Dedicated battery monitor board

Hi Vinh, welcome to the forums!

The bq78350 isn't a good fit for your application. That gauge is meant for monitoring very large battery banks and requires a lot of configuration in order to set it up correctly.

In order to thoroughly answer your questions, there are some things I'll need to know first.

You mentioned that you are using 1-2 cells. If you are using 2 cells, will they be in parallel? Series configurations require significantly more care in terms of protection and gauging. Also, will your cells have their own protection circuitry?

If you are using a single-cell (or multiple cells in parallel) configuration with the cells having protection built-in, there are plenty of easy-to-use gauges available. However, TI doesn't have a standalone gauge that only provides a simple bar graph without any advanced features. If you only care about the State of Charge percentage, the bq27621-G1 can be a good fit. It still needs configuration but only a few parameters need to be uploaded to it. A simple microcontroller setup can take care of setting up and using the gauge, as well as performing the LED bar graph display.

Hopefully I haven't overloaded you with information. The world of battery management is a pretty big and sometimes confusing place to navigate!

Regards,
Jason

Hi Jason,

Thank you for your fast reply.

My system will need 6V battery source. I think I will jus buy available battery package in retail. In this case , I believe it should be either parallel for multi cell or just one big single cell battery.

The "Stand alone" here mean: The IC can function without the need to communicate with MCU. You can program IC directly with battery management studio and then it will run it self.

In addition, I won't mind the chip have more function. Although I wont use it now, it will do no harm.

Hence, what is your function suggestion for State of Charge percentage, available percentage , warning ..etc (Capacity monitor ) ?

And don't worry , I have done all these thing from scratch. Thank to power of internet and it's magnificent Google.

I just build my own MCU, taken PIC18F8722 micro demo explorer board  as reference. And I have search everything on google before I decide to open thread here. I won't take me a lot of time to get knowledge from your answer keyword.

Best regard,
Vinh

Jason Gin said:

Hi Vinh, welcome to the forums!

The bq78350 isn't a good fit for your application. That gauge is meant for monitoring very large battery banks and requires a lot of configuration in order to set it up correctly.

In order to thoroughly answer your questions, there are some things I'll need to know first.

You mentioned that you are using 1-2 cells. If you are using 2 cells, will they be in parallel? Series configurations require significantly more care in terms of protection and gauging. Also, will your cells have their own protection circuitry?

If you are using a single-cell (or multiple cells in parallel) configuration with the cells having protection built-in, there are plenty of easy-to-use gauges available. However, TI doesn't have a standalone gauge that only provides a simple bar graph without any advanced features. If you only care about the State of Charge percentage, the bq27621-G1 can be a good fit. It still needs configuration but only a few parameters need to be uploaded to it. A simple microcontroller setup can take care of setting up and using the gauge, as well as performing the LED bar graph display.

Hopefully I haven't overloaded you with information. The world of battery management is a pretty big and sometimes confusing place to navigate!

Regards,
Jason

Hi Vinh,

Just to confirm, you will be using Lithium-Ion batteries, correct? Li-ion chemistries aren't generally available as 6 volts for single-cell configurations, and even then LiFePO4 cells would have ~6.4 volts nominal.

A fully stand-alone gauge with LED bar graphing capability would be the bq34z100-G1. It is more complex than the bq27621-G1, but it uses non-volatile Flash memory so it won't require reprogramming every time it is powered on. However, it is much more complex, and is a pack-side gauge (it should always be powered by the battery, even if the main system is not).

Jason

Hi Jason,

Yes, for now, I intend to use those battery. To be honest, we haven't order the battery yet , so it might vary to NiMH. However, my system have 3 different Voltage requirement. One is 12V directly (Can vary a bit) , 6V directly and 5V MCU system ( Have 5V voltage regulation chip , 0.1A and 1.5A).

And the inconvenient the pack-side gauge is fine. The board will be stacked on the battery itself. Hence, if battery die , the board should be unable to power on too. I might add the power on/off for it when I don't need to monitor charge status.

I don't mind to make it more complex a bit. With your guidance, I believe I can crack it easily haha :D.

Vinh

One clarification about the bq34z100-G1. It's typically used on the system-side (host-side) and not in the pack, though it could be used for either.

Hi.

So to your opinion, is it a best ? I just need simple application for my battery. Just monitor, doesn't need anything fancy.

Thank Jason. I will try to work on that IC