Battery Volts

[Kevin Valk]

I have had a little trouble with the battery and maintaining levels to start. The bike starts fine, and runs great. The issue is that I have a very slow drain and when I go to start after a few weeks, it is reading 11v. I bought a brand new gel battery with 120 CCA. The battery is fine.

Also, the bike won't start if the battery is slightly below 12V on the voltmeter. It won't even turn over if the volts are too low.

Has anyone had this issue? I put a new highoutput alternator on the bike with summer that works great. the HO ALT does not perform well at idle or low RPM, so if I get the bike started with a low battery, and take a quick ride down to the gas station a mile down the road, the bike will not start after gasing up. I carry jumper cables with me now.

Thoughts?

[WintrSol]

You need to find the drain, which should not be there when the key is in the OFF position. I'd start at the battery terminals: remove one cable (ground is safer) and connect a DVM, in Amps mode, between the battery terminal and the cable; have the meter in the highest Amps setting. You should now have a measure of how big the leak is. With the key in OFF, there should be 0 current, but something must be bypassing the key switch if there is some current. Pull the main fuse A; if the current drops to 0, either the key switch is defective, or the wire from the starter relay connector to the switch is damaged, or the starter relay has an internal leak. If the current remains, pull the main fuse B; if the current now drops to 0, you have a leak in the rectifiers in the alternator, or the wire between that fuse and the alternator is damaged. If there is still current, the only thing left is the starter relay, and the wires from the battery to it and main fuse B.

[hueco]

Great info from WintrSol. You stated a 120 cca battery. Is that a typo? That is not very many cca's. I have a Battery Mart battery rated at 220cca. That could be part of your problem.

[gordonv]

By you avatar, you have an IS. First remove the fuse for the radio and the clock (if different). Since these are known power drains. My IS is fine a month later.

[Jonesz]

One thing that you should note is that a battery at 12V is already 75%discharged. Many people think that  batteries discharge in a linear? fashion. Not so.  Do a search on this issue and you will see what I am talking about. You will see on this chart that a battery at 12V is only 25% charged.
https://www.energymatters.com.au/components/battery-voltage-discharge/

[Hooter]

What Gordon said is true. The memory in the radio may be draining your battery? Never heard of an alternator (generator yes) not putting out at low speed? Make sure "everything" is clean and tight at the battery and ground.

[Valkpilot]

What Gordon said is true. The memory in the radio may be draining your battery? Never heard of an alternator (generator yes) not putting out at low speed? Make sure "everything" is clean and tight at the battery and ground.

The GL1800 has an exciter circuit that limits alternator output until the idle stabilizes -- usually for the first 7 seconds or so.

My Valk doesn't do this.  It immediately goes to 14+ volts.