How to access and remove the battery of this ebike?

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JamesG81   10 mW

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How to access and remove the battery of this ebike?

Post by JamesG81 » Sep 26 2019 12:48pm

The battery of this ebike shows zero volts at the charging port. I want to access the battery and remove it for further testing but I am not sure how. I tried accessing it from below the frame tube as shown in the pictures but no easy access from there. I thought there is probably an easier way, otherwise everything has to be taken out and disconnected and even then it seems things in that tube are stuck.

The picture of the entire bike is also enclosed. Can anyone identify the year, make and model of this bike. I think it is an IZIP metro but I am not sure and I don't know the year either.

Thank you.

https://drive.google.com/file/d/1n_VgKd ... sp=sharing
https://drive.google.com/file/d/1SRfDfQ ... sp=sharing
https://drive.google.com/file/d/11Kz48y ... sp=sharing
https://drive.google.com/file/d/1Jp6x3h ... sp=sharing
https://drive.google.com/file/d/1wHpysH ... sp=sharing

Bigwheel   100 W

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Re: How to access and remove the battery of this ebike?

Post by Bigwheel » Sep 26 2019 1:31pm

From what I can see that is the only way they got the battery in there so it is the only way to get it out. It is probable wedged in there pretty good so might take some doing to get it out.

Disconnect all the wiring while labeling if they aren't obviously color matched and taking pictures to refer to later.

Not sure what year the bike is but I would guess late 90's to '10's. Chances are really good the battery is toast so at least you don't have to be too careful, except for not piercing them, as you will be replacing them with a new pack that imitates the old one for the most part. If you use 3500mah cells you will get alot more out of the old girl also.

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fechter   100 GW

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Re: How to access and remove the battery of this ebike?

Post by fechter » Sep 26 2019 2:08pm

Not designed for easy service. This is similar to my A2B. Sometimes the batteries go bad and swell up, making removal very difficult.
Rubbing alcohol makes a good temporary lubricant. You may need to pull pretty hard on it to get it out. On the A2B there is a flimsy pull tab intended to help get the pack out, but they generally just tear off before the thing budges. Banging on the side of the tube with a rubber mallet might help, but the metal dents pretty easy so don't bang too hard.
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Re: How to access and remove the battery of this ebike?

Post by Voltron » Sep 26 2019 5:44pm

BAPK24301A.jpg
BAPK24301A.jpg (7.75 KiB) Viewed 486 times
It looks like this when it's out... You might have the heat the frame with a hot air gun maybe if it's got too much sticky padding.

JamesG81   10 mW

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Re: How to access and remove the battery of this ebike?

Post by JamesG81 » Sep 27 2019 3:23pm

The second time I opened the lower compartment of the bicycle's frame and yanked on the cables the battery gradually came out. It was fairly easy. I opened the battery after it was out but had to heat the case to soften the double sided glue inside to be able to open the 2 halves of the battery. Once the battery was out I checked the voltage at the BMS. It was about 7.6 volts. I took out anything that was glued to the battery and while doing that one of a pair of wires that was glued to the case of the batteries came undone as shown in the pictures. I think these are temp sensors and there were 3 of them.

The one that came undone still has its 2 wires attached to each other, I think what came off was only the protection and the temp sensor itself is good. Can this be verified?

Can this BMS be reused if this temp sensor has gone bad?

What are my options at this point? How can I check this battery further? Any link to video or text that would explain what needs to be done and how to test the battery would be useful.

The individual battery cells are not only welded to the strips on each side of them but are also glued to the battery holder. How can I disassemble this further in a way that I can reassemble it later?

Thank you.

https://drive.google.com/file/d/1_SlmSU ... sp=sharing
https://drive.google.com/file/d/1aI-91D ... sp=sharing
https://drive.google.com/file/d/1wHWTAs ... sp=sharing
https://drive.google.com/file/d/1yM_bEb ... sp=sharing
https://drive.google.com/file/d/1Ufhr7u ... sp=sharing
https://drive.google.com/file/d/1DYbQqb ... sp=sharing
https://drive.google.com/file/d/1I7S8FD ... sp=sharing

JamesG81   10 mW

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Re: How to access and remove the battery of this ebike?

