Battery size for S4R?

[The Clockie]

Having been used to meaty batteries on other Ducatis, I was surprised to see just a '12' grade one nestling 'neath the tank on the S4R. It looks as though a '14' grade MotoBatt could just fit and give a little more cranking speed. Any comments?

I have a battery cable upgrade on order which ought to help.

Nick

[Darren69]

They changed the starter motor gearing so they could use a smaller Ah battery but they are still a swine to start sometimes. I can check mine later but I suspect it is the Motobatt MBT12B4 in my S4.

Upgraded battery cables like Exact start are supposed to be a big improvement for starting over the standard ones and its on my wish list.

I don't see a problem fitting a larger Ah if it is physically the same size it should fit but perhaps someone who may have done this already could advise.

[The Clockie]

I didn't know they'd played with the starter gearing, but it would make sense.

The equivalent Motobatt 14AH is the same length and thickness, but 15mm taller as per their published specs. That is standing upright rather than laying down in the bike. I suspect 15mm wouldn't be so hard to find.

Before I get into changing the new but low-spec 12AH battery, the Exact Start cable kit arrived today and is impressive in the thought that's gone into it. Just as well, considering the price! Some of the battery cables are doubled-up due to being part of the OEM loom, so the general resistance must be lower. Looking at the OEM power cable to the starter motor, it's so thin I'm surprised any amps make it through! I'll report back when it's all fitted.

Nick

[The Clockie]

Hmmm, a rethink about batteries.

Checking the MotoBatt website, it seems one doesn't have to go to a larger Ah version of the Ducati-approved MBT12B4 for an improvement in cold-cranking-amps. The MBTX12U version gives 200CCA, versus the MBT's 150. The only dimensional difference is that the Monster-installed height of the X version is 87mm versus 70mm of the original. Is there any spare clearance under the tank, I wonder?

Nick

[BobT]

12 Ah and 14 Ah are not an indication of cranking power (CCA). A Lithium battery will have the most CCA for the size/weight.

[Darren69]

You may find that with the Exact start cables fitted the MBT12B4 if its in decent condition is perfectly capable, if all 150CCA is getting delivered to the starter.

[BobT]

You may find that with the Exact start cables fitted the MBT12B4 if its in decent condition is perfectly capable, if all 150CCA is getting delivered to the starter.

I have a Lithium with well over 210 CCA quoted. Weighs in at half a kilo and has been used for 4 years now. The standard cables should cope, you will know if they are good enough by seeing if they get hot while cranking.

[Darren69]

Whilst i appreciate the advanteges of litium batteries i think there was a reason why they moved them from the engine bay under the fuel tank to somewhere else. They have a tendancy to explode if not charged correctly and knowing what i know about the charging of bikes of that era. I wouldn't risk it myself on an older bike.

[The Clockie]

My feelings exactly about Lithium batteries. I don't need the weight-loss enough to risk having a whole garage-full of tasty bikes being destroyed, as happened to one of our chaps on the Ducati ST LiST. (Which is now on Groups.io after Yahoo pulled the plugs on our decades of valuable data. Go on; you know it makes sense to have a proper sports/tourer too!)

I can report that the MBTX12 battery is very unlikely to fit beneath the tank as there appears not to be sufficient clearance. You certainly don't want to have the fuel tank (Metal! Wonderful!) fretting on the battery case.

Now, on with the Exact cable mod...

Nick

[BobT]

Yes you need to be very careful with Lithium batteries. Mobile phones, laptops, electric toothbrushes all have them and are always catching fire.
Wonder why Ducati fit them to some models.

[The Clockie]

OK, all sorted now and the new-to-me S4R now bursts into life!

It turns out that the brand-new GS-brand 12Ah AGM battery the dealer fitted claims a CCA of 180A, which exceeds the equivalent MotoBatt by 30A. It still struggled to spin the motor though, prior to fitting the Exact Start cable upgrade.


The kit I bought was specifically for the earlier S4R but nonetheless some cables were longer than necessary. That's better than being too short, of course, but it's not easy to lose several inches of heavy-gauge cable. Because Ducati terminated loom cables in with the starter feeds, Exact suggest piggy-backing several terminals but this is easier said than done. The solenoid terminals certainly don't have sufficient thread length to carry two cables, and they wouldn't likely fit beneath the plastic shroud, so I just removed the OEM section of the power feed to the solenoid.

It was a relief to find the factory used a proper 13mm hex-head bolt for the earth strap onto the engine case, instead of the little socket-head screw used previously which could never be undone on the ST series. For the earth strap I did piggy-back the old one direct from the battery, so earthing should be very good!

The bottom line is that the starter cable upgrade is very worthwhile, but don't expect to get it fitted quickly. I should add that I made my own cable upgrade for the ST4 for a fraction of the Exact Start price, using quite ordinary heavy cable and regular ends and it has always been a quick starter. Doing a DIY job on a budget means you can choose where and how to route the cable, rather than managing someone else's specification. I just got lazy this time and was seduced by all the flim-flam!

Nick