Anybody had this battery problem?

[aardvark5]

Riding up a steep hill my battery will die but if I turn it off/on it will come back on!

It isn't linked to a computer, throttle only (or perhaps this is the problem).

Any ideas?

 

[D C]

I had exactly the same problem a few months back, I used throttle only at that time.
It was the battery on it's last legs which happened without any warning.
New battery fixed it.
Dave

 

[Deleted member 4366]

Yup, battery is knackered. That's assuming that it used to work OK, otherwise it's simply not up to the job. What battery and bike is it?

 

[Nealh]

Get jimmy to recell your pack with good high quality 10/15a discharge cells, say goodbye to wide voltage battery sag and benefit from cooler running overall battery performance. He can recell at a price cheaper then most new packs with inferior batteries.

 

[aardvark5]

It is a Cyclotricity 36v 9ah that I had 4 years ago but use about 6 months a year every working day for 10 miles.

Who is Jimmy?

 

[Solarbake]

Jimmy Insat international or BGA reworks google them,
i just had a bosch battery done up from 11a/h to 13.8a/h using panasonic GA
battery,it's the dogs nuts ,cost about £300 all in,highly recommend.

 

[awol]

Who is Jimmy?

http://www.pedelecs.co.uk/forum/threads/bga-reworking-for-batteries.27494/

 

[Deleted member 4366]

Don't replace your battery with the same type (assuming cylindrical bottle battery). instead, replace it with a Dolphin (09) one. That's if you want a bit more power and range.

 

[aardvark5]

Thanks for the advice

 

[aardvark5]

Don't replace your battery with the same type (assuming cylindrical bottle battery). instead, replace it with a Dolphin (09) one. That's if you want a bit more power and range.

Where in this country is the best place to go for one?

Also, I've experimented with bigger motors and I wasn't impressed so I can't ever see me going bigger than a 250 watt motor. I presume a 250 watt motor is 36v so is it pointless me getting a 48v battery or would it still get me more miles with the equation volts x a/h = watts / average of 20 watts per mile?

eg
36 x 10 = 360/20 = 18
48 x 10 = 480/20 = 24

 

[Deleted member 4366]

You can get those batteries from Eclipse Bikes in the UK.

 

[aardvark5]

Also, I've experimented with bigger motors and I wasn't impressed so I can't ever see me going bigger than a 250 watt motor. I presume a 250 watt motor is 36v so is it pointless me getting a 48v battery or would it still get me more miles with the equation volts x a/h = watts / average of 20 watts per mile?

eg
36 x 10 = 360/20 = 18
48 x 10 = 480/20 = 24

Nobody answered the above question for me -
If I only intend to use a 250 watt motor is it pointless getting a 48v battery or is it useful for getting more miles out of it?

 

[Nealh]

Its not as simple as that voltage doesn't = range it gives more speed, for range you need ah/amp hrs.
Running your 36v 250w hub at 48v will increase the speed by about 25/30% this means the motor rpm will change and be greater, torque will also increase but the hub efficiency will change depending on your needs and the hubs rpm at 36v. This will impact on the climbing ability though will be great on the flat. You have to allow for the hub rpm increase to decide if it will be suitable for your needs. If your hub is 201rpm then it will probably be ok as the rpm at 48v would be approx. 250/260rpm and still climb well because of the torque increase. A 270 rpm hub for instance would increase to approx. 340/350 rpm and climbing would be poor and the hub would stall, the increase in torque will be wasted as heat and less efficient.
You have to weigh up the pros and cons and know the hubs rpm to do the simple maths.

 

[Deleted member 4366]

Running a 250w 36v motor at 48v brings it to life unless it's already a bit on the fast side. Typically, a 36v battery would have 50 cells in it (10S5P). The same case would be used for a 48v battery with 52 cells in it (13S4P), so in theory, you have 4% more charge to go further, but in practice, the cells in the 4S configuration are giving 20% more current, which brings down their capacity a bit, To go at the same speed with the same power, though, the 48v battery would be providing less current, so that brings it back to 4% further.

 

[aardvark5]

Thanks lads.

I already get 18 mph on the flat with just throttle so I might as well stay 36v.

So am I right in thinking that the difference in miles between a 13 ah, 14.5 ah and 15 ah are quite minimal?
Or did I read a bad blog?

My approx calculations get it to around 23.4, 26.1 and 27 miles.

I also don't understand how eBike manufacturers can claim their 36v 10ah battery can do between 25 to 35 miles but some users report up to 70!

 

[Nealh]

There are to many variables to predict range but an estimate is all they are. If you use low assist and cycle at low speeds then you can get good range, some even use no assist except for inclines so 70 miles or more is possible.
Off-road riding will sap range more then road rid.

 

[Danidl]

Thanks lads.

I already get 18 mph on the flat with just throttle so I might as well stay 36v.

So am I right in thinking that the difference in miles between a 13 ah, 14.5 ah and 15 ah are quite minimal?
Or did I read a bad blog?

My approx calculations get it to around 23.4, 26.1 and 27 miles.

I also don't understand how eBike manufacturers can claim their 36v 10ah battery can do between 25 to 35 miles but some users report up to 70!

... There are plenty of previous postings here about range . What there is not is an industry standard for comparison. Simply put the range is a combination of weight of bike and rider and tyre composition and tyre air pressure creating rolling resistance, speed of bike and stance of rider creating wind resistance, terrain determining the number brake interventions and finally the amount of effort the rider is prepared to deliver and the watthr rating of the battery.
The Bosch website has an interactive calculator showing how some of these factors interact.
Of all these the wind resistance due to speed is ultimately the most important power loss mechanism.

 

[Deleted member 4366]

To ride along at an average of 12 mph takes about 150 watts of power.

1. Rider puts in 100W, battery puts in 50W = 150W
2. Rider puts in 50W, battery puts in 100W = 150W.

Both situations go exactly the same speed with the same power, but the battery on the first one will last twice as long as the second. 50W is typical of what an unfit person would sustain. 150w is what a regular cyclist would sustain.

You can extrapolate that further:

3. Rider puts in 150W, battery puts in 0W = 150W
4. Rider puts in 0W, battery puts in 150W = 150W.

if you had a 300Wh battery the ranges would be:
1. 6 hours 72 miles
2. 3 hrs 36 miles
3. Infinite
4. 2 hours 24 miles

All those differences are for the same rider, on the same rides on the same bike with the same conditions.

Now add different hills, rider weight, wind, etc. and you can see why there's so much difference.

The only thing you need to understand is that the more watt-hours you have in the battery, the further you'll go. There's very little difference between any bikes, except that light thin bikes will be more efficient than heavy wide MTB-types with fat knobbly tyres.

 

[aardvark5]

Bugger, I never had my original battery problem fixed because I swapped over to my other bike and now that is having the same problems It now looks like a new battery. Are Eclipse still the best place to go?

 

[Nealh]

Elifebike on Ebay are selling (10s, 5p) 14.5ah Panasonic PF (10a cell ) battery for £240 delivered from German warehouse no import tax via DHL. Luna use PF's instead of 29E's for their superior performance.
The battery and base unit which is metal and plastic should sit nicely on a down tube as the base has a concave profile, though it is quite long at 435mm.