Hello,

I know there are mixed reviews on the Optima, some of the negative reviews are most likely people who haven't used the battery because they think it is over priced. But anyway, I'd like to install a Yellow Top on my 87. I want the Deep Cycle because of the advantages of the battery being able to go dead without damaging it due to the car sitting. The only side post Optima battery that I see sold at any local store is the D34/78. This one fits fine in the C5, but it won't fit in a C4. There is a new model battery which is smaller, the D75/25. Will this fit in a C4? It is the same size as the regular Red Top 75/25, but I'm honestly not sure of the Red Top 75/25 will fit either. I don't want to order it and be stuck with it. Thanks..

 

Let me go out to the car and check. I have a red top in both my cars.

 

My Yellow Top is in a non-C4. It does withstand chronic
negligence.

I've read here that the top posts on the Optima can contact brackets.
Posters have written about trimming the posts for clearance, others
have written about battery troubles after making this mod.

.

 

Don't know if they have a deep cycle, but the Sam's (Exide Orbital) AGM battery fit fine in my 87. It's worked fine for the past 6 months, but I trickle charge it once a week. I'll never buy a battery that can leak again after all the damage the best ACDelco did to my car.

 

I have a red top in my car I used the top post for my Amp wire. Installed nice. I'm real happy with it.

 

I run a red top Optima in my '87 roadster. It fits nicely in the passenger compartment under the RR speaker. It has been in the car since '01. No issues to date.
Aaron

 

What models are you guys using that fit in the engine compartment? Anyone have the Red Top 75/25?

 

I have a 96. I had to trim the bracket for the cruise control servo that sits above the battery.

Do NOT trim the top post. Ask me how I know!

 

I have the D34/78 yellow-top with side posts. I had no idea that it did not fit in the C4 so I bought it and put it in. Do I have to remove it now?

 

I have the red top in my 89 and it has been there for about 3 years. I did not trim the top post.....I simply placed a piece of 5/8" (or 3/4" as I cannot remember) heater hose on the top positive post of the battery. The piece of heater hose extends about 1/2 inch above the top of the battery post and this prevents any contact with metal parts. I cannot post pictures. If you want a picture of what I have, send a note to samlam@charter.net

 

Gday Sam Lam, how are ya mate? Have you ever considered a free account with photobucket?
www.photobucket.com
You can upload your pics to there and post them free

 

Deep cycle batteries should not be used for engine cranking as they are not designed for the large cranking current that starter motors draw. Yes, they will crank an engine but you will shorten the life of the battery doing so. Also, your thought that a deep discharge battery can handle sitting long periods and going dead easier than a conventional car battery is only partially correct. ANY lead acid battery that is left discharging for long periods will succomb to sulfating. As batteries discharge, lead sulphate collects on the plates. If you leave the sulphated plates sit, the lead sulphate gets hard and lead sulphate is an insulator. A sulphated battery will not draw current when you go to recharge it and it will then be a door stop. NEVER let lead acid batteries sit for long periods, always keep them charged up. The best way to maintain a car battery is to connect a battery tender to it which will sense when the battery needs charging and when charged the battery tender shuts off. Charging a battery shortly after it has discharged converts soft lead sulphate back to lead, but hard lead sulphate destroys a battery. Also, every time you cycle a lead acid battery (discharge, then charge back up), you lose amp hour capacity until you essentially have a lawnmower battery. If you insist on using an Optima battery, DON'T install a deep discharge one.

 

'90 and later C4s have additional brackets that the top post of the battery come in contact with depending on tolerance build-up. Most will, some won't but will have barely 1/8" clearance.

This pic will give you some idea of what I'm talking about (note the cruise control servo on the right side of the pic that basically sits on top of the battery. It's connected to a bracket that the top post of the Optima comes in contact with)...



One of these days people will learn they can't make general statements for a car that spanned 13 model years.

 

I had the cruise control on before and that was not a problem. It probably used a different bracket than the newer ones with the ECM ther too.

 

I've been using the deep cycle yellow top in my vettes for around 5 years and haven't had any problems with them. Of course they're mounted in the compartment behind the passenger seat. Never have had cranking problems with them, I have had problems with the red top.
johnny

 

I have a C4 with a Interstate Batt. I must have totaly killed this batt like 15-20 times. DEAD!!!! Charge it up and to this day it still works fine! Great batt!!!

 

Here is a photo of the Red Top Optima mounted in my 89 Vette. I have used this for about three years without issues. Note the piece of rubber heater hose that is used to insulate the positive terminal from the frame:
Hope this is helpful and special thanks for Caseythecorvevetteman for his very helpful info on posting pics.

 

Thanks for all of the replies. I don't see how a Deep Cycle battery which is designed to start a boat car engine wouldn't be able to start an automobile car engine without damaging it. The only difference would be that the boat is more demanding to start on the battery since as it would be sitting for longer periods...

Anyway, I have tried installing that yellow top, the D34/78, but the problem was that my postive battery cable wasn't long enough to fit, plus it wouldn't bolt into the battery tray without either cutting the tray or cutting the battery base. The battery was a little too long to fit. The reason I was looking at the D75/25 was because it was a smaller battery and the side posts are on the outside of the battery. The D34/78 as pictured, has the side posts in the middle of the battery and my positive cable isn't long enough.

 

No worries mate, glad to help

 

I have an 85 with yellow top, not a 100% perfect fit, but it sits in there just fine and doesn't move around.