Battery question.

#1

In reading over the rules, I am under the assumption that I am able to relocated the battery to the middle of the trunk for weight distribution and that I am able to replace the battery with a smaller “wheelchair” battery to save some weight.

However, I have not seen anyone do this really. Maybe a few have reloacated the battery but none I have noticed have moved to a smaller battery. Am I wrong in thinking that it is legal? or are people trying to add weight by using these stock sized batteries that weigh a million pounds.

#2

What leads you to believe you can go with a lighter/smaller battery?

#3

The rules do not mention battery type therefore your battery should remain OEM equivalent.

#4

Fair question. The type of battery is not addressed in the CCR, therefore that part of the car “must remain as it came from the factory”.

Bottom line up front: I don’t think anyone’s going to care if you start your car with a couple Lithium D-cells. If your regional director buys in, you’re probably good.

Details. Stating the obvious,batteries have to be replaced routinely. Lots of folks make batteries and they will happily tell you which of those are for the E30. Ultimately you’ll end up with batteries of varying quality, weight and dimensions. In the absence of any standard on how to identify that a battery is “as it came from the (BMW) factory”, there’s no right answer.

I looked thru the owners manual, OEM Service Manual and Bentley and didn’t find anything useful.

In the absence of any useful guidance on the issue, I’d just apply some common sense and drive on.

#5

[quote=“Ranger” post=57865]Bottom line up front: I don’t think anyone’s going to care if you start your car with a couple Lithium D-cells. If your regional director buys in, you’re probably good.[/quote]:blink: Bad advice.

[quote]In the absence of any standard on how to identify that a battery is “as it came from the (BMW) factory”, there’s no right answer.[/quote]It’s a size 48, I believe. Battery Size Chart. If you want to find the lightest #48 battery you can get, knock yourself out.

#6

[quote=“Steve D” post=57867][quote=“Ranger” post=57865]Bottom line up front: I don’t think anyone’s going to care if you start your car with a couple Lithium D-cells. If your regional director buys in, you’re probably good.[/quote]:blink: Bad advice.

EDIT: Interstate and Batteries+ say it is a size SLI91. The bf.c experts say MT-48. Either way, it’s the same size.

#7

There is also a theory floating around that you want the battery in the stock location as opposed to the tire well for cross weight distribution and some more weight over the RR. But that’s just a theory.

#8

Also, I was informed by Pantas at my annual tech this weekend that according to the rules a metal strap of some kind must be installed over the battery to keep it from coming out of the stock location during a wreck/roll over. I was unaware of this rule but I will be installing one soon. Just an FYI for anyone else that didn’t know this rule was out there. I think Jim can attest to this with the wreck he had in his old car in the esses at RA.

#9


8.16.1 The 12 volt battery may be relocated from the OEM location to any other location inside the trunk compartment of the vehicle. A sufficient battery hold-down system shall be installed on any battery that has been relocated from the OEM location. The battery hold-down system may not weigh more than 6 pounds.
Additional hold-down is only required for a relocated battery. It is a good idea for the stock location. The stock location is arguably a bad place for the battery in an impact.

I haven’t yet run the higher-center-of-gravity vs. lower-polar-moment-of-inertia calculation, but I moved mine next to the shock tower. If I back it into a wall, I want to be able to crank the car and get the hell out of the way!! Can’t do that if your battery is in pieces.

#10

The rules say that “9.3.3.2. Batteries may be replaced.” If it said “Batteries may be substituted” I would def replace it with a oem sized battery.

#11

[quote=“rmontoni” post=57896]The rules say that “9.3.3.2. Batteries may be replaced.” If it said “Batteries may be substituted” I would def replace it with a oem sized battery.[/quote]Good catch. The confusion will arise in interpreting “meeting or exceeding OEM specifications” as applies to a battery. Exceeding the amp rating of the original? Lighter is better and BMW didn’t want anything heavier than the OEM piece, so a lightweight one exceeds that spec?

Racing/heat/cool suits/fifty bazillion warning lights can be pretty tough on a battery. It’s a real b!tch sitting on grid at the 5 and your car won’t start…:blush: