Battery Sizes

[Tubamanandy]

Over the many bikes I`ve looked at recently, 10.4Ah bottle-type batteries seem to becoming the norm.

I`m guessing this is down to price/size and amp hours (do most people really need a 15Ah battery ?).

Is this a trend ?

 

[jackhandy]

(do most people really need a 15Ah battery ?).

?

I certainly do - I've got two.

 

[oldtom]

do most people really need a 15Ah battery ?

Similar thoughts have been expressed here in the past and in my view, the answer is no.

Apart from a number which probably represents as a very small percentage of the EAPC community, I'd speculate that the vast majority of ebikers rarely if ever ride far enough in one session to get anywhere near battery exhaustion. If my guess is correct in that regard, then splashing out the extra cash for a larger than required battery seems a bit unnecessary to me.

A few years ago, larger capacity batteries involved a weight penalty but many of the latest, large-capacity batteries come in at more or less the same weight as their smaller counterparts so personally, the option at point of sale to choose the size of power pack makes sense to me. Those whose needs demand massive battery capacity may pay the extra while those who can manage on the smaller size can pay a bit less.

Tom

 

[Deleted member 4366]

If you have a bigger battery, you get more power because the voltage will be higher. For some people ( heavyweights and speed merchants) that's important.

Many people come on here and say that they want to commute around 30 miles, which is a bit tight for a 10 ah battery.

Those people with motors that draw more than 15 amps also need a bigger battery.

You choose a battery to suit your electrical system and your circumstances. Nobody would choose to have the additional weight of a 15ah battery unless it's necessary.

 

[oldtom]

If you have a bigger battery, you get more power because the voltage will be higher.

OK, just so I'm clear about that; what you're saying is that a 36v 15a battery has higher voltage than a 36v 10a one. Have I understood you correctly?

Tom

 

[Alan Quay]

OK, just so I'm clear about that; what you're saying is that a 36v 15a battery has higher voltage than a 36v 10a one. Have I understood you correctly?

Tom

Yup, got it in one OldTom. The 15ah battery will have more cells in parallel, each having to deliver less current, so the voltage sag will be lower under load.

 

[Cyclezee]

Our entry level eZee models come as standard with an 11Ah battery and the higher spec models come as standard with a 15Ah battery.
There is of course the option to choose the battery capacity that meets the customers needs and the price of the bike is adjusted accordingly.

 

[flecc]

OK, just so I'm clear about that; what you're saying is that a 36v 15a battery has higher voltage than a 36v 10a one. Have I understood you correctly?

Tom

The 36 volts is only nominal, and in any case is usually inaccurate since li-ion are commonly made up of nominally 3.7 volt cells in series of 10, so should be called 37 volt. The nominal voltage can be different for lithium iron phosphate (LiFePO4) batteries which have up to twelve 3.2 volt cells in series so just over 38 volts nominal.

In all cases only the working voltage matters. Off the charger the 37 volt battery can be 41 volts, but under load when working the voltage varies between 32 and 37 volts according to the amount of work being done. As Mike says, the more the work, the lower the voltage, plus the voltage also declines as the battery empties.

What is a battery voltage and what is the power in watts of an e-bike motor have much in common with what is the length of a piece of string.

 

[Deleted member 4366]

OK, just so I'm clear about that; what you're saying is that a 36v 15a battery has higher voltage than a 36v 10a one. Have I understood you correctly?

Tom

Yes, for two reasons.

1. You get less voltage sag because a bigger battery can give more current.

2. A normal Li-ion battery is 42v fully charged and 31v at cut-off. It'll go down immediately to 41v, linearly to about 33v, then rapidly to 31v, so you can sider that normal use takes it from 41v to 33v linearly. If you have a 10ah battery anh have used 5ah, the voltage will be half way from 41v to 33v = 37v. A15ah battery that's used 5ah will only be 1/3 of the way down = 38.3v. The more you use, the greater the difference.

A 15ah battery will be on average 1.33v higher over a 10ah discharge. Add about 1v for less sag, which gives an extra 2.33v or just over 6% more power, which is noticeable.

 

[jackhandy]

Putting a fresh battery on @ 25 miles into a 35-mile ride is like getting a fresh set of leg muscles - particularly if that last 10 miles is uphill:
The difference really is huge.

 

[Jonah]

If you live out in the wild lands a 10Ah battery will barely get you to your local shop and back!

 

[Tubamanandy]

My journey to work is only 6 miles each way with no hills, although I am a big guy. 10Ah should be fine for me - worst case senario I could re-charge at work. I like the idea of a small, efficient (cheap ?) battery.

 

[footpump]

hi all as far as I know I have never seen a bottle battery option for over 10.4a,
the only company that seems to offer a 15a (rear rack mounted) is woosh on there sirocco model.
this is at the cheaper end of the ebike market.

I use my ebike for leisure but find the range of 25-30miles a bit too restrictive,
but buying and carting a spare battery about does not seem practicle.
as in my case ihour of charge gives app 6 milers of range.

yesterday did 22 miles round trip, mainly level 2 pas, small amount of level 3 and found the bike seemed to stuggle on a hill near home.

not sure if somethings amiss I usually get nearer 30 miles

 

[Tubamanandy]

I use my existing bike for commuting & just waiting for a new bike with 10.4ah battery which should be fine for the distances I commute

 

[Jimod]

Both my bikes have 10 ah batteries and most of the times I go out I take a spare battery on the rack.. most of my trips are over 20 miles and I'm never sure where or how far I'm going.

I'd like a 15ah battery.

 

[Tubamanandy]

I will never need my bike to do over 20 miles - is that a Kudos you have Jimod ? Just waiting for a Typhoon

 

[Jimod]

I will never need my bike to do over 20 miles - is that a Kudos you have Jimod ? Just waiting for a Typhoon

I have both a Kudos Touer and a Kudos Typhoon. Both with 10ah batteries.

If you get a Typhoon, don't bet that you won't do more than 20 miles. It's not hard to go out playing and end up more than 10 miles from home.

 

[drsolly]

My batteries are mostly 5ah (29v). Usually, when I go out geocaching, I take four of them with me, and if I'm back at the car after half the day, I swap out 2 or 3 used ones for fresh ones. So I often get through 20 or 25 ah in a day

 

[Eaglerider]

I'm a fan of big batteries. I have a 16 a/h which is great for fun outings, but when this one packs up I'll be going for 20a/h's or more.

I only use the bike for fun, and long range is what makes it fun as I can access a much wider radius from home to do some exploring. I guess if I was commuting a few miles per day, a smaller battery would do the job, but as D8veh says, I get good performance and long life as a larger battery is less stressed. Mine's a Li-Po, its 3 years old, done about 3500 miles and in these warm climes still shows a full 4 lights static after 24 miles riding.

 

[boots]

I'd love a bigger battery, I get about 12 miles out of mine.