7circle wrote: Did you check out the 300W High Voltage Rail Series from AMTEX
Input: 525 - 975VDC Single: 12 ~ 130V options
http://www.amtex.com.au/power_pdf/power_6a.htm
eg http://www.amtex.com.au/power_pdf/HVI300R.pdf
Yes, we did. TJ pointed us to Amtex about a month ago, and suggested we be sitting down when we hear the prices. The problem with those above is that although the index page claims they start at 12 V, when you look at the data sheets you find they start at 24 V. We could have got some Amtex ones modified but they would have been around $1000 each.
We cannot use a single DC-DC now. Having gone with the 450 V Tritium Wavesculptor 200 drive and hoping to upgrade to a 900 V drive in future, and planning to use two chargers to charge the two half packs separately on occasion, we need to have a DC-DC on each half pack.
It's not the supplies we are worried about with the current sharing. It's the unbalancing of charge on the two half-packs reducing the usable capacity of the pack. Yes they will automatically share perfectly under full load, but not at half-load without very careful voltage adjustment, and some resistance whether internal or external to the supplies. We may not need external diodes. We will check, with a resistor, whether they can sink current as well as source. They were in stock at Mouser so they should be here within a week.
They do have fold-back current limiting, but only if the output voltage in current limit falls below 50% of normal output voltage. This would mean the 12 V battery was stuffed anyway.
If 30 amps is insufficient, as it probably will be, we will add two more of them. The price is right. But we thought we might as well make sure the basic idea works first.