Voltage Across The Battey Before Starting

I had to replace the oe battery on my similarly aged bike a few months ago, maybe this is just about as long as they live?

 

A fully charged LA battery is 12.6v (6 x 2.1v cells). Voltage drop under load is the measure you should look at as a knackered battery can still show 12.6v. Personally I'd go with a Yuasa or Varta battery.

 

The voltage is half the story. The amps the battery can sustain (cranking) is v important.

Lithium batteries don’t like the cold however turn the ignition on (thus lights) for a few seconds whilst you don your lid and gloves then it will ‘activate’ and work as normal.

Most people don’t do this (or notice issues) as it’s normally pretty harsh conditions that need to activate the battery and most people would just take their car or wrap up warm under a blanket in front of a roaring fire.

 

The voltage drop tells the story. The cranking amps rating of a battery will drop with the voltage as the current is directly proportional to the voltage and inversely proportional to the resistance (of the load).

 

That is one clean looking Bonnie!

 

Yeah - which is why the RAC have expensive ‘load’ testers and not just volt meters.

A low voltage but high current will still crank an engine. A high voltage and low current won’t.

A battery is made of multiple cells. Voltage alone will not indicate the health of each individual cell and can mask other problems.

 

Or maybe you have a different type of electricity to me

 

It's basic Ohm's law. It's the current which turns the motor or lights the bulb, it's the voltage that "pushes" the current through the resistance. A 6v 500CCA battery wouldn't turn over a 12v starter as the voltage is too low to deliver the required current through the starter' resistance. All a load tester does is put a known load on the battery and measure the voltage drop and hence the available current.

 

Just fitted a new battery on my Bonnie a couple of days ago, it never failed to start the bike but could tell it was getting sluggish.

Also have one of these:

https://www.motone.co.uk/triumph-bo...adlight-module-battery-saver-safe-start-p2028

It stops the headlight from lighting up when you turn the ignition on, once the bike is running just flick to high beam and the back to low and the headlight then works normally.

 

The throb of my knob is such a rare occurance these days, the angle of dangle hardly changes.