Electronics > Projects, Designs, and Technical Stuff

LTC3786 3V to 18V boost converter

<< < (4/5) > >>

NiHaoMike:

--- Quote from: Hamed_ta on December 25, 2019, 02:20:57 pm ---it is designed to work with only single cell batteries to avoiding balance charging and discharging trouble.

--- End quote ---
A balancing BMS would be way cheaper than such a big boost converter.

Hamed_ta:
Does it discharge batteries balanced ? And is it efficient?

NiHaoMike:
Those BMS modules typically balance on the charge cycle and the decent ones lose little within their ratings. (It's worth noting that a good quality pack will be well matched and the balancer rarely comes into play.) To further lower losses, you can get a BMS with a higher current rating than you need and add a fuse for overcurrent protection.

Hamed_ta:
exactly the problem is that I could charge the batteries in series well balanced but for discharging under high current the unbalanced discharging problem was still there, also other reason is that in parallel, it is possible to have batteries in different capacities, right?

Siwastaja:

--- Quote from: Hamed_ta on December 26, 2019, 02:14:13 am ---exactly the problem is that I could charge the batteries in series well balanced but for discharging under high current the unbalanced discharging problem was still there, also other reason is that in parallel, it is possible to have batteries in different capacities, right?

--- End quote ---

A proper BMS takes care of all that.

The #1 task of a BMS has nothing to do with balancing, it's cell-level cutoff for both high and low voltage threshold. Meaning it controls your charger to turn off when any cell hits full, and controls all your loads to turn off when any cell hits empty.

Balancing is a bonus. Very little balancing is needed with li-ion. The prerequisite for most BMS's to be able to balance is that you do full charge cycles every once in a while. If you don't, nothing catastrophic happens, but slight imbalance may develop and reduce the pack capacity in the long run. This may be an actual issue if the user partially charges for years, for example, always running between 80% and 20%.

Note that the market is full of different products tagged "BMS", and some of them won't do shit, or are outright dangerous. Even with a proper BMS, you need to make sure you let it do its job: turn off the charger, and turn off all the loads. Some have integrated MOSFET power switches that actually disconnect the battery, and are hence easier to use, but include extra price and extra losses in these power switches.

The market is saturated with BMS ICs for 5s or 6s li-ion, so you have a lot to choose from; and a lot of appnotes to base your design on. Some have dangerous catches, but your alternative of designing a simple 1s BMS + boost converter has traps as well, so if you actually need high-power unregulated 18Vish, I would go with 5s li-ion instead of 1s + boost.

Navigation

[0] Message Index

[#] Next page

[*] Previous page

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod