Lithium Batteries: What You Need To Know

[ionbeam]

Test standards don't necessarily have to match a real world function. At 0ºF there are a number of things at play such as metal conduction going up and the chemical reactions slowing down. The SAE J537 Std. aims at a charge depletion(1) percentage and provides a fixed reference point around which many different curves can pass in determining CCA performance. There are other standards that can be used and one uses 8.4 volts as the reference voltage, but the standard being used has to be disclosed so the person seeing the report understands the differences.

When you work out the ionization (

) process for the chemical reactions, a lead/acid battery should have 2.04 volts per cell at a specific acid concentration, at a specific temperature, at a specific charge, at a specific rest period after charging. Then the curve ball is at open circuit, after all the other BS, the actual cell voltage will be ~2.1 volts. Battery voltage will rise 0.02 V for every 10ºF of temperature rise. 13.2 volts is usually an indication that the battery hasn't rested long enough to equalize before the voltage was read. With a calibrated meter

In the real world, 8.4 volts would be a pretty good cut-off voltage for starting. At this point the engine may not meet minimum cranking RPM because volts = cranking speed. The coil will be significantly weaker due to low voltage but it does have the advantage of a longer dwell time. At 8.4 volts and 100 cranking RPM the coil may still make a hot enough spark to ignite the fuel. At 8.4 volts at 5,000 RPM the coil may not be able to ignite the fuel and at 8,000 RPM at 8.4 volts -- well the engine probably won't be able to make 8,000 RPM.

(1) Not the battery depleted, just the available charge under load. A battery is >10% charged at 11.5 volts. You can find charts that show different %, I won't debate the actual state of charge, just take the point that a battery can be fully discharged by 11.0 volts.

Edit: I see Fred posted a similar thing while I was typing.

 

[Fred W]

We do that pretty often.

 

[rwortman]

I haven't jumped on the lithium battery bandwagon simply because the charging system in all my cars and bikes is optimized for lead acid batteries. Maybe in a few years the OEM's will start moving in that direction. Until then, unless I go racing, I will stick with the established standard.

 

[ionbeam]

I haven't jumped on the lithium battery bandwagon simply because the charging system in all my cars and bikes is optimized for lead acid batteries. Maybe in a few years the OEM's will start moving in that direction. Until then, unless I go racing, I will stick with the established standard.

Some cars get the Lithium thing, most electric or electric/hybrid cars use Lithium based batteries. Lithium is a lot greener to collect, handle and manage than lead, though lead isn't a fire hazard when mishandled

The trick is to find a green way to feed the batteries.

 

[J. Parrie]

Considering it's a "touring" bike that weighs 650 lbs wet,and it has luggage that is probably full of stuff, droping a liitle weight on the battery seems a bit ...optimistic.When I was racing cars, we looked at reducing 10lbs as gaining 1 HP. So with the 145hp FJR, you would gain 1HP with a lighter battery.

It is true that a lot of small weight saving can add up and changing the exhaust system would definately be noticable , but the battery....not so much.

Did I mention it's a touring bike?

Now if it was a smaller, lighter sport bike and you were canyon carving, I would be on board with weight saving.

In the end, it's not my money and people can do what they like, but to me, this Li battery upgrage for weight saving seems a bit of a streach.

It would be cheaper by a long shot for me to just diet and loose weight

Good point, however when you consider the location of the battery, it is more noticeable than you would think for the guy that rides sans luggage and passenger. Dropping 8 LBS that is up high and hanging off center on the bike is worth more than dropping much more lower and more central on the same bike.

For those who ride loaded with luggage and and/or a passenger, I would agree there's not much to to be gained.

 

[Fred W]

So the weight difference would be equivalent to, and in the same location as, ~ 5 quarts of fuel.

I've never noticed any great improvement in performance when the fuel gauge is flashing and that is about 5 1/2 gallons (34.7 lbs) weight savings.