Maha 777 Charger Issues

[jlfletc]

I have a Maha C777 Plus (Not the C777 Plus-II), which appears to not fully charge some of my Maha 7500mAh and 8000mAh D Cells. I'll use the Ds in an appliance or flashlight, until they need to be changed. Then, I'll charge them on the C777, usually two or four at a time. They'll charge for a couple of hours, and then the charger will say full, but only show about 2750 mAh of charge. I've tried discharging the batteries on the charger, and it'll discharge about 3000 mAh worth, then it'll start charging the batteries back up, but it will indicate full again at around 2800-3000 mAh. What's going on? Are these batteries actually only 3000 mAhs? Are they defective? Is the charger defective? The batteries are about 6 months old, and have been through about 25-30 charging cycles. TIA

 

[Pellidon]

Re: Maha Charger Issues

Do they get hot during charging? I use the 777+ on my Zero and sometimes on my 8NX but I run a fan on the battery to keep it cool. I have pumped 3000+ into a 5 cell pack that CT-Zero states is a 2200. I think they under rate the batteries.

Or maybe the pack is false peaking. Have you tried a second charge after the stick cools. False peaking casued me some embarassing DNF's when I was running NICAD's in my RC car.

 

[jlfletc]

Re: Maha Charger Issues

The batteries do not get very hot when charging. It's possible that the charger is "false peaking", but it is very consistent, so I'm not sure what's going on.

 

[snakebite]

Re: Maha Charger Issues

you are hitting the 180 minute timer.
it takes 3 cycles for the 9ah f cells i use here.disconnect and reconnect to start over
lather rinse repeat.

 

[Wingerr]

Re: Maha Charger Issues

The safety shutoff timer on the 777Plus is supposed to be 13 hours, so apparently the voltage is triggering the shutoff. The specifications indicate that it's supposed to be able to charge a pack with 10.4AH capacity (13 hrs at 800mA), so it should have been able to do it in a single cycle- It doesn't seem like the voltage detection circuitry on this is working as intended, since there's three instances of low charge shutoff. Naturally I've passed the warranty period before I really bothered to look into it- it's always tended to do this, but I haven't checked it until now, figuring it was the batteries.
I suspect the problem is that it's not really suited for charging multiples of two batteries; it may have been designed more for higher multiples.

 

[snakebite]

Re: Maha Charger Issues

maybe it it only 180 min on the +2 then
mine always stops at 180.i think they were trying to minimize damage if all methods of full charge detection failed.

 

[Wingerr]

Re: Maha Charger Issues

Could be. I only saw the manual for the Plus.
Odd; I just ran a pair of depleted Energizer 1700mAH NiMH's through it, and it went to 1969mAH. Could be that it's more sensitive to the brand or condition of the batteries than the other chargers.

 

[jlfletc]

Re: Maha Charger Issues

There is something to the 180 minute thing, as I've disconnected and reconnected multiple times, and the charger puts about 2600 mAh in each time, although one time it stopped at about 400 mAh, but the next time put in 2600 mAh again. I hope this thing is smart enough to know when to stop charging...... I would really like to see a newer version from Maha, that will just determine the capacity of whatever batteries are hooked up to it, and charge them fully without monkeying around with it.

 

[lemlux]

Re: Maha Charger Issues

I paid for a MHC777 Plus II and received a Plus II box with a Plus and plus manual inside in the last week or so. I'm trying to get the seller to respond to an email complaint.

This unit charges for more than 3 hours.

It also "malfunctions" in a way that delights me. It is supposed to charge Li-Ions at a rate that starts at 300 mA and declines as the battery approaches full charge.

It actually charged a fully discharged 26650 at an average rate of 620 mA for the first 45 minutes and declined to an average of about 600 ma after the first 2 hours. This particular puppy isn't as slow on Li-Ions as the specs indicate.

 

[snakebite]

Re: Maha Charger Issues

not so fast.the 777+2 i have does not say +2 on it anywhere.
if it is a +2 if you hold the discharge button down a few seconds the disch indicater will stop blinking.
at end of discharge it will hold the final reading and need a reset to go farther.

