Quando 2 limp home mode at 8.7AH - is this normal?

[kevinfox]

I've just had my Quando 2 drop into reduced power limp home mode whilst climbing a steep hill with only 8.7Ah of the battery used.
Is this normal or do I have a damaged battery?
Voltage had dropped to 28.3V before it dropped the power. On the previous charge it dropped into limp mode after 9.3AH was used although I wasn't climbing a hill at the time.
I rode home with reduced assistance and did get the full 10AH before it cutout completely, but this means I have only 9/10 usable capacity and realistically only the top 3rd before the speed starts dropping off.
The battery has been charged 4 times from new and I've noticed the charger yellow / green light goes off if you leave it plugged in for a while after charging.
Plugging a wattmeter into the mains side it seems the charger is using an extra 7 watts when this happens and disconnecting the battery removes this excess.
Could my charger be faulty and slowly be killing the battery?
I thought putting power into a fully charged LiPo was a bad idea?

 

[flecc]

I don't think there's necessarily anything wrong. The 10 Ah is nominally the capacity but that's at a fairly low rate of discharge. The Quando's powerful motor can draw current at quite high rates up to 20 amps and that reduces the available capacity.

A to B magazine tested the latest 3.3 kilo Li-poly eZee battery at various rates of discharge in November 2008 and found the usable capacity as low as 7.5 Ah and didn't report higher than 8 Ah. They didn't say which bike they used, but it was probably their eZee Forza which they used on the previous eZee battery test of the 4.4 kilo Li-ion.

What you experienced was probably just the effect of the high current drain in climbing that hill.
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[kevinfox]

Thanks for the reply Flecc.
Do you know if the Quando 1 is faster than the Quando 2? I went out for the first time with my partner on her Quando 1 and she was easily pulling away from me on the flat despite claiming to not be on full throttle.
Do you think the charge light off and 7 watts going into the battery mode of the charger is something to worry about?

 

[flecc]

Both Quandos are nominally the same, but later models of all types have had the controllers tuned down a fraction to make life a bit easier for the batteries. Apart from that, if she has the previous 4.4 kilo Li-ion battery Keith, it will be a little bit faster since it's voltage is slightly higher than on the latest Li-polymer that you have. According to A to B, the voltage on the polymer battery is maintained quite well throughout the discharge though, so the small performance difference should close up as they discharge. If her Quando 1 has the earlier controller though, it will remain just a bit faster.

I don't know about that residual current drain on your battery charger when charge is complete, but I'll recharge my battery and check the current drain when charge is completed and let you know the result later.
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[kevinfox]

We both have the same battery, hers was dead when we bought the bike so we got a replacement.
The different controller design would explain it. I'll try and note how the battery voltage alters as it discharges to see if the voltage makes sense, mine seems to take a nosedive towards the end especially when under load, although the capacity is correct if I hardly use the power.

The charge mode goes
yellow (charging for 5-6 hours)
green (charged for a while)
off (adding 7 watts into the battery as measured at the ac input)

Thanks again!

 

[flecc]

I've always unplugged mine at green, which is what eZee recommend, hence my never spotting the current drain after the LED goes out. I didn't even know they went out like that, but I'll check to see if mine does.
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[flecc]

I've done that recharge now. The battery was nearly fully charged so only took a few minutes to drop to green, at which the current dropped to 11 watts. From then over about a half hour it gradually declined to 5 watts at which it stayed permanently.

Since my battery is different, it's not a Li-polymer one but the latest type of Li-manganese rigid cell type, that small variation is possibly due to that.

So it seems your charger and battery are ok, but I don't think it's advisable to leave them on charge indefinitely once the LED changes to green since it isn't what eZee advise.
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[eddieo]

So......it's not a good idea then to let the battery charge overnight?

 

[flecc]

That's ok Eddie, since the charge takes up to five hours, the post charge period isn't very long. eZee say that's not a problem, they just don't recommend leaving the charger plugged in long term.

The BMS is supposed to cut the charge anyway once it's complete, but judging by the behaviour of our charger/battery combinations, some current still appears to be getting through afterwards since it sticks at 5 watts and Kevin's sticks at 7 watts. Those are fairly high trickle charges so they would be undesirable long term, but the odd few hours at end of a main charge aren't a problem.
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[eddieo]

Thanks Flecc!

I realise this is about Ezee battery/chargers......But the same goes for Wisper?

 

[flecc]

Probably, they use the same HP (HighPower) charger now, and both use similar polymer battery technology.
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[kevinfox]

Many thanks Flecc, I'll put it on a timeswitch.

I've done that recharge now. The battery was nearly fully charged so only took a few minutes to drop to green, at which the current dropped to 11 watts. From then over about a half hour it gradually declined to 5 watts at which it stayed permanently.

Since my battery is different, it's not a Li-polymer one but the latest type of Li-manganese rigid cell type, that small variation is possibly due to that.

So it seems your charger and battery are ok, but I don't think it's advisable to leave them on charge indefinitely once the LED changes to green since it isn't what eZee advise.
.

 

[kevinfox]

Oddly enough my charger takes 6 watts when it's not plugged into the battery. The additional 5 watts I mentioned takes it up to 11 watts and that is the difference between battery plugged in and not plugged in once the green light has gone off.

The BMS is supposed to cut the charge anyway once it's complete, but judging by the behaviour of our charger/battery combinations, some current still appears to be getting through afterwards since it sticks at 5 watts and Kevin's sticks at 7 watts. Those are fairly high trickle charges so they would be undesirable long term, but the odd few hours at end of a main charge aren't a problem.
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