How to design a circuit that protect 7 lithium-ions in series

[Qizhang Du]

There are many ICs that protect Li+ battery string(<=4 cells in series).

Now I have a project that I have to design a circuit that protect 7 Li+
in series. There is no IC which is designed for string larger than 4 cells.

The way I choose to design the circuit is to use 7 single cell protection ICs
in series, one chip protecting one chip. But the problem I met is the
circuit can not provide overcharge protection when the battery voltage go up
very fast.

Is the way I choose wrong? Anyone could give me some advice?

Thanks in advance.

 

[James Meyer]

There are many ICs that protect Li+ battery string(<=4 cells in series).

Now I have a project that I have to design a circuit that protect 7 Li+
in series. There is no IC which is designed for string larger than 4 cells.

The way I choose to design the circuit is to use 7 single cell protection ICs
in series, one chip protecting one chip. But the problem I met is the
circuit can not provide overcharge protection when the battery voltage go up
very fast.

Is the way I choose wrong? Anyone could give me some advice?

Thanks in advance.

Use only four cells in series and follow that with a DC to DC switching
converter to get the 28-30 volts you need.

Jim

 

[Qizhang Du]

Thank you. But 4 cell pack will give twice the current than using 7 cell pack.
Also,the best converter's efficiency is 90%,the other problem is I have to
handle is the heat if I go in this way.

BTW,my 7 cell pack have to output 6-10A.

Qizhang

 

[Ban]

There are many ICs that protect Li+ battery string(<=4 cells in
series).

Now I have a project that I have to design a circuit that protect 7
Li+
in series. There is no IC which is designed for string larger than 4
cells.

The way I choose to design the circuit is to use 7 single cell
protection ICs in series, one chip protecting one chip. But the
problem I met is the circuit can not provide overcharge protection
when the battery voltage go up very fast.

Is the way I choose wrong? Anyone could give me some advice?

Thanks in advance.

I think your approach with single controllers sounds good. I am also sure it
will be possible to incorporate an overvoltage protection, maybe with some
additional parts or with different charge controllers. Did you ask the
application engineer of the controller manufacturer to assist you?

 

[Ban]

There are many ICs that protect Li+ battery string(<=4 cells in
series).

Now I have a project that I have to design a circuit that protect 7
Li+
in series. There is no IC which is designed for string larger than 4
cells.

The way I choose to design the circuit is to use 7 single cell
protection ICs in series, one chip protecting one chip. But the
problem I met is the circuit can not provide overcharge protection
when the battery voltage go up very fast.

Is the way I choose wrong? Anyone could give me some advice?

Thanks in advance.

I think your approach with single controllers sounds good. I am also sure it
will be possible to incorporate an overvoltage protection, maybe with some
additional parts or with different charge controllers. Did you ask the
application engineer of the controller manufacturer to assist you?

 

[Ban]

There are many ICs that protect Li+ battery string(<=4 cells in
series).

Now I have a project that I have to design a circuit that protect 7
Li+
in series. There is no IC which is designed for string larger than 4
cells.

The way I choose to design the circuit is to use 7 single cell
protection ICs in series, one chip protecting one chip. But the
problem I met is the circuit can not provide overcharge protection
when the battery voltage go up very fast.

Is the way I choose wrong? Anyone could give me some advice?

Thanks in advance.

I think your approach with single controllers sounds good. I am also sure it
will be possible to incorporate an overvoltage protection, maybe with some
additional parts or with different charge controllers. Did you ask the
application engineer of the controller manufacturer to assist you?

 

[James Meyer]

Thank you. But 4 cell pack will give twice the current than using 7 cell pack.

You were going to use 7 cells anyway. Two four-cell packs in parallel
could handle the current.

Also,the best converter's efficiency is 90%,the other problem is I have to
handle is the heat if I go in this way.

BTW,my 7 cell pack have to output 6-10A.

Qizhang

OK. One other solution is to use MOSFET switches to allow two four-cell
packs to be discharged in series and then putting them in parallel for charging.
MOSFET switches are almost 100% efficient. This solution means that the battery
system cannot be used for running your project while it is charging. That may
or may not be a problem.

Both my suggestions have been used successfully in some robotic
applications where I work.

