Hi all,

Have any of you found a group 75 AGM battery that would fit in our Blazers?

I have found two. One from Interstate, MTZ-75DT, and one from Odyssey ODP-AGM75 86.

I would appreciate learning of any other alternatives before I make a choice.

Thanks

 

I've recently learned that the Red Top and Yellow Top Optima Batteries are also AGM batteries. NAPA has an AGM battery but it is not clear if it is still available.

 

I have a NAPA agm dual terminal battery in my Blazer that I got a few years back I believe in 2016. It is dead now, as I found out over the summer. I need the dual posts for my winch and I much prefer the agm. I can find a dual post battery no problem, and I can find an agm battery no problem. The only batteries I can find that meet my requirements are Optima and Odessy. I gave up on Optimas 15 or so years ago. They were great when the first came out, and for a few years after. They decide to raise their prices quite a bit and drop the quality drastically. I haven't tried Odessy, probably spelling the name wrong, but they are the priciest of the bunch, just under $400 in my neck of the woods.

So, I'm torn between paying the big bucks for the Odessy or just getting a much cheaper lead acid battery that comes with a whopping 3 month warranty. If memory serves me right, I believe you can fit a BCI 34/8 size battery in there. Pretty sure I have ran that size before that had both of the wants I need. I believe I'll give it a try as they are easy to find in that size. If I'm wrong, I'll just return it. The difference in size between the two is 1" length wise and I believe the same in width.

I need to get one sooner rather than later as my elk tag is coming up in a couple of weeks. I also need to replace one of those ^#$* remote oil line to boot. I'll let you know if a 78 fits as I plan on getting it this week.

 

Thanks. That is great info.

I don't know if it would have changed things or not, but I went with a group 78 Optima Yellow Top over the smaller stock group 75. The group 78 Yellow Top specs for CCA match the Red Top group 75 starting battery specs.

It took some fiddling around to get the new tie-down figured out but I got it in.

 

I ordered a Napa Legend 78 size today and it will be in on Saturday. The cold front that you are probably in the midst of isn't supposed to get here until Saturday night.

 

I was outside just now and we are getting our first snow with expected lows in North Idaho in the high teens!

When I looked at the NAPA AGM group 78 battery, I noticed that its base was too large in the corners of the stock battery tray. You might have to cut out the rounded corners for it to fit. Good thing taking the tray out is easy. I had to take mine out after I dropped one of the hold-down threaded rods. LOL I also went with the Optima because it was what was in stock locally.

As for the dual post design, I don't need it at the moment, but I'm liking having the flexibility it offers.

And yes, elk and deer season are upon us! Gotta get ourselves and our rigs ready!

 

In case anyone comes across this, here are the options for AGM batteries I found in Oct. 2023.

The stock size for my 99 was a group 75. However the slightly larger group 78 batteries can fit although some modification of the battery tray to cut off the rounded corners may be necessary. I If using a group 78, the original battery hold-down mechanism might not be usable. An over the top type will likely be needed with some modification of the battery traying being necessary.

 

Picked up the battery this morning and wiggled it into place. Evidently I never had a 78 in there before because, as you mentioned, it wouldn't sit down flat in the tray. It was easy enough to modify the tray with my Dremel using a cut off disc and a grinder attachment. The rear corner next to the fender was the culprit. Rather than pull the tray, I just cut out the corner part with the tray in place. I will need to pull the tray in the spring to protect it from rust, though.

The reason I didn't pull the tray was the weather. Woke up to our second snow of the year, and the temp was in the low 30's when I started. Of course, it started snowing while I was doing the job, and the temp was dropping. When I got done, first thing I did was to build the first of many fires for the coming winter. Too hot in the house at the moment, though, for me. The wife is comfortable, and that is what counts around these parts.

 

I LOVE my Dremel with a cut-off wheel!!!

Woke up to about 20'F here in North Idaho.

What are you using to hold the battery in place? The stock wedge thing that grabs the bottom lip of the battery? I was not able to do that with the Optima.





The Optima did come with a replacement wedge shaped to go around one of the cylinder shapes of the battery, but I couldn't use it because the replacement one only works at the center of the battery and the threaded rod for the wedge is in the wrong position for the group 78 battery.

 

I used the stock wedge with no problems. The battery doesn't sit evenly across to the hold down bolt, but it still works. Just need for some decent weather to get that oil line in now that I have all the parts I need. Had to order new connectors that go in the radiator.