New battery - Have I been conned?

Can anyone check my logic and calcs please...

 

I decided to upgrade from 36V 8.8Ah old style bottle battery to 36V 14.5Ah new style bottle battery because I need to travel longer distances.

 

So just got a 36V 14.5Ah Panasonic battery from China (reputable dealer but don’t want to say who at the moment). I fitted it to my bike but got the same old 30’ish miles out of it instead of 50’ish that I was expecting. So I charged it from flat via an energy monitor and found that it only takes 280Wh to charge.

 

I calculate that 280Wh at 36V is 7.77Ah.

 

And since you can’t get more out of a battery than you put in the battery output must be less than 7.77Ah due to charger inefficiency.

 

My other bottle batteries that are 36V 8.8Ah & supposedly Panasonic take over 300Wh to charge from flat. I calculate that 300Wh at 36V is 8.3Ah. So they are pretty much what I would expect for that size battery.

 

By my reckoning I’ve paid extra for the 14.5Ah Panasonic version but actually got nothing better than an old style 8.8Ah bottle battery – if that!

 

The question is have I been conned or did they accidentally put the wrong batteries in the battery box?

 

Any ideas?

The 14.5ah one has 50 cells instead of the 40 that your old one has. That's easy to check. It should weigh about 25% more. To check whether they're Panasonic cells, you have to open it and check what's written on them. Genuine Panasonic ones don't have Panasonic written on them though!

 

With any new battery, you shouldn't be too quick to judge it. Wait until it's done a couple of charge cycles before measuring it. Let us know how you get on.

Thanks for your reply d8veh.

 

Yeah I researched the weight etc before buying and the battery does weigh more but they're in completely different cases of unknown weight so very hard to tell - I'll see if there's more I can do to check that though.

The difficult thing is that the cells of very different capacities and qualities all seem to weigh the same 45g-47g so no way of knowing by weight what is inside.

 

My other batteries worked best on arrival and it was all downhill from there! I was under the impression that the initial full cycling of batteries only applied to older battery types and I've just found the following extract on Battery University.com (http://batteryuniversity.com/learn/article/how_to_prime_batteries)

 

"Additional formatting makes little difference because the maximum capacity is available right from the beginning, (the exception may be a small capacity gain after a long storage). Nor does a full discharge improve the capacity once the battery has faded. A low capacity signals the end of life. A discharge/charge may only be beneficial to calibrate a “digital” battery; it does nothing to improve the “chemical battery.” (See BU-601: Inner Working of a Smart Battery) Instructions recommending charging a new battery for eight hours do not cause harm but this is “old school,” a left-over from the old nickel battery days."

 

Either way I can't imagine it making the huge difference needed to accept a charge of nearly 500Wh instead of 280Wh.

 

Cheers

 

Ian

any battery will have a label stating its voltage and capacity, even if it does not have the information about the factory that assembles it.

If yours doesn't then it's not good.

Like the label on this one:

 

The label may be on the underside of the battery.

 

http://wooshbikes.co.uk/2014/batteries/mini/square-bottle2.jpg

Very interesting Trex, thanks.

No labels other than tiny QC date. So, not looking good!

Have you or has anyone else got one of the new style batteries that is performing as expected? If so, where from?

(Just checked my older style bottle batteries and their labels state 9Ah, not the 8.8Ah I thought they were, but that's just detail.)

There are plenty of good quality batteries from vendors advertising on this forum. Woosh, Eclipse, Cyclezee, Kudos, Panda, Cyclotricity etc.

I usually buy from bmsbattery.com if I can't find what I want. Bmsbattery's price is fair, quality is average.

Thanks for that Trex.