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

On 2 Jun 2005 23:59:19 -0700, kongchi snipped-for-privacy@21cn.com (Qizhang Du) wroth:

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

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

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?

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ciao Ban
Bordighera, Italy

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?

--
ciao Ban
Bordighera, Italy

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?

--
ciao Ban
Bordighera, Italy

On 3 Jun 2005 23:23:15 -0700, kongchi snipped-for-privacy@21cn.com (Qizhang Du) wroth:

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

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

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?

--
ciao Ban
Bordighera, Italy

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?

--
ciao Ban
Bordighera, Italy

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?

--
ciao Ban
Bordighera, Italy

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?

--
ciao Ban
Bordighera, Italy

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?

--
ciao Ban
Bordighera, Italy

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?

--
ciao Ban
Bordighera, Italy

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?

--
ciao Ban
Bordighera, Italy

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?

--
ciao Ban
Bordighera, Italy

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?

--
ciao Ban
Bordighera, Italy

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.

have

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

OK so far from here - hitting "next" and watching headers change was interesting to the extent that watching the timestamp of the message ID increment (and noting the delta minutes) was fun, but I already knew you wouldn't do anything so lame on purpose. ;-D

Cheers! Rich

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?

--
ciao Ban
Bordighera, Italy

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

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ciao Ban
Bordighera, Italy