Bike usage and battery range

[UrbanPuma]

Hi Flecc,

Not sure if the cycle computer wheel size is correct as the booklet didnt have the exact wheel size as my bike = kenda 16 x 2. 175 is what is written on the wheel.

The computer booklet only had two sizes for my wheel size:
16 x 1.50 and 16 x 1.75. I used the latter one. Don't know if this is correct but my mate was travelling at the same speed as me and the reading was the same so i assumed it was correct.

What do you think?

UrbanPuma

 

[flecc]

That's going to be very close to correct, so not worth changing UrbanPuma.

Clearly you were riding quite slowly, so you'll improve things by using higher speeds, both the range and avoidance of cutouts. If you still get cutouts though, check those battery contacts. Also don't forget the switch off, pause, and on again routine to get going again, avoiding the need to pedal all the way home.
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[UrbanPuma]

Hi Flecc,

Thanks for the adivce. The puma battery connection consists of a long white tube which screws onto the side of the battery. Are you familar with this type of connection?

Before i take the bike out i screw in in tightly, however, do you think i should be checking it during my rides also?

UbranPuma

 

[flecc]

That should be alright if it's a screw in type UrbanPuma. I'm not familiar with the contact arrangement on those, although I've seen them in passing.

It's mainly the blade type connectors that can give contact trouble. I'm fairly sure it was the lowish riding speed and high battery drain at that speed that caused the trouble before.
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[UrbanPuma]

Ok, thats good to hear - no serious problems then. I shall increase my speed and see how i get on.

Thanks for helping again flecc.

Have a good day

ps..do you know where and how much i can get a schwable big apple tire for a 16" wheel dahon curve bike?

 

[UrbanPuma]

With reference to my last email Flecc, my friend has a lump in her tyre - should she just replace the 16" big apple tyre or does the inner tube need to be ordered separately also?

Thanks

 

[flecc]

Yes, St Johns Cycles stock the Big Apple in the 16" size, and you'll find it on this page.

The present inner tube should be ok as they stand slight stretching, but St Johns also do the very good Schwalbe low loss tubes on this page.
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[UrbanPuma]

Thanks Flecc

I'll check out those links.

Cheers

 

[mikescave]

EZEE Liv Battery Life

I have been using my eZee Liv an with a Lithium manganese battery since May. I travel about 3-4 miles a trip - half mainly downhill with little pedalling and the return with some uphill sections. and flat sections which require pedalling. I do about four of these trips a week.

When I first had the bike I could do two return journeys before the 'yellow' (half charge?) battery light came on. Recently howver, I have only been able to do one round trip before the 'yellow' comes on, just at the end of the trip on the last incline.

Is this sort of deterioration normal? I have always charged the battery after every trip as recommended - so keeping it topped up, and the bike is kept in a cool place.

Does anyone have thoughts on this?

Thanks

Michael

 

[flecc]

Battery meters aren't very accurate indicators of capacity Michael, but experience so far on Li-ion batteries indicates about one third capacity loss in each year. The oldest eZee one I know of lost 35% in the first year of use.

The loss each year relates to each start point, so the loss in the second year is about a third of what it had at the end of the first, therefore a declining amount of loss. Here's a chart I made up showing what 33% annual loss means for a 10 Ah Li-ion battery with range losses as well. Pick the column starting closest to your range when new:

Year - - - Capacity - - - Range 1 - - - Range 2 - - - Range 3

1 - - - - - 10.0 Ah - - - - 30 miles - - - 20 miles - - - - 15 miles
2 - - - - - -6.7 Ah. - - - - 20.1 - - - - - 13.4 . - - - - - 10
3 - - - - - -4.5 Ah. - - - - 13.5 - - - - - -9.0. - - - - - - 6.7
4 - - - - - -3.0 Ah - - - - - 9.0 - - - - - -6.0 - - - - - - -4.5
5 - - - - - -2.0 Ah - - - - - 6.0 - - - - - -4.0 - - - - - - -3

With your fairly short journey you should be able to get quite a long useful life, where someone doing a longer journey would be much more limited in how long they'd get out of a battery.

Since Li-ion use on bikes is still quite new, there's very little practical experience, so much of what's here is based on the lab tested theory.
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[mikescave]

Battery capacity loss

Thanks flecc, that give me some idea of what to expect - just didn't want to find I suddenly get stranded!.

Michael

 

[flecc]

Little chance of that Michael. As you see, the loss proportionally reduces so is never sudden.

As the range reduces, a point can come where you get the power cut out on a hill. This is due to the battery protection circuit cutting out when voltage drops below a safe level where the battery could be damaged.

Any time that happens, just switch off, pause and switch back on again. The meter light will come on again and you'll be ok to ride off again. To avoid it happening again immediately if still on the hill, put a bit more effort into the pedalling and use a touch less throttle. On the flat and up to speed the battery will continue to recover.

This cut-out happens due to chemical exhaustion, the current being demanded being a bit beyond what the battery cells can deliver. Just cutting the throttle a bit and compensating with the bit more pedal effort reduces the demand to within the acceptable.
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[mikescave]

Thanks once again because the bike is and much envied.

However, I am also reassured because what you describe re hills is exactly what happens - a brief 'yellow' - I pedal a bit harder, then on the flat 'green' reappears.

Michael

 

[flecc]

That's it exactly Michael, a symptom of the fact that the meter uses the battery voltage to "guess" at what it contains. As the throttle is opened, the current drain into the motor drops the voltage, so the meter shows that drop as a drop to amber, and eventually to red. Back up to speed on the flat and it's back into green, since at the highest speed the efficiency is highest, so the current usage lowest and the battery voltage highest.
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[UrbanPuma]

So....if the green lights on the LED dont come on again Flecc, does this mean its the battery thats dead and nothing to do with battery chemical exhaustion?

 

[flecc]

Yes, if the light stays at red, it needs recharging. If it rises from red back to amber, it means its running low but still has some charge.

When a battery cuts out due to overload while it still has plenty of charge left in it, it doesn't immediately recover the full amount it had before it cut out. If you were to leave it after cut out for at least 15 minutes, it would then recover most of what it had before, but not all. This reflects the fact that any chemical reaction like recovery takes time to complete.

In other words, running into cut-out situations shortens the range a bit on that trip. It's back to full range after the next charge though, so little lasting harm.
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[UrbanPuma]

Thanks again Flecc,

You've been a big help.