Ninebot one E+ power reduction

[Thumper0511]

Happy new year to you all..... :-)

I have noticed over the past week that the power of my NB1 E+ seems to have reduced.  My route to work is the same each day and I have been commuting for the past 4 months everyday.  There are a couple of steep hills which my NB1 has gone up normally with relative ease.  I have noticed over the past week that it struggles more now to go up these same hills.  Today for example I did not get a run up properly to one of them and it really struggled where as before I have had the same situation (due to pedestrians) but it has been able to gather more speed whilst climbing the hill.  Is there anything I can check like the MOSFET's for example (although I don't fully understand how these work) as they manage the power regulation right?

Any advice would be greatly appreciated 

 

Thanks

[Keith]

I don't know the NB very well, but it probably has multiple MOSFET's in parallel. One or more failing open circuit could give you reduced power but it seems unlikely, and they are just as likely to fail short circuit which ought to stop it working at all.

Battery is the much more likely candidate. You don't say where you live, so has it got a lot colder?  You also don't mention what the NB is reporting its battery state as at the time you are having problems? Of course you might also have put a bit of weight on over Christmas ;-) ?

Seriously, if your daily journey takes a lot out of the battery, or you don't charge it until it is very low, then the capacity of the battery will reduce fairly quickly, quite possibly significantly in 4 months if used that way every day. Cold weather reduces capacity significantly so voltage drops faster and also, in itself, reduces voltage. Reduced voltage will result in reduced power, the effect, I think, you may be seeing. However, this would be coupled to your wheel's battery monitor reporting a faster decrease in capacity as well, at least whilst the wheel is under load, it may well recover when stationary.

If the problem is in the power train, rather than the battery then the effect, as far as your battery monitor is concerned is likely to be that you are drawing less power from the battery, it's voltage would remain higher and the monitor would show a healthier voltage then previously even though you are struggling to get up a hill.

there are a number of "should's" and "possibly's" here as there are too many unknowns. A short circuit in part of one of the motor windings, for example (albeit very unlikely) would reduce power and draw much higher current.

[Thumper0511]

Thanks Keith,

A very good point around the weather and battery.  I will take a look at the battery output as I'm heading up hill on the way home tonight.  Unfortunately I did not check this reading when all was well before so nothing to compare it to but it's a start.

Regarding charging I was aware of the method for keeping the battery healthy and rarely run on a low charge i.e. below 20%  (once in fact) and always charge to full each day (without leaving plugged in for hours).

Like you said there are a few unknowns however I think by monitoring the power draw via the app whilst riding to see if this starts to point to a possible cause.

It's not very bad but is certainly noticeable and so a little annoying.

Thanks again for the comments - very helpful indeed :-)

[BecauseFun]

Without knowing where you live, I would agree with Keith that cold weather and its effect on the battery would be the most likely candidate to describe what's happening. Since I always like to rule out the simple things first, I will add that if it is a lot colder now where you live then it was last week, tire pressure can also be affected, by 1 to 2 PSI per 10 degree drop in temperature. Here in the Northeast the temperature was in the seventies just recently and now it's in the twenties, and 10~ less PSI would definitely be noticed, as an under-inflated tire increases rolling resistance.

So my guess would be the battery and tire pressure in the cold, but the only other thing that comes to mind that hasn't been mentioned yet is that the 1.3.5 firmware was also released recently. "Less power on steep hills" would definitely be something that you think would have been talked about already since a number of people have upgraded, so I strongly doubt new firmware would be the issue. But if it's not cold where you live and you have recently made the move to 1.3.5, then I would not take firmware change completely off the table as a possible explanation to what you're experiencing. ( also, I see that you have posted again while I was typing, I am replying to your original post) 

[Thumper0511]

Hi BecauseFun,

Thank you to you too for you comments.  I apologise for not providing enough information in my original post - I will list out some of the current unknowns:

1. Location is South East London
2. Temperature drop 15 degrees down to 6 degrees (Centigrade)
3. Hill gradient ~20 to 25 degrees (there are two steep hills both about 100 metres in length)
4. Tire pressure 55psi (just topped up around Xmas) - tyre is stock Kenda
5. Firmware 1.2.7

[Gunthor]

Hi Thumper0511,

Since appr. 6-8 weeks I experience a similar behavior with my Ninebot One E:

1. It still reaches 20 Km/h when the street is level (neither incline nor decline).
2. But I cannot travel the same distance as in the past.
3. It no longer drives but crawls uphill.
4. When leaning forward to accelerate I faceplanted twice so far (1: ~22%, 2: ~17%). I thought I warn you because I think this will be your next experience!
5. I did not get any warning sound when crawling uphill or shortly before the faceplants!

In August I regularly depleted the battery on my trips so I think I accelerated the aging process of the battery (only drove ~3.400 Km so far) and now need a new one. I think the manufacturers of unicycles need integrate the following functions:

1. Intelligent battery charger that will shut off when the battery is fully charged.
2. An audible signal when the battery is on 20%. This way the user will know that (s)he will accelerate the battery aging process when driving on.
3. A function that takes the aging weakness of the battery into account in order to give audible signals before shutting down when "crawling" uphill.
4. An app function that tells the user when it is time to replace the battery.

As for me I am thinking about getting a new battery and later on selling the Ninebot One E and get a Ninebot One P.  This way I can travel further without depleting the battery when it is getting warm again.

[Thumper0511]

Hi Gunthor,

Thank you for your response.  This sounds like what i am experiencing around the same gradient.  I cannot accelerate just main rain speed to crawl.

im gonna take a look at power readings on app whilst travelling up hill to see what it tells me.

it is cold at the moment on morning commute so this may contribute.

[esaj]

If it's cold outside, that will also affect the battery life a lot (especially below 0C), the voltage will drop much faster and you can't get nearly as much out of the battery as around room temperature.

It's currently -25C (-13F) outside here. Last night it dropped to -31.5C at best (-25F).

[Vanquiz]

Holy... And I thought here 16F yesterday is already cold, where do you live? @esaj

[esaj]

1 minute ago, Vanquiz said:

Holy... And I thought here 16F yesterday is already cold, where do you live? @esaj

Finland, the land of iglus and polar bears... well, not exactly, but it is cold during the winter   Probably even colder up where vee73 lives.

[esaj]

Split the cooling/heating discussion here:  http://forum.electricunicycle.org/topic/2381-mainboard-battery-cooling-heating/