Jim

 

[Ban]

There are many ICs that protect Li+ battery string(<=4 cells in
series).

Now I have a project that I have to design a circuit that protect 7
Li+
in series. There is no IC which is designed for string larger than 4
cells.

The way I choose to design the circuit is to use 7 single cell
protection ICs in series, one chip protecting one chip. But the
problem I met is the circuit can not provide overcharge protection
when the battery voltage go up very fast.

Is the way I choose wrong? Anyone could give me some advice?

Thanks in advance.

I think your approach with single controllers sounds good. I am also sure it
will be possible to incorporate an overvoltage protection, maybe with some
additional parts or with different charge controllers. Did you ask the
application engineer of the controller manufacturer to assist you?

 

[Ban]

There are many ICs that protect Li+ battery string(<=4 cells in
series).

Now I have a project that I have to design a circuit that protect 7
Li+
in series. There is no IC which is designed for string larger than 4
cells.

The way I choose to design the circuit is to use 7 single cell
protection ICs in series, one chip protecting one chip. But the
problem I met is the circuit can not provide overcharge protection
when the battery voltage go up very fast.

Is the way I choose wrong? Anyone could give me some advice?

Thanks in advance.

I think your approach with single controllers sounds good. I am also sure it
will be possible to incorporate an overvoltage protection, maybe with some
additional parts or with different charge controllers. Did you ask the
application engineer of the controller manufacturer to assist you?

 

[Ban]

There are many ICs that protect Li+ battery string(<=4 cells in
series).

Now I have a project that I have to design a circuit that protect 7
Li+
in series. There is no IC which is designed for string larger than 4
cells.

The way I choose to design the circuit is to use 7 single cell
protection ICs in series, one chip protecting one chip. But the
problem I met is the circuit can not provide overcharge protection
when the battery voltage go up very fast.

Is the way I choose wrong? Anyone could give me some advice?

Thanks in advance.

I think your approach with single controllers sounds good. I am also sure it
will be possible to incorporate an overvoltage protection, maybe with some
additional parts or with different charge controllers. Did you ask the
application engineer of the controller manufacturer to assist you?

 

[Ban]

There are many ICs that protect Li+ battery string(<=4 cells in
series).

Now I have a project that I have to design a circuit that protect 7
Li+
in series. There is no IC which is designed for string larger than 4
cells.

The way I choose to design the circuit is to use 7 single cell
protection ICs in series, one chip protecting one chip. But the
problem I met is the circuit can not provide overcharge protection
when the battery voltage go up very fast.

Is the way I choose wrong? Anyone could give me some advice?

Thanks in advance.

I think your approach with single controllers sounds good. I am also sure it
will be possible to incorporate an overvoltage protection, maybe with some
additional parts or with different charge controllers. Did you ask the
application engineer of the controller manufacturer to assist you?

 

[Ban]

There are many ICs that protect Li+ battery string(<=4 cells in
series).

Now I have a project that I have to design a circuit that protect 7
Li+
in series. There is no IC which is designed for string larger than 4
cells.

The way I choose to design the circuit is to use 7 single cell
protection ICs in series, one chip protecting one chip. But the
problem I met is the circuit can not provide overcharge protection
when the battery voltage go up very fast.

Is the way I choose wrong? Anyone could give me some advice?

Thanks in advance.

I think your approach with single controllers sounds good. I am also sure it
will be possible to incorporate an overvoltage protection, maybe with some
additional parts or with different charge controllers. Did you ask the
application engineer of the controller manufacturer to assist you?

 

[Ban]

There are many ICs that protect Li+ battery string(<=4 cells in
series).

Now I have a project that I have to design a circuit that protect 7
Li+
in series. There is no IC which is designed for string larger than 4
cells.

The way I choose to design the circuit is to use 7 single cell
protection ICs in series, one chip protecting one chip. But the
problem I met is the circuit can not provide overcharge protection
when the battery voltage go up very fast.

Is the way I choose wrong? Anyone could give me some advice?

Thanks in advance.

I think your approach with single controllers sounds good. I am also sure it
will be possible to incorporate an overvoltage protection, maybe with some
additional parts or with different charge controllers. Did you ask the
application engineer of the controller manufacturer to assist you?

