Battery issue?

[Brents]

Hi and thanks. I'm new here. Just recently a beautiful 1989 GS came back into my life after many years. The bike is running great and is in really nice condition. The previous owner just installed a new battery (I know him well). The battery is always dead after sitting for a few hours. When it is plugged into a trickle charger the light will never switch to green (even right after riding) and the bike won't start. Maybe it's a faulty new battery but I sort of doubt it. I really want to get this resolved...our summers are short and I have many roads to explore...Thankyou.

P.S. the battery light is red when at low idle, but goes off when rpm's increase

[Zombie Master]

Have the battery tested at a battery shop first.

[Rob Frankham]

Q1 Why did the previous keeper replace the battery?
Q2 Are you using a trickle charger or a smart charger (Optimate or similar)
Q3 If you ride the bike for a reasonable distance, stop then restart, does the bike re-start?

From the information given, I'd say that either the battery is knackered (technical term) or the bike isn't charging properly. The charge light going out implies that something is happening but it may not be giving a realistic charge.

I'm not taking the trickle charger into consideration because it will take a long time to charge a discharged battery. That's not what a trickle charger is for, it's to maintain the state of charge on a battery that is already pretty much fully charged. If it's a smart charger, that's different.

If the charger is a smart charger, then the failure to charge the battery implies that the battery is bad... or the charger is screwed (another technical term).

Initial actions. Get the battery load tested. An auto electrical shop is the best bet. Modern load testers will tell you whether the battery is dead, discharged or good to go. If possible, also get them to test the charge circuit. A good auto electrician will be able to tell you what is wrong... if they can remember how to diagnose a basic charge circuit.

Get yourself a digital multimeter and get some idea of how to use it. A 'cheapo' meter from the local hardware store is as good as any and will do everything you want (and a lot more). It is also a good idea to get a spare set of leads with crocodile cllips on the end. They're available online and make life a lot easier. In this instance, you can tell a lot from the voltage at the battery terminals under various circumstances.

1) Connect your leads to the meter making sure that they are connected to the right terminals on the meter (Get this wrong and you could destroy the meter! RTFI). Switch the meter to a DC voltage range in excess of 12 volts. Most cheap meters seem to have a 20volt range which is ideal.

2) With the ignition off, connect the red lead to the positive battery terminal and black lead to the negative terminal. The meter will give a reading. If it's below 10 volts, the battery is beyond recovery. If it's less than 11.5 volts, the battery is suspect or discharged. If over 11.5 volts, it may well be OK. These are rough figures and should be taken as a rough indication of battery state.

3) Switch on the ignition... the voltage at the battery will drop slightly. It is not charging and there is a current drain. If it drops more than say half a volt, the battery is suspect.

4) Switch the ignition off.. the voltage should recover to or very close to it's original value. If it doesn't, then yes, you guessed it, the battery is suspect.

5) Start the machine and allow it to idle... The voltage should be much the same as in 2 above, perhaps a little less.

6) Increase the revs to around 2500rpm and hold for several seconds... the voltage should increase rapidly at first, slowing to settle between 13.5 and 14.5 volts. If it doesn't, then the charge circuit is not working correctly.

7) Increase the revs to - say - 5000 rpm for a couple of seconds. The voltage shouldn't increase beyond around 14.5 volts. If it does, the charge circuit isn't regulating. It's worth bearing in mind that a battery won't cope with being overcharged for very long and will be damaged.

I'm assuming that you don't have a background in electrics, hence the detailed instructions. My apologies in advance if I'm teaching grandma the art of egg sucking.

If it appears that the battery and the charge circuit are good, then it is time to start looking at parasitic current drains... that is to say where electric current is leaking even when the ignition is off.

Do the above, and let us know how you get on.

Rob

[Brents]

Rob, thank you very much for your detailed and concise reply to my question. I will follow each of those steps carefully and let you know the results. You are correct in my lack of knowledge in motorcycle electronics (although I have read "Zen and the Art of Motorcycle Maintenance" three times". The previous owner did replace the battery because of similar symptoms. Thanks again!

[jagarra]

When you look for a meter, look for a DC mill amp scale on it too. Since you mentioned the previous owner had the same issues prior to replacement of the battery, sounds like your issue may be a parasitic drain.

[SteveD]

Nice "how to" Rob. Thanks.

Last year I bought a cheapish load tester and I've used it lots.

It tells me available CCA, state of health, state of charge etc...easy to use. I think the decent version is made by Ancel but mine was isn't that one and much cheaper.

[Brents]

Thank you all for your kind and concise remarks. It seems that it was just a faulty battery causing the trouble even though it was new. The only thing I can figure is that the previous owner let the new battery die then jumped it with a car or put it on a high amp charger and destroyed a couple of the new battery cells. All is good now and thanks again.

[Rob Frankham]

It would be wise to check the health of the charge system. If the charge voltages are way too high, it won't show on the charge lamp or anywhere else but it will destroy your new battery in double quick time. This would also explain why the bike appears to have gone through two batteries in a short space of time. Even though the conclusion I gave above are now redundant, if you follow the sequence ot tests, it will give a fairly good indication that all is as it should be... or not. Any questions or problems, just ask.

Rob

[Brents]

Thanks Rob, that's a really good point about possible overcharging. I need to get yet another new volt meter and do the test you described. It would explain why a new battery is already shelled./Users/brentshawks/Desktop/IMG_1287.jpg