History review of Bosch Nickel-Cadmium (Ni-CD) AL60 & AL60 DV chargers

[Kiriakos GR]

First ever released Bosch AL60 charger this shown in the market at 1992, this charger were designed to be first multi-volt charger this serving battery design of Bosch TYP:
7,2V 2607300001 1,2 Ah
9,6V 2607300002  1,4 Ah
9,6V 2607335176  1,7 Ah
12V  2607335014  1,4 Ah
12V  2607335180  1,7 Ah 
All tuber type ( Knolle accu -> in German ) Ni-CD battery.

Difference of voltage output mostly translates to different length of half to bottom battery pack compartment.
Due pictures comparison it seems that 9,6V battery and 12V are brother models, and this translates that it is very possible 12V version to be easily clip on and be used at 9V power drill.

First released Bosch AL60 charger this came with Bosch label in which word of   ACCU (battery) are capitalized.
This charger can do 4,8V & 7,2V & 9,6V & 12V, Bosch due their Ni-CD cells capacity selection it did limit Amperes output to 1.4A (entire series using 1.4Ah Sanyo).
Such charger also named as 1 Hour Bosch charger at 33W.
Code: 2 607 224 152

Later on, Bosch created first AL 60DV this be identical model to AL60, only difference for Europe this is product label with out German text.

Practically AL60 & AL60DV (rev1) these are well build chargers, both using real transformer and PCB this is using few smart IC and minimal amount thru-hole electronic components.
PCB other than having multi-volt detection, this also using temperature detection due a connection with in-battery located sensor. 
Temperature sensor this is actually a resistor sensitive to temperature change, and resistance changes according to Celsius change.

Soon I am going to have one AL60 (AL60DV rev1) Bosch  2607224226 and detailed pictures will be presented.

Speaking of Bosch, they did produce several products by reusing AL60DV label and by adding further more numbers so to separate models, example AL60DV xxxx.
Such chargers are totally different in many ways and primarily they are incompatible with first AL60 or Rev 1 AL60DV.
Newer AL60DV xxxx these serving different battery case, additionally they use more modern but less reliable pulsing power supply this serving as mains transformer.
Additional issue looks to be that charging of half damaged batteries and because this process lasts longer, several components gets damaged due overheat.

My own research over the internet so me to find just of curiosity, pictures of AL60 (AL60DV rev1), this it did drive me in to pictures of later on made chargers, which several shown symptoms’ of damage.
Interestingly enough it seems that Bosch it did push the envelope of fast chargers to it limit.
I did spotted 4.8A and even 5.6A fast chargers.
Here are some facts that very few are aware of.
Made in Japan Sanyo batteries they were premium quality, but they are not made any more.
Sanyo Ni-CD cells (of the past) were able to tolerate higher charging voltage even up to 1.7V and also to be abused with out damage.
Within 2017 all that we can find this is  “Made in China” compatible Ni-CD, them not build up to highest specifications’ of old SANYO Ni-CD.

Outcome of all latest changes this is that rapid chargers of old days, nowadays they will deteriorate much faster any latest produced “Made in China” compatible Ni-CD cells.

Naturally, charging current this is always related to battery capacity.
Therefore if we do purchase true capacity of 2000mAh (2.0Ah) Ni-CD, then C1 charge this is 2A and any specified as one hour charger this is up to specifications’.

From the other hand all Ni-CD will eventually deteriorate and cell capacity this becomes lesser and lesser.

Therefore and in conclusion, if you do seek for optimal charging current for maxed battery pack life, this is 2.0AH battery with 1.4Ah charger.

[Kiriakos GR]

In above message I did a good analysis of  two models of 33W ( AL60 & AL60 DV)
Next revision of AL60DV charger this is 44W 1.9A and at voltages range, much older 4.8V option this is now removed.

This AL60DV 44W charger can do  7,2V & 9,6V & 12V & 14,4V  (Bosch code 2607224275)
Circuitry this is identical to AL60 or and 60DV at 33W,  inner changes that Bosch did this is mainly two output transistors be replaced with ones having a bit larger case and  dimensions.
Inside main component still is a robust transformer.

