Battery Life (when to change)

[Mainsail]

I had a battery in my pickup that would alternately be totally dead but without explanation test fine only an hour later. The theory was that one of the plates inside had become loose and would short against one or more of the other plates, giving indications of being a totally dead battery. Then, on the drive over to the parts store to get tested, the plate would settle back and the battery would behave normally.

I just had to replace both Group 31 batteries in my old military CUCV M1009 (Chevy Blazer) and those ain't cheap; if the one on my bike acts up it'll be replaced at first indication of a problem.

 

[rippin209]

I second that, when in doubt change it out

 

[Tiny Tim]

The health status of your battery is its ability to provide a given number of amps for a given amount of time. This is what the ampere / hour rating is. it is usually stated in a given number of amps for one single hour. i.e a 20A/Hr battery will provide 20 amps for 1 hour or 40 amps for 1/2 hour etc.

The only true way to assess the state of a lead acid battery is to carry out a Deep Discharge Test. This gives an Ampere / Hour (A/Hr) capacity which can be compared to the A/Hr rating printed on the battery.

The A/Hr capacity of a lead acid battery will naturally decrease over time. Each mechanic will provide different recommendations but, in my opinion, anything less than 50% of the original indicates replacement is required.

Every good car / bike workshop will have a tester or any competent Fire Alarm / Security Alarm engineer.

As a rider of a NC750S DCT which can't be started with a low or flat battery, I always have a li-ion jump starter in the frunk. I've never needed it yet for my bike but have had to use it several times for others.

This is the type of tester that I use. It isn't cheap (around 200 UK pounds which is around 250 Dollars) which is why borrowing one to test your battery is a better idea in the first instance.

 

[showkey]

There are many choices in the battery test market that can be found in the US from $30-$100.

 

[HarveyM]

I installed a cheap voltage meter on the bike (using a keyed outlet). Primarily because I started using heated gear, but it also allows me to monitor the battery's charge before starting, and the state of the bike's charging (voltage regulator) system.

 

[ste7ios]

Coulomb counting is not necessary for a lead acid battery. The battery voltage is enough to know how much charge can it hold, and a load test will confirm its status.

Coulomb counting is necessary for other chemistries like lithium where their voltage is almost flat during their discharging...

As a general rule when a lead acid battery can hold only the 50% of its named capacity (12.5 V for a Yuasa AGM battery), it’s time to replace it. (Or sooner if you need some reserve capacity to feed accessories like an alarm).