Hi -

I suspect this will be an easy question for this crowd.

The battery (new optima red top - 1000CCA) is trunk mounted with a big (possibly 0GA) wire leading to the starter. It was set up with a trunk mounted battery when I bought the car.

The car will always start, but the first time I turn the key it tends to crank really slow (almost sounding like a weak battery, so I put in the new optima, but same results with a brand new battery). It usually takes a second crank to really get it going so it wakes up and starts. Behaves similarly warm or cold.

One time I left the lights on and the old battery died and I needed a boost from the AAA guy. He hooked it up with his booster cables to the trunk mounted battery and the car fired up like a brand new car...got me thinking maybe I don't have enough battery to do the job if I'm intending on keeping the battery in the trunk.

Is there anything I can do to help this (short of moving the battery under the hood)? I like the trunk mounted setup for now.

I have a spare (new-ish) optima red top - could this be linked up with the other battery in some way to improve starting (right now it's just collecting dust)?

Thanks!

First off how is it grounded. I would get a long jumper and check resistance to ground from the neg post to the engine block or better the starter case. Then positive cable at the battery and the pos lug at the starter. When you find the resistace is more than a few tenths on either side evaluate how well the battery is grounded and or check for corrosion on the cables. If resistance is good where is the ground wire running to, and how large is it. If it is grounded somewhere in the trunk how is the engine grounded to the chassis. I have to think a 42 year old car is going to have corrosion in most areas the current will need to travel. Those little ground straps to the back of the heads may be trying to work much harder than they should. If you are confident with the ground, have the starter amp draw evaluated at your local auto parts store. If the starter is within spec the easiest solution might be installing the battery back under the hood. If the positive cable is easily removed I might take a short cut and move the battery temporarily under the hood, run a good ground cable from the battery to the block, carefully coil up same the positive cable and attach it to the battery. Be very careful to protect that positive cable from rubbing anything. If it shorts you will more than likely experience fire. If everything is better you are either running a ground to the block or moving the battery back under the hood.