Lithium Batteries

[Jody]

My KTM 690 duke needs yet another new battery, this time I'm getting a lithium as I had one on my superduke years ago and it was fantastic.

But some are 70 euros and some are twice that price !

Are the more expensive ones better?
Is there a brand I should aim for, or any to avoid ?

[roadster]

Conventional batteries can be managed electronically simply by monitoring overall voltage and current and that is what a bike rectifier/regulator does. If a set of lithium cells are wired in series to give about the same 12-13 volts they won't respond well to the charging regulation of the standard regulator. One reason is that if the individual cells do not quite match some become undercharged and some overcharge and they are not as tolerant to this as lead-acid cells. This reduces the life of the cells but also generates heat during charging which can ultimately lead to the well publicised spontaneous combustion. The more expensive substitute lithium batteries have built in electronics which provides independent cell by cell monitoring and management to make the battery compatible with standard regulators.

So you should look carefully at the technical details to understand what you are buying. Different types of lithium chemistry also make a difference but I don't know enough about that to even describe them.

[A_morti]

I got a lithium battery with my g650gs, and it was about the most reliable part of the bike.

I wanted to buy one for my fz6, and the guy at the shop talked me into spending a fair bit less on an AGM battery, because lithium batteries supposedly weren't happy attached to old style shunt regulators and they'd had a spate of them failing early due to that. He'd sell me one, but knowing what I was going to do with it, he wouldn't be able to honour any warranty.

I didn't feel like arguing about it and took the advice. Probably good that I did since it turns out the Fz has a battery drain and lithium doesn't like hitting rock bottom.

I also got one with my cbr250 and it's not given me any trouble at all.

My only problem with them is that they'll give a consistent 13.8ish volts, right up until they are empty. So you can forget checking the voltage with your meter, you have to get at the battery itself and push the tester button on it. That's often a shit job on bikes where the battery is by the steering neck.

You will need a special charger for it if you ever need to charge it. However they basically don't discharge at all even if you winter the bike, so unless you have a battery drain or leave the lights on, you're not likely to ever have to charge it.

You pays your money and you takes your choice.