View Full Version : Installed Optima Battery in 3

12-18-2009, 06:57 PM
My wife has an '06 3. Last week, the battery started to reach the end of its useful life and it was clear a replacement was needed as soon as possible since I didn't want her to be stuck out on the road somewhere.

General Information
The Battery Council International (BCI) determines specifications for lead-acid storage batteries. One of their functions is to provide a list of standard battery dimensions codified under the title of BCI Group number. Each group number specifies a given battery size in terms of length, width, and height, as well as the terminal polarity; left hand positive, right hand positive or centerline layout. Looking down on the top of the battery with the terminals closest to you, a R/H positive battery would have the positive terminal on your right. Finally, the terminal location is also listed - top, side or both top and side. BCI publishes a Battery Replacement Data Book each year and the latest 2009 edition costs ~ US $7. For more information, go to:

BCI Group Number charts can be easily found online. When seeking a replacement battery, securing one of the same group number as OEM will ensure correct fitment. Keep in mind that there may be some variation from the standard, depending on the manufacturer, which may require minor adjustments when fitting certain replacement batteries. Using a battery of opposite terminal polarity may result in the cables not being able to reach the terminals.

Battery Types Used in the 3
The '06 FSM lists specified battery types using Japan Industry Standard (JIS) type numbers. Two of the types listed, 50D20L and 75D23L are equivalent to BCI Group 35 in terms of dimensions and terminal polarity layout, according to the BCI Battery Replacement Data Book (2007 Edition).

The third type listed, 80D26L, is now fitted to late-model Canadian 3s, according to TheMAN. This type is equivalent to BCI Group 34R both dimensionally and in terms of terminal polarity layout. Although not listed in the '06 FSM, TheMAN states that the type 55D23L, equivalent to BCI Group 35, has been fitted to certain L3 (2.3 L) models.

The OEM battery in my wife's car was 3 years, 4 months old, a no-maintenance type made by Panasonic. The model number is (JIS) 50D20L and is molded on the battery top. It has R/H-POS polarity. After removal, I measured the case size to provide comparative data useful in selecting a replacement.
50D20L Dimensions L x W x H, inches (mm)
7 13/16 x 6 11/16 x 7 13/16 (198 x 170 x 198)

Note: Height measurement is to top surface of battery (clamping surface) and does not include terminal length.

JIS Battery Designation Code
This information is taken from the BCI Battery Replacement Data Book (2007 Edition). For example:
50 D 20 L

first 2-digits (50) = performance ranking
first letter (D) = classification by battery width x container height
next 2-digits (20) = approximate battery length in mm when multiplied by 10
Last letter (L) designates polarity. R = standard left-hand front positive terminal; L = reversed right-hand front positive terminal

Selected BCI Group Number Dimensions and Terminal Polarity (Generic)
BCI Group Number _____ L x W x H, inches (mm) _______ Polarity
35 ____________ 9 1/16 x 6 7/8 x 8 7/8 (230 x 175 x 225) ___ R/H-POS
34R ___________ 10 1/4 x 6 13/16 x 7 7/8 (260 x 173 x 200) _ R/H-POS

In the next post I'll cover battery selection and installation.

Happy Motoring!

12-18-2009, 10:12 PM
Having switched to an absorbed glass mat (AGM) battery in my Protege, 3 years and 8 months ago (and still going strong), I wanted the same type for the 3 because of its many advantages and superior longevity. In fact, the only disadvantage of the AGM types is their high initial cost which, however, probably more than evens out in the long run. But that's material for another thread. Incidently, the Protege also uses the BCI Group 35 battery type.

I'm currently using an Exide Orbital AGM battery in my Protege - part number: ORB75DT-84.

There was a large-scale test of automotive batteries in the November 2009 issue of Consumer Report (CR) magazine in which a number of AGM batteries were tested along with conventional flooded electrolyte types. Although no BCI Group 35 batteries were tested, in BCI Group 34/78 the AGM batteries were rated 1st (Sears Diehard Platinum), 2nd (Optima Red Top), and 3rd (Deka Intimidator), in that category. The Exide Orbital was rated 8th. The Sears Diehard Platinum, as well as the Optima Red Top and Exide Orbital, are available in BCI Group 35 but the Deka Intimidator is not available in that Group. Unfortunately, the Deka Intimidator, Model 9A34, is available only in BCI Group 34 with L/H-POS polarity but not available in the required Group 34R so would not be usable in the 3.

