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Hugues
06 May 2012, 0911
Hi guys,

i'm watching the May 4th 2012 video of Jack Rickard (evtv.me). At 37min 37 sec, they start to talk about problems they had on one of their build, they were blowing up fused and DC-DC converter. He says when he pressed hard on the accelerator, the voltage of the battery would sag. The problem was with the caps on the dc-dc converter, they would not react immediately to the sag and they ended up "driving" the motor with high amps (reverse flow).

Does that make any sense to you ? He said the solution was to insert a diode on the input of the dc-dc converter.

Any of you guys protecting your dc-dc converter this way ?

thanks, and sorry if this has been discussed before,

frodus
06 May 2012, 0929
What DC-DC do you have?

Sometimes, as is the case with Vicor, the datasheets, manual has some application notes on what you should do.

Athlon
06 May 2012, 1024
sound very strange to me , integrated caps have a very limited amount of power , nothing enough to really damage anything , also if your battery sag for example from 320 to 280V , this is only a 40V sag and also will take almost a second to occur , when you connect the DC-DC to the main you have a very higher inrush current (from 0 to 320V) so if a DC-DC survive to the first connection will never be damaged from the sag.

Hugues
06 May 2012, 1026
I've got the Sevcon converter:
http://www.sevcon.com/dcdc-converters/dcdc-converters.aspx

i checked the datasheet, does not seem to show any schematics...and the converter did not come with any manual.....

Athlon
06 May 2012, 1030
With Sevcon there are no problem , DC-DC are self protected from any issue.

NonPolluter
07 May 2012, 1048
http://www.dailymotion.com/video/xqjxst_how-to-install-diode-in-xlr-plug-world-s-first-constant-voltage-solar-ebike_lifestyle
http://www.dailymotion.com/video/xqjxl2_part-5-inline-diodes-in-vancouver-gadgeteers-world-s-first-ebike-charger-with-constant-current-pv-sy_tech




Hi guys,

i'm watching the May 4th 2012 video of Jack Rickard (evtv.me). At 37min 37 sec, they start to talk about problems they had on one of their build, they were blowing up fused and DC-DC converter. He says when he pressed hard on the accelerator, the voltage of the battery would sag. The problem was with the caps on the dc-dc converter, they would not react immediately to the sag and they ended up "driving" the motor with high amps (reverse flow).

Does that make any sense to you ? He said the solution was to insert a diode on the input of the dc-dc converter.

Any of you guys protecting your dc-dc converter this way ?

thanks, and sorry if this has been discussed before,

Hugues
08 May 2012, 0949
finally found the user manual for the Sevcon DC-DC converter:
http://www.electricmotorsport.com/store/pdf-downloads/sevcon_dcdc.pdf
funny it was not on the Sevcon website,

at the beginning of page 8 it says:
Reverse voltage protection is provided for on the input via a diode that allows current to flow in the correct direction only.

Voilą !