st4s battery going flat - Page 2

**996pinman** · 17 Jul 08, 08:52 AM

I put the other battery under the seat by removing the tool tray to the rear of the tail. Cheapest decent batteries I could find were from an epay shop mdsbattery_uk. The Varta batteries claim one ah more than most others, every little helps. Bent & drilled a piece of aluminium sheet & used the original holes to secure it. Heavy duty velcro to battery & aluminium sheet stops any movement. Used one of the mounting points to earth it & heavy duty battery cable along the frame to join the two positive terminals. Using a gel battery means it doesn't matter what angle the battery sits. Not being blessed with ABS I don't know if the block goes that far back. The beauty of this mod is it can be reversed 'cos there's no cutting/drilling etc on the bike. Hey it looks OE! Trying to attach some pics but me & computers don't get on, Cheers,
Alan.

**Derek** · 17 Jul 08, 09:13 AM

That's a very neat installation Alan and could be fitted to the ABS model. The ABS block is where the forward tool box is mounted on the non-ABS models. The downside is that I would loose all underseat storage.

**996pinman** · 17 Jul 08, 09:29 AM

For me losing underseat storage was a small price to pay. Touring Europe last year (before the mod) was a bit fraught, never knowing if it would fire up, trying to bump it outside one hotel. I mean, who goes touring with a set of jump leads!! Certainly looking forward to next months jaunt more now,
Cheers,
Alan.

**Ghost** · 17 Jul 08, 09:33 AM

Looks like it grew there.

**JRC45** · 17 Jul 08, 05:53 PM

Having two batteries in parallel will certainly give more "oomph" when starting ( if both batteries are fully charged, at any rate ). As 996pinman stated earlier, both batteris have to be exactly the same, otherwise some of the current will just flow from one battery to the other. The only thing that bothers me about this kind of installation is the extra work-load on the charging circuit - alternator, regulator etc. Basically it either works twice as hard, or has to work for twice as long. If you run it on a lot of short journeys, you run the risk of having two half-charged batteries instead of one fully charged one, which is not really a benifit...

**Derek** · 17 Jul 08, 07:49 PM

No. The alternator only has to put back in what's taken out of it. Whether there are two batteries or one, the same energy is required to start the bike, but 2 batteries has the benefit of the extra capacity so that the voltage is less likely to drop below the critical level. The 5.9 ECU shuts down if the voltage drops below 10.5v

**goughy** · 20 Jul 08, 07:14 AM

hi all bought a new battery and all is now well

just tuck it for an mot and passed with no worrys so all ready for them grin factor ride outs cheers for all your help.

**JRC45** · 21 Jul 08, 07:09 AM

True, as long as you don't flatten ( or more than half flatten ) the batteries trying to start the engine. If both batteries become discharged ( either by trying to start a "reluctant" engine, or by a current drain on the bike when it is switched off ) then the charging system still has TWO batteries to charge, not ONE.
"Top Tip" buy an Optimate, keep a good eye on your battery electrolyte levels, and keep all your electrical connections clean and lightly greased. You'll be amazed how much longer your battery will last...
PS... Goughy, glad to hear your bike is now back "up and running"

Quote:

Originally Posted by Derek

No. The alternator only has to put back in what's taken out of it. Whether there are two batteries or one, the same energy is required to start the bike, but 2 batteries has the benefit of the extra capacity so that the voltage is less likely to drop below the critical level. The 5.9 ECU shuts down if the voltage drops below 10.5v