Post by JamesG81 » Sep 27 2019 4:42pm

Actually there are 50 cells in the old battery not 40.

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fechter   100 GW

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Re: How to access and remove the battery of this ebike?

Post by fechter » Sep 27 2019 6:02pm

You should try measuring the voltage of the individual cells. If any are below 2v, they are likely to be permanently damaged.

The temperature sensor is a thermistor. You can measure the resistance between the two wires to test it. You probably need to disconnect at least one wire from the board to get an accurate reading. Not knowing the part number of the thermistor will make it challenging to find a replacement if it's broken. If you get a reading that's 5-20k ohms it's probably still good. Depending on the design of the BMS, it may work without it connected.

The BMS can most likely be re-used if there is no obvious damage.

The typical repair route for the pack is to cut or grind off the tabs on the cells and tear the cells off the pack and replace them with new cells and spot weld new tabs. You would need a spot welder made for nickel strips and some nickel. Soldering directly to the cells is not recommended but I've seen people do it with good results.
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JamesG81   10 mW

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Re: How to access and remove the battery of this ebike?

Post by JamesG81 » Sep 27 2019 8:40pm

To test the individual cells: Can I take the strips off one side and then measure the voltage? Or do I have to take the strips off both side to be able to measure the voltage of each cell?

Thank you.

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Re: How to access and remove the battery of this ebike?

Post by JamesG81 » Sep 27 2019 8:43pm

By the way the links in my post are pictures of the battery etc. In case you did not check them.

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fechter   100 GW

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Re: How to access and remove the battery of this ebike?

Post by fechter » Sep 27 2019 9:51pm

There will be 10 groups of parallel cells. Just measure each group without tearing anything apart. All the cells in a group will have exactly the same voltage.
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JamesG81   10 mW

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Re: How to access and remove the battery of this ebike?

Post by JamesG81 » Sep 28 2019 9:39am

https://drive.google.com/file/d/11vFqrn ... sp=sharing
https://docs.google.com/drawings/d/1mVb ... sp=sharing
The above links show how the voltages of each group of 5 cells were measured and what was obtained. The voltage numbers steadily decreased from the positive post to the negative post and all are very low. What does these numbers suggest?

Can the positive and negative wires of the battery be connected directly to the battery charger of the bicycle to see how far the batteries charge up WITHOUT the BMS? What are the safety risks if this is done?

Thank you.

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fechter   100 GW

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Re: How to access and remove the battery of this ebike?

Post by fechter » Sep 28 2019 11:48am

Yes, you can bypass the BMS and put some charge into the pack. Cells that low need to be charged at a VERY low current until they get above 3.0v, something like 100mA or less. Once all the cells reach about 3v the BMS should start working again and you can charge through the normal charge port at a normal rate.

The problem (according to the experts) is once the cells get below something like 2v, copper on the internal connections will start dissolving and when you charge them the copper can plate out in in places where it doesn't belong. This increases the risk of fire when charging. I've revived cells from near zero and they "seemed" to be OK after that, but the increased risk of fire is probably still there.

Charge in a place where a pack fire won't set your house on fire.

The only reliable fix is to replace the cells.
"One test is worth a thousand opinions"

JamesG81   10 mW

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Re: How to access and remove the battery of this ebike?

Post by JamesG81 » Sep 29 2019 8:36am

Thank you for the reply and the caution regarding possible increase risk of fire. I will charge them in the garage on concrete or metal away from other things.

So if I need to charge the pack at very low amperage of 100mA or less, how do I do it? I was thinking of using the original bike charger which is rated at 4 A. I don't even know if this charger will work with a depleted pack like this but even if it does how do I know if the amperage it is giving the batteries is low enough?

