NiMH charger and battery question

[rhymemaze]

Hi. I would like to get a battery charger that will accept AA/AAA/C/D cells (9V optional). I have done some reading from Silverfox and others on the chargers and narrowed it down to these guys:

This is the cheapE:
http://thomasdistributing.com/shop/...html?SP_id=&osCsid=lde2f6dhge1rkmmmkaq0i826p1


This one seems competent:
http://thomasdistributing.com/shop/...html?SP_id=&osCsid=lde2f6dhge1rkmmmkaq0i826p1


This is the big daddy:
http://thomasdistributing.com/shop/-maha-mhc808m-aa-aaa-c-d-battery-chargerbrdeluxe-8-cell-professional-battery-chargerfull-lcd-displaybrspecial-price-8997-p-517.html?SP_id=&osCsid=lde2f6dhge1rkmmmkaq0i826p1

….and this one from all-battery.com:
http://www.all-battery.com/t6278universalsmartfastchargerwith32-cellpackage12aa12aaa4c4d-new.aspx

Please give some opinions on these chargers and any other AA/AAA/C/D chargers that might be worth looking at. I'd like to keep the price down but do want the features to get the most life out of the cells.

Also, I plan on getting the low-discharge cells ( Eneloop AA & AAA and Accupower low discharge C & D cells) from Thomas Distributing though that all-battery.com site shows that I can get the same amount of Tenergy batteries with the charger I linked above for about $100 less than the Accupower 20 charger and all low discharge batteries. Cheaper is not always better, and would like to hear from experienced users of these Tenergy calls vs the low-discharge. I am steering towards the low-discharge cells but the ~$100 difference has me asking you guys for a second opinion. Thanks for any information here.

 

[mdocod]

I would suggest sticking to the plan of eneloops and Accupower LSD cells. As for the charger...

I have not seen a review yet, but on paper I'd say this appears to be the best value I have seen to date:
http://www.batteryjunction.com/md-3000-charger.html

I think I would take that one over the accumanager to get the faster charge rate.

The 808, as you have said, is probably one of the nicest multi-bay chargers available that can do up to D size cells. If you're willing I say go for it, 2 amp charge rate is fantastic.

[edit in] avoid that "cheap" charger you linked to, looks like a piece of crap IMO.

 

[rhymemaze]

Thanks for the feedback. That MD300 looks good. At first glance, it appears there is more space between each channel than the Accupower 20 which will help cool the batteries better, right? I like the MAHA c808m but not sure I want to go there based on price. The MD300 and Accupower20 are a good comparison it seems.

By chance do you know the charge rate of the MD300? I was reading on this forum how batteries should be charged at a certain rate to maximize life of the cell. The Accupower 20 charge rate is 750ma I believe. Is that too high for AA and AAA? I have not got the charge rate information straight yet.

{edit}
My bad I found the charge rate.

AA/C/D is 1600mA +/- 200mA (depending upon exact input voltage; 100-130 and 200-240)
AAA is 500mA +/- 50mA (as above)
9V is 80mA +/- 20mA (as above)

http://www.cpfmarketplace.com/mp/showthread.php?t=187985
Thanks again.

 

[mdocod]

The 1600mA charge rate is actually pretty ideal for AA cells, as is the 500mA charge rate for most AAA cells. Ideally speaking, a charge rate of ~2.5A or more for C cells and 5+ amps for D cells would be ideal, but that's not something you don't find very often in cradle chargers... maybe if we could cannibalize the circuit from an Energizer 15 minute charger.... hmm....

 

[rhymemaze]

mdocod,

thanks for that information. So is the MD3000 charge rates better for cell life versus the Accupower 20 where the charge rate is 700mA across all AA/AAA/C/D?

 

[mdocod]

That would be a tough one to answer without having both chargers in front of you and the ability to do some testing to see which one is terminating the charge most accurately and keeping the temperature lowest on the cells.

Faster charge rates have the advantage of producing a stronger "signal" that the charger can use to determine when the charge should be terminated. I have a BC1HU which is similar to the accumanager, same 700mA charge rate, and it suffers from missed termination on C and D size cells sometimes because of it's very slow charge rate for those large cells. Eneloop brand AA and AAA cells are remarkably robust and are going to provide a LOT of service with either charge rate. IIRC silverfox abused some eneloops in an energizer 15 minutes charger (like a 10 amp charge rate) through, I think it was 100 cycles, and the cells still worked very well after all that abuse, compared with energizer brand cells, which tend do go south after a few dozen cycles in that charger.

Eric

 

[rhymemaze]

So, "in theory", the 1600mA charge rate on the MD3000 would be better for C&D cell termination vs. the 700mA? I understand that testing would have to be done to give the most accurate answer. As my avatar suggests, I am unenlightened on this .

I'd really like to get a hold of the manual for the MD3000, but I emailed battery junction and was told they will not have a manual and that the warranty was 6 months. Though on the marketplace forum here, MattK says that the manual is coming and the warranty is one year. I'd like to know how to properly discharge on the MD3000 and get an overview of how to optimize the tech before I get set up.

I appreciate your responses. It is helping to sort things out for me.

Kevin

 

[mdocod]

So, "in theory", the 1600mA charge rate on the MD3000 would be better for C&D cell termination vs. the 700mA? I understand that testing would have to be done to give the most accurate answer. As my avatar suggests, I am unenlightened on this .

yes. that would be the theory

I'd really like to get a hold of the manual for the MD3000, but I emailed battery junction and was told they will not have a manual and that the warranty was 6 months. Though on the marketplace forum here, MattK says that the manual is coming and the warranty is one year. I'd like to know how to properly discharge on the MD3000 and get an overview of how to optimize the tech before I get set up.

I appreciate your responses. It is helping to sort things out for me.

Kevin

I doubt it will be that complicated, most of the time you are just going to take cells you want charged and slip them into the charger and walk away. Every couple dozen cycles it would be ideal to do a complete discharge (I think you just push a button on the charger for this), followed by a full charge, and leave the cells on the charger for awhile after termination (trickle charging)... Like 5+ hours of trickle charging for the AA size, 10+ for C, and 20+ for D.... This deep cycle followed by a mild over-charge at a trickle rate will help break down large crystal formation within the cell, improving cycle life and performance.

 

[rhymemaze]

Every couple dozen cycles it would be ideal to do a complete discharge (I think you just push a button on the charger for this), followed by a full charge, and leave the cells on the charger for awhile after termination (trickle charging)... Like 5+ hours of trickle charging for the AA size, 10+ for C, and 20+ for D.... This deep cycle followed by a mild over-charge at a trickle rate will help break down large crystal formation within the cell, improving cycle life and performance.

Thanks for spelling that out for me. Is there a considerable negative effect on cell life if I am charging AA's for ~1.5 hours as the MD3000 indicates and then leave them on the charger past the 4 bars (100%) for 5 hours every time? I don't plan on doing that, but curious. Also, I assume that when the 4 bars show on the display it goes into trickle mode automatically then, right?

 

[mdocod]

Trickle charging for a few hours after a regular charge isn't too big of a deal, many chargers actually technically need a few hours in trickle-charge mode after the regular charge has terminated in order to get the cells truly topped up. Until the specifications for the charger are released with a PDF manual, it's going to be hard to be exact with answers on this though, as I'm not sure what rate the trickle is set to, or if it even has one (almost all Nickel chemistry chargers trickle charge after the "fast" charge is complete).

Eric

 

[lonesouth]

bump...

has anyone played with an MD3000 enough to give some input to the quality?