Maha CF-777Plus][

After a few years with a CF-777, I thought a plus would be a nice improvement and allow me to charge all of my Liion cells as well as my less than 4 cell packs (3 D cells for the Maglight, etc.)

Well, first impression is that it looks great and the mechanicals are much improved. The display is handy, but I have to think that it would be much easier to use *if it had more than one button*. I understand only having one button on the 777 where you only used a few LEDs for display, but on the plus they spring for a custom looking LCD display, but *still one button*.

Other gripes is that the discharge rate and the Liion charge rate are too slow--if there was a another button, maybe we could set it to some other value. Charging a 2.8Ah Liion at 400 mA/h. Hmmm, see you tomorrow--time for a long nap. What's the smallest Liion cell anyone has? I've got a little AA diameter, but 50% longer cell that's 700mAh and some prismic cells that are about that.

Then there is the high pitched squeal it gives off when charging Liion cells. I'm just glad I don't own a dog. It's bad enough being human near this thing. Okay, can't put it in the bedroom. Wonder if the 13 hour time out timer applies to the Liion mode. At only .4Ah, that only comes out to 5.2Ah. Hmmm, I'm pretty sure I've seen bigger packs. Hmm, laptop has a 4.8Ah 10.2V pack and it's three years old. Wonder what a new one would have?

There are nice features, though. You can have it simply charge a battery--from dead or partially charged. You can discharge a battery and automatically charge it back up--to wake up old NiCds, maybe or to form new cells. Or, you can just discharge the pack and leave it that way--good for reading off the capacity of a fully charged pack. I guess that's not bad for a one button charger. Though, it's no Sauce Light Wand! Now, that's a lot of function for one button.

What does everyone else think about this device? All in all, I'd recommend it as a good tool--like all tools, only use it for the jobs its applicable to.

Will, I think 400 ma for a 2.8 ah lion pack is as fast as you should want to go. Still may be too fast... I use the' li 'setting to charge my nimh's that get too hot (to hold) on the nicad setting..
I reported that noise it makes too, but no one believed me! At least 2 people posted they didn't hear anything..I guess you and I are just high frequency tuned people

People on other forums (Ham radio?) reported that at least the earlier versions of the 777 Plus would overheat, melt things, smoke and possibly catch fire if the AC input was momentarily interrupted while they were charging (as with a very short duration power glitch). Does anyone know if this problem has been corrected in the current version? Are there any warnings about anything like that in the documentation? There were also reports of ruined battery packs, I don't know whether they related to the previously mentioned problem or not.

John

Seems to be a problem with MAHA chargers in general...my MH-C204F will do the same thing, so I am just careful and watch it and know that if those AAs that should take 4 hours to charge have been in for 7 it might be time to take them out

Saaby; really? I thought those maha 4 aa C204F dealies were supposed to be the best most reliable chargers of their type around..not true?

Dang reliable, really quite a nice charger, but it does happen. Doesn't happen often and as long as you watch it you're fine. Like I said it's a "3 hour" charger so you just have to make sure it doesn't toast your batteries for much longer than 3 hours. Never actually heard of a charger melting or anything like that but it makes the batteries very very hot to the point of ruining them.

I had it happen to me, charged some Nexcell 1600s for 9 hours instead of 4, didn't seem to harm the batteries this time though. I've said it and I'll say it again, it seems to be constant abuse the ruins NiMh cells...not one time incidents like this one.

I've had a 204 melt the shrink wrap casings off of a set of Nexcells--older 1.3Ah cells. So, it can happen. This is all more incentive for me to design my own battery charger. I'll put a nice big LED display on it, too...

then the ccrane must be the king now? anyone had this one melt anything? and they're only $35 (shipping included) now.

I want a CCCrane but there was one thing I didn't like about it...can't remember what though. When I do remember I will tell you then you can defend it ok

**EDIT**

I just remembered. You can't have 2 cells charging and then add 2 more, it only has 1 charging circut. You have to let each set of 1 to 4 charge and then add the next set. Maybe I will get one for home use but my Maha is still going on vacations with me where I don't always have time to wait for 1 set to charge before starting another set.

About the only drawback with the Saitek/CCrane that I can see, is the series wiring. -But that's why you get the charger for $35.
p.s.-after roughly 2000 uses, no problems-(yet)

Ted,

The data sheet that I have for the sony li-ion cells that I want to charge shows a charge current of 1000mAh for a 1.6Ah cell. So, 400 for a 2.8 (pair of 1.4Ah)Ah cell *is* low by a factor of 5.

WRT the high pitched wine. I only hear it on Li mode and only for single cells (all the time during charge) and double cell (late in charging). I've not charged triple nor quadruple cell packs, yet. I've got a few, but I just haven't charged them, yet. I'll see how those go.

Oh, turns out that the new ][ version of the charger has a different li charging mode alg. It seems to charge about 1.5 times faster than the old one. For a large cell, the first hour racks up 600mAh. Still a bit lame for >1Ah packs (which almost all of mine are). Oh, and the discharge/analyze function only seems to discharge to 3.0V/cell, not the normal 2.5V. So, the capacity reads a good 10 to 15 percent low. I've got a 1.1Ah pack that consistantly comes in just under 1Ah on the analyze function. I'm tempted to do a manual discharge to 2.5V next time to make sure the missing 100mAh is really there. So much for a useful analyze function.

