6v Battery Backup

[Lowbarn]

Following everyone’s very helpful replies to my various woes, I’m now up and running again.
Last nagging issue is a non charging dynamo. (It worked fine until I renewed the bearings!)

In order to keep running pending repair of the dynamo, I’m thinking of adding a backup 6v battery.
For use in daylight and hand crank starting only. 
Is it ok to simply connect this battery across the main battery terminals?
Or should I connect it in via the dynamo charging circuit?

I recall somebody mentioning this the other day, but cannot find it.
Richard.

[AustinWood]

The dynamo on our car hasn't worked for a very long time. With a fully charged battery we went to the Scottish Austin Seven Club AGM in Blair Atholl in November. On the Saturday we went to Rannoch Station and on the Sunday returned home. All together about 350 miles and always used the starter. When we got home the car was still fine. Starter still worked as it should.
Back in the 60s I had a 1930 fabris saloon. The dynamo didn't work and the starting handle had fallen off. I did a tour round the Highlands from Dundee and next day drove home to Cambridge. About 500 miles altogether. The first time the starter wouldn't work was 15 miles from home when I ran out of petrol and needed a push to get going again.
We still have no dynamo and this is my everyday car. I use a battery conditioner to keep it topped up and have no worries whatever that it will let me down. I always use the starter.
I would say you have no need to worry.

[Steve kay]

The Ruby has had two batteries for some time. These were not for starting, but for night driving, and particularly for night nav rallies. Twelve hours in the dark was beyond the capacity of the battery, but this is all unnecessary now with the wonderful LED lights. Not got round to removing a battery yet. It looks rather jumbled under the bonnet. Battery master switches to keep the scrutes happy, water temp gauge line very visible, the red straps are for lifting out the battery, although there is an old fashioned school of thought that says lifting straps are for hairdressers and real men lift their batteries out with their fingernails, if not with their teeth. The small visible sockets are for another marvel  of modern science, the CTEK charger. Much recommended to me, and I am now convinced what a good system it is for our sorts of battery. 

   

[Hedd_Jones]

And an air filter. Whatever next!

The dynamator on my saloon has carked it, still using it though. Starts fine on the handle which saves most of the electrickery, I work on the BMW principle and don't use the semaphores, and with the aim of keeping all hard won momentum, use the brakes (and thus stop lights) sparingly. I hadn't charged it in at least a month, and when I robbed the Exide battery for the chummy the other day, it still had enough go to run the bacon slicer more energetically than the Lincoln Battery it replaced.

The chummy I sold last April had been run for nearly 2 years with only ignition wiring, (and yes no reflectors).

My conclusion is if you don't go out in the dark, and are capable of starting the engine on the handle you probably don't 'need' a dynamo.

[John Cornforth]

Hi

The simple answer is to connect the second battery in parallel with the first. It will effectively increase the ampere-hour capacity and lengthen the time before it runs out. Having said that, if your main battery is in good health and you are only draining a couple of amps to run the ignition, it will do that for many hours running.

May I make a plea for all batteries to be clamped or strapped down securely. You don't want them moving around and short circuiting if the worst happens.

[Lowbarn]

Thanks for the advice. I’ve done some checks and I can get 20 hours out of the battery without headlights.
Hand starting is not an issue, so good to go!

If I was the type of person who just likes to get things working however.

Would I be able to pick up a Lucas C35A with the distributor end plate?

Then I can get mine off the car for repair and still be able to use it.

Richard.