For unknown reasons there is no available any datasheet  from old SANYO industrial Ni-CD 1,2V  so me to discover ultimate allowed charging current.
Within 2017 only information's available are about SANYO Cadnica,  this is 1800mAH and max charging current this is 2.7A
Therefore 1800 Cell & 2.7A max charging this math translates to C1,5 as Fast-charge rate.   
Alternatively 2000mAh confirmed cells they would do C1,5  at 3A.
In conclusion neither AL60DV 44W this can not be considered as battery-killer simply because this is not powerful enough. 

[Kiriakos GR]

By assuming that I did steal proper pictures from what Google steal over the years,  here is my composed picture this demonstrating slight component level change between 33W & 44W AL60DV.

Addition of heat-sink at its one active component this is possible, but I would not do it with out carefully removing these two components from the PCB, so to not stress components leads.

 

[Kiriakos GR]

Bosch 2607224000 charger this is 1.3A and gives the impression that this is the father of AL60 & AL60 DV chargers.
It is made in West-Germany, and follows one wise design speaking of metallic contacts at charger compartment, contact points are wide as is battery contacts too.

Identical wide contact points they are also at my own (Slow charger Bosch 2607224200 this be 9,6V 400mA)

It does not makes sense even today of why Bosch changed product design about wide metallic pads and started to use thin contacts instead.

Chargers list with wide metallic pads:
AL60  - 2 607 224 152   1.4A
Bosch - 2 607 224 200   400mA
Bosch  - 2 607 224 000  1.3A
 

[Kiriakos GR]

Next topic which I did explore this is about Bosch NTC thermistor inside 9,6V (& 12V) battery pack.

At 90s, Chinese electronic parts industry was in the kindergarten, and Bosch battery pack was using European made thermistor (Made by PHILIPS).
Unfortunately even me I do not have original 6.8K NTC because I lost it over the years, by rebuild my battery pack over and over.
My current basic charger does not use NTC protection, but now I am aiming at eBay about getting faster charger with NTC support, and if I do succeed, then I will need to spent a bit more cash and get one NTC thermistor.

MAKITA battery packs also using NTC but this is 10K Ohm, and therefore this is not compatible for Bosch 9,6V or 12V Ni-CD that specific Bosch chargers expecting to cooperate with.
Wrong selection of NTC thermistor value this would cause problems, because charger this receives false information regarding actual battery cells temperature.
Wrong NTC will deliver fault alert and charger will not start or cut-off.
Bosch charger expects this to detect three conditions according to NTC and cells actual temperature:
a) Battery with NTC support
b) Battery too cold
c) Battery overheated

Practically entire series of Bosch fast chargers, they work with smart electronic control.
They automatically detect battery pack voltage range,  they do charging by using pulses.
a) Pulse amplitude this defines output voltage.
b) Pulse duration this defines charging current (ampere).
c) Trickle charge this is just a different combination  (setup) of amplitude and duration (Pulse parameters).
An exception this is AL60 that works with timer and does a hourly charging cycle with out sensing actual stored energy in the battery pack.
     
What this technology of 90s smart electronic control this is missing, this is detection of internal battery resistance.   


Bellow there is a collection of very interesting pictures, and I would say extremely valuable in 2017.
You may see original NTC of Philips (red) and also of another unknown manufacturer 6.8K NTC that Bosch factory did use in their battery assembly line.
Last picture this is great example of NTC thermistor operating theory.

Proper NTC thermistor selection for compatibility with AL60 & AL60 DV chargers, this is research that I am going to perform. 

[Kiriakos GR]

Speaking of battery pack rebuild or buying a new, I have some thoughts to share.

