The histrory of V-228 or T-228 9V Ni-MH / NI-CD Charger 120V 60Hz

[Kiriakos GR]

One decade back, I got from the USA four of 9V Ni-MH batteries these branded as Tenergy.
The batteries were offered with one Plug-In Type Ni-MH/Ni-Cd Battery Charger, two ports 9V Block Model T-228.

Due the fact that this charger is not supporting 240V, I did test it once with step-down transformer, and I just keep it as a spare one.
The charger came with out datasheet, and or carton packaging.

This week I did discover a photograph of retail packaging, and the information's over it this was a blast to me.
Charger technology this is ancient, as it was primarily designed to charge 9V NI-CD 
I never owned any 9V NI-CD, so I was totally unaware that these batteries they are supporting 120 mAh as Max regarding capacity.

Long story in sort, all 9V Ni-MH they support much higher capacity.
But this specific charger, USA import, this only supporting slowest charging rate because it was designed to retain compatibility with NI-CD 120 mAh as Max

If you own such a charger, just be aware that its simply slow by design.
Below are photographs giving you a hint of charging times when using higher capacity Ni-MH.   


Charge Times
9V NiMH 150-180mAh - 12-14 Hours
9V NiMH 200-275mAh - 18-22 Hours

[Kiriakos GR]

Today I decided to run few tests on this charger.

There is a back plate, this informing of maximum charging current this be 16mA.

Inside there is a copper transformer  120V to 12V AC.
The charging circuit per port,  this has two transistors, few resistors , few diodes, and not a single capacitor. 
This is 100% analog technology.

I am currently testing an aged 9V NIMH, the charger does not look able to output more that 9.5 mA and voltage output this is 9.600 V
I do plan to leave the charger active overnight, my PC this logging voltage and current simultaneously due my FLUKE 8846A and it special measuring function.

Personally I do own two modern ANSMANN chargers, the Energy 8 along of the  Energy 16 model.
Both able to deliver 70mA per 9V port.
This is named as fast charge mode .

But I am now very puzzled, at 2018 I got four 9V NIMH with the specification of 42mA as charging current.
And today they are not at the best shape, while one of them stopped working.

The new question is,  did I got poor quality cells?
Or ..
Did the high performance ANSMANN chargers, was too much for these average quality cells?

Either way, I am now researching  this sector of 9V NIMH and chargers.
In a few days I will have enough clues.   
   

[Kiriakos GR]

Regarding charger model, I found another rebrand of it in the USA ( This available at the Year 2015)

Lenmar PRO 9V2 battery charger

Key Features and Benefits:
Charges in 10-16 hours
Plugs directly into AC outlet
LED as charge activity indicator / LED goes off when battery this is removed.

----------------------------------
Either way, due these analog chargers, I came closer to older NIMH charging knowledge. 
This Low-Current charging at 10mA, this is also named as constant charge, this be absolutely harmless for the 9V cell.
Permanent charge 10~12mA this is the grandfather of modern Trickle charge = 7mA.

Current flow of 10~12mA this is very dependent to battery internal resistance.
Therefore an old battery with high internal resistance this will not aloud us to measure a high current flow from the charger.

[Kiriakos GR]

After testing my own charger with 120V step down transformer, I did discover that this charger it does deliver according to specifications.

By charging a 8.4V NiMH Cell (this be in a good shape), the charging circuit elevates charging voltage up to 10.5V as it should do.

The problem of this charger, this causing overheat at it own housing, internal AC/AC copper transformer this gets hot at 57 Celsius with or with out load.
My next decision this was rescuing this usable charger, by actual conversion to 235~240 direct input. 

The electrical conversion it was not that easy, 120V factory transformer this has precise output of 12V.
All named as 12V copper transformers, they deliver much higher output than 12V.
Then I was forced to inspect several 9V named copper transformers, and my lucking find, this delivers 11.85V at 240V.

This 11.85V at 240V ACV copper transformer,  with an capacity of delivering 1000mA, this also run hot at no-load, at approximately  48 Celsius.
In the positive side of things, my converted charger this does not include any foreign heat source in it housing. 

[overvolt]

This ACV conversion, it waked up memories.
We are close to forget, that its in their nature at copper transformers, of them heating-up even without load.

Its a fact that only elder electricians, will enjoy most this presentation. 
Nice work!

[Kiriakos GR]

This charger it is an addition to my fleet of chargers which I never had before. 

