Kalkhoff/Panasonic charger

[warmrain]

Hello all, I am trying to determine whether a (Kalkhoff)/Panasonic "25v" charger I have is working properly.

It is a Panasonic NKJ039 model; stated output "29.3v 1.8A" charger which came with an old Kalkhoff Tasman bike with 25v panasonic motor. I bought a replacement battery last week and it will not charge when put in the charger -- battery has 4 (of 5) lights showing on self test, and voltage between output terminals of battery is now down to 25.8v (from initial 27.4) after some usage on the bike.

Picture below is of the pins on the charger.
I believe pin labelled '2' is positive output, '3' is a dummy, '4' is neg, and '5' is a sensing/battery monitoring pin of some sort.

My question is:
(a) What does pin '5' sense? What voltage perhaps does it need to sense?
(b) Should a battery reading 25.8v start charging when inserted? (Nothing happens at present).
(c) Should there be a voltage between '2' and '4' when the charger is plugged into the mains but battery not plugged into the charger?

Essentially I am trying to figure out what normally triggers (and stops) the charger to deliver a charge; or is it just broken? (...and can it be fixed.)
My previous battery could be charged up from various intermediate states of discharge.

Thanks.

 

[flecc]

Sounds like the charger may be faulty. However, if you use this link and scroll down to the foot of the page, you'll see the 26 volt Panasonic battery connections identified by function. The charger uses connections 1 to 4.
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[warmrain]

Sounds like the charger may be faulty. However, if you use this link and scroll down to the foot of the page, you'll see the 26 volt Panasonic battery connections identified by function. The charger uses connections 1 to 4.
.

Thanks FLECC. Some useful information there.

However I would like to be certain that my charger is faulty (or unfixable) before I throw it away. Do you or anyone else know whether this or similar Kalkhoff/Panasonic '29.3v' chargers should show 29v at the charging terminals when plugged into the mains, without the battery plugged into the charger?

I would also love to know how & whether the battery communicates/influences the charger in some way BEFORE the charger will start working.

Posters NRG & 10mph had some discussion about this charger/battery in the past but the posting did not give me the info I need. I wonder if they still have their chargers?....

 

[flecc]

Thanks FLECC. Some useful information there.

However I would like to be certain that my charger is faulty (or unfixable) before I throw it away. Do you or anyone else know whether this or similar Kalkhoff/Panasonic '29.3v' chargers should show 29v at the charging terminals when plugged into the mains, without the battery plugged into the charger?

I would also love to know how & whether the battery communicates/influences the charger in some way BEFORE the charger will start working.

Posters NRG & 10mph had some discussion about this charger/battery in the past bit the posting did not give me the info I need. I wonder if they still have their chargers?....

I don't know if they show a charge with no battery connected. I don't have one to try and NRG and 10 mph aren't often in the forum these days

I believe Tillson may still have the 26 volt battery system, so you could ask him if he can check if the charge shows a voltage to a meter withno battery connected. This link is for a page that sends him a message.
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[warmrain]

I don't know if they show a charge with no battery connected. I don't have one to try and NRG and 10 mph aren't often in the forum these days

I believe Tillson may still have the 26 volt battery system, so you could ask him if he can check if the charge shows a voltage to a meter withno battery connected. This link is for a page that sends him a message.
.

Thanks. Will do.

 

[Nealh]

I have never tried or tested the 26v Panasonic,
but most chargers will show max voltage output at the charge lead.
24v would show 29.4v
36v shows 42v.
48v shows 54.6v.

 

[warmrain]

I have never tried or tested the 26v Panasonic,
but most chargers will show max voltage output at the charge lead.
24v would show 29.4v
36v shows 42v.
48v shows 54.6v.

Hmm...
Thanks.

 

[tillson]

I have one of the old type Panasonic chargers. I don’t use it often these days, because I bought an after market battery with a plug-in high-speed charger which doesn’t require the battery to be removed from the bike.

I will check the pins to see if there is any voltage output. They can be a bit temperamental. I actually have two old type chargers, one of them seems to work on a random basis. Sometimes it will charge battery, sometimes it won’t. There is nothing you can do to make it work. It just seems to be a case of charging the battery when it feels like it.

