2002 SUBURBAN: Will my big auxillary battery fit in the right side tray?

[Saabologist]

Does anyone know if my battery will fit in the space on the right side of the engine compartment, where the second battery is intended to go?
I was about to buy the parts to install the second battery for my fridge and other accessories, but need to find out if the battery will fit into the space.

Details:

- I measured the battery. It is 13x7x8.5 inches (like a group 76 battery). It's a Duracell 120 ah battery with posts on top.

- I measured the space, it seems that it would be close, but I am not sure about the depth with the posts on top of the battery and fit issues because of the coolant reservoir and some protruding bolts.

- If I buy the auxillary battery tray, I am not sure my auxillary battery will fit.

THANKS for any experience and advice with this very specific issue!

 

[rayra]

Came to the right place (lol)

I fit a 34/78 battery in my factory Aux location. The factory Aux tray replaced the curved top support bracket that ties the top of the fender to the firewall. The tab on the cowl the curved bracket went to still fit fairly close to the top of the battery, so I elected to cut it off. Even without having a top post battery.

DIMENSIONS IN INCHES*: 10" 6.88" 7.63" LxWxH

I'm not sure you can get a 13" battery in there. The aux tray mounts on bolts protruding from the firewall. So measure the distance from the firewall to the reservoir and subtract about 1-1/4" and see if you have room for the length.

And the closer you get to the coolant reservoir, the more you run out of room for a top-post battery. I'll look tomorrow and see if I have any floral arrangement foam blocks laying around, I can try an old hot rodder's trick and put a block on my Aux by the reservoir and slam the hood on it. That sort of light foam crushes easily and I'll get an exact idea of how much headspace there might be for a top post there, hard up by the reservoir. If I still have a block of foam laying around.
(DON'T use normal styrofoam for this trick, it won't compress very much, you'll damage things)


eta - depending on your power architecture plans, you might be better off moving the starter battery to the 'Aux' location (passenger firewall) and putting the BFF in the 'Starter' location. IIRC there's no overall battery length restriction in the Starter location. You'd just need to extend / alter the cabling arrangement to retain the Starter battery as the Starter, etc.


eta2 I can't even find a Grp 76 on any battery size charts. Sure it's not 78?

 

[Saabologist]

That's a great suggestion to just swap start and house battery!
I might end up doing that.

Here's a jpg of battery dimensions by group:
https://www.jegs.com/Sizecharts/bcigroup.html

It's really nice of you to help me spec this out. I will take the corner brace out and make a cardboard box the size of my battery to see if it will fit in there before I proceed.

Thanks much,

 

[Martinjmpr]

When I was doing mine I measured and it's tight - IMO anything bigger than a 34/78 (factory size) will not fit.
.
I hadn't thought of swapping the house and starter batteries - that could work as there is more space to work with over on the driver's side forward area of the engine compartment....

 

[Hillbilly Heaven]

Since we are talking about the aux battery tray, does anyone have a part number for it?

 

[Martinjmpr]

Since we are talking about the aux battery tray, does anyone have a part number for it?

.
Here's the Amazon link with the part no.
.
https://www.amazon.com/gp/product/B00GTJV9RY/ref=oh_aui_detailpage_o09_s00?ie=UTF8&psc=1

 

[Hillbilly Heaven]

Thank you

 

[Burb One]

I can concur after looking around, I couldn't get confirm anything bigger than a 34/78 fits, so that's what I went with

 

[rayra]

I looked today, couldn't find the block of foam I was recalling. I might have used it up as a dremel bit holder in that tool box tray. But the top height is close by the coolant reservoir, I'm not even sure a Grp 34 or dual-post marine battery in that longer size would even fit there.

Too, I checked in the front corner, the PCM is mounted very close to the factory Grp75 starter battery tray. I'm not sure if a 78 will fit there, either. But the online starter battery options at chain auto stores show both 75 or 78, so I guess it does. In hindsight I should have got a 78 for my starter when I bought my new battery. I matched size with the cheap junk I had in there from the used car dealer, without even considering a larger size. My power-hungry power plans didn't come until later, and then I put a 78 in the aux, a few months after the 75 in the starter. Fresh Interstate batteries, ~4mos apart, via Costco. So I can pretty much get pro-rate help all over, if I start having unusual battery trouble.

/anyone want to buy a 1yr-old Interstate Grp75? lol


I'm using a 200A solenoid as a bridge, while running there's almost no voltage loss to my Aux side. Yet somehow the 78 always seems to hold 3/10ths of a volt HIGHER over the starter battery, at rest. And usually just 12.7 vs 12.4, respectively. Might be the parasitic loads I added, USB charger ports all over, dashcam that runs for several minutes after key off. That's all tapped into factory wiring circuits. Eventually I'll shunt that stuff over to an Aux-connected fuse panel, when I get around to adding lights and ham radio, do some more in-dash work. Then I guess I'll see if the resting voltage disparity swaps between batteries.
And very soon I'll have my portable folding solar kit in a lockable roof deck mount and it will be trickle-charging my Aux / 'House' power stuff all the time. At which point I expect the voltage disparity to grow. Not that it matters much.

Most of the juicy juice details and pics start here -
http://forum.expeditionportal.com/t...-seeking-inputs-on-my-inputs-and-ouputs/page3