I used to recondition car batteries and I have a charger that puts out constant current which helps to bring back lead acid batteries that have been depleted beyond what regular chargers can do. That charger, I think can put out only 12V though and this is a 36V pack. Can this 12V charger work with a 36V pack? (I maybe wrong about this charger only being for 12V)

I think a charger for lithium batteries that can put constant current might work in this case. Can you direct me on how to go about this? What charger did you use when rejuvenating those pack that were near zero? Can the original bicycle charger be used?

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fechter   100 GW

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Re: How to access and remove the battery of this ebike?

Post by fechter » Sep 29 2019 7:58pm

One way is to use the stock charger with a resistor in series with the output to limit the current. I've used 120v incandescent light bulbs before and it worked. Otherwise a resistor around 150 ohms or so with a high power rating. The best thing is a current limited bench power supply. It is also good if you have a way to measure the charging current. To use the stock charger it will be necessary to bring the power out to pair of wires. Depending on the connector type, you might be able to jam wires into the sockets or find a mating connector. Another approach is to use the stock wiring and put the resistor across the BMS from charger negative to battery negative. This will probably be the easiest if you already have the pack out.
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JamesG81   10 mW

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Re: How to access and remove the battery of this ebike?

Post by JamesG81 » Sep 30 2019 2:04pm

I made a diagram of what I think you mean by using an incandescent bulb in series with the battery and charger to charge up the depleted battery. The image below shows it. Is this correct? Thank you.
https://docs.google.com/drawings/d/1CVf ... sp=sharing
The following image can be zoomed in so you can see the details of what I mean. Please use it after looking at the above picture first to understand what I mean.
https://drive.google.com/file/d/1rhD3je ... sp=sharing

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fechter   100 GW

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Re: How to access and remove the battery of this ebike?

Post by fechter » Sep 30 2019 9:57pm

Yes, that should work. It would be nice to have an ammeter, but the bulb will give some indication of current flow. It should barely glow at first then as the cells come up in voltage it won't be visible at all. You can check individual group voltages while it's charging. Once the lowest one reaches about 3v, you should be OK with the normal charge current. This may take more than a day. At that low of a current, things are pretty safe from a fire standpoint.

What's the watt rating of the bulb? We can get a crude estimate of the current from the voltage across the bulb when it's charging.
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JamesG81   10 mW

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Re: How to access and remove the battery of this ebike?

Post by JamesG81 » Oct 02 2019 8:14am

The Wattage of the bulb is 25 W.

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fechter   100 GW

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Re: How to access and remove the battery of this ebike?

Post by fechter » Oct 02 2019 11:01am

That should work fine. My guess is the lamp will measure around 50 ohms. If you measure the lamp resistance with your meter, it will stay around this value as long as the filament doesn't start glowing. From there, the current will be the voltage across the bulb divided by the resistance.
In any case, that should be limiting the current to a safe value.
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Re: How to access and remove the battery of this ebike?

Post by www.recumbents.com » Oct 02 2019 11:56am

Or you can use an old cell phone charger to charge each cell group separately at very low current.

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Re: How to access and remove the battery of this ebike?

Post by Voltron » Oct 02 2019 12:10pm

Keep in mind that if the whole battery was actually at under 8 volts for a good while, even if you manage to get it charged it will be an open question about being dangerous to use. With an external battery it would be easier to charge in a safe spot... Do you have someplace safe to park the whole thing?

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Re: How to access and remove the battery of this ebike?