Then, I checked for the lowest prices I could find. Diehard Platinum P-5 (only available at Sears) = US $190; Exide Orbital (Remy Battery online) = US $160; Optima Red Top: Model 35 (local Autozone) = US $209 ???; Optima Red Top: Model 35 (1st Wholesale Battery Sales) = US $150. Since it was the second highest rated battery in the CR test, and available at the lowest price of all the sources I checked, I ordered it from their website last Sunday:

The price includes a height adaptor (spacer) and shipping. The battery also comes with a removable carrying strap. The company is in Nebraska and I received it today via UPS ground. The battery arrived in an extremely well-protected shipping carton surrounded by some foam-like material. I actually had to vacuum the battery to remove all the foam particles! After unpacking, I measured the battery voltage with my Wavetek HD160 DVM. It read 12.6V which according to most sources, indicates a battery ready for installation without the need for a prior charge. The company claims all batteries are factory fresh and fully charged on arrival. The Optima battery is also available direct from the Optima website but at a substantially higher cost.

The Optima Red Top is a starting battery. Optima also makes Yellow Top deep cycle batteries for those who have, for example, high current-draw aftermarket audio systems.

Brief Specifications Optima Red Top (Starting)
BCI Group 35: Model 35
CCA at 0 deg F (-18 deg C) = 720
Dimensions: 9.3 x 6.7 x 7.7 (237 x 170 x 195); Weight: 31.7 lbs (14.4 kg)

BCI Group 34R: Model 34R
CCA at 0 deg F (-18 deg C) = 800
Dimensions: 10 x 6.8 x 7.8 (254 x 173 x 199); Weight: 37.9 lbs (17.2 kg)
Cost at 1st Wholesale Battery Sales: US $165 (includes shipping)

Important note: Optima measures height to the top of the terminals. Actual case height is ~ 1" (25.4 mm) lower.

FYI, virtually all batteries available in the US are manufactured by just three companies: Johnson Controls (makers of Optima), East Penn (makers of Deka), and Exide.

Tools Required:
3/8" drive ratchet
3" extension
10 mm deep socket, 6-pt
10 mm box wrench

Open hood and put support in place.

Remove battery cover from battery box by spreading locks at front of cover and pulling forward. No tools required. Battery duct need not be removed. Set cover aside.

Remove negative battery cable by loosening clamp bolt with 10 mm box wrench. Then remove the positive battery cable. Move cables out of the way as much as possible.

Remove flanged battery clamp nuts with ratchet, 3" extension and 10 mm deep socket, and then remove clamp from battery.

Battery is now ready to be lifted from box.

Install in reverse order.

The proceedure is very simple and takes little time. Which was a good thing since it was 22 deg F when I did the job, today. I have no garage and must do all my work on the driveway - summer or winter. In fact, installation is so easy it would be criminal not to do it yourself.

The Optima Red Top comes with a height adapter (included in the price) which raises the battery off the tray by 1.25". The Optima is lower in height than the OEM battery but using the adapter will almost exactly equalize their heights and ensure that the battery will be properly clamped down. Don't forget this step.

I applied a light coating of Red Line synthetic grease to the threaded part of the hold down rods on which the batttery clamp is fastened to prevent future corrosion. Be careful when tightening the flanged battery clamp nuts that you don't apply too much torque as a cracked battery case could result. Use your judgement and just snug them up sufficiently to hold the battery firmly in place.

If you wish, a light coating of dielectric grease (I use Permatex brand) can also be applied to the battery terminals but unlike conventional flooded electrolyte batteries, no corrosion ever forms there over the life of the battery so this step is not necessary, IMO.

Finally, for those who have need of the higher energy BCI Group 34R Optima Red Top battery, the battery tray and box is long enough to accomodate its greater length, so fitment shouldn't be a problem.

The new battery did the job. The car starts normally again and everything is good. I hope my wife knows what a treasure I am.

Happy Motoring!

Photo 1: Battery cover
Photo 2: OEM battery
Photo 3: Optima Red Top
Photo 4: Diagram of R/H-POS polarity

12-19-2009, 03:19 PM
:thumb: definitely a descriptive writeup- good choice on the battery, i've been running a optima redtop for the last 4 years myself. i wasn't aware of a battery council thats also good information

12-19-2009, 05:45 PM
Thank you, Ryan. :)

Happy Motoring!