Battery Maintenance And Charging
Here's all you need to keep your Mustang's battery in top condition
From the June, 2012 issue of Mustang Monthly
By Mark Houlahan
Photography by Mark Houlahan
One of the most feared aspects of car repair, maintenance, or even a restoration is the vehicle's electrical system. Watts, volts, ohms, and other terms swirl around most people's heads like sharks circling a bleeding surfer, and at the heart of that electrical system is one of the most misunderstood parts--the battery. In our Mustangs, be it vintage or late-model, the starting and charging system is based on a 12-volt negative ground service, so we're not going to bother with six-volt or positive ground systems for this story.
As the heart of your electrical system, your battery, must not only be able to start your Mustang by supplying enough power to the starter, but it also must be able to provide auxiliary power for key on and key off accessories (when the engine is not running and therefore the alternator not supplying the vehicle's power, for things like listening to the radio or the interior lights illuminating when the doors are opened). Lastly, the battery must be able to store this power between vehicle use (but not long-term storage) so that the car will start the next time you use it.
So why is it that this most important part of your electrical system is so often just left to fend for itself and never given maintenance until that fateful day when you get up early to head out to a car show and you find your Mustang in the garage with a dead battery? Your club members are meeting for the drive to the show in 20 minutes and you're standing there with the hood up wondering what you should do.
Taking care of your battery is really a simple process. It is something you need to add to your regular maintenance schedule. You check your engine's oil level on a regular basis right? You need to check your battery's level on a regular basis too. Keeping your battery properly charged not only means you'll be able to hop in and twist the key when you need it most, but the battery will last longer and save you money. Of course, there are a few preventive measures you can perform on your battery as well, and we'll go over those as well.
Batteries do not last forever. They should be considered a consumable item. That being said, sometimes it is best to start off with a new battery if your battery is of a questionable history. Just bought a classic Mustang and there's no real indication of the battery's age? You might want to play it safe and simply buy a new battery. Depending upon location, you can often guestimate how close you are to needing a replacement battery. In hot climates like Florida, Arizona, and Texas, you're probably going to see three years max out of a high-quality battery.
Today's batteries are typically a sealed, maintenance-free design, so there's little you can do to service the battery except for keeping the terminals clean. Often an "eye" on the battery will tell you its condition. If your battery does have removable service caps to allow checking the battery's level, then you should check the level at regular intervals. Be sure to remove all jewelry before servicing your battery and wear eye and hand protection. Remove the caps and check the fluid level. The fluid level should allow for the battery's lead plates to be completely submersed. If not, you can carefully add distilled water to bring the level back up.
If you own and know how to use a hydrometer, you can also check the specific gravity of your cells if the caps are removable. The same can be said for the battery's open circuit voltage (measured across the terminals). If you own a volt-meter, you can check the voltage too. Use the above chart to determine your battery's state of charge.
Finally, external condition is just as important as the internal condition. Case damage, terminal damage, and more should all be things to look for on a regular basis. Of course, if your battery is properly secured, there's little chance of external damage, but we've seen cases nicked when being dropped into place, so be careful and don't rush things when installing your battery.
The previous two batteries...
The previous two batteries are lead acid flooded batteries, meaning their case is essentially a plastic box with fluid that floods the battery’s lead plates. There are other battery types, including gel-cell and AGM, or absorbent glass mat. Probably the most popular AGM battery is the Optima, which uses spiral cell technology where the lead plates are tightly wound into a cylinder form and sandwiched with the absorbent mat that holds the electrolyte and prevents it from spilling. The Optima battery is sealed and there is nothing to really do maintenance-wise save for keeping the connections clean and tight and ensuring the battery is charged.
This "maintenance free" battery...
This "maintenance free" battery actually has removable vent caps. If you're not sure if your caps can be removed, a bit of gentle prying with a small flat-blade screwdriver should help determine if they are removable or not. The terminals are in great shape on this battery and there's no case damage, but we do see some terminal corrosion that needs to be taken care of; more on that later.
We frequently get tech questions...
We frequently get tech questions from readers about what's the best Optima battery for their application. Optima has tech bulletins, tips, and more on their website where you can find answers to many of the questions. However, answering the "right one for me" question is fairly simple. Optima offers three main battery types, all denoted by colored tops--RedTop, YellowTop, and BlueTop. The BlueTop is designed for marine use, so we can rule that one out for Mustangs. The RedTop is a cranking or starting battery, so it should be considered if your primary concern is starting the car, no matter the temperature or starting demands. The YellowTop has cranking power similar to the RedTop, but also features deep cycling capability, which means it can support demanding electrical loads like big audio systems, high key-off electrical loads, and so forth. The YellowTop can "bounce back" from being deeply discharged without damage, unlike conventional batteries.
