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Old April 23rd 05, 03:57 PM
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Default MAHA MH-C777PlusII MAHA MH-C777 battery reconditioner recommendation?

Just two questions..
1) Has Maha fixed the alleged bugs in these users' reports/review
posted on other boards? (snipped below)
2) Any recommendations on a universal battery analyzer/conditioner for
NiMH and Li-On, if cost is not an issue? (One that doesn't have any
safety concerns, and works unattended. Purpose is to recondition
weak/bad/dead cells.)

Thanks for all replies. If this is not the correct forum, sorry,
please point me in the right direction (URL/link.)


http://www.eham.net/reviews/detail/2515

bought a MH-C777PLUS-II. The batteries being charged with it seemed to
me to be getting way too hot... About 50 to 70 degrees F above
ambient.
I called Maha and spoke to the engineer. (Lucky for me the engineer
answered the phone that evening, because later, when I spoke with
anyone else they had no technical understanding of how this model is
supposed to work, not even tech support.)
During our phone conversation the engineer and I determined that my
MH-C777PLUS-II was overcharging. Maha arranged to send me a
replacement unit. I received the replacement a week later. I tested
the replacement unit, and it had the identical problem.
The problem is that these units overcharge the cells. The unit is
supposed to stop rapid charging and switch to a float charge when the
Negative Delta Voltage is at about .007 volts per cell. My tests have
determined that the units do not switch to a float charge until the
Negative Delta Voltage (NDV) is .065 volts per cell. (almost 10 times
greater than spec.) I'm sure you'll agree this is an unacceptable
amount of overcharging and is harmful.
I have charged and recharged seven different battery packs many times.
I have tested with five different brands of batteries. I have tried
NiCd and NiMH. Sizes range from 1000 mAh to 2200 mAh. I have plotted
Current, Voltage, and Temperature. The amount of overcharge is about
the same on any battery pack, any brand, and either NiCd or NiMH
chemistry. In total, I plotted about 50 charge cycles.
When charging SHOULD BE considered complete, (that is... the Negative
Delta Voltage is at about .007 volts per cell) the temperature of a
battery pack was typically at 85 to 95 degrees. Very reasonable
temperatures for rapid charging at 800mA. In my tests, the ambient
temperature was always around 70 degrees F.
HOWEVER... THE MH-C777PLUS-II KEEPS CHARGING ANYHOW ! By the time the
MH-C777PLUS-II units stop overcharging and switch to a float charge,
the battery case temperature has often risen to 140 degrees F.
Certainly not healthy for the cells.
Just to clarify: The NDV is not erratic. It is always wrong about the
same amount. Funny thing... the NDV is off by an amount very close to
one decimal point! I wonder if that could be caused by a programming
error of exactly one decimal point somewhere in the algorithm!! Could
that be??
It seems unrealistic to assume that I have received two bad units,
especially since they have serial numbers that are numerically far
apart, different looking boxes, and reprinted manuals etc.
Five times I requested Maha to agree to test my units and confirm my
findings. They never responded.
Please learn from my mistake. Do not buy one of these.


After sending back several defective MH-C777PLUS chargers to MAHA,
they sent me a MH-C777PLUS-II.
It didn't take long to realize that this thing is no better than the
original. I tested using some of my older packs, since the original
liked to cook them. The results are the same. It charged a 1200mAh
pack up to over 2000mAh before I decided to disconnect it before it
melted. The temperature sensor obviously doesn't work. I tried to
discharge a good pack, and it just froze up after a few minutes. Maybe
by the time MAHA releases the C777PLUS-IV, they will get it right.


I've had this unit for about 6 months now. It seems to work OK on
NiCads but be careful with Lithium Ion. My unit nevers completes a
charge. Instead, it goes into a non-stop beeping mode after a couple
of hours. Removing the battery doesn't help, you have to unplug it. I
talked to the Maha people at Pacificon. They acknowledged there was a
problem with all of the MH-C777 Plus chargers. Their recommended fix
was to buy a MH-C777 Plus II and scrap my "old" unit. No trade in of
course. Not exactly what I would call good customer support. I'm
considering going after it with an ice pick to break the speaker so at
least I don't have to listen to it. Another issue with this charger is
that unless you are right on top of it when it finishes the battery
condiditoning cycle, you will not know how your battery is doing.
There should either be a "start charge" button or some way to recall
the battery capacity at a later time. All in all, I wish I hadn't
bought this charger and am quite disappointed.

http://user.fundy.net/cyclist/review...777PLUS-II.txt

From: Per Elmsäter Subject: BC Maha C777PLUS-II
review Date: Tue, 25 Nov 2003 00:39:22 +0100 Message-ID:


This message has been edited and resubmitted by Per Elmsäter.