[ QUOTE ]
lemlux said:
I paid for a MHC777 Plus II and received a Plus II box with a Plus and plus manual inside in the last week or so. I'm trying to get the seller to respond to an email complaint.

This unit charges for more than 3 hours.

It also "malfunctions" in a way that delights me. It is supposed to charge Li-Ions at a rate that starts at 300 mA and declines as the battery approaches full charge.

It actually charged a fully discharged 26650 at an average rate of 620 mA for the first 45 minutes and declined to an average of about 600 ma after the first 2 hours. This particular puppy isn't as slow on Li-Ions as the specs indicate.

[/ QUOTE ]

 

[lemlux]

Re: Maha Charger Issues

Snakebite:

I sure hope you're right. The procedure you mention is not in my documentation.

I'll try that tomorrow when I get my hands on it again.

Anybody else experience a 600+ mA charge rate on Li-Ions?

 

[lemlux]

Re: Maha Charger Issues

Snakebite was right!

I apparently do have a Plus II. Keeping the discharge button depressed causes "Discharge" to stop flashing.

A Plus II that charges Li-Ions at >600 mA instead of 400 mA and discharges at 360 mA rather than 300 mA.

I lucked out.

I need to send an apology email to the vendor now.

Snakebite: Did you receive a separate Plus II documentation that described the procedure to defeat the automatic recharge after 15 minutes?

 

[snakebite]

Re: Maha Charger Issues

there was a little slip in the manual.
maybe you missed it or it didnt make it into yours?

 

[lemlux]

Re: Maha Charger Issues

Snakebite:

If there was a little slip, I inadvertently threw it away with the box. I have the PLUS manual and the PLUS FAQ.

 

[dee]

Re: Maha Charger Issues

Anybody ever get to the bottom of the 3 hour cut off?

I've just go my 777Plus2 (brand new, Plus2 marked on charger, box, manual & slip in box) and it does exactly the same thing - 3 hours and displays full.

This is a major PITA as one of the main reasons I bought this was to charge a 14V bike light which I want to leave charging overnight & then use in the morning. If I'd known about the 3 hour cutoff I'd have bought a cheaper charger for the flashlight cells & a dedicated one for the bike light! Can't even get round it with a timer switch as the charger reports an error if it's powered up with a pack connected!

 

[Kurtos]

Re: Maha Charger Issues

?

I've been able to keep a charge cycle on my plus II for 8-9 hours for my bike light battery. I'll try running down on a ride today and paying attention to the charge time.

 

[Illuminated]

Re: Maha Charger Issues

How many cells are you charging at once?

I have the 777 w/o display, and I don't think it recognizes unusual combinations like 8.4V, 10.8V, etc.

Just a thought...

John

 

[Brock]

Re: Maha Charger Issues

Hummmmmm, I have never had it run longer then 180 min either. And here I thought it was just lucky. So is there a way do get the 13 hours to work? I thought it was odd that it stopped charging, then I put them in the 1HU and it charged them for about 4 more hours.

 

[dee]

Re: Maha Charger Issues

Not sure what's going on. I tried mine with some 6V 2450mAh camcorder cells last night and they charged just fine - took 245 minutes.

The D cells though will only do 180 minutes per charging, doing them as 1,2 or 3 in series. Also, the auto cut off doesn't work for the D cells, it just keeps dumping 180 minutes worth of charge into them each time the charger is reset. Luckly I don't think this will damage my D cells as their spec sheet says they show no degredation if over charged at 900mAh but I'm a bit wary about charging AAA/AA cells in this charger - does it actually cut out before 3 hours on cylindrical cells at all?

 

[Brock]

Re: Maha Charger Issues

I wonder if it has a 3 hour limit on the leads? If it does have a 3 hour limit and no auto shutoff with the lead this charger won't be very helpful. I was going to use this to charge 8 9000mA D cells, at this rate I would have been better off getting 2 more Vanson 4 D chargers. /ubbthreads/images/graemlins/frown.gif