Aloha All,
My 94’ Eunos Roadster was struggling with an old battery, draining quickly when left for a few days, nothing left on in the car. Decided battery replacement wouldn’t hurt so ordered a Bosch S4 battery for the car (S4 001 - Type 063).
Since fitting the battery this week, I’ve noticed that the car struggles to start and usually requires a few attempts, but doesn’t need jumping. I’ve driven a few long journeys to charge up the battery just to make sure it wasn’t flat. I’ve also cleaned and greased the terminals.
Anyone had any experience with these batteries? Or have I made a mistake with the spec?
It is important to work out where this issue lies.
If the starter is spinning at the correct speed, your issue is not with the battery
If the starter is slow/sluggish, there is an issue.
A good guide to the health of a battery is voltage across the terminals, measured with a multimeter; ideally around 12.6 volts.
If the old battery was draining quicker than expected there is the possibility of parasitic current where the battery discharges when car not in use.
I think you may have a couple of issues here, a non battery related starting issue and parasitic current prematurely draining your battery.
If the car generally runs well and starter motor spins fine, I would be looking at the aged dealer fitted immobiliser you probably have fitted to this car.
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Maybe one of these could help diagnosis the problem
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Starter seems to be slow and sluggish, after a few attempts it generally kicks into life. I’ll see if I can find multimeter to diagnose the battery.
It’s worth checking your earth to the car body as well as at the battery terminal end.
It may also be worth replacing the whole earth cable.
Have you tried charging the battery separately, just in case the battery isn’t charging properly?
A failing alternator (diodes) can also become a drain on a battery.
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