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MG Midget and Sprite Technical - Car wont start

Hi Everyone, so the MG has been difficult to start this year despite being on trickle charge all winter. BTW its a 1275 MG midget RWA 1974.

It has started once I take it off charge, but if its left 2 days it won't start.

I have tested the battery over 2 weeks. Unconnected it was charged to 13.26 V and over 1 week only lost 0.69V.

Did the same test over the following week with it connected and the battery went down to 12.41V - and overall loss over a fortnight of 0.85V.

Then tried to start the car and the starter tuned the car over for a second or two and then wont turn it at all.

I have cleaned the battery terminals, replaced the earth lead under the car and cleaned under the solenoid to make sure it has a good ground.

Does this point to the starter, solenoid or coil needing replacement?? Or are there further tests I can/should undertake. I have a multimeter but I am no expert with it.

Any help much appreciated guys

Andy

Andy Davies

Hi Andy - After it wound for a couple of seconds then wouldn't turn at all---what does the battery voltage measure then (at the battery posts) and what does it measure while you try to start it when it's not turning over.
William Revit

It doesn't look like you're losing very much charge at all.

Following charging, the battery will drop to around 12.6v anyway. That is to be expected.

Dave O'Neill 2

whats its voltage under load I have had batteries that seem fine till you put them under load.
mark heyworth

Can you try starting it from another vehicle with jump leads or using a powerpack?
Jeremy MkIII

Hi William - after the attempt to start at the battery post the voltage was 12.04V

I will try and get the reading whilst I am starting it.
Andy Davies

I'd try starting it with a known good power source and see how it goes. I know a local guy that used a battery conditioner and that said all was good for about 4 years until he tried to start the car and no joy, I connected a known good battery with quality heavy jump leads and the engine started right up, the 1st time in about 10 years, a Rover V8 EFI. He replaced the battery and within 6 months the same situation but the battery was replaced under warranty. After that he just put the battery on proper charge every month or 2 and I don't think he's had any further issues.
David Billington

So I have just checked the battery whilst my glamorous assistant tried to start the car and it went as low as 5-6V!
Andy Davies

Time to change the glamorous assistant?😉
David Cox

As you have already cleaned up all the contacts, with a battery voltage that low under cranking I would get another battery.

Bill (small green pleasure machine) exAA patrol who was a regular BBS poster, test was ISTR start with battery about 12.8v ,crank 15sec - voltage shouldn’t drop below 9.5v and recover to 10.5v after the 15sec cranking. Should be in the archives !

Anybody know how Bill is doing - haven’t heard from him in a while - he used to organise the Brum tunnels runs.
richard b

Bill posts on the MASC Facebook group from time to time. But I don't think regularly. But did post a thumbs up symbol on something I sent last week so I guess he is ok.
GuyW

If you need a new battery, Tayna Batteries are very competitive price-wise and deliver quickly. There is also a discount code for a 5% discount - NUMBER27YT

https://www.tayna.co.uk/
Dave O'Neill 2

Andy
You almost certainly need a new battery. Nominal voltage for a fully charged battery in good condition is 12.6v (if you've just removed the charger it will stay higher for a while).

I've just checked my Sprite battery and it's 12.9v (I suspect the DMM is reading a bit high). The car last ran 8 days ago. The battery is 3.5 years old and has never been on a charger and the car is used very little between October and April. You shouldn't need to use a charger very often unless there is parasitic current leakage.
Bill Bretherton

Thanks for all your help. New battery on its way.
Andy Davies

This thread was discussed between 26/08/2024 and 27/08/2024

MG Midget and Sprite Technical index

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