Battery recommendation for 52 flash please

[Minto]

Looks like I need a new battery, what are you guys using and where from?
1952 plunger gold lash, positive earth 6 volt, still running magneto ignition if that makes a difference.
Cheers folks

[morris]

Check with Paul Goff.
http://www.norbsa02.freeuk.com/goffybatteries.htm
AGM recommended as no spillage possible with that type of battery.
Got a 6V AGM 13AH for the plunger years ago, still doing the job perfectly.
 

[Greybeard]

I bought this pair from Goffy. 13AH capacity. That was 7 years ago. No problems yet.
There is not much room inside the rubber case between the battery and the lid so I soldered cables to the battery tags and I have a waterproof connector beside the regulator.

The magneto has no need of a  battery  BTW.

[Swarfcut]

I'm tempted the other way, to the cheap end of the market. On a magneto ignition bike, the low current  drain of typical use, pilot and tail light when parked up, and a bit of power to excite the dynamo, does not call for a large capacity battery. When under way, the dynamo output is designed to balance the total electrical load, plus a bit in reserve to top up the battery. Large capacity is certainly useful if you park up with the headlight left on, but not the way I would ride.

By my reckoning 4-5AH looks to be adequate, and Toolstation  stock a 6V  4AH sealed lead acid battery, usually used as a battery back up in security systems. The price makes it an attractive, if non standard, alternative.

Swarfy

[duTch]

 I think a ' B38-6A ' is about the largest capacity in 6V @ 13Ah; equivalent as specified stock, and High capacity is handy if the genny stops playing at inconvenient times but any 6V jobbie will do to run lights & brake light at standstill- just don't  do Lithium as they not compatible with the charge system i'm also inclined to cheap and nasty for various reasons

[trevinoz]

Swarfy, the battery doesn't have part in exciting the dynamo unless it is being used to flash the field.

[Swarfcut]

Yes, Trev, my mistake. Of course it doesn't...the cut out isolates the battery from the dynamo. Dynamo relies on residual magnetism to initiate the output. Shown to be a fool once more..... just a slip of the keyboard, sorry.

Cheers

Swarfy.

[Greybeard]

But a car dynamo has a battery feed, no?

With a dynamo car, my understanding of the behavior of the ignition light is that when the ignition is switched on power goes to the dynamo field windings via a lamp in the dashboard. When the engine starts the dynamo back feeds to the battery via the same lamp. The effect is to balance the voltage of the lamp so it goes out. Simple and clever.

[RDfella]

Swarfy -  maybe you're thinking of alternators that require a bit of a shove to get going. .

[muskrat]

G'day GB.
That's how I have and ignition/charging light hooked up on my A10 Cafe.
Cheers

[trevinoz]

The "ignition" light is connected between the battery via the switch and the "D" terminal. When the armature voltage rises to the same value as the battery supply, the light goes out.
This system is used on motorcycles with coil ignition and a dynamo.

[duTch]

 I think it was maybe rookie or somone else in the Mediterranean who was showing off his fancy ignition switch rigged  up that^^ way a couple of years ago...

 I don't want to hijack the thread but  just quickly; a question slightly related but not A7/10 or even BSA but similar to A65 charging,... but first the facts
    I've been wondering how to connect a discharge warning light to a CL90E  ("66-69 Hoonda) which has similar to A65 circuit but no zener diode...two wires from alternator to rectifier # '1' & '3' plates # '2' plate to ignition switch..... (~like A65/50), and 3 wire from alternator goes to h' bar light switch,  which I was thinking to connect an idiot light that will hopefully glow (as intended) if charging ....
   The question is whether there"s a connection I can do so the idiot light glows when discharge only- other than a simple connection to the ignition switch? ...I have a wiring diagram but not with me

[Swarfcut]

Trev. Thanks, always wondered how it was done.

Swarfy

[Minto]

Thanks everyone, I’ll get to bro Goffy this weekend.

[BSA_54A10]

FWIW I only fit Cyclons now days.
You can't beat the spiral cell technology for robustness.
Had one fall off the bike on the way back to Dunkelg and bounce along the road by the wires for quite a distance before I became aware of it.
Typical weather 4' / hr of horizontal rain making it hard to go forward even in first gear.
That battery ran for another 10 years.
It also makes a difference with what globes you are running.

A std 45W headlamp & 5 W tail lamp pulls 9 amps ( more like 10 when you account for all the grubby joints).
So if you dont touch the brake that is 30 min from a 5 Ah battery