Battery charging

[Bikemad]

What I want to know is for example, wire nº 5 coming out of the battery in wich connettion must go...??

Looking at your pictures it appears that:
1 goes to 1
2 goes to 2 etc.

like this:



Hopefully this modified diagram will make it a bit more obvious.

Alan
 

[TOM]

We will help you solve this problem at once.

[TOM]

Robert,
 you have to know the order your cells are connected in order to know which way to connect those wires. You may have to strip down your battery to expose all the wires so that you can reconnect them correctly. Below are two diagrams taken from different types of bms's that may help you determine how to do it. Assuming the connector for all the little wires has them in sequential order then you should be able to take it from there.

Muzza.

Hello Muzza
Your drawing is very good.BMS1 is suitable for 36V LiFePo4?BMS2 is suitable for 72V LiFePOo4?
Robert uses LiFePO4 and red BMS is another kind of Lithium Battery.

[muzza.au]

Your drawing is very good.BMS1 is suitable for 36V LiFePo4?BMS2 is suitable for 72V LiFePOo4?

Actually I didn't draw them, I just copy and pasted them. I guess the voltage would depend on the number of cells in each diagram.

Muzza.

[Bikemad]

Your drawing is very good.BMS1 is suitable for 36V LiFePo4?BMS2 is suitable for 72V LiFePOo4?

I guess the voltage would depend on the number of cells in each diagram.

BMS1 16 cells 48 to 64V  (12 LiFePO4 cells@3.0V=36V)
BMS2 24 cells 72 to 96V  (24 LiFePO4 cells@3.0V=72V)

I assume that the BMS is specific (or adjustable) for the cell type and capacity so it can correctly monitor the voltage and current:

Cell Type     Typical Volts/cell
LiCoO2               3.7 V   
LiMn2O4             4.0 V   
LiFePO4              3.0V,3.3V
Li2FePO4F           3.6 V

Robert's battery appears to be a 12S 3P pack (12 sets of 3 cells in parallel).

Alan

Details amended 23/09/09

[robertozm]

We will help you solve this problem at once.

Hi Tom.
I have not solve my problem yet.

Hi BikeMad:
My battery is a LiFePO4 36volt 15amp, from GM Model LFP3615

Hi guys.
I hope you can help me.  I will tell you what has happen and which are my doubts.

Tom told me to conect cell 1 to position nº1 in the BMS conector, and so I did, but nothing happens, so I decided to measure voltage, and I found 36.1volt from the wires out of the battery, and 36.1 volt from the wires of the BMS, but when I measure after the shunt of the cycle analyst I only had 5.1volt.  I wrote to Ebike, and very quickly they answer me they have never have a shunt burnt, and to try continuity.  They were right, the shunt was ok.  So it must be the BMS, so I disconected, and plug the battery without BMS directly to the cycle analyst shunt, AND IT WORKKKKKKKKK:)

At this point in the bike´s life, just to see the wheel turning, it is amaizing!!!   But, the wheel doesn´t move until the wheel is in motion, then I throttle.  But if the wheel comes to a stop, then again I have to push the bike in motion and move the throttle.  And I heard 2 beeps, I think it means motor hall sensor malfunction.  Does anybody know how to solve this malfuntion.  Do you know if the problem with the start is related to this?

What happens if I use the batery without the BMS?
Does anybody have a wiring diagram of the batery cells and the conector of the BMS?

Thanks for your time

[Bikemad]

What happens if I use the batery without the BMS?

It is not a good idea to use LiFoPO4 battery packs without the cell protection that the BMS should provide.

If the cells are not balanced during charging, there is a chance that one or more cells may become more imbalanced during "unmonitored" use which could lead to permanent damage of the cells with the lowest voltages. I strongly recommend that the BMS is sorted before you use the bike.

Perhaps you can give us some more details as to how you ended up in the current situation;

What was the original problem that made you decide to cut the BMS wires in the first place?

Does the replacement BMS look identical to the original one?

Was the battery charging correctly? And if so, what was the fully charged battery voltage? (36.1V seems a bit low)

It might also be useful to measure the individual voltages of each of the 12 sets of paralleled cells (triple cells) and see how similar the readings are.

