st4s battery going flat

**goughy** · 03 Jul 08, 07:02 PM

help my st4s battery keeps going flat my optimate says battery is good but if its left for a few days without been on the optimate the battery will go flat anyone got any advice?

**nogaromill999** · 03 Jul 08, 07:40 PM

If the battery goes down that quickly you either have a knackered battery or a drain to earth somewhere.......

**Derek** · 03 Jul 08, 07:48 PM

How old is the battery? Mine lasted 5 years and despite the Optimate green light coming on it ceased to hold a charge more than a day. New battery solved my problems. The bike will easily sit for 2 weeks or more and start immediately now.
Unless you have an alarm fitted, the only current drawn by the bike when it is off is the immobiliser light flashing and that's next to nothing and does off after 48 hours.
If in doubt connect a digital meter set to read current between the battery +ve terminal and the battery +ve cable. Do not turn on the ignition. There should only be a few milliamps current drawn by the immobiliser.

**JRC45** · 03 Jul 08, 11:17 PM

"How old is the battery?" is probably a good question... it sounds like you have one dead cell in the battery. What happens when this occurs is that it causes the internal resistance of the battery to go up : because of that the battery charger thinks that the battery is fully charged. If you have a hydrometer check each cell in turn... fully charged they should all be around 1250, or slightly more. if you get one cell ( usually an end one ) around 1150 then it's time for a new battery. The more infrequently the battery gets used, the more likely this is to happen ( it's caused by sulphates settling in the bottom of the cell, and shorting out the plates ). Generally if you get more than about two - three years use out of a lead acid battery these days, especially a small one like a bike battery, you're doing pretty well... Shop around though : many small, independant battery shops are far cheaper than bike dealers, and they often know which batteries from other bikes will fit ( e.g. Kawasaki zephyr 550 is the same as 600 Monster ). Hope this helps...

**Derek** · 04 Jul 08, 11:10 AM

You might find it rather difficult to use a hydrometer with most modern bike batteries. They are either gel filled, or use an absorbent mat so there is no spare acid to suck up. That's if you can get into it, because they're usually sealed as well.

**JRC45** · 04 Jul 08, 08:43 PM

Whilst I would disagree that "most" bike batteries are now gel or sealed, some are. If yours is either, then the easiest option is to swap it for another battery and see how you get on... ( My normal technique for testing anything electrical that goes wrong with my ST4 is to borrow the relevant bit of the wife's Monster

)

**goughy** · 05 Jul 08, 09:31 AM

many thanks to your replys sounds like a new battery is the answer! dont know how old the battery is only got the bike in january but i will say i love it cheers again, now if the rain stops i might just get out for an hour or 2,3,4

**goughy** · 05 Jul 08, 10:15 AM

Quote:

Originally Posted by JRC45

Whilst I would disagree that "most" bike batteries are now gel or sealed, some are. If yours is either, then the easiest option is to swap it for another battery and see how you get on... ( My normal technique for testing anything electrical that goes wrong with my ST4 is to borrow the relevant bit of the wife's Monster

)

cheers can i borrow your misses battery lol

**JRC45** · 05 Jul 08, 01:24 PM

I'd love to lend it to you, mate, but I get in enough trubble for using it myself !

Here's a thought though, disconnect the battery from the bike... then see if it still goes flat over a few days. If it does, then you know it's the battery that's at fault. If it stays ok, then you have an earth / fault on the bike somewhere. Let me know how you get on...

Quote:

Originally Posted by goughy

cheers can i borrow your misses battery lol

**goughy** · 05 Jul 08, 04:17 PM

Quote:

Originally Posted by JRC45

I'd love to lend it to you, mate, but I get in enough trubble for using it myself !

Here's a thought though, disconnect the battery from the bike... then see if it still goes flat over a few days. If it does, then you know it's the battery that's at fault. If it stays ok, then you have an earth / fault on the bike somewhere. Let me know how you get on...

thats a bloody good idea will do cheers

**goughy** · 10 Jul 08, 05:44 PM

Quote:

Originally Posted by goughy

thats a bloody good idea will do cheers

removed battery from bike left since sunday put it back on last night and the bike stared!!!!! it turned over slowley though going to leave it on the bike for a few days to see if it still starts!!! if it dosent then its back to HELP ANYONE PLEASE

**JRC45** · 10 Jul 08, 10:02 PM

If it only turned over slowly, then it's a good bet that it is the battery that's on the way out. Does your bike have an alarm / imobiliser ? If it goes flat quicker on the bike then it's just because there is a current drain on it when it's connected. Disconnected it has no drain, but if it still goes flat, then I know what my bet would be...

**Masher** · 14 Jul 08, 08:58 AM

I agree! Get a new battery, but get a good one, there are many posts on here as to what would be the best to get!

**996pinman** · 16 Jul 08, 04:55 PM

Hi folks. Just joined today so no flaming if I'm not doing something obvious. Had the battery problem on my st4s & Googling battery/st4s it seems a common gripe. I bought 2 batteries, replaced the original & stuck one under the seat. 11/12ah just ain't enough at times for a lump that size. The same battery is used on a 600 Fazer! Both batteries have to be exactly the same i.e. new. Anyway I've had no problems since. Anyone interested & I'll send a pic. Changing chain & sprockets ready for Europe next month. Please look for my thread as I'm not sure to go 1 down on the front or bigger rear,
Cheers,
Alan.

**Derek** · 17 Jul 08, 07:59 AM

Sounds like a very good move

- but I've got an ABS block under the seat!