BSA Owners' Club Forum

The BSA Workshop => Singles => Topic started by: Phil C on 13 February, 2019, 12:43:22

Title: Battery condition
Post by: Phil C on 13 February, 2019, 12:43:22
Hello everyone, I confess this is not specifically related to BSAs. I guess it could apply to any bike, but the reason I'm posting this is because of a problem I have with the battery on my (2011) Bonneville T100. I hope that's okay, this once., given that it could apply to a BSA.

About, say, three weeks ago, when I went to start the bike, the battery was flat (just a click sound when I pushed the starter button.)  I stuck my Optimate 3 on it and charged it up, after which the bike started.

I last took the bike out about a week ago.  This morning I went to start it (having put on my thermals etc etc!),'ve guessed it, the battery was flat (just the click again.) My question is: does that mean the battery needs replacing?

I have put the Optimate3 on it and the Optimate's LED3 light has come on. I find the booklet hard to understand, but I think that means the battery is extremely flat, and (not sure) it might be that the Optimate's recovery mode won't engage unless the battery is disconnected from the bike (at present the Optimate is just connected via the wire which sticks out from under the seat specially for it.)

Anyway, has the battery had it?    Phil.
Title: Re: Battery condition
Post by: berniej on 13 February, 2019, 13:32:11
I'm sure you'll be forgiven for mentioning the 'T' word but, if not, I'll mention it too and we can both be kept in after school  ;)

It's actually quite a relief when I press the button my T140 and only hear a click - at least it means that it's not going to kick back and write off a few hundred 's worth of sprag clutch and pinions yet again ;D  ;D  ;D

But seriously, I guess it does sound like the battery may have had it - it's that time of year when they tend to give up in my experience.
Unless of course there's some ongoing drain on the battery that's causing it?

The Optimate 3 seems to get good reviews but one of the 'smart' chargers that I use doesn't seem to be too clever and always seems to report that the battery is fully charged far quicker than I would have expected so I tend to use an old-fashioned 'dumb' charger for a few hours instead.


Title: Re: Battery condition
Post by: Phil C on 13 February, 2019, 14:10:33
Thanks Bernie. But I've just taken the battery off the bike and put my multimeter acroos the terminals:  12.68V.  That should be fine, shouldn't it?   Phil.
Title: Re: Battery condition
Post by: Phil C on 13 February, 2019, 14:16:55
Quite amusing: the 2011 Bonneville T100 won't start; the 1965 BSA B40 has just fired into life second kick.  So I think I'll take that for a quick run down the road, and mull things over.

But anyway, back to the Bonneville battery: 12.68 volts should be fine, shouldn't it?

Title: Re: Battery condition
Post by: A10 JWO on 13 February, 2019, 17:26:12
I started a thread recently about my 600 Ninja eating batteries every time the temperature dropped badly. I had a factory alarm fitted to the bike and blamed that and the cold. I have now taken the batteries off of my bikes and they are in the airing cupboard keeping warm. Not saying that all batteries do this, but it worked for me.
Title: Re: Battery condition
Post by: Bees on 13 February, 2019, 18:04:24
How old is the battery?

Had the exact same thing on my Moto Guzzi this winter, Battery only 3 years old, hadn't ridden it for a while (a couple of months) tried to start, nothing, charged up and it started fine, but following week nothing again.

Winter kills of suspect batteries. I suppose the same thing can apply to classic bikes but the battery only needs enough in it to power the coil, not crank over a cold engine so probably has to be more knackered for it to prevent starting.

Title: Re: Battery condition
Post by: Phil C on 13 February, 2019, 18:31:38
I've just typed out an update, then as I was about to post it I saw Bees had posted a comment, so I reviewed the thread, and lost my reply! So anyway, here is an update (sorry if you get two!)

Even though the battery was showing 12.68 volts on my multimeter, I put it on my little AA charger and after about twenty minutes it was full (wish I'd checked the voltage at that point, out of interest.) So anyway I stuck it back on the bike, and it started first time. So I don't know if it was the battery or something else. The click sound when I pushed the starter this morning made me think battery, but then the 12.68 volts made me think possibly not. Maybe it was me (eg did I leave the sidestand down, and would that cause a no-start?) Anyway I'll see if it happens again. I don't know how old the battery is - the bike is 2011 and it was on the bike when I bought it nearly two years ago.

A10JWO, Bees, and Bernie, you mention cold winter weather affecting batteries. If the low temperature was affecting the battery, would that show up on a multimeter reading? I mean would it show low volts? (stupid question probably.)

Title: Re: Battery condition
Post by: AdrianS on 13 February, 2019, 18:43:47
Low temps do affect a battery - especially if not used very frequently.
The recovery mode on these Optimate type chargers are very good at reviving batteries that have plates that are a little sulphated.

Have you checked for battery drain while on the bike? My Bantam had a very flat battery the other week. I was surprised as it was a nearly new battery and has always appeared to have plenty of charge in it. It turned out that the rectifier was shorting the battery out.

My normal 6v charger wouldn't touch the battery. I put another 6v battery in series with it and connected up my optimate and hey presto! the battery charged and held its charge.
Title: Re: Battery condition
Post by: Bees on 14 February, 2019, 06:56:12
Im no expert with electrics. But my understanding is that as its a 12v battery its always going to show 12v once it's been on the charger but what happens as it breaks down is that the battery can't deliver the current. I.e Amps correctly.

The starter motor draws a lot if current and the battery doesn't have the 'oomph' to do it.

I'm not sure how you check amps on a battery but i bet if you did you would find your battery would be showing a duff reading even though it still shows 12v..

Just my theory
Title: Re: Battery condition
Post by: ANDY HIGHAM on 14 February, 2019, 10:10:01
A fully charged battery should read 13.8v - 14.4v.
If you put a voltmeter on the battery while it is still on the bike, turn the ignition on, ideally you should still have over 13.5v, turn the headlight on the voltage should still be over 12.5v, press the starter button and you should still have over 11.0v while cranking
Title: Re: Battery condition
Post by: Phil C on 14 February, 2019, 10:59:57
Thanks Andy. So would you say 12.68 volts (measured after taking off the bike) would suggest a battery problem?   Phil.
Title: Re: Battery condition
Post by: Phil C on 14 February, 2019, 11:15:54
Just tried to start it again. Click. Think I might replace it.   Phil.
Title: Re: Battery condition
Post by: Bess on 14 February, 2019, 11:18:44
     Maybe worth a read,

Best wishes...