First of I am supporter of Ni-CD cells because this technology regardless downsizes of it, this is superior for battery packs having self life of 5~6 years at people hands whom does not frequently use their tools.
I am electrician and not a carpenter, my rechargeable tool this is used occasionally, neither Ni-MH and neither Lithium cells they do survive after 24 months no matter of how gently they will be used.
Ni-MH and Lithium cells they are internally chemically active by far more than Ni-CD, chemical reaction alone this destroying battery cell to the point of total destruction even when a battery cell this stays unused.

Regarding Ni-MH battery packs of 9 & 12V for specific Bosch products, my professional advice this is do not buy them.
Firstly, you have no clue of whom made these Ni-MH cells.
Secondly, you have no clue if unbranded Chinese factory this paid any attention to add NTC protection this qualifying according to Bosch standards ( Charger technology of 90s).

Cordless power tool makers they are aware of limitations of Ni-MH and Lithium cells, but for them this is an opportunity, they will increase their profitability by selling more battery packs.
If you think of me as weird thinking person, I will re-insure you that there is by far more weird thinking people out there ...  there is a You-tube video in which a Russian guy this drilling small holes over Ni-CD cells so to add water in them ( refill of battery liquids level )         
   
Stupid people at European Union council they did recently declare Ni-CD as dangerous for the environment, but they did not consider of how many metric tons of Ni-CD they do pile up in to a year time, in comparison to innocent Ni-MH and Lithium cells, which they do create a triple amount as landfill waste in the form of dead batteries.
Battery recycle organizations does not invest that much at recycling small batteries especially when max profitability this comes from car batteries recycling.

In conclusion, while newer batteries technologies does not offer significant benefits to the end user, even so they are now cost more and they live less.
Neither it is wise to trash reliably build cordless tools, because battery packs this is now harder to find.

 
You may interested also to read these topics :
 
Fake capacity Sub C Ni-Cd 2500mAh (eBay) - True capacity less than 900 mAh     

New Ni-CD drill battery Vinteky / tiggopower : Capacity tests - Mini Review
       

[Kiriakos GR]

eBay auction that I was aiming for, this it did go well. 
My very own AL60 (AL60DV rev1) Bosch  2607224226 charger this is on the way to Greece and also this charger comes with a bonus !! 

German owner of this charger he also own a damaged 12V drill and a dead battery.
At the same shipping fee, he did donate to me his own dead battery and now I have the hope that original thermistor this is still attached over the battery pack connector even if battery cells these were replaced with Chinese cells distributed in the German market under other branding.

Goods were shipped 25 November,  shipping time this is estimated around ten days.
What I am planing to do this is in-depth analysis of this charger behavior by the use of multimeter data-log and also by inspecting charging pulses with my oscilloscope.
No one ever did such measurements over the years, and my analysis results they would be extremely interesting. 

I did run some tests at my fresh rebuild 9,6V Ni-CD battery this having temporally an 10K thermistor,  and I did verified that at 25C this thermistor resistance were 9.3K and at dangerous temperature of 45C this measured 6.6K of resistance.
An 6.8K thermistor this should have resistance of 3.9K at 50C and  therefore 10K thermistor this is totally incompatible in this application.

For additional reinsurance in case that incoming thermistor this is not over the battery pack or this is wrong value, I did purchased an countdown timer module with electrical relay,  this can terminate charging according to adjustable time limit.
220V module - Adjustable countdown timer 99 Min with Led display

I did read other people ideas about substituting NTC thermistor by a regular 6.8K  6K8 resistor, but if you do follow this path then you are in danger to prematurely destroy your battery pack.
Overheated battery pack and immediate charging this translates to battery cell destruction.
Lets not forget that all those chargers were designed to work with old SANYO Ni-CD and that newer Chinese Ni-CD they are not made at equal high standards.
 
Therefore many interesting electrical tests and measurements will be performed soon, and all information's will be posted in this topic.
As you may see at the pictures, charger this comes with it Users Manual and this is a third bonus. 
   
 
 

[Kiriakos GR]

Among with my new (to me) charger I have also received from Germany as gift one 12V battery pack  (not genuine Bosch)  this supposedly compatible with AL60 & AL60 DV charger.

