First Look: Maha C777Plus2 and 18650 li-ions

[KevinL]

Where I come from we have a saying...thou shalt avoid being bitten by the same snake twice.

The snake, in this case, is unprotected lithium ions.

Those of you who remember The Incident took great pains to point out to me that it was the fault of the charger and not of the cells. This time, I'm doing things a little different.

Precautions: use of a pro-grade Maha C777Plus2 charger designed specifically for lithium ions. Using one cell at a time ONLY, a single 18650 in a SF U2. Charging only one cell at a time. Disposing of overdischarged cells immediately, although it has been communicated to me that the U2 shuts down at 3.15V and thus should not dangerously-discharge the cells. Halon 1301 10kg extinguisher beside the test bench. ("Nothing works as good as Halon") Kevlar helmet rated to stop NATO 5.56x51mm ball rounds should The Incident happen again.

Am I missing anything? Or should I go with Pilas instead?

Edit: I just chopped up a Dell Latitude LM P133's battery pack and salvaged 3 x 18650s out of it. I think they're 1300mAH units - not bad for a 8 year old laptop. It had 9 cells, 6 of which were corroded beyond all hope and discharged to around 0.1V, but 3 of them are 2.5V and 3.5 flash amps - salvageable!

It's kinda sad to chop up the pack, especially since this laptop means a lot to me, but the pack has been dead for around 3 years already, and I guess it's better that the pack donates its cells to science and lets them live on in a cutting edge light of tomorrow /ubbthreads/images/graemlins/smile.gif

Gonna get my C777 soon..


(Update: Got it. scroll down for first impressions.)

 

[vacuum3d]

Re: Advice needed: Maha C777Plus2 and 18650 li-ion

Kevin,
I have the C777Plus-II. I don't recommend it for charging Li-Ion because it doesn't stop at v4.2. I have a variety of Li-Ion cells. Some stop at v4.4x, and some stop at v4.3x. The lowest I've seen it stop the charge was at v4.27. These numbers were measured after the batteries have been rested overnight. The manual even says the charge voltage reading is not accurate.

If someone knows a way to adjust the charger to stop the charge at v4.2 would be much appreciated.


ernest

 

[KevinL]

Re: Advice needed: Maha C777Plus2 and 18650 li-ion

I thought the Maha's problem was being excessively conservative and UNDER-charging them to 4.1V? Hmmm..

I gotsa bad feelin bout this...... /ubbthreads/images/graemlins/crazy.gif

 

[flashlight]

Re: Advice needed: Maha C777Plus2 and 18650 li-ion

Sorry Kevin, nothing to contribute here but isn't Halon hazardous to the health? /ubbthreads/images/graemlins/icon3.gif I see the 'Evacuate room when halon is discharged' signs at the MRT stations. /ubbthreads/images/graemlins/grin.gif

 

[KevinL]

Re: Advice needed: Maha C777Plus2 and 18650 li-ion

Just kidding about the Halon actually, you can't buy them any longer (banned under international treaties - dangerous to the environment, depletes ozone, etc.etc.)

Where I used to work we had a large datacenter, also protected by the automatic fire suppression system. We used to say "It'll put any fire out in 30 seconds - and YOU out in 20 seconds, so when the alarm rings, YOU LEAVE." /ubbthreads/images/graemlins/grin.gif

Thanks for inspiring me to spend money /ubbthreads/images/graemlins/evilgrin07.gif

 

[gregw]

Re: Advice needed: Maha C777Plus2 and 18650 li-ion

Hi Kevin,

I've never used the Maha chargers before, so I really don't know how good/bad it is.. However, I do remember that about 1.5 years ago, when I was just getting into using bare Li-ion for my RC helicopters, a US vendor originally sold the older version of the Maha charger for a while, but there were a few incidences of over charging which caused the vendor to stop carrying them. I hope the current version takes care of this problem, but from the post from vacuum3d, I'm not too confident that they've resolved the problems.

Just FYI, I use a Schulze ISL6-330D for all my charging needs, and so far, it's performed flawlessly. If you're looking for a strictly Li-ion only charger, you might want to consider some of the ones on this page.

