MZ250 ETZ. Running without Battery?

[ajb235]

I would like to run my 250 ETZ without a battery. I have connected a 6500 microfarad condenser across +ve and -ve battery leads and removed the battery. But no spark and will not start. My bike has the 3 terminal regulator which is connected correctly.
Starts and runs OK with the battery, charges at 14.2 volts.
Sorry my Technical German is not good, hope someone on the forum has the English!
Thanks
Ajb

[muffel]

Hi Ajb,

well, I'll try an answer.
I think, there is no need for the condenser, if you are using the standard ignition ( with contacts) you have to switch on the ignition, put the second gear in, start a short run with your bike, jump on it and let the clutch go - it works, be a man and try it.
Hope you know what I mean because my English is not perfect.

regards

Uwe

[MartinR]

Right, you have to push your bike. Otherwise you will not get enough rpm for the alternator to produce current for the ingition.

[ea2873]

if you want to use the bike without a battery on long term, buy a powerdynamo generator. http://www.powerdynamo.biz

[lothar]

My bike has the 3 terminal regulator which is connected correctly.

Hi Ajb,
the by muffel described procedure works only with the standard relay regulator which has 5 terminals (D-, DF, 61, D+, 51).

Type in URL
http://www.miraculis.de/aw/mz/mz.html

click "Bücher" - scroll to "Bedienungsanleitung für MZ-Motorrad ETZ125 und ETZ150 (englisch)"
There you will find an operational manual in English. It´s rather similar to the ETZ250.
Look Fig. 3 switch position (2) for pushing the bike.

Fig. 35 shows the 5-terms-regulator. Using other regulators it is not possible to start the motor without battery.
Why don´t you want any battery at all?

An other way to save the battery is to mount a powerdynamo generator system. It works generally without any battery.
But I wouldn´t recommend because the original ETZ generator is better in some special points.

On the other side it is not worth paying £180 instead £20 for a new battery ...

Phil Speakman´s MZ Shop will advice you for sure ... http://www.themzshop.com/

Kind regards
Lothar

[ajb235]

Many thanks for the quick replies in excellent English, you put me to shame!
My main reason for wanting to run without a battery is to save weight. I am building a lightweight Cafe Racer and hope to be well under 140 kg, with the benefit of faster acceleration due to reduced weight. I have lost some weight also, but would love a beer right now!
I will man up and push, I did originally build the bike without Kickstarter to save weight, so If it will start on a push, I can remove it.
But do I have to have the 5 terminal regulator to do this?

Thanks for all your help with this. Once I get the bike starting running without a battery I have reed valve to fit.

AJB

-- Hinzugefügt: 27. January 2016 22:52 --

Many thanks for the quick replies in excellent English, you put me to shame!
My main reason for wanting to run without a battery is to save weight. I am building a lightweight Cafe Racer and hope to be well under 140 kg, with the benefit of faster acceleration due to reduced weight. I have lost some weight also, but would love a beer right now!
I will man up and push, I did originally build the bike without Kickstarter to save weight, so If it will start on a push, I can remove it.
But do I have to have the 5 terminal regulator to do this?

Thanks for all your help with this. Once I get the bike starting running without a battery I have reed valve to fit.

AJB

[seife]

If weight is a concern, then you could use a smaller battery like this one: http://www.reichelt.de/Blei-Vlies-Akkus ... ANGUAGE=EN

The "problem" with the original generator is, that it is separately excited, which means (basically) that it needs power to generate the magnetic field which is necessary to generate (more) power. Now usually, even without the external power there is always some remaining magnetic field in the rotor and this will suffice (with sufficient rpm) to generate enough current to create a bigger magnetic field and to "bootstrap" the alternator. But this does not work with unmodified electronic regulators, because of circuit specifics.
Now that's all possible to solve, but then you still need to push the bike relatively hard to get it to run, and in the worst case (no remaining magnetic field in the rotor) it might not start at all. That's why I would opt for a small battery, which is not too heavy. Alternatively one of those modern Lithium batteries might be an alternative for this use case, they are even lighter.

[ajb235]

Thanks for the good explanation of how the ETZ alternator works. It's clear now. I think I will look at the LiFePo batteries, which can be small to provide the initial excitation current. Once running, I only require electrical power for a spark, and occasional lights and indicators etc, all of which the alternator will supply. No electric starter, so the battery can be small and light. I will need to be careful with charging, these batteries need a special balancing charger, so the bike charging circuit, for lead acid batteries may not be suitable. Maybe that once the bike has started I can isolate the battery using a relay.

[seife]

There are LiFePos made especially for motorcycle use, they should be usable as a drop-in replacement. They do have balancing / protection circuits built in. Example (german shop): https://www.louis.de/en/artikel/jmt-lit ... =134288607 there is one with 1.2AH which weighs 400g..

[muffel]

A British custom MZ - sounds good. Please be so kind and give us some facts about your project.
One important thing, all the guys here are mad keen on pics, I'm sure, if you post some you'll get as many useful hints as you want.

regards

Uwe