 

[Ban]

There are many ICs that protect Li+ battery string(<=4 cells in
series).

Now I have a project that I have to design a circuit that protect 7
Li+
in series. There is no IC which is designed for string larger than 4
cells.

The way I choose to design the circuit is to use 7 single cell
protection ICs in series, one chip protecting one chip. But the
problem I met is the circuit can not provide overcharge protection
when the battery voltage go up very fast.

Is the way I choose wrong? Anyone could give me some advice?

Thanks in advance.

I think your approach with single controllers sounds good. I am also sure it
will be possible to incorporate an overvoltage protection, maybe with some
additional parts or with different charge controllers. Did you ask the
application engineer of the controller manufacturer to assist you?

 

[Ban]

There are many ICs that protect Li+ battery string(<=4 cells in
series).

Now I have a project that I have to design a circuit that protect 7
Li+
in series. There is no IC which is designed for string larger than 4
cells.

The way I choose to design the circuit is to use 7 single cell
protection ICs in series, one chip protecting one chip. But the
problem I met is the circuit can not provide overcharge protection
when the battery voltage go up very fast.

Is the way I choose wrong? Anyone could give me some advice?

Thanks in advance.

I think your approach with single controllers sounds good. I am also sure it
will be possible to incorporate an overvoltage protection, maybe with some
additional parts or with different charge controllers. Did you ask the
application engineer of the controller manufacturer to assist you?

 

[Ban]

There are many ICs that protect Li+ battery string(<=4 cells in
series).

Now I have a project that I have to design a circuit that protect 7
Li+
in series. There is no IC which is designed for string larger than 4
cells.

The way I choose to design the circuit is to use 7 single cell
protection ICs in series, one chip protecting one chip. But the
problem I met is the circuit can not provide overcharge protection
when the battery voltage go up very fast.

Is the way I choose wrong? Anyone could give me some advice?

Thanks in advance.

I think your approach with single controllers sounds good. I am also sure it
will be possible to incorporate an overvoltage protection, maybe with some
additional parts or with different charge controllers. Did you ask the
application engineer of the controller manufacturer to assist you?

 

[Ban]

There are many ICs that protect Li+ battery string(<=4 cells in
series).

Now I have a project that I have to design a circuit that protect 7
Li+
in series. There is no IC which is designed for string larger than 4
cells.

The way I choose to design the circuit is to use 7 single cell
protection ICs in series, one chip protecting one chip. But the
problem I met is the circuit can not provide overcharge protection
when the battery voltage go up very fast.

Is the way I choose wrong? Anyone could give me some advice?

Thanks in advance.

I think your approach with single controllers sounds good. I am also sure it
will be possible to incorporate an overvoltage protection, maybe with some
additional parts or with different charge controllers. Did you ask the
application engineer of the controller manufacturer to assist you?

 

[Ban]

Sorry for these multiple posts, OE got a hickup and kept that post in the
outbox and whenever I changed reading the NG it synched and sent a copy, but
never cleared the outbox. Seems to have to do with my newsserver. Now lets
see if everything is ok

 

[James Meyer]

Sorry for these multiple posts, OE got a hickup and kept that post in the
outbox and whenever I changed reading the NG it synched and sent a copy, but
never cleared the outbox. Seems to have to do with my newsserver. Now lets
see if everything is ok

Well (so far) I've only seen this one once.

Jim

 

[Rich Grise]

Thank you. But 4 cell pack will give twice the current than using 7 cell pack.

This is not accurate. 4 cells in series give exactly the same current as
7 cells in series provide.

Perhaps you mean that, because the terminal voltage of a 4-cell pack is
4/7 the terminal voltage of a 7-cell pack, that the current _demand_ by
the load will be 7/4 times (plus inefficiency) what it was at the
higher voltage? This is true, for the same power delivered.

Also,the best converter's efficiency is 90%,the other problem is I have
to handle is the heat if I go in this way.

BTW,my 7 cell pack have to output 6-10A.

Eek! OK, I would be speaking out of turn if I tried to make any
suggestions as to designing a switcher that could substitute 4
cells for 7. Six to Ten _Amps_?? You're obviously not talking
about 2200mAh 'A' NiMHs. =:-!

Sorry.
Rich