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Batteries & Chargers Discuss Li-P, Li-Ion, NiMh, Nicad battery technology and the chargers that juice 'em up!

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Old 04-26-2012, 10:17 PM   #1
mclarkson
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Default 4-button charges vs. "better" chargers?

I know this is a re-tread of questions asked and answered (somewhere) a million times, but ...

I have had a number of '4-button' chargers (long boring story). I mostly use the Thunder AC6 at the moment.

I have two problems.

1) I've had four 4-button chargers and none of them consistently brings my cell voltage up to 4.2. They'll say they're done, and report 4.2V, but checking them on other equipment typically shows 4.16 or so. The only chargers that consistently bring my batteries up to 4.2V are the cheap 'wall wart' chargers that came with RTFs.

2) They sometimes take FOREVER to finish up a balanced charge. Batteries will get up to 4.18 or so very quickly and then spend 30-60 minutes doing the charge/drain/charge dance.

4.19 4.19 4.20
4.19 4.20 4.21
4.19 4.19 4.20
4.20 4.19 4.20
4.19 4.19 4.19
4.20 4.19 4.20
(repeat for an hour)

I think I recall seeing a video review a while ago that implied this was a problem with cheap 4-button chargers, and that better chargers would charge the cells separately or something and avoid this annoying behavior.

Am I crazy? If I go with a better charger, will I get accurate charges without the endless cycle of fill and drain on the end?

Thanks.

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Old 04-26-2012, 11:18 PM   #2
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You are talking about 1 or 2 hundredths of a volt, do you really think it's that important to get to exactly 4.2 volts? Some would say you are better off only charging to 4.15 which is something you can do with better chargers like Cellpro.

Additionally you don't necessarily have to wait for the balancing to finish. If your packs are balanced you don't necessarily have to balance with every charge. Understand I'm not saying to charge without the balance lead attached. That would eliminate important safety functions of the charger. But you can choose a charge mode that does not balance to save time and then balance when you have time or when the cell balance seems to be drifting a bit.

I've found that most if not all my packs stay pretty well balanced and don't need a balance charge every time. Again I always have the balance lead attached so that charging will stop when any cell gets to 4.2 volts and I always monitor cell voltages when charging, balance mode or not.
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Old 04-27-2012, 12:05 AM   #3
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1. You can recalibrate the -4-button chargers if you feel you must.
2. The amount you are talking about is insignificant.
3. Slightly under volt is better for the lipo in the long haul with almost no real decrease in effective performance.

fly
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Old 04-27-2012, 04:56 AM   #4
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You have been buying cheap chargers that don't/can't balance very well.

Buy an FMA or an iCharger.

They WORK.
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Old 04-27-2012, 09:56 PM   #5
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Agree, buy FMA cellpro and actually trust your charger.

I wanna be a pirate. Arrrrr

AMA - 885997
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Old 04-27-2012, 10:12 PM   #6
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More than the 4.16 vs 4.20 issue, I'd like to eliminate the endless balancing dance.

Will the Cellpro or iCharger perform differently here?

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Old 04-28-2012, 01:21 AM   #7
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Originally Posted by mclarkson View Post
More than the 4.16 vs 4.20 issue, I'd like to eliminate the endless balancing dance.

Will the Cellpro or iCharger perform differently here?
It will balance better than what you have.
But if your battery is shot it will not fix it.
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Old 04-28-2012, 01:30 AM   #8
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Possibly.
The problem is we have no idea of the quality or some of most of the components in the various 'clones' The Imax B6 was well known to be a poor balancer with crappy components.
I have an AC-6, pretty much the same I would guess. It does OK but I have 2 Cellpro 4S and I trust them way more. If a cell seems flaky, it goes on the Cellpro for a better inspection of it's charging. The AC-6 does a lot more of it's major work with discharging to storage and NiXX cycling than lipo charging, 2 things the Cellpro 4S won't do.

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Old 04-28-2012, 02:22 AM   #9
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Originally Posted by mclarkson View Post
More than the 4.16 vs 4.20 issue, I'd like to eliminate the endless balancing dance.

Will the Cellpro or iCharger perform differently here?
I've got the Cellpro Powerlab 8 charger. This charger allows the user to directly configure exactly how the charger functions with your batteries, and also allows specifying the maximum voltage per cell. It also allows setting how low the charge current drops off to when the charge cycle is complete.

This is an expensive charger, but I believe all of the Cellpro chargers operate in a similar process.

The Cellpro charger allows you to define a number of charge rates for different types of cells. For example, I've set mine up as below:

Charge #1 Charges A123 cells at 28 Amps, to 3.65 Volts per cell, 0.6 Amp Cut off.