I also suggest you re-check the hall sensor connections to ensure all wires are connected correctly before going further with the hall sensor diagnosis.

What controller are you using.

Does anyone have a voltage reading for the 36V 15Ah LiFoPO4 pack when fully charged?

Alan
 

[robertozm]

What happens if I use the batery without the BMS?

Hi BikeMad.  Thanks for your time.
It is not a good idea to use LiFoPO4 battery packs without the cell protection that the BMS should provide.

If the cells are not balanced during charging, there is a chance that one or more cells may become more imbalanced during "unmonitored" use which could lead to permanent damage of the cells with the lowest voltages. I strongly recommend that the BMS is sorted before you use the bike.
I had my doubts, that is why I placed this post
Perhaps you can give us some more details as to how you ended up in the current situation;
I needed the wires of the conector of the Bms be longer, so by mistake I short 2-3 wires while cutting the wires, so I had to order a new one from Golden Motor and that took a while.  I decided while the new Bms was in transit, I took a picture, and unsolder all the wires coming out of the battery and replaced them with thicker and longer ones, but when I went to have a look at the picture, the file was missing and since then I have been asking for help, without much success.
What was the original problem that made you decide to cut the BMS wires in the first place?
I needed them, to be longer
Does the replacement BMS look identical to the original one?
Yesm it is the same
Was the battery charging correctly? And if so, what was the fully charged battery voltage? (36.1V seems a bit low)Yes, the battery was working find as far as I know, but I never measured the voltage.  Since the Bms is "under suspicion" I have not recharge the batery, mayby that is why it is low now.

It might also be useful to measure the individual voltages of each of the 12 sets of paralleled cells (triple cells) and see how similar the readings are.
All of them had the same voltage 3.2 except 1 that was 2.8volt.
I also suggest you re-check the hall sensor connections to ensure all wires are connected correctly before going further with the hall sensor diagnosis.
Ok.  I will check them, but I am pretty sure these conections are ok
What controller are you using.
Magic Bac-281

Does anyone have a voltage reading for the 36V 15Ah LiFoPO4 pack when fully charged?

Alan
 

Thanks

[Bikemad]

It might also be useful to measure the individual voltages of each of the 12 sets of paralleled cells (triple cells) and see how similar the readings are.

All of them had the same voltage 3.2 except 1 that was 2.8volt.

I would disconnect the BMS and use a 12V battery charger, with a 12V 21Watt bulb in series, connected to just the low cell to slowly bring it back up to approximately the same voltage as the other cells.
However, it will need to be carefully monitored to ensure the voltage does not go too high!
It should not be allowed to exceed 3.6V during charging.

Alan
 

[robertozm]

It might also be useful to measure the individual voltages of each of the 12 sets of paralleled cells (triple cells) and see how similar the readings are.

All of them had the same voltage 3.2 except 1 that was 2.8volt.

I would disconnect the BMS and use a 12V battery charger, with a 12V 21Watt bulb in series, connected to just the low cell to slowly bring it back up to approximately the same voltage as the other cells.
However, it will need to be carefully monitored to ensure the voltage does not go too high!
It should not be allowed to exceed 3.6V during charging.

Alan

Hi Alan:
Thanks for your time.
I have measure the diferent cells as you can see in the table attached, there are 2 very low cell I don't know if they will need to be repair...
The BMS board I have it is out of order.  So I don't know if to wait until the new one arrives, or it is very urgent to get those 2 cells recharge.
Thanks

[Bikemad]

I have measure the different cells as you can see in the table attached, there are 2 very low cell I don't know if they will need to be repaired...
The BMS board I have it is out of order.  So I don't know if to wait until the new one arrives, or it is very urgent to get those 2 cells recharge.
Thanks

Roberto,

I would charge these cells as soon as possible to get the best chance of recovery.

All LiFePO4 can go down to 2.0V, but we'll get longer battery life if we keep a few 'electrons in the tank'.

The 2.16V cell will hopefully recover, but the 1.52V cell may not.

