Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Weak new battery???

Do as Ray suggests. The jump lead direct from the battery negative to the starter mounting bolt will bypass all other earths. If the engine spins ok then clean all earths as that is the problem.
Care, though, make sure don't touch any other parts when connecting. Connect the motor end first then battery negative.
If no improvement then give the battery a charge then retry.

Don't forget that it is possible , the starter need to be replacement

Stefan

If, as you say, that this battery is worse than the old one, then why should it be bad earths, as the old one was connected to the same system? To me, in this case, it points to the battery itself. If someone on this forum has a similar model, perhaps they could check the Cold Starting Amps (CCA) on their battery. Your 330 Amps seems a bit low for that engine.

Those were my thoughts Doug when I suggested a full charge and volt check on battery near the beginning of this thread. I also thought the capacity/CCA a tad low but the effects of this would not show up until the battery had reached significant age. Even this battery as new should spin the engine over fine. Remember the factory M3W battery is only 30 a/h and has to turn over 1000cc pots (bigger than those on a Dodge Viper).

Still a good idea to check battery earth to chassis and flexible chassis to engine block earth strap, but if it was generally ok before fitting this new battery, in this case it's unlikely to make a difference.

Hi all
Here where I am:
First, thank you all for contributing.
I wrote in frenglish that my battery was loaded, may be correct english is fully charged. V=12,7, the same than the old one (not so old, BTW, but left unused for some time and cantilevered dangerously and poorly supported, , decision to change was for both reasons). New battery exceeds morgan spec for a 1600: 36Ah, nothing about CCA in the owner manual... i was suspicious on the small power but it was the strongest able to fit the allowed space behind seat without cantilevering. (hope you understand what I try to mean in english!!!)
Lower performance with new small battery could explain by higher internal resistance than the big previous one 540A CCA.
Just to say I am on the track of poor earth.

And here I am in trouble... I have no car lift, so I can access behind seat (connection battery to frame seems OK with ohmmeter, same value than shortened test probes), now I look for the flexible chassis to engine block earth strap.
I filmed with my phone the area of the gearbox from below, but was not able to identify any earth mesh...
I printed the list provided for US roadster and I searched again: result none was identified????
also considering to jump starter body and battery ground.
If somebody can provide a photo of what I am looking for, It will help. thanks in advance

Hi Toucan,
I have the same battery as you installed one year ago. Had the same poblems also. Today I was checking al the jonits and to my surprise it seemed that the plus connection was not tight enough. So after I fixed it, the car started as it should! So also check the plus!

Hi all
Here I am.
Slight improvement after cleaning all identified contacts on the starter circuitry.
Sand paper of everything, including removing the RR wheel to access frame battery strap, and all positive including solenoid starter. It seems I don't have a starter relay, and I still don't have identified the chassis engine block earth strap. However it exists somewhere as negative circuit is effective????
Starting ok after 10 sec cranking with 5°C... still not perfect but does the job...

The chassis to engine earth strap is at the tail end of the gearbox and is made of something slightly less robust than wet spaghetti. An additional strap in the engine bay where you can see it is well worthwhile and not expensive.

Good advice, Paul, thank you 😊

Agreed, and better to have an earth strap from chassis to engine block as its to that the starter motor is bolted, so forming the earth return. Make sure you use the correct very flexible flat braided earth strap material for this purpose.

Using an ohm meter to check for earth strap integrity is not the best test in this case. The meter may show good continuity for the tiny test current but not necessarily when 300 amps for starter is flowing. A good visual and mechanical check for clean corrosion free bare chassis connection points is more valid.

Having said all this I still suspect the new battery. If possible a set of jump ieads from another vehicles battery, connected correctly and directly to the terminals of yours would prove the point, if there was a substantial improvement.