Charge #2 Charges A123 cells at 14 Amps, to 3.65 Volts per cell, 0.3 Amps cut off

Charge #3 Charges A123 cells at 7 Amps, to 3.65 Volts per cell, 0.3 Amps cut off

Charge #4 Charges A123 cells at 0.8 Amps to 3.65 Volts per cell through the balance wires only

Charge #5 Charges standard NiH cells

Charge routine #1 is for a 4 cell parallel pack (eq 6S4P A123 This setting will charge anywhere from one to 8 series cells)
Charge routine #2 is for a 2 cell parallel pack (eq 6S2P A123 This setting will charge anywhere from one to 8 series cells)
Charge routine #3 is for a 1 cell parallel pack (eq 6S1P A123 This setting will charge anywhere from one to 8 series cells)

Note that charge routine #1 pulls 50 Amperes out of the 12 VDC battery!

Each of these charge rates is programmed on the Cellpro charger LCD display that shows exactly what the charge rate is. You can't make a mistake with these type chargers. If the battery chemistry doesn't match the Cellpro settings, it won't charge the battery.

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Old 05-14-2012, 05:51 AM   #10
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I'm thinking about the Cellpro 4S Gold. I fly mostly 3S 450-2200s.

I can't tell what dang adapter I need to charge my batteries though.

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Old 05-14-2012, 06:02 AM   #11
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Originally Posted by mclarkson View Post
I'm thinking about the Cellpro 4S Gold. I fly mostly 3S 450-2200s.

I can't tell what dang adapter I need to charge my batteries though.
The Cellpro 4S charger has apparently evolved to the Cellpro Multi-4 system. If you look at the respective Cellpro web page, it has a place where you can click to determine which adaptor cable you need.

Take a look:
http://www.store.revolectrix.com/Pro...Cellpro-Multi4

If you want to customize your Cellpro charger, also pick up one of the USB adaptor cables on the bottom of this web page. This allows you to put your name in the Multi4's LCD display, along with customizing the charger to work with the type of batteries you are using.

I've got my Powerlab 8 to work with A123 cells with charge mode #1 charging at 28 Amps, Mode #2 at 14 Amps, mode #3 at 7.5 Amps, mode #4 for charging an two cell receiver pack A123 pack through the balance cables at 0.9 amps, mode #5 for charging transmitter batteries and so on. These are programmed into the Cellpro charger with the USB adaptor and are fixed.

Several other modes are for charging LiPo batteries at several different charge rates.

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Old 10-27-2012, 09:00 PM   #12
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33 bucks shipping!?! From Maryland??? Shipping is 34% of the purchase price?!? Really??? Effing nutz!!!!! cellpro is out....
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Old 10-27-2012, 11:34 PM   #13
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I would highly recommend EP Buddy.

http://epbuddy.com/index.php?main_page=index&cPath=17_1
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Old 10-28-2012, 02:26 PM   #14
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Default Termination and resting voltage differential

Unfortunately with the std cc/cv charge routine on today's chargers it is impossible to get a resting voltage equal to the termination voltage. (let's ignore the balancing for now because they are two different things) It is impossible especially as the termination point is based on current.

As the pack,leads,ports,charger circuits get closer to 0 resistance and the current setting gets lower the difference between resting voltage and stopping point gets closer. The only way to get them equal on average circuits charged at any great speed is to simply WAIT (almost like the proverbial frog jumping half his distance) toward the end. (I know it is a bad analogy) There is another way and that is to allow the cell to go over voltage and then settle back down to a resting voltage. This is cheating , but the i-chargers do allow up to 4.3 voltage termination.

The balancing "dance" at the end is quite another matter , but the reasons are the same.

If we had a circuit that included the charger,lead,connections and cells that had 0 resistance then we could theoretically charge them very quickly without a temp increase and terminate at exactly 4.2 volts and the cells would also hopefully rest there at that same exact 4.2 volts until used. Theoretically if we had the same 0 resistance and perfectly matched and balanced cells then the same scenario could be true with multi-cell pack in series. Charge quickly in series until termination and rest point are equal. The balancer would not even be doing ANY work at all , but would just be along for the ride.

PS. Selecting "fast" charge of course makes this problem worse with the result of more voltage differential between termination and rest. Using a higher termination voltage and the "fast" setting can be a good workaround for this popular "problem"

ps. Anyone remember hallwoo? with his "voltage clamp"?
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Old 10-29-2012, 03:20 PM   #15
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Originally Posted by Yakfishingfool View Post
33 bucks shipping!?! From Maryland??? Shipping is 34% of the purchase price?!? Really??? Effing nutz!!!!! cellpro is out....

$33 represents an Express Mail S&H charge for a small parcel from the US warehouse. The standard USPS Priority Mail S&H charge from the US warehouse is $7.99 if the product can fit in a flat rate envelope or $12.99 in a small shipping box. Most chargers fall into the latter catagory.

Regards,
Jamie Marks
REVO USA
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