Currently due my ANSMANN Energy 8 and Energy 16 (as combined),  I can charge a number of six 9V PP3 simultaneously, due micro controller supervision.

Constant charge Slow Speed, this has an hidden advantage, it can assist new and unused batteries, them to recover at full capacity, if they lost any when they were in storage.

8.4V PP3 this has inside seven cells, DV detection it can happen while most of the inner cells get charged.
But there is no warranty that all seven cells inside they were fully charged.
We simply assume that all cells inside they have identical internal resistance in mOhm, and that under manufacturing, they were pass identical quality control (QC).

After much of thought, I did realize that Constant charge, this is the only method this working if favor of balancing.
First charge by such a charger, this is a warranty that all cells inside they were fully activated = “Forming Charge”.
Then a charger with micro controller, this will have to deal with a 100% balanced battery.   

Trickle charge of 7mA, this is powerless to assist balancing.

To me every detail this it does matter, I do consider my NiMH batteries equal to financial investment.
Any prematurely failed battery, this is measurable money loss to me. 

[Kiriakos GR]

V-228 charger this is not a box full of resistors. 

I am not going to help at PCB and diagram replication.
This thing using a pair of push-pull amplifier transistors per slot.
S8550
C9013

By the use of my oscilloscope I did discover RMS AC Max pulse voltage.
The circuit uses the incoming 50Hz or 60Hz as synchronization frequency.
The problem is that at 50Hz I am not able to get 16mA of current, and I get as maximum 13.5mA
In other words,  V-228 this gets a bit slower when working at my side of the pond.

Without a battery there is no DC voltage output. 

According to my latest findings, I will have now to recalculate my charging tables.
This detail / discovery, it will extend the required hours of a standard charge.

My new puzzle :
Is it worth the time and money of me to replicate V-228 circuitry?
Or should I pay 15 Euros, and get a similar European charger? 

My actual need, this is of me having available four slots for 8.4V PP3 for standard charge.

[Kiriakos GR]

I have excellent news to share.   

This unique electronic circuit design of V-228, this motivated me enough to add voltage monitor external connector.
Then I did activated my heavy weapons 

This V-228 charger, it is now converted to High End power source for battery capacity forming !!
Since today I am able to monitor both charging bays voltage.
Additionally for my benchmarks with identical batteries, now I am able to see top-up voltage status, and I will be able to terminate the charge, as soon both batteries they are at the same level.

Ideally I would like to have 25mA output per slot, but either way I will keep testing with 13mA, until I get better chargers in a few weeks of time.

I am proudly present my humble test setup ...    (with wireless communication). 

Note: First testing session still in progress ...

[Kiriakos GR]

Final conclusion  ... 

8.4V PP3 worldwide this has as nominal voltage specification at standard charge the value of 10.3V.
The theoretical 10.5V   this is maximum allowed.

These poorly made ANSMANN datasheets, they mention 10.5V in text, but the damn standard charge graph, by zooming in, it does show 10.3V.
The voltages as 10.4V up to 14.5, these are references relative to Fast Charge.
I do not perform any fast charge here.... 

According to my own charger, this succeed to reach highest charging voltage CH1 10.196V and CH2 10.175V .
This is approximately 100mV lower from the ideal 10.300V

An good designed charger this should be able to load a NiMH at 80% SOC, this little charger delivers much higher performance with a pair of new batteries.

Just for the shake of correctness, I am now using my bench-top and professional PSU, output voltage at 10.3V, both batteries connected in parallel.
Both of my ANSMANN Typ280, they require a current of 19mA from the PSU, and both stay frozen at 21C.

Just as experiment I did force 10.400V for two hours, and one of the two batteries this started to get warm at 50mA CC Mode.
When I lowered the voltage to 10.300V,  both batteries temperature returned to ambient. 

I could never imagine that just 100mV on top, they will have such an impact.   

I feel much more educated now, about 8.4V PP3 charging conditions, and of what can cause a Thermal runaway.
Now I am fully aware of what technology my new charger for 8.4V PP3 this it must using, and output current this is must be also selected carefully.


About my V-228 testing process I did ended it, when I realize that there is no voltage increase at any of my batteries.
An tiny voltage fluctuation this appeared at both charging channel simultaneously, but I did realize soon enough,  that ACV Mains fluctuation this was causing it.

This was a long journey, over 40 hours of monitoring and experimenting, but I did learned a lot !!