In our opinion, the first...
In our opinion, the first thing this battery needs is a shot of flat black paint, but we'll worry about that later. You might have noticed that the battery is not retained in the tray. Many modern battery case designs, even though they are listed as Group 24F, do not have the proper hold-down ridges molded into the case, but we have a fix for that we'll show you a bit later. This battery has raised vent caps that are removable for checking fluid levels, and the posts are quite dirty.
Here's that unsecured yellow...
Here's that unsecured yellow case battery in a '66 Mustang battery tray and the solution--a conversion battery tray (PN 10732-1C) from National Parts Depot. Available for $14.95, the tray requires the use of the '67-'70 style retaining rods and hold-down bracket (PN 10756-1K and PN 10718-2A, respectively). The tray bolts in place of the stock tray using the stock tray's fasteners.
One side benefit of the new...
One side benefit of the new tray design is that without the side hold-down clamp, the tray is shortened to meet the case side wall, leaving a couple of inches of space for a larger radiator, fan shroud, wiring, or anything else that might have been in the way with the stock wider tray with side clamp.
Something else to consider,...
Something else to consider, especially for those using flooded batteries, is an anti-corrosion mat. NPD stocks them under PN 954-1A for under five bucks. You simply cut it to fit your tray and place it under the battery. If your battery leaks or over flows from overcharging, the mat will absorb the battery's electrolyte and minimize damage to the battery try and fender apron. That's cheap insurance in our books!
With our flat top, maintenance-free...
With our flat top, maintenance-free battery back in place, we decided to give it a more correct look with NPD's Autolite Sta-Ful battery cover. These plastic covers drop right over a Group 24 flat-top battery and include separate vent caps (so you can position them any way you like) and a positive terminal post warning tag like the originals.
A nice detailing touch is...
A nice detailing touch is a correct set of battery cables. Not only are these cables made for the application, thus being the proper length with the proper end sizes, they add a nice touch of originality to a Mustang. When you order battery cables, you'll get a positive and negative battery cable, plus the starter cable. You should inspect your cables regularly and replace them as a complete set if any need replacing. We also recommend the standard red for positive and black for negative, especially if you're buying parts store replacements, so that helpful person won't blow up your battery while trying to jump start your Mustang.
Having the properly sized battery for your Mustang is just as important as having the proper capacity. Generally speaking, using the battery group as originally specified by Ford is the easiest way to ensure things go smoothly. If your Mustang uses a Group 24F, don't use a Group 58, and so forth. Problems like terminals on the wrong end of the case, cases too wide or too tall (hitting the hood of the car or the inner fender), or simply the footprint of the case being too large for the battery tray are all issues that can be solved by simply using the proper battery group for your application. There are still companies that make the proper battery cases for our vintage Mustangs; you just have to look for them. However, they are getting harder to find.
One solution for '65-'66 owners is to update the battery tray to a conversion tray that uses the '67-'70 style hold-down assembly. While not correct for concours use, it is a solid and safe solution that bolts right in and cost less than $30. For those who can find the correct battery group, try to purchase a flat top, maintenance-free battery and then you'll be able to use an Autolite replica battery cover that slips over the battery posts and makes your universal battery look like a correct Autolite.
Maintaining your battery means ensuring it is properly charged as well as taking care of the battery's fluid level, connections, and exterior condition during the months you use your Mustang. All you need is a few simple tools to keep your battery's connections in proper working order. As we said before, add your battery to your list of regular maintenance items or get in the habit of checking the condition monthly, or perhaps at each oil change (especially for those daily drivers out there).
Charging a discharged or sulfated battery is a simple process, but it is imperative that the proper charging equipment and safety procedures be followed. Standard flooded batteries are much more susceptible to sulfation of the lead plates. This limits the battery's performance and can cause a no-start or lack of charging. Modern battery chargers and maintainers have a de-sulfation mode that helps break down these sulfates and put new life into older batteries. Look for a quality charger/maintainer that has multiple battery type settings so you'll only need to purchase one product no matter what type of battery you are charging.
Lastly, never consider your car's alternator as a battery charger. If your battery has died from leaving the lights on or other roadside issue, you should really charge the battery fully before starting the car, versus jump starting it and then driving the car to charge the battery. We've all done it, especially in an emergency, but the best case scenario is to have a friend or family member bring out another battery and charge the dead one properly at home.