With the BMS disconnected, you can use a 12V car battery charger, with a 12V 21Watt bulb in series, connected to both the low cells to slowly bring them back up until the higest reading cell is the same voltage as the other cells. (3.25V)

Carefully monitor both cells (Individually) to ensure the voltage for each cell does not go too high!
As soon as one of the cells reaches 3.25V, disconnect the charger from this cell and reconnect to just the remaining low cell and continue until the low cell is also up to 3.25V. Note that the last cell will charge much quicker on its own, so monitor it more cafefully.

Each cell should not exceed 3.6V during charging.

When the new BMS arrives and is installed, charge the battery and monitor each cell to ensure they are charging evenly.

Good luck with the cell recovery.


Alan
 

[Helgeo]

Roberto,
Do you know anyone engaged in the RC-hobby? If you can borrow a charger for RC LIPO/LIFEPO-batteries you can safely charge individual cells.

A charger like this would be useful: http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=7898&Product_Name=Turnigy_420_Balancer/Charger_2S~4S

Helge

[robertozm]

Roberto,
Do you know anyone engaged in the RC-hobby? If you can borrow a charger for RC LIPO/LIFEPO-batteries you can safely charge individual cells.

A charger like this would be useful: http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=7898&Product_Name=Turnigy_420_Balancer/Charger_2S~4S

Helge

Hi Helge.
Unfortunatly I don't know anyone engaged in RC...
The only chargers I have is the one that cames with the battery, a Nickel Cadmium Battery charger with an output of 1.3volt and 150ma, or a few old phone mobile chargers I could rip off...

I don't know if first I have to unsolder the low cell from the battery, or if I just "plug" the charger to the sense wires of the group of cell, while still phisically together in the battery??
In GoldenMotor, they told me to recharge the battery with the bms and let the charger and Bms to work, but according to the people here in the forum, this could end up in an explosion or fire, so I don't know what to do.
Please helpppp

[Bikemad]

The only chargers I have is the one that cames with the battery, a Nickel Cadmium Battery charger with an output of 1.3volt and 150ma, or a few old phone mobile chargers I could rip off...

I don't know if first I have to unsolder the low cell from the battery, or if I just "plug" the charger to the sense wires of the group of cell, while still phisically together in the battery?

Roberto,

As the bms is suspect, leave it disconnected to avoid further problems.

An old mobile phone charger, with an output between 3.7 and 5V, should be OK for one 3Volt cell pack at a time.  It may take a long time to charge a 15Ah cell at 0.4A, but it will be better than nothing.

You will not harm the cell, so long as the voltage remains below 3.6V, but not so sure about the charger.

It is not necessary to unsolder the cells from the pack, simply connect the wires from the charger directly to the cell.
Spot solder the charger wires to the cell if you don't have any suitable clips and monitor the cell voltage, but don't forget to keep an eye on the temperature of the charger as well! If it gets too hot, switch it off and allow it to cool before you resume charging.

Good luck and keep us posted.

Alan
 

[robertozm]

The only chargers I have is the one that cames with the battery, a Nickel Cadmium Battery charger with an output of 1.3volt and 150ma, or a few old phone mobile chargers I could rip off...

I don't know if first I have to unsolder the low cell from the battery, or if I just "plug" the charger to the sense wires of the group of cell, while still phisically together in the battery?

Roberto,

As the bms is suspect, leave it disconnected to avoid further problems.

An old mobile phone charger, with an output between 3.7 and 5V, should be OK for one 3Volt cell pack at a time.  It may take a long time to charge a 15Ah cell at 0.4A, but it will be better than nothing.

You will not harm the cell, so long as the voltage remains below 3.6V, but not so sure about the charger.

It is not necessary to unsolder the cells from the pack, simply connect the wires from the charger directly to the cell.
Spot solder the charger wires to the cell if you don't have any suitable clips and monitor the cell voltage, but don't forget to keep an eye on the temperature of the charger as well! If it gets too hot, switch it off and allow it to cool before you resume charging.

Good luck and keep us posted.

Alan
 

Hi Bikemad:
Thanks for your help.
I have just finish. I have conected a Nokia charger to the group of cell that are 1.52volt ., and in order to avoid overheating, I have placed a fan near the charger and the battery.

My main concern is that the voltage reading in the multimeter is rising quite rapidly, Now I have 2.61 volt and raising every minute and a half.
I will keep watching, I hope it wiil stabilized at a given voltage. 

Thanks