Optima Battery

[1993R]

So what size fits in the stock fox battery tray? Group 58 is what the R came with. I hear there are fitment issues as well.

 

[tistan]

tistan, I’m sorry to hear about the problems you’ve been having. I’ve included some troubleshooting directions below, to help determine if there might be problematic battery, alternator or some other issue that giving you problems.

Fully charged, with the engine not running, your Optima (either Red or Yellow?) should measure over 12.6 volts. If you charge your battery (either Red or Yellow?) with a deep cycle battery charger, it will get to approximately 13.0-13.2 volts. Voltage measurements of the battery when the engine is running are the output of your alternator. This measurement should be approximately 13.7-14.7v. The alternator may not get your battery to the higher voltage of a deep cycle battery charger – but that isn’t necessarily a problem.

If you don’t have a multimeter you can test this by starting your vehicle and turning on the headlights. If they are dim, it indicates the lights are running off the battery and that little or no juice is being produced by the alternator. If the lights get brighter as you rev the engine, it means the alternator is producing some current, but may not be producing enough at idle to keep the battery properly charged. If the lights have normal brightness and don't change intensity as the engine is revved, your charging system is probably functioning normally.

If this checks out okay, you should check whether or not the battery is holding a charge, or if something on the vehicle is discharging the battery. A high parasitic draw ("key off" load) can quickly discharge a battery and decrease its service life. This may be caused by an aftermarket stereo, alarm system or even a bad fuse.

A vehicle can be tested for a high key-off load with an ammeter or DMM on the DC amps setting. With the ignition off, disconnect one of the battery cables. Connect one ammeter lead to the battery and the other to the cable. It may be necessary to wait several minutes after first starting your measurement for some items to “go to sleep”. The normal current drain on most vehicles is about 25 milliamps or less. If your key-off load exceeds 100 milliamps, you can isolate the problem by pulling one fuse at a time from the fuse panel until the ammeter reading drops.

The one other thing I wanted to mention is that we encounter a lot of people who have problems after they have jump-started their battery. Any battery that is jump-started should be fully recharged with a battery charger as soon as possible. An alternator may not be able to fully charge a deeply-discharged battery and relying on one to do that could lead to a cycle of dead battery/jump/dead battery/jump until either the alternator or battery fails.

If you have any other questions, please don’t hesitate to contact me.

Jim McIlvaine
eCare Manager, OPTIMA Batteries, Inc.
Optima Batteries | Facebook

I have a new one now, but the old one I charged on slow 2.5 amp charger. I also had advanced auto charge it. They tested the battery and according to their tester it was good. I charged it and just left it out of the car with the same results. It would charge to 13.9 volts when my charger read full and the next day it would be back down to 11.8 volts. This was in my 05 GTO. Then the one in cobra started doing the same thing, so I had to buy a new one for it. I have factory stereo and no alarm on either car. I am on about 8 months with no problems right now so we will see how it works this time.

 

[OptimaJim]

1993R, unfortunately, Optima doesn’t offer an exact-fit replacement battery for every application– including Fox body Mustangs. However, you can measure the dimensions of your existing stock battery to see if there’s an Optima that will work for your vehicle. Below is a link to the product specification page where you can find exact dimensions for Optima RedTop batteries:
Optima RedTop Specs - Red Top AGM Batteries by Optima

You can also check with other guys who are running Optimas in Cobra Rs, to see how they did it. If you are using an Optima battery in a custom application, it is important to consider the following:

• Hood Clearance – There should be at least ¾” clearance between the top of the battery terminals and the underside of the hood.
• Trunk/Interior Mounting – If your battery is mounted inside the passenger compartment, the battery must be vented to the outside of the vehicle. Optima group 27, 51, 78, 34C, and 31 batteries all have ports for connecting a vent hose.
• Side Terminals – Optima 34/78, D34/78, 75/25 and D75/25 batteries have both top and side terminals. If you are using one of these batteries in a vehicle that uses the top terminals, it is important to ensure that the side terminals cannot come in contact with anything metallic (for example, the firewall or fender well), thereby causing a short. We suggest keeping the post protectors on the terminals you are not using.
• Battery Modifications – Cutting, drilling, trimming or otherwise modifying your Optima battery may present a safety hazard and will void the warranty.
• Mounting – Your Optima battery must be securely mounted. The terminals are not intended to be used to secure the battery. Using the terminals in this way will damage the battery and void your warranty.
• Heat – Protect your battery from high heat, such as turbochargers or exhaust manifolds

I hope that helps, but if you have any other questions, please don’t hesitate to ask. I appreciate your interest in Optima batteries.

tistan – I hope that your current RedTop continues to perform well. If you see any signs of trouble, feel free to PM me, and we can look at some of the issues most common to your car that could be the culprit.

Jim McIlvaine
eCare Manager, OPTIMA Batteries, Inc.
Optima Batteries | Facebook

 

[drkhrse]

So what size fits in the stock fox battery tray? Group 58 is what the R came with. I hear there are fitment issues as well.

I run red top #34 (top post only) in both my 93 teal cobra (custom hold down) and my 93R (stock hold down). I've never had a problem with them and had them for years. I simply disconnect them when not in use.


You can see why I like the red top, :thumbsup: