944t AGM battery question

[aporschefan]

I don’t drive my ‘91 944t enough and sometimes can go months and months and months without driving it. I do have an isolator switch but forgot to use it last time and, knowing me, I suspect this could happen again. I can’t trickle charge it unfortunately.

So I need replace the battery. The two options I’m currently considering:

1. Bosch S5A11 AGM — 80Ah / 800A / 315mm

2. Bosch S5A13 — 95Ah / 850A / 353mm

I’m fairly sure the S5A11 will fit without issue.

The difference between the original specification (65-75Ah?) and 80Ah is helpful but not significant. The difference between 65-75Ah and 90Ah is , imo, much more significant. I appreciate the 90Ah battery is heavier and larger so it’s not without a trade off.

Has anyone gone as far as fitting the S5A13?

If anyone has done this, did you need a specific bracket? If so, which one?

Are there my other options anyone wants to recommend?

Thanks in advance!

[aporschefan]

Read a little more since the initial post. It looks like the Bosch S5A11 may fit but needs a bracket? And that the second option isn’t really an option.

Is anyone able to recommend a bracket to use with option 1? Is it off the shelf or needs fabrication?

[elisered]

AGM batteries do not respond well to being deeply discharged. I would steer clear of this type given the circumstances you describe.

[aporschefan]

Thanks.

I’ve measured and unless there was a specific off the shelf tray, I don’t think I’ll bother with a physically larger battery. Seems like too much faff.

[AW10]

And AGM batteries require a higher charging voltage so not the best idea for a car that didn't originally have one fitted.

[williamp]

could you use a solar powered battery tricle charger??

https://www.autoexpress.co.uk/exclusive/43793/best...

They are good enough to keep a battery topped up. Doubt they could revive a dead battery though