nguyen365

Don't know what's going on. I wonder if I need a bigger battery or I need to test to make sure my alternator is even charging my batteries. I have a small oddyssey 680 battery engine bay (these are junk) btw linked up to the stock s2000 battery which is relocated to the trunk and I'm having trouble starting the car in the mornings. I'm running 91 and e85 together.

I'm thinking about getting the battery load test done and having my altanator checked out. Any other suggestions?

Maybe get a bigger battery with better cca? Maybe just run full 91 until it gets warmer in the summer months April till November?

Mijae007

Get a standard size battery. You relocated to the trunk right? Make sure its an agm dry cell battery so you dont have poisonous acid spill all over your interior lol.

Charper732

I had this issue with a Optima red top when I relocated to the trunk. I had to add multiple grounding locations to fix it, one 2 gauge and two 8 gauge. Doesn't help that there really isn't a good ground location in the trunk. I used the mounting point for the shock on mine.

LostMarine

change your negative battery cable. i searched for weeks tryin to figure out WTF my electrical issue was. Battery relocated to trunk. i checked all fuses, replaced entire power wire etc. as soon as i swapped the neg cable, boom, all power no issues.

Mijae007

If thats the case, make sure to sand down any paint at the grounding point to ensure a good ground. I used a bolt just behind the passenger side seat with 0ga welding cable (same as my positive) with no issues. Used a yellowtop optima.

flexer

Its not the battery its the relocation that is killing you. When you relocate a battery to the trunk most use too small of wire running to the front and the wire quality is usually crap which only exaggerates the problem now that you have added a ton of length. Next thing is as others have stated above that grounding to several points in the trunk is a must.

LostMarine

Although I agree with you, that wasnt my case. the wire itself went bad somehow, looked 100%. Thats what took weeks to diagnose. when i say instantly grounded new wire, all power came back. tried old wire, dead as nuts. something inside it went to shit or disconnected under the casing. would never be able to tell visuallly

engifineer

Curious as to why folks relocate the battery to the rear and run more heavy wire, on a car that is already distributed 49/51% to begin with? So making it more rear heavy and adding more weight in cables? Personally, I would just run the battery in the stock location, or is this to make room under the hood for something else?

Mijae007

For most of us in FI, its to make room for the hotside turbo setup, move it due to high heat exposure in the factory battery location, or for some to clean up the bay for a cleaner look. Im sure weight ratio remains more or less the same since additional weight is also added to the front due to FI components.

engifineer

Ah, makes sense. I thought it had to be mostly for room on the FI side. I guess I can see the engine bay cleanup .... but I look at the S as a function >>>>> form car.... so dressing the engine bay up didnt even come to mind :P