Morris Minor Owners Club

The battery on my 58 morris is on the way out, The car is still running on poz earth and dynamo, So is putting a slightly bigger battery on ok, I am just going to us a halfords one as it is local and i really should get round to making this traveller neg earth at some point.

No problem fitting a bigger battery, just make sure it fits in the tray without fouling anything.
Just think of it this way, a battery is like a bucket, the bigger it is the longer it takes to fill. So the Dynamo will take longer to charge a bigger capacity battery.

Don't forget that if you change the polarity of the car the battery terminals will be the other way round so if you are thinking about changing the car polarity and the battery needs changing then now would be a good time to do both and get a battery with terminal positions to suit. As long as the battery fits the tray it does not matter what size it is providing it has enough power to operate the starter motor. You will probably find that size for size today's battery's are more powerful than the ones fitted to our minor's originally.

Don't go for small and cheap. Halfords sold me a tiny ( well it looked tiny in the battery compartment) battery which was recommended for Minors according to their guide. It was no good at all. Get the best you can afford and one which copes with radio etc even when a dynamo is fitted.

Thanks guys, I looked at halfords online and saw they have calcium batteries, Something new maybe? Amgrave yes i had not taken the neg earth swap into account so as it seems pretty straight forward i will do that first.

You can use 12V 90 or 95 Ah battery - No problem - you can use it long lime about 5 years - and if you have dynamo, the big battery good for it - you can use it in Night for head Lights not drain quickly - best of luck

Sandun
Sri Lanka

Thanks Sandun, I am ready to swap to neg earth this weekend, I have removed the ols Pye radio to check it and it can be swapped to neg earth, I will do a forum search on the earth swap as i think some year models have issues with certain electrical bits not working, fingers crossed in advance

No automotive type of lead acid accumulator will last optimally if left in a state of partial discharge for long. That is a basic fact of life. Any lead acid battery should be maintained as close to full charge as possible, or plate sulphation will occur. This may be reversible, but if not the cell capacity will be permanently dimiminished.

The charge available to the battery should always (ideally) exceed the average usage. The regulator is there to limit any excess charging capacity causing overcharging of the battery, leading to other problems - particularly with modern valve regulated batteries.

In all instances where power usage exceeds generator output, the voltage available will be reduced from typically 14.4V to around 12.5V, or less. That approx two volts reduction, or more, will seriously affect things like the light output from headlamps. Try it for yourself - compare the brightness of your headlamps with engine off and with engine on and charging with a fully charged battery (revs up a bit). It is considerable.

MOST of Morris in here use 12v 90Ah lead acid Battery with dynamo - My car battery also 12v 90Ah with dynamo and neg earth and it has Lucas voltage control box- you not want to adjust your cut out if it is big battery - mean of the Ah draining time (An Ex. if can use 3 hours 45Ah - 90Ah can use 6 hours)- Remamber before u set your battery to the car - full charge it -13.5v is full charge battery it will protect your battery life -after that your dynamo will do it No Problem - the big battery not get big time to full charge -Bz the battey charging day by day when you use it - set your battery and start your car chack Voltsge Battery terminals it should be 13.6V and not more if it is more it mean want adjustment control box - and change your igniation coil terminals if it is neg earth -Best of Luck

Thanks i will be having a day in the garage this weekend so i hope to have a few things sorted, maybe i will get the accuspark fitted aswell...

After a think and a look around the car i have worked out i need to change the old radio to neg earth and as it has a gold coloured petrol gauge i need to swap that, It was an old post from bmcecosse (Roy) i spotted about the petrol gauge and flashing the dynamo, nice to feel he is still helping.

After a bit of a diversion into the wiring loom i am now running negative earth and fitted a 72ah battery, appart from the fuel gauge swap over it was pain free and now i can fit the power spark ignition, and i will test the voltage to check am not damaging the battery, thanks all for advice.