Post by JamesG81 » Oct 02 2019 1:03pm

I originally measured the voltage of each cell of the battery as the following picture shows:
Picture one:
https://docs.google.com/drawings/d/1dpW ... sp=sharing

But I was informed the correct way to measure each cell is as the following pictures shows:
Picture two:
https://docs.google.com/drawings/d/1TWZ ... sp=sharing

The numbers on each cell unit is what I measured.
Is the second picture the correct way to measure the individual cells of this battery or was the original way I measure is the correct way?
With an external battery it would be easier to charge in a safe spot... Do you have someplace safe to park the whole thing?
I don't know what you mean by the above sentence. The battery is out of the bicycle as many pictures I have posted here shows. Is that what you mean? To take the battery out of the bicycle before charging it. If so it has already been done.
Or you can use an old cell phone charger to charge each cell group separately at very low current.
If using the bike's original charger does not work, or if I find it more convenient to use the above mentioned method, how do I charge each individual cell? Do I charge each cell using the charger leads the same way I hooked up the multi meter to measured the voltage of each cell as shown in the second picture above? Or do I hook the cell phone charger as shown in picture one above?
Yes, that should work. It would be nice to have an ammeter, but the bulb will give some indication of current flow. It should barely glow at first then as the cells come up in voltage it won't be visible at all. You can check individual group voltages while it's charging. Once the lowest one reaches about 3v, you should be OK with the normal charge current. This may take more than a day. At that low of a current, things are pretty safe from a fire standpoint.
I will do as you have instructed here but I need to get a few things ready so it will take me a while.

Someone said the following to me: " When a cell is discharged below its rated limit , It is ruined. Metal precipitates form in the electrolyte. These can link up if the cell is recharged, and cause an internal short circuit that will overheat the cell and start a fire." I presume this increased fire hazard is ONLY on this first charge (the one I will attempt to do with very low amps), because once the first charge is done then the metal precipitation is back in suspension in the electrolyte and the increased risk of fire due to internal short is no longer. Am I right? Or is the increased risk of fire remains high even after a successful first recharge?
Precipitation:
https://docs.google.com/drawings/d/1r7g ... sp=sharing
Last edited by JamesG81 on Oct 03 2019 11:05am, edited 2 times in total.

Voltron   10 MW

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Re: How to access and remove the battery of this ebike?

Post by Voltron » Oct 02 2019 6:18pm

Hi... I know it's out of the bike for now... I meant after you charge it up this time. Are you planning to take it in and out of the frame every time after this first charge?
If so, then it's easier to store and charge the battery in a safe, fire proof location.

If its getting reinstalled semi permanently, then the whole bike should be stored away from people and structures.

It could go up just while sitting, not just while being charged or run on the bike. It could be a serious risk if you lived in an apartment building and stored it inside, for example.

Charging won't drive the metallic dendrites completely back into suspension... The risk will remain.

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Re: How to access and remove the battery of this ebike?

Post by Voltron » Oct 02 2019 7:03pm

I looked at your text different voltage voltage pictures... Something is weird. I think you're measuring right on the first one. They should give you the same totals, just the second way will show cumulative numbers as you go down the line. But yours show wrong spreads between the two pictures, like maybe you touching the wrong spots in the second one.

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Re: How to access and remove the battery of this ebike?

Post by JamesG81 » Oct 03 2019 11:24am

OK Voltron thanks for clarifying what you meant. So the increased fire risk remains. I plan to install everything back into the bike's frame (where the battery storage is) and bolt everything up and use the original charging plug to recharge. I think the extra big frame made for the battery and the other electronics should contain any possible fire as other than some melted wires and electronics there isn't anything to spread a possible fire and not much oxygen either. Unless the battery can explode so forcefully that it can rupture the frame. Is that possible?
The following pictures show the position and location of the battery:
https://docs.google.com/drawings/d/1AIp ... sp=sharing
https://docs.google.com/drawings/d/1G3W ... sp=sharing

My multi-meter was running out of battery while I made the measurements. I have new batteries for the multi-meter and will measure the cells and the accumulation of the cell voltages again and compare and post.

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Re: How to access and remove the battery of this ebike?

Post by docw009 » Oct 05 2019 12:02pm

Both measurement methods are correct, as long as you state how it was done. So you got 10 cells, all between .60 and 1.2 volts. You want to recharge them? Playing with fire, if you ask me.

October used to be fire safety month. Sparky the fire dog, if he's still around, would tell you to dispose of those cells in a safe manner. I agree with Sparky.

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