This is a battery pack assembled in China by a source called as :
Golden Dragon
Or
gd-battery
Or
Shenzhen Unite-Fortune Development Co., Ltd.
Fine Dragon Technology Limited


Either way while this Chinese brand it did add named cells at 2000mAh what they also did was to add WRONG VALUE NTC thermistor and this translates that battery cells was totally unprotected by the BOSCH charger at the incident of overheat.

Month of December in Greece this translates to extreme cold, indoor temperature with doors open this is 11 Celsius at day time, first measurement of NTC in Ohms this was about 11K.
Then I thought to gently elevate NTC temperature by using a 2,4V light bulb as heater so to raise the temperature at 20C ~ 25C and to measure NTC thermistor resistance at specified temperature by the manufacturers.
And finally at totally appropriate conditions specific NTC measured 10,2K which this is unacceptable ….

It does not need much of imagination that several thousands consumers’ whom get such “ For Bosch made battery pack “  these they would be destroyed prematurely because of such wrong selection of parts, and this is happening because very few they study their lesson before they start products production.

At specific used battery pack, there is ten cells, three of them they have create unrecoverable behavior (They are no able to storage energy), and rest seven cells they look alive.
Currently  I am attempting to gently recover its one cell at full charge level, and as soon they will be balanced, I am going to start battery capacity evaluation procedure, so to find out how usable they are.

[Kiriakos GR]

Dear friends this is the most interesting part of this topic and best technical adventure which I am enjoying right now, and I do love every minute.

As introduction I will say that this charger came to me from the hands of hobbyist in woodworking, I did discover hard evidence inside it.

Externally (housing) this is in great condition (aesthetics), after a good wash of top and bottom cover, this is now looks as new.
Naturally I did tested functionality and it works as expected.
My first impression from PCB and parts as you may see in the pictures this looking as to be assembled yesterday, and not 20 years ago!

All shine over PCB and parts comes from varnish which this is spayed everywhere (factory work), and this stopped any attempt of moisture this causing corrosion.

Among other things I did inspect the one and only electrolytic capacitor and it is also like new.
PCB revision 95122-001
Large IC this is a mystery, even me I did failed to find any relative information’s.
Regarding TYN208, I did checked eBay and there is availability. 

Now let’s get to the technical part of this story.
Despite the fact that this specific version of AL60DV this is built like an armored tank (and this is the reason that I selected it), with the use of a bit extra magnification I did discover soldering aging marks.
Soldering issues these are noticeable at two large diodes, and at both TYN208, everything else this is perfect.
Now I am convinced that lack of proper cooling at TYN208 this caused huge temperature variation (expansion – contraction) and such repeatability over time this stressed the soldering.

And I came with one idea at trimming down memory chip heatsink and also I did use SEKISUI #5760 (Double-sided Thermal Conductive Adhesive Tape), so to decrease operating temperature of TYN208 and to minimize these side effects.
As you can see in the pictures I did a very professional work!   

Speaking of charger electronics operation I can confirm that electronics producing charging pulses at frequency of 100Hz.
What looks as very interesting this is the shape of the pulse it self at AC, this looks like sea-water medusa  ( jellyfish ) and I got two screen shots by mostly focusing to adjust my Oscilloscope so this to capture the shape of the pulse than me measuring the activity, which I will do later on.
Even so I am very lucky because by testing the old battery which I also received with this charger I did manage to record charging pulses and trickle pulse charge (second screenshot).       
   
Next to follow would be a more detailed analysis of how charging by this charger works, DV sensing will be monitored with external meters and all details will be posted later on. 

[Kiriakos GR]

And finally here we have final pictures of slightly improved  AL60DV with a technical touch-up from this century 

According to AL60 & AL60DV User manual, AL60DV has a unique additional future and a very significant one.

Now one last tip for people with skills in electronics repairs, most unusual part on this PCB this is a yellow component with three pins, and this is actually a component named as ceramic resonator   part naming this is 4.00  ( possibly 4 MHz ) and V marking translates to part revision.
Ceramic resonator could be with two pins configuration and with tree pins configuration, the second has internally one capacitor this working as load, this increasing stability.

