Electric bike: diagnosis of a lithium-ion battery 24V

[Christophe]

Following the problem raised on this subject https://www.econologie.com/forums/experience ... t7946.html about the cuts in strong demand of current of the battery Lithium Ion of our VAE, here is the dismantling and the diagnosis of its battery following the proposal of a badly charged element by Dirk Pitt here: https://www.econologie.com/forums/post202726.html#202726

Operating room:



4 output poles: 2 * 28 V (?)


2 * 0V (on the right) and 2 * 28V (on the left) (I do not know where the + 4V come from with the battery, see below), wiring:

| | | |

+ 28V + 28V 0V 0V



General beam:



Integrated 30A auto fuse:



An integrated thermal? (and if he was the problem?)

I do not know how it is wired because the engine pulls more than 5A:



Battery elements:


It is wired as well

Here are the measurements with respect to the 0V (red thread):

| | | | | | |

0V + 4V + 8V + 12V + 16V + 20V + 24V

Measure between each element N, N + 1 gives: 4.02 to 4.04 V (very constant therefore).

I do not know where the extra 4V comes from.

Note: the battery is CHARGED!
Edit erratum: no in fact the battery had already done about 15 km (so about half discharge). But the indication leds were still "full" (hence the measured voltages)

Details on the elements of the battery; there are plates printed on the elements (control of charge or discharge?):



So what should I do? I unload and re-measure the tension of each element?

I briefly recall the problem: the bike turns off (as if it were OFF, turn off the battery and turn it on again to restart the assistance) during too big climbs (too steep or too long) AND below a certain speed (if you pedal more strong, it does not cut).

The bike and the battery have just 2 years (4 / 2009)

This regardless of the state of charge of the battery. This can happen after 1 km after a full charge. Nothing during 15km (flat) and OFF at the 1ere coast. Obviously this becomes more common as the battery approaches the discharge.

[Gaston]

Connecting a charge to charge a few amperes (2 car headlight bulbs in series can do the trick to start) and redo the voltage measurements (during the discharge) to see if they are still balanced.

[Macro]

5A under 250V ca 1250W the 24W said 1250V thermal said 52V it made the XNUMXA ...

[Alain G]

Hi Christopher!

The voltage of the battery can be good to no load and still fall sharply when climbing hills!

You must take the reading of the voltage during the climbs of a slope!

Do you have a battery gauge with multiple LEDs on the bike?

If yes, do you notice an abnormal drop?

The battery may lose its amperage capacity and give you a good vacuum voltage reading so the controller to not completely discharge the battery falls into protection!

What is the controller model?

[dedeleco]

To see these infos, this battery gives an emax power of 28V x 5A = 140W max !!
With thermal fuse 5A, this fact is certain!
But to climb a good hill, as I ride grandfather happily without assistance, 200W and more demand sometimes and therefore the battery overheats (more than me) its fuse and stops for security until the next test!

This shows me that I do not need this type of insufficient electrical assistance for me!

The battery is normal very likely !!

Test it, to be on, being discharged by measuring the voltages of each element with even more 5A to see the thermal fuse cut for safety, and see that everything is normal !!

Several 220V heaters in parallel of several KW can serve as test resistor !!

[stipe]

Dede, the engine / battery pair come in support, so in addition to your 200W, so in your rating instead of providing 200W you will only provide 120 and the 80 motor missing etc ...

So your reasoning is not applicable here, especially since this behavior was not seen early in the life of the bike (before winter).

Edit: Dede, this actually says if you already do everything you want with a normal bike, you don't need assistance;), the assistance would be to do "more"

[dedeleco]

Okay good to die less in side!

But the rest of the argument remains valid because a thermal fuse of 5A (often a bimetallic (nothing transistor) spring heated by the current ages with time and weaker spring, triggers at lower current) ???? ? Very, very classic.
cheap thermal fuse
http://thermostats.en.alibaba.com/produ ... ector.html
http://sanmenfeida.en.made-in-china.com ... 9700-.html

Measure the T of individual batteries as they can heat up to over 65 ° C and trigger the thermal bimetallic fuse, especially for batteries that get older by heating more?

[Alain G]

Dede

This is why I ask Christophe to measure the voltage in real operating conditions, if he sees a net power cut, it will mean that the battery protection is HS or that the controller / motor unit draws more than amperage!

[Gaston]

Dede

This is why I ask Christophe to measure the voltage in real operating conditions, if he sees a net power cut, it will mean that the battery protection is HS or that the controller / motor unit draws more than amperage!

It is much easier to measure the tensions of the different elements on a table than under a riding saddle of bicycle, that is why I suggested to measure it with a load simulating a consumption (ideally of 250W, but two bulbs of lighthouse in series already represent 110W, which may already weaken the desired element).

[Alain G]

Hello Gaston!

I was talking about measuring the cells separately but the whole battery to see in the first place if the problem actually comes from the battery!

This will make it easier to identify the problem instead of pulling left and right, it is the advice of a technician used to diagnose problems!