The 'E' Type Forum

Hi
A friend had a 62 coupe which has an engine which is higher compression due to head being skimmed in past. He had trouble turning it over in the standard starter so had a high torque one fitted.
Yesterday it wouldn’t start after stopping to fill up, he had a lithium battery starter pack which he attached and it started in first turn.
Question
1. Do high torque starters need a more powerful battery?
2. Is it worth trying anew lead acid battery?
3. Are there lithium iron batteries available to fit classic cars?
Robbie

Answers...
1. Probably not...they claim to be more efficient and so should consume slightly less power for the same output torque/mechanical power....personally I think the original Lucas starters are unfairly maligned but that's another story!
2. Possibly replace. However if the battery started the car from cold first thing and then failed later on in the day as the fuel stop it is more likely to be a charge issue. Either the battery is not actually being charged and has run flat providing power to the ign and other ancilliaries while driving, or it was being over charged severely and was damaged....it can happen. Symptom is a very hot battery and a system voltage of over 15 volts with the engine running. I would check the charge system before replacing the battery.
3. Possibly but they will be extremely expensive!

His battery is dead, or not charging.

So

1. No
2.Yes
3. Probably but as lead acid batteries work properly why spend more?

Thanks fellas

I think it is highly unlikely that you can get any Li-ion starter batteries which would fit and they require highly sophisticated internal charging protection circuits if the fire risk is to be minimised. Even the one which starts my 150cc or so mower is about 1/8 the volume of a car battery so that one for a large engine would presumably be very large and heavy

PS having had a look to see if any suitable batteries were advertised, the only one I could find was a 120 AH battery , which proclaimed itself as containing much more energy per kg than a lead acid equivalent . When one looked at the small print , however, the uses were all "leisure" uses , eg boat, caravan, electric bicycle . It is clear that Li-ion cannot reliably produce the starting amperage which is needed ( and indeed my mower battery has failed after only 3 seasons )

Could just be a bad earth on the starter motor, and just a coincidence that the jump battery worked that time.

Yes ...well check that
Thanks

My E-Type had a high torque starter fitted when I bought it. It's supposed to crank faster than the old Lucas unit. It's also considerably smaller, lighter and "only" draws 150A when cranking.
I'm not sure what the Lucas starter's CCA is but I wouldn't be surprised if it's considerably higher.

You can get lithium batteries with extremely high short term discharge rates...in excess of 500 amps....however their overall capacity in terms of their aHr rating is usually low....around 20 to 30 aH. They are intended for race use where lightness is everything. The manufacturer usually states they are not suitable for day to day driving. They all contain internal charge management and over charge protection....they are hugely more expensive than lead acid equivs...

Lithium ion batteries have a C rating and the current they can supply is the Ah rating times C.

That is a 20Ah battery with a 20C rating will provide 20 x 20 = 400 amp

This is from the model plane batteries I use in RC models. The normal C rating is for continuous current supply and there is usually a burst C rating which is higher for short (~10 second) burst currents which is what would be needed for starting an E-type.

Some modelling batteries have 35C normal and 65C burst rating, but such batteries are far too small for a car.

Sounds like a battery failure to me
Or and a bad earth
Fit a new 80 ah plus battery and then try again and see if the problem goes away
Joe