Lithium versus lead acid

Until the amp hours are equivalent I won't switch over as I use my bike all year. Worth watching if you are considering so you can make sure you have the right charging arrangement

https://www.youtube.com/watch?v=edM1KPThP4k

Not sure the amp hours will ever match the lead acid battery, unless you enlarge the entire battery, which sort if defeats some of the advantages of the lithium in the first place.

If you're using the bike all the time, then surely you'll hardly need a charger? Equally, why would you need such a long amp hour rating?

Another detail I don't really understand is that all the LiFePO batteries I've looked at have in-built PCBs that manage current input/output (well, this seems true of most lithium batteries, inc. Those in your phone), so I'm unclear how all the fancy charger stuff integrates with that?

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What struck me when I looked into this (never having bothered), was how little discussion there is of the different capacities. If, for example, you go on a week-long trip in the colder months and have a satnav, music etc connected, do you also need to take a charger with you?

Exactly which charger is less of an issue really, as long as it works. Companies are bound to over-sell. By 'charging arrangement' I meant the general set up - I communted in London for over a decade without a garage, and it was a real faff to charge the battery, meaning it didn't happen that often. I would have killed a lithium battery in no time.

Has anyone run a lithium in a bike parked outside and used all winter eg in London? How did it hold up?

Well, mine lives under cover, but it's not heated, so outside temps. I ride all year too...

Just taken the plunge with a LiFePO battery, but to really compare I'll have to report back in a year or so! And then after that, it needs to last at least 10years to justify its cost against a lead acid battery. Saying all that, it starts the instant I press the button. Which is not how the old one ever behaved. If the cranking power is as claimed (seems to be!) Then presumably you're taking less out of the battery at each start up, meaning it'll replenish itself more quickly? But electrics are not really my thing, someone else might have to correct my thinking!

Lastly, getting the battery out isn't a pfaff at all? Just need s screw driver, that's it. No?


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I don’t agree with “fact” 1. The advantage of lithium batteries is that they don’t self discharge. And so are ideal for long layups. If theres something draining the battery I’d perefer th fix it rather than mask with a charger. JJH

Can that not be calculated? Standing current draw in mA versus Ah of battery to give you the approx number of days to zero. I don't know how to determine exactly when it would fail to start the bike, but you would get a rough idea

JJH said:

I don’t agree with “fact” 1. The advantage of lithium batteries is that they don’t self discharge. And so are ideal for long layups. If theres something draining the battery I’d perefer th fix it rather than mask with a charger. JJH

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Ah yes. I thought the same. Goes exactly counter to everything I've read (and subsequent purchased in the basis of).

But I forgot as there were a number of other points in the video!

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Slipperyeel said:

Ah yes. I thought the same. Goes exactly counter to everything I've read (and subsequent purchased in the basis of).

But I forgot as there were a number of other points in the video!

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The most important thing I got from the video was who made it. I wonder do they sell battery chargers? Oh they do. What a considence. JJH

JJH said:

The most important thing I got from the video was who made it. I wonder do they sell battery chargers? Oh they do. What a considence. JJH

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You're far too cynical. They're just trying to help


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Slipperyeel said:

You're far too cynical. They're just trying to help


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Yes. So helpful. It’s all snake oil. JJH

NicD said:

Until the amp hours are equivalent I won't switch over as I use my bike all year. Worth watching if you are considering so you can make sure you have the right charging arrangement

https://www.youtube.com/watch?v=edM1KPThP4k

Click to expand...

Lead acid amp hours are not what they seem to be. A starter battery will deliver just 30% of its charge at full current. After that, you will struggle to get 1 amp and even then it's likely to go harmfully low before the full amp-hours are exhausted. LiFePo batteries will deliver 95% at full current so a 4AH LiFePo will give the same usable power as a 14AH lead acid. LiFePo will be scrapped by over discharge but anything worth buying has a management circuit that shuts it off at a safe level. Lead acid will cope with over discharge but life will be shortened and they can be scrapped.

Below 5 degrees C the internal resistance of a LiFePo will rise and starter current will struggle. The fix is to run the starter for a few seconds they try again. This warms the battery cells, resistance drops and the starter works fine on the second attempt. There is no over-current issue because the slow start is due to battery resistance which limits the current. Once warm it works fine.

Cold lead acid will also struggle and then you only get the one chance - if the engine does not start you are stuck. However that's not likely to happen until -10 or lower.