AGM batteries can be a bit tricky, as they have different considerations for charging. Older 12-volt chargers will usually only charge an AGM type battery to approximately 80 percent, which is why we again recommend a newer charger/maintainer that has an AGM setting. AGM batteries, like flooded batteries, do well with a lower amperage charge (1-10amps). Charging at higher rates generates a lot of heat, which reduces battery life. AGM batteries are most known for not "taking" a charge if they are deeply discharged, often meaning below 10.5-volts at rest. If your AGM battery is drained below 10.5-volts, you'll need to charge it either by using an AGM specific charger or by connecting the discharged AGM battery in parallel with a good battery so that the traditional charger "sees" the good battery and charges appropriately.
|Voltage||Approximate State-of-Charge at 80°F Average Specific Gravity|
|11.89 or less||Discharged||1.120 or less|
Hopefully you've got a battery...
Hopefully you've got a battery post/terminal brush in your tool box. If not, there's no excuse not to have one, as they run just a few bucks at any auto parts store. This is your number one tool for post/terminal maintenance. They quickly and easily clean the terminals for the best connection.
Once you've removed a battery...
Once you've removed a battery terminal from the battery post, it is often difficult to reinstall the terminal over the post due to the distortion of the terminal clamp (usually caused by over tightening). A battery terminal spreader simply allows for a quick and safe way of spreading the terminal open enough for it to fully seat around the battery post. Then the terminal can be tightened properly to retain it to the post. If you find you're having trouble removing the terminals in the first place, a terminal puller is another tool you can look into for removing the terminal easily from the post.
Our cleaned battery post is...
Our cleaned battery post is ready to accept our battery cable. As you can see, the post's surface is clean of any accumulated corrosion or dirt and the surface is spotless.
Just as important as the main...
Just as important as the main battery cables is the engine ground cable. Because the engine sits on rubber isolators, it does not inherently have good grounding capabilities for sending units, ignition, charging system, and more. A simple ground strap from the back of the engine to the firewall is what Ford has used for decades and it works well. Again, a concours-type ground strap like this one from NPD means it will be the right length with the proper eyelets for your application. Don’t forget it, especially those doing engine swaps, as it’s easy to leave it on the old engine.
The same tool can be used...
The same tool can be used to clean battery cable terminals as well. Just remove the protective cap and twist the brush into the cable terminal to clean the surface.
While not 100 percent necessary,...
While not 100 percent necessary, we rarely need an excuse to buy new tools, right? So hit the tool store for a set of terminal pliers and a terminal spreader. These tools will help remove and install your cable ends without damaging them or your battery posts.
The terminal pliers are designed...
The terminal pliers are designed to grab the square head of the terminal pinch bolt and hold it while you remove the threaded retaining nut. If you've ever dealt with a soft terminal and a spinning pinch bolt, you'll know why they invented these pliers. They hold the bolt securely and prevent it from spinning and damaging the terminal.
Optima has recently released...
Optima has recently released their very own charging solution, the Optima Digital 1200 charger. Designed to maximize the Optima AGM battery's condition, the charger can also be used on traditional flooded batteries. It features a digital charge gauge that shows all connection types, warnings, and state of charge messages as the charger goes through its six-step charging/maintaining process. The charge leads feature built in LED work lights for connecting to batteries in dark locations such as a trunk mounted battery. The charger also features a USB charging jack for cell phones and other small devices.
If long term storage is common...
If long term storage is common for your Mustang, a battery terminal disconnect switch like this one from NPD (PN 957-3) is a simple solution. It even comes with a small fused jumper wire to maintain your aftermarket radio's memory while still preventing major discharge from leaving the lights on or a door open. We still recommend a battery maintainer be connected, but this switch reduces the amount of time the maintainer is needed.
We've owned this CTEK battery...
We've owned this CTEK battery charger/maintainer for about four years. The Multi US 3300 is a slim unit that can be used on flooded batteries or AGM batteries just by selecting the battery type on the face of the unit. It has a quick connect feature so you can use permanently mounted ring terminals or the typical spring clamps.
If your AGM battery falls...
If your AGM battery falls below 10.5-volts open-circuit voltage, a standard charger might not recharge the battery. While we recommend a modern charger with an AGM circuit built into it, if you're in a pinch with a standard charger you can simply connect a known good battery in parallel (positive to positive, negative to negative) and then connect the charger to the cables directly as shown. This will allow the charger recognize the voltage of the good battery and start providing a charge. Maintain this charging connection until the open-circuit voltage increases above 10.5-volts, then you can remove the second battery and jumper cables.
CTEK's latest model is the...
CTEK's latest model is the MUS 4.3, which has an eight step charging/reconditioning process that can solve many battery problems, including deeply discharged flooded batteries, sulfated batteries needing reconditioning, AGM specific charging, a winter charging mode, and more. Like all CTEK chargers, the connections are spark proof, reverse polarity protected, and short-circuit proof. You can literally clip the clamp on leads together and nothing happens. No sparks, no arcing, no blown fuses. Try that with your old bench top charger.