The old Kalkhoff bike still goes well & I used it this morning to ride into town and buy a few bits and pieces. It’s over 10 years old now, and is on its second motor and the second battery. It pulls like a train and easily has the legs for a 50 mile ride. I think it was about £1200 ten years ago, but with the tax relief on the first thousand from cycle to work scheme, I think my total outlay was just short of £1000. Great value for money.

 

[tillson]

I’ve checked my battery charger. There is no voltage output when the battery is not sat on it. It must detect the presence of the battery via one or more of the pins.

 

[warmrain]

I’ve checked my battery charger. There is no voltage output when the battery is not sat on it. It must detect the presence of the battery via one or more of the pins.

Thanks very much indeed for that test & info.
I take it there is no voltage when plugged into the mains across ANY pair of pins (when the battery is not connected).

That still leaves me with the puzzle of WHAT makes the charger want to start delivering a charge.

I think I might try opening the charger to check all the connectors before also speculating whether my new battery is in some way incompatible with the charger ... unless someone with more electronic knowledge understands how this Panasonic charger works...?

 

[flecc]

That still leaves me with the puzzle of WHAT makes the charger want to start delivering a charge.

That's likely to be the residual voltage of the battery switching on the charger. Connection one I've given as charge monitoring is could well be involved in that, together with the charge positive connection four.

You could check if there a signal voltage across connections one and four.
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[tillson]

Thanks very much indeed for that test & info.
I take it there is no voltage when plugged into the mains across ANY pair of pins (when the battery is not connected).

That still leaves me with the puzzle of WHAT makes the charger want to start delivering a charge.

I think I might try opening the charger to check all the connectors before also speculating whether my new battery is in some way incompatible with the charger ... unless someone with more electronic knowledge understands how this Panasonic charger works...?

Yes, plugged in switched on etc. I tried all pin combinations. No voltage.

 

[chris_n]

Terminal 1 is likely connected to terminal 4 via a thermistor which will switch the charger off if the battery gets too hot. You may find a voltage between 1 and negative (2). Maybe Tillson could check his as well.

 

[warmrain]

Terminal 1 is likely connected to terminal 4 via a thermistor which will switch the charger off if the battery gets too hot. You may find a voltage between 1 and negative (2). Maybe Tillson could check his as well.

Thanks for that suggestion.
Firstly, to eliminate misunderstanding (because FLECC has referred to the pins in a different numbering sequence) I have put up below a new photo with pins on my old battery & charger numbered A to E.

Pin A on the battery connects into + (POS) for the motor on the BIKE but has no connection on the charger. Pin B is also +(POS) and connects to the charger. Pin C is NEG and (I believe) connects to the battery meter on the bike but has no function on the charger because it connects to a charger pin which is a dummy (not connected internally to anything but just used to help register/orientate the battery onto the charger). Pin D is 'common' NEG for both connection to bike and to charger. I have never before quite figured out what Pin E does on battery or charger (it has no connection on the bike) but I have found generally that the voltage on the battery between Pin E (NEG) and either of the two positive pins will mirror the same voltage as found between the two main 'output' pins, A & D.

Are you suggesting therefore that the charger has to see a suitable voltage from Pin E of the battery before it will start (and continue) charging?
[...And what limits will that voltage have to stay within ......]

 

[chris_n]

That is exactly what I am suggesting, between D and E there should be something. What it will be depends on the sensor type hence why I suggested Tillson could maybe check his too.

 

[warmrain]

OK, an update.
SUCCESS !! I have managed to get my charger working!

Some details of voltage testing of the charger WITHOUT being connected to the battery:
After rest overnight without being plugged in -- zero volts across any pair of terminals. On plugging into the mains, intially zero, then after a few seconds I hear a very very faint click followed by a jump up in voltages across some terminals BUT in REVERSE polarity (of expected).
Between B & E = 10.9v with 'E' positive.
Between D & E = 12.3v with 'E' positive.
Between B & D (the main charger output pins for battery) = 0 v.
On then unplugging the charger from mains, both these voltages decay slowly over several hours. [This suggests to me they are residual voltages on some sort of internal capacitor.]

I then opened up the charger. Rather fiddly job as it is held together by 'security Torx' screws which have a raised 'pip' in the centre. I needed to go source a corresponding 'security Torx' screwdriver (of T10 size) which has a hole in the centre of the business tip.

