Ok this is what I have been feeling for a while now.
When accellerating at full throttle I can feel the power coming in waves. It is a bit like driving a normal car with a dodgy AFM.
The first time I felt it was when my bike was a few months old on a deep discharge ride during the final meters home at zero bars. But lately it is happening at a higher and higher number of bars. Even without going for a red battery light.
Are these waves of power cells that are reversing or for some reason having a sudden high resistance?
Any similar expierences or possible explanations?
Thanks
Can you feel the battery reversing or degrading?
Fri, 10/22/2010 - 15:08
#1
Can you feel the battery reversing or degrading?
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Support V is for Voltage
Are the fluctuations down or up?
I mean, when it first happens, do you get a power drop or a power surge?
Whatever it is, it is not a reversing cell by itself. They just gently drop down and then stay down. You would not feel a single reversing cell, neither does the stock-BMS.
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There is always a way if there is no other way!
The bike will accellerate, but during the acceleration (say from 20 to 80 km/h) it feels like it is not giving full power then climbs to full power again, holding back a bit, full power, etc. Untill you reach your chosen speed.
Once you go EV, Gas is history!
My bike was doing that aprox. 1-2 months before serious battery degradation. But it can also happen because of colder temperatures, where the battery pack voltage, at high load, dips much lower that at 20°C-25°C range.
I imagine it's your battery hitting 115v.
maybe X-vectrix can help us.
I guess that when you twist the grip to full power, the voltage drops too much. The system limits the release of power in order to prevent the battery going below that safe voltage. You can call them computerized limiting waves = CLW.
As more cells are damaged, they cannot sustain their voltage under load. You are aproaching the second step of damage. Soon, despite having charged to full you'll always feel the CLW. The bike will never accelerate as usual.
I'm the second damaging step since 3-4 months. I'm trying to minimize the damage by only discharging to 11/17 bars, and recharging whenever possible. It works.
After some months of riding with the battery damaged, I've realised that the NIMH cells are very resistant to odd conditions. A lithium battery under this challenging conditions would have died long ago. The vectrix battery packs fail due to underengeneering, needs more ventilation, more electronics... But It seems that the chemistry is good.
Yup, same here, second year in a row,
I know it's the cold, the difference is huge.
Voltage seems to drop more easily, but when you ride a few kms, it gets better.
Also, the red light comes on more quickly, so my bike needed a deep discharge to reset the gauge.
summer: about 60 km of range
winter: about 45 km
"doing nothin = doing nothing wrong" is invalid when the subject is environment
So, either it is the cold or it is the first signs of battery degradation.
It still is not that cold here. The batteries are usually around 15c at the start of my commute.
So that means that after 8000kms and within one year the first signs of degradation already appears.
And I really did my best to conserve them, I read this forum for months even before I got my bike so I was well prepared. :-(
Once you go EV, Gas is history!
Not necessarily. My battery is still in top notch condition, yet I got red battery telltale, on Friday, at 7 bars left with battery at 120V and 11°C. Luckily I was 100m away from a gas station (the irony :-) where I did a 45 minute opportunity charging from 0 battery bars and drove home and parked in an underground garage, which is currently at 13°C.
Today I recharged the battery up to 146V at 8 bars and the battery got warmed up to 17°C. I drove to my father and back and when I arrived home, the battery was at 19°C, 1 bar left on the gauge, 128V, which is plenty battery power left (aprox 7 bars should be remaining).
Which brings me to my point; the battery at 11°C has the same useful capacity as the battery at 19°C with 7 battery bars left on the gauge. Maximum power output is certainly lower too, that's why you can experience variable maximum acceleration. I'm not feeling it, because I drive no faster than 70km/h and accelerate gently, but I did with my first pack, when I took no special care and drove up to 100km/h with heavy acceleration.
It's like a car battery in winter at the start up. If the ICE doesn't start immediately, the electric starter rpms will go down and vary it's speed.
Edit: Check out this graph:
The cut-off point is at 118V, that's 1.56V/cell. You can see, how the cut-off is reached earlier with the lower battery temperature.
And this:
Just one brief thought - it may not be entirely due to the battery condition. I had a similar riding experience when my motor controller had a few problems. One of the motor phase connections was progressively burning out and would go high/low resistance as it heated/cooled due to my riding demands. In the end I'm afraid that it failed completely. An early tell-tale sign was a very pongy smell of hot PCB phenols when you lifted the seat. Nothing else smells like it so you'll know if the problem gets worse and is attributable to this failure mode! The good news is that the new MC has gone for approx 12000 miles so far... It does indeed feel like someone else has control over the throttle, doesn't it!
Good luck.
Drew
Drew
I have not smelled anything funny yet, and because it only happens when the gauge is below 50% I doubt that it would be a connection.
I will keep an eye on it though. Winter is coming and I will check better how it behaves and what the temperature and gauge are at when it does happen. Last few days were ok again.
Once you go EV, Gas is history!
I'm still betting on the temperature..
I live near you, and temps have been relatively high again, haven't they?
"doing nothin = doing nothing wrong" is invalid when the subject is environment
Little update
It may still be temperature related but there must be more to it. It has been really cold (-5C) here and I have not had the problem for a while now. On Wednesday I started my daily commute with a battery temperature of 5 Celsius.
I do think that I may have an explanation now. Because looking back, both periods where I noticed this behavior were right after long storage.
1st time was right after I received my bike and was doing its first 5 deep discharges.
Second (and last) time was after my bike was back from repairs (it was gone for 6 weeks!).
After doing some deep discharges it now has completely disappeared. Even during the recent cold temperatures.
So it seems this is only after long storage and therefore probably bad balanced cells. Perhaps combined with colder temperature.
I will continue to keep an eye on it but for now it seems my bike is back in good shape.
Once you go EV, Gas is history!
It seems really possible. Mik has already shown us how some cells have higher self discharge than the rest.
I still think NIMH packs need some kind of BMS.
Hi there.
I´m Testing NiMH for my Panda (the 78AH version of the Vectrix cells). I had problems with some of the blocks
because of poor capacity. Theese two discharge graphs are from one block with 10 cells. The black one was the
first test, the battery had been charged to 14,5V, the cells started to get warm at this stage. only one cell
stayed cool.
As the test was interupted I disconnected the empty cell and started the test with the remaining cells which had
still about 25 AH left (sorry no graph yet)! First thought: "ok got a pack with a bad cell" Second thought during
another test: "What if..." Well I charged the complete pack with about 70 Ah. The result is the second test with
the red line. It is one and the same block! The batteries had been stored for at least two months or longer and I
don´t know how they where managed during use, but as I look at the connections they had no single cell management
only a blockmanagement.
I agree with R a management is needed maybe single-cell-based. Only other solution is using the Vectrix very regular
by using much of the available Ah (maybe down to 15% and charge it to 90%. I decidet to charge it once or twice a
week while it is in its winterhibernation.
Greetings Mike