Due to input from the bikecurrent mailing list I bought a Maha
MH-C777PLUS-II charger recently. One of the reasons I chose it was
because it was capable of charging up to 12 cells which is something I
wanted due to the simple fact that I have 12 cells in my battery-
pack. I am primarily using it to charge these 12 NiMH cells to 4500
mAh according to their specs. Thanks to the digital readout I can see
that this is what I'm getting. I can do a discharge cycle where it
will automatically continue by charging at 800 mA. This shows that I
receive between 5100 - 5200 mAh. This of course is a higher number
than I receive at discharge, 10-15 according to Maha, and seems quite
normal. When full I can also do an analyze cycle which then discharges
the full battery at a rate of 300 mA. I have not done this yet on my
bicyclepack, since discarging at this rate takes a very long time.
Charging is usually 420 minutes from empty. Another feature apart from
the digital readout is of course several diffferent means of detecting
a full charge.

- Negative Delta V - Zero Delta V - Delta Temperature - Timer. ( It
always cuts off after 13 hours ) If you have more than 13800 mAh =
10.4 Ah you can start a new cycle after 13 hours and it will then
detect a full charge by one of the other three methods, according to
the manual.

So far only the Negative Delta V has terminated my charge.

It will also charge all NiMH, NiCd and Lithium-Ion, Lithium Polymer
chemistrys. 1-12 cells of Ni and 1-4 cells of Li. It will however not
discharge a single cell. You must have a minimum of two or three
cells. I forgot which.

My simple Sigma Mirage lighting system is now the brightest system in
our forest. My 20 overvolted 20W beam definitely feels bigger and
brighter than for instance a Niterider Blowtorch. The 5W beam is
plenty enough except when going fast. I get a max of 9 hours and a min
of 2.25 hours. Having a button by my thumb makes it easy to switch
down to 5W as soon as I hit a long climb for instance. So I figure I
can easily stay out 4-5 hours and have all the light I need, or
commute for 9 hours. Thankyou all on the bikecurrent mailing list that
guided me to this solution. I am as of now not using a LVR but it will
come as I refine this setup What I am doing now is running two
packs of six cells each in parallell. This gives me 9Ah and 7.2V. Ie
20 overvoltage. Of course it's way over 8V when I start out but the
bulbs haven't blown yet. When charging I connect all the cells in a
series to avoid problems. This is of course done automatically by how
the connectors to the batterypacks are bridged. When I connect the
lights to the four pole connector coming out I get a parallell
connection and when I connect the charger to the same four pole
connector I get a serial connection. Very simple actually. The
bridging is done on the incoming connectors. Out of the batterypack I
just have two plus and two minus on a four pole connector that know
nothing of each other.

Now to the criticism. Well it wasn't the cheapest charger around but I
believe it is worth it's money. Especially since I can use it for many
other appliances also. The temp sensor is on a very short cable, about
15 cm to be precise. This makes it awkward sometimes when charging
something except cellphone batterys and other small stuff. I think
this is what they had in mind when designing it since there are plenty
of small springy contacts on top, makin it easy to connect all sorts
of small batterypacks. Plus a short cable with alligator clips on it.

However : Here comes my biggest cause of concern. The charger does not
easily detect what kind of batteryconfiguration you are hooking up
unless you connect it to the naked minus and plus poles. Then all you
need to do is tell the charger if it is a Li or Ni cell you are
conecting. The manual states that when using the charger directly on a
charge connection that is protected with a diode, rather than a
discharge connection, then the charger cannot detect polarity. They
continue by saying that all you need to do then is figure that out
manually and switch it over if needed. There is a polarity switch on
the charger. Well I thought, no problem I have a Voltmeter. So I
connected straight into my Cateye Ellipsoid bikelight where the
original charger goes in. It is 5 NimH cells and they supply a 9V
charger with a 300 mA current. Well the Maha charger started out
reading something around 6 V but after only a few seconds it went
straight back up to 22 V. It was no time before my bike light was
smoking ;( Well you win some and you lose some so I figured there was
just too much electronics inbetween and decided that the next time I'd
see if I could get a voltage reading first, before I started. This
time I tried an electric screwdriver and measured 3.55 V. I connected
the Maha charger. It showed 3.55V for a few seconds, then it went
straight up to 14V. This time I was a little quicker and I think I
saved it. Anyways it is still functioning even though it smelled quite
a bit of plastic. This is actually too bad since many times it is
quite a hazzle getting hold of the naked poles without any electronics
inbetween. I could really appreciate a manual override where you could
tell the charger how many cells are there when needed.

But, for the batterypacks that I build myself it is absolutely super
and I can surely recommend it. Also for cellphones, digital cameras
and such of course. I analysed my wife's cellphone battery when she
complained about it going dead as soon as she talked a minute. The
digital readout told me it would only hold a 25 mAh charge so we
didn't have to wonder any more. I must say I really appreciate this
simple digital display.
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