I then lifted out the charging terminal from the charger and plugged it firmly into my NEW partly discharged battery [CAUTION!: need to get the pins correctly oriented!] and Eureka!! it started charging the battery!

The pins on my charger are not burnt or corroded and the pins on my battery are new. I believe the Kalkhoff charger simply has a design flaw in its construction which means that batteries which sit on it don't get the pins inserted deeply enough. I had noticed incidentally that my new larger bodied higher capacity battery did not sit as stably on the charger, albeit the pins still *seemed* to insert OK. I have a suspicion that TILLSON's problem with intermittent functioning of his charger may be due to the same problem. I now have a new project in front of me which is to lead an extension wire out of the charger to a 'flying plug-in' connector for the battery.

Now, some voltage measurements with the battery operating with the charger:
Battery OFF the charger (initial state) :--
pins A-D = 25.8v [battery output pins]
pins B-D = 25.8v [battery charging pins]
pins B-E = 25.3v [? battery monitoring/communication pins?]

Battery ON the charger's corresponding pins (charger then switched ON at mains).
pins B-D = 26.0v [ie charger outputting voltage 0.2v above battery initial]
pins B-E = 23.0v [the ?'monitoring' pin has 3v less than main pair.]
pins D-E confirm 3v difference (with D neg, E 'pos').

At end-of-charging after several hours (charger power transistors gone cold, battery LEDs all gone dark) and battery still connected:
pins B-D = 28.9v
pins B-E = 28.3v
pins D-E = 0.62v [Note decrease in difference voltage.]

AND the BONUS.
I had thought my old Kalkhoff battery was dead. No LEDs lit on pressing test button, voltage across all 'main' pins A-D, B-D was only 2.4v (two point four); across 'monitoring' pins B-E also 2.4v; across 'battery meter' pins A-C 2.2v. No response putting it into the Panasonic/Kalkhoff charger.

For a laugh, I plugged it into the detached pin block of the charger .... and it started charging!

I now have an old "Dead" battery charged to 29.2v albeit I suspect its overall capacity is low despite the appropriate voltage. I will try it in due course to see.

I remain curious as to what and how the 'monitoring' pin 'E' works on charger and battery. I had thought after finding 10.9 / 12.1 v reverse voltage on that charger pin that pin E was used by the charger to detect a minimum battery voltage of at least > 12v before deciding to operate (this perhaps being related to the 'unsafe' minimum voltage below which one should not charge a Li-Ion cell), but clearly it worked even with a battery voltage of 2.4v . So, what is its function and how is it connected into the circuit(s)?

Thanks to all who have helped in this investigation so far!

 

[flecc]

Congratulations on getting it working. I can't guess how that monitoring pin functions, but your guess at a capacitor being involved makes sense.

In my experience Panasonic chargers can be eccentric. The 24 volt charger for the first unit that used NiMh batteries was much bigger than usual with its circuit board encapsulated in very deep opaque resin, leaving the only visible items as three large heat sinks sticking out above the resin. All that complexity might have been forgiven but for the fact that they all failed early in life.

Panasonic hastily arranged for Taiwanese company Metco to supply one of their chargers modified to suit and they worked well. However they soon replaced it with another design of their own which also often failed!

Not a good record from a company that makes so many other excellent electronic items, including rechargeable cells and batteries.
.

 

[Nealh]

Well done and a great result, and to boot a reserve get me home battery for longer rides.
You may be surprised and that ' dead ' battery may still hold some decent capacity, in which case if you don't need it for extra range alternate the pair in use to keep both healthy.

 

[warmrain]

Well done and a great result, and to boot a reserve get me home battery for longer rides.
You may be surprised and that ' dead ' battery may still hold some decent capacity, in which case if you don't need it for extra range alternate the pair in use to keep both healthy.

Thanks for the suggestion. I guess its a trade off whether to lug it along as my new battery is substantially larger capacity wise and should cover most circumstances - if it lives up to its stated capacity rating ... delivered from Germany but in small print says 'Made in China'. Some good stuff is made in China -- all those hub motors used by various UK bike manufacturers are made in China I believe. I couldn't bring myself to pay £600+ to 50Cycles, and this is less than half of that.

 

[Nealh]

If old one is good and you alternate them daily/weekly or what ever the routine they should last a good few years.
With my batteries even if left for a short while I always leave at about 37.5 - 38.5v and charge the night/day before use.