Diode Selection

[Anonymous]

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[fechter]

If you're keeping the BMS in the circuit, then the diodes across each pack would be a good idea.
You could use the same diodes for that.
Yes, it does make sense to use diodes across each pack as well as to isolate the parallel strings.

 

[olaf-lampe]

I'm not sure about your application but 25A might be a little to low. And you also should use a heatsink or find a decent place on the frame for the diodes.
-Olaf

 

[Anonymous]

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[fechter]

Diodes used across the BMS for protecting series connections will normally not be doing anything and should not need a heatsink. Parallel combining diodes will take the full current all the time and will need a heatsink. You can use multiple diodes in parallel for increasing the current rating, but they should be mounted on the same heatsink so they run at the same temperature.

 

[Tom_D]

They are 50A but 25A for each input, the diodes have two input one output, nicely setup for parallel connection. The application is for 3s2p of 18.5V (5 cell LiMn) packs each with BMS in circuit. My maximum amp draw appears to be 32A, and this would draw from two banks, so it seems sufficient. I have 30A fuse and 30A limit set on cycle analyst. I couldn't find any higher rated shottkys at digikey, what is everyone else using, and where do you get them?

Here is a higher rated schottky I used (from Digikey) Rated 120V, 60A (30A each leg):
http://search.digikey.com/scripts/DkSea ... %2F45GI-ND cost $3.14
with specs:
http://www.vishay.com/docs/88976/v60120c.pdf:

Also see schottky diode discussion with construction pics at:
http://www.endless-sphere.com/forums/viewtopic.php?f=14&t=4226&st=0&sk=t&sd=a&start=30

Now riding this around everyday, combining 48v sla pack with 48v LiFePo4 pack in parallel, works great!

--Tom_D