Starting Without A Battery

[Kurt in S.A.]

Is there anything in the manual (owners or shop) that indicates the singles can be started without a battery?  The one thing that is different with the singles is that they are battery-coil ignition and hence require that the battery be in the circuit.  This is different than the magneto twins where the battery is essetially just a reserve to drive the lights, etc., when the bike is at low idle.

I'm pretty sure the battery has to be in play here...I lost all power to my R25/2 several months ago when the crimp on the battery ground wire came loose.  A quick reconnection to the battery ground and I was on my way.

[Kurt in S.A.]

[berndr253]

Hi Kurt,

as fas as I know a battery is absolutely necessary for the singles to start. Reason is simple, because there is nothing what can generator power by using the starter. If you want to generate power you need a permanent magnet and some coils.
That is the difference to the twind you've discribed. In fact you have to kick fast and hard to generate enough power for generating the power - the power of the ignition spark of the single just depends on the power of the battery.

Bernd

[Kurt in S.A.]

Bernd -

Along those lines, then, would say pushing the bike to a sufficient speed and then popping the clutch create the generator power you mention?  I still think it won't based upon my experience when running down the road and the battery earth was lost.  The bike shut down.

I suppose I should clarify.  I'm sure there's a difference between no battery and a weak battery.  If there's no battery, I think I agree that bike wouldn't start.  However, in a weak battery situation, then "popping the clutch" will start the bike...I've done it on my /7 and old car.

[berndr253]

Kurt,

running as fast as you can without ANY battery will never result a starting engine like our single-ones. In fact if there is a low power then the generator can start producing electricity and if you can push you bike fast enough it may be that the generated power is high enough to get the engine alive.

I'd never tested something like that, it is much easier to fit a reserve battery from somewhere to get the bike alive.

Bernd

[mekgyver]

Kurt, fit a well charged batterie,
of course fit the connetors,
then try to run the engine.
if there is a low powered battery, may be at the end of its lifetime,
you can try to get high revs, if you have enough power in pushing the bike,
first at second gear, final at first gear (throwing without the clutch) down a hill for 20m
the engine will run, if you have some experiences and the right fuel mix. 
Bernd, a small guy, has never had this power, so he can't believe in this   

best regards, mek         

[berndr253]

Mek,

indeed the power is not just depending on size - it is also depending on the downhill gradient!! 

Bernd

[Kurt in S.A.]

Thanks guys...I'm not really having a problem just trying to make sure I understand.  Someone in another forum here said that his manul indicates that "to get the bike started you either need juice in the battery or the ability to get it rolling quick enough to bump it, with the battery disconnected."  I've tried to tell him that you must have the battery connected.  He's trying to get his R27 figured out and couldn't understand why the bike stopped running when he temporarily lifted the battery ground.  I'm still shaking my head over that... 

[mekgyver]

Kurt,
the regulator, which switches the field either to ground for max induction
or shut down the field to D+,
switches when the bord-voltage B+ is high enough (~7V)
The engine reaches this easy, if there is a battery powered field.
Otherwhise you have only the memory induction on the field,
then you have to rise rpm until the regulator switches.
After this you make sure, the revs do not fall under a limit,
shown at the red light. If it comes , you loose.  ... try again.
If battery is down for ever, disconnect it.
Noris, as the manufakture, gives the help :
connect for the starting procedure D+ with B+
may be,you don't need a downhill for 20m 
and disconnect it at high revs.
A damaged or not proper battery is a strong user for the generator, disconnect it, if so.
Noris named a recommened capacity with 7-8 Ah, not more !
Many users are riding with 4 Ah GEL-type, me too for over 10 jears 


mek S(elve-shut-down) 

[† Knut]

With the MZ-B you don't need a battery....





Knut

[guyfang]

Greetings,

Its my understanding that the battery is needed to excite the generators fields. Once the fields are flashed, the regulater keeps the generator fields energized, producing the voltages needed to keep the bike running. But only so long as the battery is in the circut. To be able to start an engine without a bettery, you need a rotataing magnet and coils. Or am I missing something here?

Guy

[Rütz]

I'm sure there's a difference between no battery and a weak battery.  If there's no battery, I think I agree that bike wouldn't start.  However, in a weak battery situation, then "popping the clutch" will start the bike...

No, it is vice versa.
It is definitively easier to start the Bike, when the battery is disconnected, then with a weak/empty battery.
The weak battery will suck off all current before the coil just gets one electron.

Some bikes (e.g. DKW) of this (DC-Dynamo-)era had es special switch (disconnecting the batterie and bridging the regulator), to ease starting with low battery.

To start without battery, you must accelerate the engine to more than 1.000 rpm (with empty battery it has to be 2.000 rpm and with empty and dull battery it is impossible)...
...and hold the speed up there for several seconds! Not until 1-3 sec. above this speed the coil will start with the first sparks.
That is because the DC-dynamo has a annoying delay, before it starts producing current.

Engine will shut down immediately, when rpm's will fall below the critical limit (e.g. when shifting gears), but it won't restart immediately, when rpm's exceed the limit (popping clutch). ...due to the delay due to the retarded selfinduction of the dc-dynamo...


