GearHack: Revision: Installing a Light-Weight Car Battery

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Installing a Light-Weight Car Battery

Back when we were track-racing our cars, we used to spent nights dreaming up ways to make it go faster. One way was to lighten the battery. Reduce the overall vehicle weight and your engine had less mass to move. But we didn't learn about the additional benefits of having a light-weight battery until after we stopping racing our vehicles:

Hauling less mass, saves gas.
Some light-weight battery costs less than regular car batteries.
Some light-weight batteries are sealed and maintenance-free.

The first benefit is obvious, even if minute. Originally we never considered it, but with the huge increase in gas price, every bit counts.

Light-weight battery made for other purposes than starting cars generally cost far less than regular car battery. Most likely due to the less demand in those industries. After all, most of us need a car to get anywhere nowadays.

This third benefit is really the driving force of using these batteries in everyday driving. One of our friends left his car battery in the trunk of his car. It tipped, spilled onto the trunk carpet and a rag. The next day he found the remaining of what we guessed was a rag. It completely decomposed due to the battery acid. The following photo shows corrosion on the battery mount. I had to throw that mount away, because it could not be dissembled.

With a sealed-lead acid battery, you won't have to worry about corrosive acid spilling in your car. You don't have to top off its water level. You can transport them in almost any fashion.

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Picking a Light-Weight Battery

It's not so easy picking a light-weight battery for cars. We must find one that matches a standard car battery in as many aspects as possible. These aspects include voltage, amp-hours, longevity, charging characteristics, etc. Fortunately, those light-weight batteries are out there and we have found several replacements.

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Hawker Genesis G16EP

When we first started looking for light-weight batteries for our cars, we found the Hawker Genesis G16EP battery. It costed about $50 bucks, but has since then drastically increased in price.

It is only 13.8 pounds; About a third of the weight of a regular car battery.

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Hawker Genesis G13EP

Later, we found a surplus of Hawker Genesis G13EP battery. We were able to pay $25 for each battery. The G13EP is slightly smaller than the G16EP and weighs only 10.7 pounds. We were thrilled with this battery.

The following photo shows the size difference between the Hawker Genesis G13EP and G16EP.

But the surplus stash of Hawker Genesis G13EP didn't last long. With the Hawker Genesis G16EP price sky-rocketing over the roof, we soon started looking for another source of light-weight batteries.

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Universal Battery UB12180

The Universal Battery UB12180 is a good candidate. This battery is about the same size as the Hawker Genesis G16EP. It weighs about the same as well. In fact, if you look at the specs, you'd say it is the same battery. The only difference is the terminal on top of the battery. It has a bladed terminal used for wheel chairs and golf carts. At less than $50 a pop (including shipping), it's an excellent car battery replacement. Sources for this battery are listed in the "Related Links" section below.

After using this battery for about a year or so in three different cars, we can say that it is practically the same as the Hawker Genesis G16EP. Only minor difference is that the Hawker Genesis battery can be mounted in any orientation, the Universal Battery UB12180 has to sit up-right. More detail about this constrain in the mounting section.

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Technical Details

The Universal Battery sealed lead acid battery requires a voltage limited charger set to the following voltages: float charge 13.5 - 13.8V, cycle service 14.1 - 14.4V maximum. The design permits rapid recharge at these voltage settings. F.A.A., C.A.B., I.A. T.A., and D.O.T. air transport approved. Ventilate well. Do not install inn airtight container. 12V 18Ah.

Constant Voltage Charge at 20 degrees C	Voltage Regulation	Initial Current
Standby Use	13.6 - 13.8 V	2.7 A
Cyclic Use	14.5 - 14.9 V	5.4 A

Do not short circuit.
Avoid total discharing (deep discharge).
Do not charge in a sealed container.
Replace every 3 - 5 years.
Warning: Risk of fire, explosion or burns. Do not disassemble or heat above 65 degrees C or incinerate.

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Converting to Car Battery Post

In this section, We will explain how to convert the battery posts on these light-weight battery to the ones acceptable by your vehicle.

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Hawk Genesis Batteries

The part you will need is the following:

Odyssey 3217-0006 SAE Terminal Conversion Kit (Convert M6 Bolt Terminals to SAE 3/8" Receptacle Terminals)

With the part listed above, all you have to do is screw it into the battery terminals of the Hawker Genesis battery and you are good to go.

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Universal Battery UB12180

The part you will need is the following:

Odyssey 3217-0006 SAE Terminal Conversion Kit (Convert M6 Bolt Terminals to SAE 3/8" Receptacle Terminals)

The vertical battery post on the Universal Battery UB12180 makes it difficult to convert to the SAE battery posts. The first bright idea we had was to use golf cart cables. Connect one end of the cable to the vertical battery post blade, while connecting the "Odyssey 3217-0006" post to the other end.

This conversion is good if your existing battery cables doesn't reach. And it allows you to orient the battery the way you like. But after driving with it for a few days, it occurred to me that having moving parts (golf cables wiggling) may not be a good thing in the long term.

The next solutions was to use L-brackets. You can pick up metal L-brackets from your local home improvement store. Following photo shows the L-brackets screwed onto the terminals.

The UB12180 battery comes with screws and nuts. You can use them to fasten the L-brackets to the battery. The photo below shows the L-brackets mounted onto the battery.

With the terminals mounted to the top of the UB12180 universal battery, you can mount it into your car much like any car battery. It's just one third the size of a regular car battery. The following photo shows the battery mounted upright in the car battery compartment.

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Laying UB12180 Down is a Bad Idea

Apparently, UB12180 didn't not like to lie down. In one of our cars, we mounted the light-weight battery sideways in order to lower the center of gravity and provide a larger mounting surface. This car has difficult starting, whereas the other cars that mounted the batteries upright started just fine. Swapping UB12180 batteries with other cars showed that the problem didn't move with the battery, it stayed with the car. After mounting the UB12180 up-right the problem went away. We destroyed one battery in the process of troubleshooting this problem; we crank the engine too many times.

Our guess is that the chemical in the battery may lose contact with the battery terminals when it is lying down. It's obvious this battery is not designed for mounting in any orientation, whereas the Hawker Genesis batteries could be mounted sideways.

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Mounting in Your Vehicle

If you get the Hawker Genesis battery, you can mount them sideways in your vehicle, which lowers the center of gravity.

To lay the Hawker Genesis battery down, you have to screw the battery cables onto the battery post first, because they are too hard to work with when the battery is laying down.

Once the cable has been screwed onto the battery posts, you can lay the battery down as shown in the photo below.

We have to get a special battery bracket (see photo below) that can mount a battery that low. The battery bracket that came with the car has threads that ends too early. Note that we added wing nuts to the top for additional cover.

Photo below shows the Hawker Genesis battery mounted in the vehicle.

This battery is mounted into a 2001 Subaru Impreza 2.5 RS, where the engine hood had ventilation holes. We installed a sheet of plexiglass on top, using additional wing nuts, to route water away from the battery post (see photo below).

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