Personally what makes me truly happy this is that specific chargers they use true pulsing technology for charging, and advantage of pulses VS a regular DC power block this is that pulses they have the ability to better activate internal battery cell chemistry.
NI-CD cells they are famous about losing their performance peak when they stay unused for few months, pulse charging will help them to recover at peak performance much faster (at  less charge- discharge cycles), and additionally aged NI-CD they have better chances to become fully charged with pulse charging than with regular power block or laboratory power supply ( both delivering constant DC volts).

     

[Kiriakos GR]

While this topic it is about last produced in EU  Bosch rechargeable power drills and chargers,  today I had the opportunity to examine three dead genuine Bosch batteries from next product series (after 90s).

This Bosch No: 2 607 335 273 Battery style introduces slight design differences.
1) Thermistor this is 6K8 but  this is different production with different B-Value.
2) Bosch added one fourth contact with one resistor,  technically this is described as Key contact point (APT contact point named by Bosch), this resistor possibly works for identification, and power-drill this expects to find such a resistor so to identify type of battery and voltage (Use of 18V battery at 12V drill, this would be catastrophic for electronics and DC motor).
3) Third change this is at both battery and charger port, now additional plastic walls added inside and first generation AL60DV & AL60 chargers and batteries cannot be mixed with this newer product design.

Benchmarks which I did at specific (unbranded but by Bosch installed) 6K8 NTC this show that indeed at 25C this is 6.8K but at 50C this NTC resistance now measure 2.8K and this measurement it is a proof of technical changes made at newer produced NI-CD Bosch chargers (electronics operation). 

[Kiriakos GR]

By studying technology in use behind this old Bosch AL60DV, I did feel that when I will decode it operating modes, I would be surprised and impressed.
And right now I am surprised and impressed !!     

Today I did manage to put together one second battery pack, this having used and usable Ni-CD cells, so to evaluate this charger with out using my fresh build battery pack.
Despite the fact that AL60DV charger this is powered by a regular transformer, this is a true pulse charger with amazing functionality.

My test setup details are that I did use battery cells (battery pack) this be at 60% charged as it proved by the needed charging time.
Charging pulses were at 1A measured by a fast multimeter, but when I did peak measurement this measured an impressive number of 5A.
Trickle charge pulses these are at 400mA average, and double pulses repeat them self's every 400ms.

By using my Oscilloscope I did manage to record pulses exactly as they are speaking of shape.
Previously I did posted few screenshots when I did some quick tests with one battery pack this having several damaged cells and testing results was funny shapes but interesting.       

I am tremendously satisfied by seeing what AL60DV can do, such powerful pulses they can truly wake up any half-sleeping NI-CD cell, and this will be charged at full capacity no matter what.

From the other hand, AL60DV this is a double sided axe, fresh made NI-CD with fake listed capacity they will actually suffer because this charger it is not a toy.
Additionally any battery packs not having original BOSCH NTC or exact part replacement, these packs are also in danger.

Personally because I did all recent expenses, at getting new cells to rebuild my battery pack, at buying this AL60DV, at buying original thermistors, then one wild thought it did pass from my head, and this is what I will do if my drill goes bad one day due mechanical damage?
And I found the solution in the German eBay for once more time,  and now I am the owner of another Bosch drill, this is GSR 9,6V and comes with two but dead original Bosch batteries.
Drill and dead batteries for 9.99 euro plus 11 euro shipping, and now I do feel secure.   

My own drill this is SR 9,6V (0~500 rpm) and GSR 9,6V this has additional high-speed mode (0~400 rpm & 0~900 rpm selector).
Dead genuine battery pack would be a good resource for genuine NTC in case that information's leaded me to order specific NTC from Taiwan, they were not 100% correct.

Either way, because of my decisions and by spending my own cash in this exploration, any one who will landed in this topic, he will never get misleading information's,
All my orders will arrive in 20 days or so, and my epilogue would be a simple verification of all posted facts.