battery internal short

Thats exactly the thing...

For a battery to cause a power loss when driving it would have to be a dead short capable of draining all the 50 amps plus from the alternator. That means its going to be very obviously melted and destroyed.
This is not the same (apparently) as the OPs problem.

 

No -- the ignition switch has no effect on the external lights (and you indicated those also go "out").

 

I agree with the sentiment that the Interstate Batteries are the way to go. The one I just replaced in my 400i was well over ten years old according the the dealer.

I have always had great luck with the Interstates especially after adjusting for cost.

And, back to the original topic, YES failing or failed batteries can be the cause of strange symptoms. The battery is an essential part of the voltage regulation system on almost all cars. A non functioning battery can lead to unexpected voltage changes and other problems.

Battery life is a function of many things. I had a Merkur XR4Ti with battery a couple inches from the hot turbo charger. That car could go through a top quality battery in 18 months and the longest I had one last was 30 months.

 

Definitely abnormal behavior per the OM, wiring diagram, and the logic shown on the schematic (and how my TR works). Do you have any obvious (unknown) wiring modifications? If something was changed to link the external lights operation to the ignition switch operation, and it was done in a way that significantly increases the current flowing thru the ignition switch contacts = that would not be good for the longevity of the ignition switch contacts...

 

No, that's my bad (I had TR on the brain, not 512TR) -- F neglected to add the external lights to the list of "CIRCUITS OPERATED BY THE KEY" on page H7 in the 512TR OM, but did add the qualifier "With the switched on ignition key..." to the headlight operating instructions on page L2 -- so that seems stock for your model (and not any help in deducing the source of your trouble -- so the ignition switch should remain on the suspect list -- along with all the primary power connections).

If you can identify something that is not controlled by the ignition key (like maybe the courtesy door lights), when the problem occurs, if you try operating that something and:

if it still works = keeps the ignition switch on the suspect list, but

if it also doesn't work = quasi-exonerates the ignition switch and condemns one of the upstream primary power connections.

(Of course, opening the door at 50 mph when everything cuts out won't be an easy reaction -- but maybe operating the overhead map light might be doable)

 

any chance the added fuse circuit is shorting to ground on the chassis? any movement of the added fuse block?

 

You are the boss of your own battery, of course. And, it's hard to beat the bang-for-the-buck associated with cheap batteries, at least when it comes to life span vs cost. I've used plenty of cheap batteries over the years. However, there's more to the story.

For my 360 Modena I'm going to stick with a good quality AGM battery; the type Ferrari specifies for my car. Ferrari doesn't recommend you use an ordinary " mundane" flooded lead acid battery and they do that for good reason, at least for the 360. Here's why.

My car is made from aluminum and I feel better if I don't let acid contact the structure of my car. In addition, the battery is essentially mounted in the passenger compartment, so I prefer not to have acid and/or hydrogen gas inside my car, but that's just me.

My car is nearly 15 years old and the battery compartment looks brand new because an AGM battery (except when abused by over charging) won't vent gas or release acid. You can't say that about ordinary lead acid batteries.

When people post pictures of a badly corroded battery compartment, the photo nearly always also shows a conventional " mundane" battery.

I'm all for saving money and that's why I do a lot of my own work on my Ferrari, but as far as I'm concerned, I'll spend the extra money on the proper battery. Other owners can suit themselves; it makes no difference to me. But I think they should know the potential downside.

 

Howdy JIMBO,
Put a new battery in your car and see if that takes care of your issues.
AGM batteries are my preferred way to go, especially if the battery is in an inaccessible place like in my 355.
Cheers,
Marc

 

If your car was originally equipped with an AGM, then certainly you should go with like for like.

But the OP was talking about a 512TR, and I think the 360 was the first all aluminum chassis.
The 512TR, I think, has a mix of aluminum and galvanized panels over a conventional tube frame.
My 328 is all galvanized steel (and fiberglass/plastic).

In 40 years, I've never seen a conventional battery "leak" acid.
And even back then, it was from over-filling a battery that predated the "maintenance free" ones.

If you have a battery inside the cabin space, you certainly don't want outgassing.
People who relocated the batteries on Celica GT-Fours, away from the turbo, to the rear of the hatchback often switched to AGM batteries for just that reason.
The acid battery in my EVO X, being in the trunk, has a vent line, in case of over-charging.

But the same model Interstate battery I have in my Alfa and 328 is sitting on a plastic shelf in my utility room to power my backup power inverter.
No leaks.
(I do charge it with an automatic charger at no more than 2A to minimize the chances of outgassing.)

I've had eight or nine different lead acid batteries in the '79 Alfa, since it was new, and the holder (in the trunk) is not at all corroded.

One reason you see conventional battery holders -- like in the 328 -- corroded is not so much from the battery as from the open space for venting, which exposes the holder to the outside environment -- rain, road spray, etc.

I put the same type of Interstate in the EVO VIII (engine bay) after nine years, and the original Panasonic acid battery left no traces on the holder.
(Oddly enough, Mitsu put the lead acid battery on a holder directly over the aluminum heads, but high up where it wouldn't get road splash.)

I know of people who switch to AGMs (or even more exotic) to reduce weight.
But my 328 is already 200 lbs tail-heavy (hence the fatter rear wheels), so there's no need to reduce weight in the nose.
(Similarly, the Alfa is horribly nose-heavy, so there's no need to lighten the trunk.)

And Optimas are notorious for not liking deep discharge, so for a car that sits out salted road winters, it's not always a good option.
(The Optima also didn't play well with my Schumacher maintainer.)

I wouldn't put a lithium ion battery in a car. The lithium batteries used on e-cigs have a lot of juice for the size and weight, but I won't charge one unattended, due to the risk of fire.

My preference for convention batteries may date to the time, many moon ago, when I was working at FAA and researched lead-acid batteries heavily, to build a battery reconditioner to revive the Alfa Spider's battery after winter. (When I was running the spider in summer and an Alfetta GT in winter, and there weren't any "computerized battery maintainers" available, because CPU chips were still expensive.)

 

I have nothing against lead acid batteries in my 575M or my other cars that I can actually inspect the battery. My 355 on the other hand he battery is in an inaccessible place (right front wheel well behind the headlight) I feel better using an AGM battery.

 

Have a nice, trouble free drive!!

 

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Would you mind telling me which Interstate battery do you use in your 400i? And how has your experience been thus far with Interstate brand?

I'm looking to replace my battery which is loosing charge and needs to be recharged every few weeks.

Thank you