The electronics wizards will have the best responses, but my guess is that 12Ah might be OK, but 4Ah is too little. Maybe it has to do with how often the system operates, too. If you're in 20 miles of stop/go traffic, it might not do the job, or the battery life will decrease. If you're in a suburban/rural setting, it might be fine for 12Ah....but what say the pros?

For purposes of testing, I'm going to find a 200A, 14Ah battery, and the big thing is Size. 5.75L x 5.75H x 3.5W. Height might be allowed to be a bit higher, but L and W are pretty much limiting factors from the size of the container. However, IF the pros say that 12Ah will be fine, then the options are much greater.

 

On a relateted note, has anybody been able to get the dashboard light to go OFF without replacing the battery? Fuse? Wire?

 

I’m only willing to get a new battery to get rid of the light. It’s me really a mental thing. Lol

 

Same here. I just had the main battery checked and it is OK. The two notices/warnings are the idiot light on the dash, and the message that says, "Low Battery, please Start Car". My guess is that the aux battery's low voltage (less than 2V) is causing that message and the idiot light?

 

They might make one with the smaller post, but the one I saw has the post that's the same size as a normal car battery, and ours needs the small post.

 

I’m going to order this. If tomorrow’s trip to the battery shop does not pan out. Ez no adapters

 

Randy, where did you find that? I couldn't see the site address on your post.

wombat

 

How much is shipping to the USA? I'm thinking about using the bolt that clamps the terminal, maybe 1/2" longer, and threading right into the box post, meaning no adapters. Still on the fence until you know what cost will be, delivered. As most might guess, this isn't about the money as much as its about not wanting to spend more than needed to simply kill the idiot light..

 

[QUOTE=wombat;2172532]Randy, where did you find that? I couldn't see the site address on your post.

wombat[/https://www.google.com/search?rlz=1C...&bih=623&dpr=3

 

148 delivered. Going to call the jag dealer and interstate battery tomorrow

 

Looks like $160 today, so hope you ordered it.

 

After spending a ton of time trying to find a battery that fit the correct dimensions, I went to WalMart and got one of theirs ($78.88). Instead of fussing around with post adaptors, I had an eye spliced onto the existing Neg cable, and bought a double-eye cable from NAPA (total, $10). I had to enlarge the vent hole on the rear of the new battery, but other than that, install was simple.
NO more ECO light, and NO more "Low Battery, Please Start Car" message.

less than $100 to fix a pesky issue.....priceless.