 

[Tweek]

Re: Advice needed: Maha C777Plus2 and 18650 li-ion

I'll shamelessly plug the Great Planes Triton while I'm reading this thread, I have one, and use it for charging just about every non-typical consumer battery (read everything but AA's) I've got. I love the thing! I'm thinking about getting another! /ubbthreads/images/graemlins/grin.gif

Chris

 

[red_robby]

Re: Advice needed: Maha C777Plus2 and 18650 li-ion

i use the C77plusII, and never had a problem with over charging Li-ion cells

 

[KevinL]

Re: Advice needed: Maha C777Plus2 and 18650 li-ion

Maha's on the test bench right now with an 8+ year old lithium ion cell. I got one that has the new packaging, new manual, new logo and all. It's definitely the Plus2 model. (some were Plus2 models shipped with Plus-only docs/box)

The only thing is that the high pitched screech is quite real. You won't sleep well with this one, but I don't intend to sleep with it on - I'll be sitting here waiting for the cells to finish.

This is one nice slick charger apart from the acoustics. I love the 'fill' gauge, so if you are doing an attended charge, or popping in every 30 minutes to see whether it's done, you can stop when you're ready. Let's say you get to around 90% of the cell's capacity and you decide it's not worth the hours of waiting to top it off, grab 'n' go. (better for lithium ions, so they say - point of diminishing returns).

Since I'm doing a full charge of a very depleted cell at 2.5V that has sat for literally three years after its pack died, the mAH capacity numbers during charge would be very close to the actual capacity that the cell can hold.

Here's the shocker.

I pulled the cell from a 9-cell pack, 10.8V, 3900mAH, wired in a 3x3 configuration (3 parallel 3 series). That means each cell has 1300mAH nominal capacity.

4.5 hours later, the Maha hasn't 'officially' finished but the cell has hit 1310mAH. A DMM check of the voltage says 4.12V.

WAY TO GO for a 8 year old Sanyo cell!! /ubbthreads/images/graemlins/bowdown.gif Dell really gave me *PREMIUM* cells in this pack - I always knew that laptop had that something special extra. Oh and get this, during its service life, I estimate I put 1200 charge cycles on that pack because it was discharged once a day average (sometimes twice), every day, for 3.5 years.

 

[rick258]

Re: Advice needed: Maha C777Plus2 and 18650 li-ion

I'm interested in this charger also. From reading the manual it states that to charge individual cells you need a cell holder and I am not aware of one for the 18650 so how does one charge the 18650 with this charger. Thanks Rick

 

[KevinL]

Re: Advice needed: Maha C777Plus2 and 18650 li-ion

Note to Maha C777 owners: set your chemistry properly.

I had two cells charged to 4.27V because of a $#*(up relating to the chemistry setting. Fortunately, since I was around, I saw the voltage going too high and checked the status panel in time to stop it from getting out of hand. You WILL get overcharged cells if your Ni/Li selector switch is set wrong.

Mine terminates the charge properly when the cells reach 4.2V with the selector switch in the right position. I usually get something like 4.18-4.20V, nothing over.

 

[flashlight]

Re: Advice needed: Maha C777Plus2 and 18650 li-ion

[ QUOTE ]
KevinL said:
Note to Maha C777 owners: set your chemistry properly.

I had two cells charged to 4.27V because of a $#*(up relating to the chemistry setting. Fortunately, since I was around, I saw the voltage going too high and checked the status panel in time to stop it from getting out of hand. You WILL get overcharged cells if your Ni/Li selector switch is set wrong.

Mine terminates the charge properly when the cells reach 4.2V with the selector switch in the right position. I usually get something like 4.18-4.20V, nothing over.

[/ QUOTE ]

That happened to me too just today Kevin /ubbthreads/images/graemlins/jpshakehead.gif I put 6 2100mAH NiMH AAs in a battery holder & rigged them up with the clips & had them going for at least an hour without thinking at all why the heck the voltage read 8.something volts when it should be around 6 right? Then I realise that I had it on the Li & not NiMH setting! /ubbthreads/images/graemlins/icon15.gif Did a discharge/recharge & the cells seemed to be ok except that the charger cut off again after about 1.5 hours with an Err3 display which either means that it terminated the charging when the cells reached the preset cutoff temperature of above 51 degrees Celsius or that they were fully charged already. /ubbthreads/images/graemlins/icon3.gif