Cheers,
David

cannot recommend the 777+ yet.
a friend bought one at hamvention.
he put 10 5 ah d cells in a holder and charged/discharged them.
during the discharge cycle the power glitched and the charger melted down and burned the leads off the holder.
he took pics and sent them to the cpsc.
maybe they will order a recall?
heard a lot of reports of this happening but this is the first i have seen myself.
if you buy one use it outdoors or make sure your fire insurance is paid up!

Willmore, that's news to me about the high charge rate for lions, I don't have any lions so I wouldn't know, I just use the "Li" setting for some nimh battery packs..
The Maha site says it won't drain 1 or 2 batteries, or any pack under "2.4 volts"-
Here, I think, is their explanation of the discharge vs. capacity isssue, sounds like the 10% discrepancy you noted may be within the tolerances Maha considers "close" --

"...
"discharging capacity" refers to the actual energy "stored" in the battery pack. This number refers to how long the battery pack can last. If the final discharging capacity is close to the rated capacity of the battery pack, then the battery pack is in good condition...."

The Maha777 wasn't designed for Lion at all, I am pretty sure, as the 777plus is..I think the Lion charge rate on the plus is 400ma, lower than the nicad or nimh settting on the 777, (650ma/h )
--by the way I also use a Polder cooking thermometer in conjunction with the Maha, I set it for 95 degrees F. and it goes off before the batteries get too hot..!

Ted,
The ][ version of the new 777 plus has a new alg for charging Li cells. It seems to start at 600mAh instead of 400 and it tapers less agressively--which means much faster charge.

A proper Li-ion charger is a current regulator set for around C followed by a voltage regulator set for 4.2V/cell (for new chemestry cell, 4.1V for old). It looks like the ][+ isn't all that bad.

As far as discharging 1 or 2 Ni cells, they're right, it doesn't do it well--it gets the voltage and current measurements way off. I put one 800mAh NiCd cell on and hit discharge. I went away and then came back. At which time, it said that it had pulled 1.5Ah out of the cell an it was still at 1.5V. Right, 1.5V, 2x more current than the cell can handle, right. Told it to charge the cell and it put 650 into it, so it had only pulled out 575-600 or so. Yep, doesn't do 1 cell too well.

I'm not sure that using the Li setting for smaller capacity packs is a good idea. The charge termination criteria for Li and Ni cells are completely different. Li is more voltage based and Ni is voltage inflection/temp (more temp with this charger) based. As the saying goes, exercise caution.

Will, where is the "][" or "2" or 'II' in the Mah'a suffix anyway? I am aware of the '777 and the '777plus' but no "777plus2" -- am I missing something?
Yes after the Li charge for the nimh pack I switch to nicad charge rate, and attach the thermometer as I mentioned, the batteries finish off soon after that, usually while I'm at the computer..sometimes the thermometer alarm goes off first, sometimes the maha and thermometer simultaneously (that's always satisfying ) - sometimes the maha first, though I think i found the ideal temperature setting for the Polder thermometer to properly 'cook' batteries; 95 degrees F. !

i've never had anything bad happen with my c204f *yet* you need to make sure your batteries are close to the same voltage when you put them in since they dont have a individual charging circuit. i also have the trickle charger that can do 1-4 batteries at a time. its hotter than the c204f on trickle charge. so i wonder whats harder on the batteries? a quick charge or a trickle that keeps them fairly hot all day. either way ALWAYS leave the plastic door open while chargeing because it will help with cooling. just to be safe i wouldnt leave home with batteries in it but i think its reliable if used properly. my dream charger would be a c204f with individual charging circuits so i could toss in odd numbered batteries and not have to worry what voltage they are.

Oh, sorry, Ted, thought it was general knowledge. There is a new revision of the 777+ called the 777+][.

Cheanges:
New Li charging protocol (more agressive)
Indefinate hold at end of discharge (called 'analyze' mode)
Reset button on front of the case--it's the only way to get out of analyze mode.

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by mrchri5:
my dream charger would be a c204f with individual charging circuits so i could toss in odd numbered batteries and not have to worry what voltage they are.<HR></BLOCKQUOTE>

Then check out the Ray-O-Vac NiMH/Cd charger. Four bay, charge *per cell* and fast charge in NiMH mode good enough to fully charge 1.6Ah cells in an hour. I think the NiCd mode is lower as those cells tend to be smaller.

I've had mine for several months and never had it cook anything. It has refused to charge cells that it thought looked suspicious, but a little time on a constant current source and it'd take'em. Seems a nice device.

IMHO, charging individual cells at a time is the *only good way* to charge anything--Ni, Li, Pb, etc.

Willmore - I know you just suggested "checking out" the Ray-O-Vac (assuming no responsibility for what would happen next). I now own one too (bought the last one at my local WAL*MART). Looks impressive so far. I don't know how I have managed accumulate so many things that use three AAA or AA cells, but I've never really been happy with my Maha MH-C124S as it always seemed to heat batteries up more than I thought a relatively slow charger should have. Thanks for the tip.

John

Are you guys talking about the 3-in-1 Rayovac Charger (plugs into the wall) that is around $10?