Depending on individual wiring, in R27 when disconnecting battery ground you will disconnect dynamo ground in the same moment.
In this case the bike will shut down in any case...

!Warning!
-> Disconnecting the battery while the engine is running may harm a electronic regulator!
With the original electro-mechanic regulator it is 100% safe.


Take care
Ruetz

[berndr253]

Hi Rütz,

you write things which makes me crazy thinking about induction procedures. I am right when I say, that producing electricity is only possible with a (permanent) magnet system?

If that is correct it might be interesting to know how this magnetism can be realised in a system without a permanent magnet OR an electrical generated magnetism. The battery in our one cylinder bikes is necessary for the power of the ignition coil AND in the starting phase for the magnetic field in the field coil.
Without a battery there must be a "rest of magnetism" inside that field, otherwise electricity never can be generated.

If there is something wrong in what I said, please let me know

Regards

Bernd

[Kurt in S.A.]

Bernd -

I don't know if it's related, but something of a similar issue comes up on the '70-on bikes, although more specifically with the charging circuit.  The generator lamp on these bikes is part of the path for the charging system.  If it is burned out, the bike will not charge.  This lamp circuit passes battery voltage to the alternator (not a generator) to provide the initial magnetism.  Once the bike is running it creates its own magnetism and the bike charges.

If the bulb is burned out and there is sufficient residual magnetism, the bike may actually charge once it gets running.  Typically, it won't but it's possible.

Kurt

[axel69]

Hi Rütz,

you write things which makes me crazy thinking about induction procedures. I am right when I say, that producing electricity is only possible with a (permanent) magnet system?

If that is correct it might be interesting to know how this magnetism can be realised in a system without a permanent magnet OR an electrical generated magnetism. The battery in our one cylinder bikes is necessary for the power of the ignition coil AND in the starting phase for the magnetic field in the field coil.
Without a battery there must be a "rest of magnetism" inside that field, otherwise electricity never can be generated.

If there is something wrong in what I said, please let me know

Regards

Bernd

Hi Bernd,

not entirely wrong but ...
We are dealing with a tiny rest of magnetism which is held in the iron of the field. So if you turn fast enough there will be some very low current. And it will increase as you take this current to feed the field.

Axel

[Rütz]

Hi Bernd,

as Axel says: You're absolutely right, theoreticaly.   But in reality there is always "rest of magnetism"... everywhere.
Even a single atom swinging in the right direction is enough to start the induction of field current.

If a DC-dynamo is not run for a very long time and then started first time, the inducted current is of random direction. Which means, it may start in "wrong" direction with swapped plus and minus.
In this case, the rest-magnetism in the field-coils must be primed (repolarised) again to the right direction. You shurely have heard/read of this.
But it will start!


The AC-dynamo of the slash-models is different in this case.
It has rectifier diodes in the field circuit !
As all diodes, these have a "forward voltage" (Durchlaßspannung), which does totally block the low starting voltage of the selfinducting field.
Those dynamo's can't start by its own!
As Kurt says, they need the charge lamp to start. The lamp provides the field circuit with a start voltage higher than the forward voltage of the diodes.

Regards
Ruetz

[guyfang]

Greetings Ruetz,

We use two "C" cel batterys taped togather. Works also. Once the fields are flashed, it should run on without the batterys.

Guy

[Jürgen 57]

Reading this discussion I remember a chapter in a book 'Motorrad Elektrik' of Rudolf Hüppen.
There is one chapter describing how to start the bike with an empty battery - In principle it should function as follows: disconnect the cable at terminal 15 of the ignition coil - do not forget to isolate the loose cable well! Then connect terminal 15 by using an additional cable with D+ at the dynamo or the regulator.
If the bike is pushed the minimum voltage to get first sparks might be reached already below 1000 U/min. This additional cable can remain connected until the battery is fully charged or replaced by a fully charged battery. This 'bridge' is not disrupting the function of the regulator.
If there is no battery connected the engine speed has to be maintained at a level that the cut out switch of the regulator (Rückstromschalter) stays closed otherwise there will be no more power supply by the dynamo!

According to Hüppen pre WWII DKW motor cycles had a special position for the ignition key to activate this 'Push Relieve Mechanism' (Schiebeerleichterung).
If it is of interest I could either scan the respective pages (if this is not violating copyright / Clemens?) or translate the chapter when I have more time.

Last but not least: NO GUARANTEE it functions - I had no chance yet to test it myself. This might only function well with the original regulator. Electronic ones where at the time when the book was published not yet in common user!! With electronic ignition systems this will also not work.

Greetings

Jürgen 57

[Kurt in S.A.]

I'd be interested in seeing this specific section, especially if it applies to the R27.

Thanks...

[Rütz]

Hi Kurt,
you may have a look into the official Repair Manual ( ), Chapter "E" (electrics):
On p. 138/139 and p.144/145 there is a description of some tests, which have to be done with disconnected battery and running engine!

Ruetz

[Kurt in S.A.]

Kewl...I'll check that out!  Now that I look at my R25/2 repair manual, I see virtually the same situation for checking the dynamo.

Kurt