MZ/MuZ Riders

Now it is up and running I need a decent battery, if I leave it for too long it just goes flat.

I have checked that it is charging and it is, I have also checked that there is no leakage with the ignition switched off, the battery looks pretty old so I want to replace it.

If I use it every day no problem, but leave it for a week or more the voltage drops to about 3 volts.

I want to replace it with a sealed battery, but there does not seem to be any 6volt 12AH ones available.

This being the case I am thinking that I dont need a 12AH one anyway as I wont be riding in the dark so all the battery needs to support is ignition, indicators and stop lamp, so probably less AH will not matter.

Any thoughts / recommendations ?

Thanks.

Don't know what your individual requirement will be, but you could use a 12v battery. The charging system on the Mz, only pumps out about 80a at 7.5 - 8v.
So that's all the 12v battery will have in it. But don't trickle charge the battery at anything over 8v. I used to start my Ts 125 with a 12v car/motorcycle battery charged at 9v (I also used it to power my 9v Boshe battery drill too (but at 12v 75ah). Even started it once or twice at 12v 75 ah with no problem. As long as the Mzs dynamo and points box are OK. Once or twice is OK. But never, and I repeat NEVER jump it from your running car (or motorcycle) battery via jump leads. As this will melt every component in your dynamo system. But anything under 8v should suffice. As strange as it sounds. As explained earlier, the dynamo system on your Mz will charge your battery last, engine first. But you could fit a large storage capatisor (for the engine) and a smaller battery for the lights, indicators, brake light. Or convert it to any small six or 12v altinator system. If you know someone who is good with a lathe.

Think I'll put a 6V 6AH bettery in the bike.

As you say MZ would have specified 6V 12AH for a reason, but I will not be riding at night so cant see that the battery is going to drain just powering the ignition for 90% of the time.

Dynamo output seems pretty healthy, shows a little over 7 volts at anything above about 3000 RPM.

12v battery just does not seem right.

Is it not the case, that because the voltage regulation varies on the MZ's (and most old vehicles with mechanic regulators), that a lead acid battery would be best for the purposes of absorbing spikes and lows in the charging?

Which is one reason I don't have any batteries in any of my vehicles that aren't lead-acid. But also, the battery I bought for my ES250 recently was a 6N11A-1B Battery at £27.95. Cheapest lead acid of that type I could fnd.

Andy, I fitted two 6ah 6v batteries to my TS wired in parallel so the operate at a nominal 6v but have a little extra in reserve. They are standard lead acid and came ready to use from Tanya batteries who do a postal service for lead acid batteries. Battery reference was 6N6 3B, this worked for me, cheap too!

Andy

Hello


The capacity of the 6V dynamo/alternator is 60 W.
Regarding that you might put on the light sometimes, You have 40 or 45 W front light, 10 W back licht, 2 x 21 W Indicator and sometimes 21 W brake light

So you see why MZ recommended a big battery:
Because you consume more than is produced by the dynamo.

For a short time the dynamo can produce up to 90 W, but even this is not enough.
And this maximum production is only at a high rev. drive.

So when you drive mostly short distances the battery won´t charge enough.

The ETZ has about 210 W...

By the way:
Here in germany it is obligatory to drive with lights on all time.
This helps to be seen better by other drivers...

Guesi wrote:This helps to be seen better by other drivers...

I don't think that's true at all. I won't go into why.




Yes, the 5.5 or the 9 ah are the best for the 250/251. For some reason 9ah fits perfectly into the battery tray and recommended, but 5.5ah is also permissible. I used a 5.5ah battery (it did rattle around a bit though!) for several years on my etz250. At the end of it's life, the charge of the battery was just enough to start the engine- but indicators/lights would stop the engine at the immediate junctions, but after quarter of a mile it charged up enough to allow me to use indicators/lights at a standstill, for a few months anyway- until it died completely. - I suppose a 9ah battery is best though, and it does fit so very nicely in the tray.

By the way:
The parking light is always on when you turn on the light....

But nevertheless the 60 W dynamo is not enough tzo feed all the bulbs and ignition needs.
But do was you want, it is your bike and your choice.

I simply wanted to explain why MZ recommended a big capacity on the 6V bikes...

And about "lights help to be seen better by other drivers" :
It definitely is true...

I was an instructor for motorcycle safety trainings and believe me, I know what I am talking about in this particular case....

Personal experience has me disagreeing on that. DRLs are a blight.

Science has no chance against personal experiences

here on my side of the pond
a bike with its super bright lamps ruins my depth perception
and i cannot judge how far away they are

So youn´t have to fear the MZs, becaue they have no super bright light