Product selection. 12 volt lipo charger.

Quick response. Yes 3s configuration. I thought I seen some data sheets were the battery can be disconnected from the power circuit for charging through the I2c commands??? The charging circuit will be independent from the robots power supply buss. My thought is that each battery pack will have its own charging system. Because this is a humanoid style robot I need to stash battery packs were there is room and the best location for weight distrubution. While I haven't set in stone the size of the packs yet we can assume for now that a common 2600 Ma pack. And there will be multiple batt packs all connected to a common charging buss and a common power buss. Are there chips that allow adjustable charge current settings ? I'm really intrested in feedback from the battery charger. Some data sheets show voltage feedback, connection temp , is it charging. Again I know what I want but mabe explaining it technically is confusing. Thanks again John.

John,

So in effect, you would like to have multiple packs charged through one charger? This is doable as long as they are the same pack, and the I*R drop of the cabling between them is not too large. If you will have a lot of cable, you may need to have multiple chargers (one for each pack, or a group of nearby packs). The reason I say this is that the I*R drop of the cable may cause the charger to go into CV to early, and your packs will not be evenly charged. Doing this would technically be possible, but you will likely run into some issues.

If you are set on having I2C, you may want to look into the bq24773. but if you have the option to move to smbus then you have more options, like the bq24725A. Most of our host controlled chargers communicate with SMBUS, and i think the bq24773 is our only i2c part currently.

If we are on the same page, then the ability to disconnect your battery from the system rail is called a "Power Path" topology. A power path topology will choose to power the system from your adapter if available, that way charge current is not stolen from your battery. The charger will connect battery to the system when needed.

The alternative to this is an "NVDC" topology, where the battery AND the system are both powered off of the DC-DC converter (almost all battery charger IC's are a DC-DC converter at their core, usually a buck converter). These are some terms that you will want to look into if you are learning about chargers.

i said that first sentence wrong. any charger/ battery can access the charging buss at any time. The main controller will decide whenandnow many

Hi John,


Sounds like a pretty interesting project!

I am not overly comfortable with microcontrollers, so I can't speak to the arduino's ability to write with both SMBUS/I2C with the same library. I do know that they are pretty similiar communication protocols, though, so it is definitely possible.

If you cannot get the library to work and have to work with I2C, then I would suggest the bq24773... You can make it "power path" by placing a schottky diode between battery and system. You can refer to the bq24650 EVM schematic( www.ti.com/.../sluu444a.pdf ) for a better picture of what I mean. The only problem is that you lose a little efficiency (shottky diode drop instead of FET turned on).

If you would like the full datasheet for the bq24773, send me an email at d-wiest@ti.com and I will forward it to you - the full datasheet is not published to avoid "copy-cat" parts that are lesser quality.

Sent u an email starts with onecaveman so check your junk box if you don't see it in your inbox. Also project is slowed down due to work ot and holidays

John,

No problem, I received your email and sent you the datasheet.