The ISL78600 battery management system provides the high accuracy needed across the full battery operating temperature range for precise, state-of-charge measurements to extend vehicle driving range and the life of high performance Li-Ion batteries. To accomplish this, each ISL78600 device utilizes a 14-bit temperature compensated data converter that scans 12 channels in less than 250 microseconds.
To achieve the highest possible reliability for intra-system communication, the ISL78600 utilizes a high noise immunity and transient tolerant communication scheme. This fully differential daisy-chain architecture allows the use of low cost twisted pair wiring to stack multiple battery packs together while protecting against hot plugging and high voltage transients. Additionally, The ISL78600 allows for easy connection to microcontrollers via either a 4MHz (or 2.5MHz with Filter enabled) SPI or 400KHz I2C interface.
6 to 12 cell voltage management
Supports full range of Li-Ion cell chemistries
Cell voltage measurement accuracy ±2mV
VBAT measurement accuracy ±72mV
Cell voltage scan rate of 20μs per cell
Proprietary Daisy chain communications system
Robust EMI performance
Excellent system transient resistance
4MHz SPI interface
Integrated system diagnostic functions:
Cell over and under-voltage
Open cell monitoring wires
Open temperature monitoring wires
VBAT and VSS connection integrity
Voltage reference function
64 lead TQFP package
amberwolf wrote:Why not just use that existing open-source charger for a starting point? Since we don't need as high a charging current, and probably not as high a chargng voltage, the actual power-conversion stage(s) don't need such large components, but the software itself should be easily adaptable, from either Valerun's version,
http://www.diyelectriccar.com/forums/sh ... 59210.html
the older one that Jack Bauer is building, (with one codedump attached here, for instance:
http://www.diyelectriccar.com/forums/sh ... tcount=272 ) (more data buried in his build thread:
http://www.diyelectriccar.com/forums/sh ... hp?t=35098 )
or from Simon Rafferty's original designs.
http://www.diyelectriccar.com/forums/sh ... 36627.html
Ricky_nz wrote:A good 2 - 5KW charger would be great for fast charging a reasonable nanotech pack.
I would like anything that could take up to 230V @20A single phase input because bigger is better...
Realistically up to 2-3KW would probably be a good goal for ebike use as a fast charger although a really small <500W ultra compact one would be handy as an onboard charger.
Those car chargers seem to be non isolated, for an ebike pack where it is harder to protect wiring than a car.
I would think an isolated design would be much safer.
Could also be pretty spectacular on 240VAC if the switching device were to fail short into a <100V lipo pack
I've thought of doing something about a high power charger but I'm too busy with my other projects so i'll just watch this thread with interest for now.
heathyoung wrote:Unisolated make it cheap, isolated forward converters that are wide range adjustable require specialised magnetics and design know-how.
Its very easy to blow the crap out of your devices when designing forward converters, they are a nightmare.
For a less crap design - look here: http://www.neon-john.net/Induction/Roy/ ... verter.htm
It uses a proper IGBT driver, that also takes care of output current limiting, easy to get components, and is nicely adjustable.
There are a few things that are bad about this design - the input caps are under spec, for this sort of current you need a good, low ESR cap with a high ripple current. (ie. 7.5A @ 600uF - not cheap - you need to series/parallel 4 to get here) I'd also be putting a decent cap on the output for ripple suppression and overshoot.
The inductor also needs to be specified - the design fails to mention the size, but my calcs put it at 170uH for Vin of 300V and Vout of 150V. His other design uses a 300uH from memory, but this is far from optimal.
Its a good start though, I'm drawing up a PCB to support this design, with multi-voltage compatibility (ie. 120/240VAC), with current limiting.
Alan B wrote:Looks like a decent start!
pelle242 wrote:Would probably use a arduino and LCD shield to prototype this:
http://www.ebay.com/itm/High-Quality-Ar ... 2a15872a1a
http://www.ebay.com/itm/LCD-Keypad-Shie ... 5647353467
Less than $40 total, not the end of the world to toast a few during development.
So basically building a buck converter shield...
Alan B wrote:I haven't taken any PC power supplies apart yet. So they have voltage doublers? Interesting. Do PC power supplies use IGBTs? I would think whatever they used is probably what we need to use. Perhaps even re-use what's there? Heatsink, check.
500 khz is not hard for an FET. Requires a good driver though, and good diodes. Might not want to go that high.
Since we want to have a programmable user interface with cell type, voltage per cell, number of cells, max current, shutoff percentage, time limit we need a micro. If we have a micro what's the SMPS chip needed for? Seems like extra parts.
For equipment protection I'm thinking an SCR crowbar across the input fuse. Output voltage ever spikes up too far, blow that fuse. Set the watchdog timer on the micro to shut everything down if it gets stuck, and use a real PWM output so it can't get 'stuck' on. I suspect the RC chargers work this way and they manage it up to a kilowatt.
Winding the inductor is not a big deal.
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