA, and they seemed to terminate reliably on anything I threw at them (no excessive heat, though they were capable of heating cells if cells were repeatedly removed and replaced as soon as 'full' was indicated), but I don't know what their termination was based on.

It seems that where a particular charger may fail to terminate at low charge rates, that is most likely to happen with old cells, and so may result in cells being OK and having correct termination until they reach 'late middle age' but then having a somewhat accelerated decline in their twilight years.

http://www.candlepowerforums.com/vb/sho ... w-charging
and
http://www.candlepowerforums.com/vb/sho ... n-go-wrong
may be informative
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Re: Good rechargeable setup

Postby NZcaver » Mar 20, 2013 2:09 am

Extremeophile wrote:I wonder why the LaCrosse default charge current is 200mA then? You'd think they might know something too. And if the cells are charged independently then what's the relevance of the #1 and #4 slots

Charging your batteries at 200mA just because it's the default charging current is about as relevant as always running a headlamp at maximum brightness because it happens to be the default setting.

Inserting a pair of batteries in slots 1 and 4 allows you to up the current to 1500mA or 1800mA. You can't charge a full set of 4 like that, because the transformer and charger circuit aren't rated for that much current. This is covered in the instructions.
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Re: Good rechargeable setup

Postby Caver John » Mar 20, 2013 8:27 am

I use the eneloop AA's and Aaa with an eneloop charger, no problems. Although for my headlamps, I use Tenergy 18650 cells with a Tenergy charger.
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Re: Good rechargeable setup

Postby NZcaver » Mar 20, 2013 2:11 pm

Caver John wrote:I use the eneloop AA's and Aaa with an eneloop charger, no problems.

FYI, the 'dumb' chargers that come with Eneloop batteries will likely kill your Eneloops within a year or two of regular use. Then when you buy more Eneloops and charge them with the same charger, the cycle continues. It's a type of planned obsolescence intended to sell more batteries.
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Re: Good rechargeable setup

Postby Extremeophile » Mar 20, 2013 5:16 pm

NZcaver wrote:
Extremeophile wrote:I wonder why the LaCrosse default charge current is 200mA then? You'd think they might know something too. And if the cells are charged independently then what's the relevance of the #1 and #4 slots

Charging your batteries at 200mA just because it's the default charging current is about as relevant as always running a headlamp at maximum brightness because it happens to be the default setting.

I'm not sure I understand the analogy. A battery charger is doing one thing ... charging batteries. I would think the default settings represent some compromise. I understand that higher charge currents make it easier to detect the -dV needed to terminate charging, but surely too much current can cause overheating and shorten the life of cells just like overcharging might. 1800mA on a AAA sounds dangerous.

Inserting a pair of batteries in slots 1 and 4 allows you to up the current to 1500mA or 1800mA. You can't charge a full set of 4 like that, because the transformer and charger circuit aren't rated for that much current. This is covered in the instructions.

Sounds like you need to be smart to use a smart charger. I'm not sure I meet the requirements. I can feel my brain overheating ... too much internal resistance.
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Re: Good rechargeable setup

Postby NZcaver » Mar 20, 2013 7:45 pm

Extremeophile wrote:I'm not sure I understand the analogy. A battery charger is doing one thing ... charging batteries. I would think the default settings represent some compromise. I understand that higher charge currents make it easier to detect the -dV needed to terminate charging, but surely too much current can cause overheating and shorten the life of cells just like overcharging might. 1800mA on a AAA sounds dangerous.

Sounds like you need to be smart to use a smart charger. I'm not sure I meet the requirements. I can feel my brain overheating ... too much internal resistance.

As stated in earlier posts, charging at 0.5 to 1C (capacity, not Celcius) is considered the optimum current for the charger to detect the -dV and terminate charging. We're not talking 1800mA for AAA cells - obviously that charge rate is more appropriate for AA cells. I suppose one does need to be a little smart in order to use a smart charger optimally, otherwise one is destined to keep going around in circles beating the dead horse.

:beatinghorse:
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