Warm tank above battery. Any ideas?

12008v. What's under the back of the tank cover, above the battery terminals? I've had the battery on an Optimate. I started it earlier so the engine has some residual heat. The tank above the terminals of the battery is warm to the touch. The battery is cold. Where's that heat coming from?

Are the battery terminals warm?

No.

No. The terminals aren't noticeably warm. But I can feel some warmth from the very rear of th tank.

It looks like you have a thermal camera take a picture. I don’t think there is anything above the battery

I found that quite worrying. It's all cooled down a bit now. But it was really quite noticeable to the touch - just the last few cm of the tank before it meets the seat, but also up underneath above the battery terminals. I am now wondering if the fuel could have been warm, because looking at the exploded diagrams there really is nothing up there, is there. So either the heat was transmitted to the tank from the top of the battery, but the battery is not warm, or the heat is coming from the tank. Does the pump heat the fuel much?

I would have thought the heat from the pump would be negligible

Are you sure it's not your gut hanging on the back of the tank? Look at me from the side and I look like an incubating Emperor Penguin using the tank as an egg!

How very dare you, Mr Roper. I weigh about 65Kg, I'll have you know!

But seriously - this worried me. There was a small area of the tank there that felt distinctly warm to the touch. I'd had the battery on a tender for a few hours (I think I've killed another one), and I ran the engine for 20 mins or so

Heat from stationary motor goes up warms up fuel and pump plate, nothing else there.
You only need to charge it 1 day a month if you buy quality batt.

Yeah. I think that's it. My catastrophising imagination runs away with me if I spend a long time in the garage by myself.

As for batteries, I think I've killed this one. It's less than 3 years old, but despite showing over 13v, it won't reliably start the bike unless it is used every day. It's probably my fault for buying a 16A/H. I bought it because that was what was on the shelf on the day I needed one. This time I'm going to order a 20 A/H and wait the few days for it to arrive.

Yes. 20AH is a minimum.

You might try a lithium battery like many of us. Has plenty of starting power, way more CCA. Mine has never really needed to be charged even though it sits all week. Takes up less room and weighs nothing in comparison. A few bucks more but I think way worth it.

A few guys here have them batts, turn key on for a few min & it warms up batt.