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Discussion Starter #1
I have a new meanwell DC to dc sd-200 that seemed to work fine and now shuts down whenever I switch on or connect my headlight. I checked the headlight actually 2 of them. They operate at 3.5 amps. LED Taillights work even an 80 watt (6.6 amps) fan works fine. The converter is rated at 16.7 amps (200 watt). With Taillights disconnected headlights will work. I tested for shorts but found nothing. An 80 ohms resistance was traced back to the meanwell. It shuts down instantly with no sign of power, not even a glow out of headlight
Is there a way to test this? Is this a surge/spike issue?
Thanks in advance
This the electric dnepnr sidecar motorcycle
I added the fan and in early testing it is keeping the motor much cooler no more burning motor smell?
 

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If the headlights are tungsten, the startup current can be five to ten times higher than the nominal 3.5 A.

This is a common issue with pumps, fans, tungsten lights and other loads with a high startup current when using an inexpensive DC/DC to replace lead-acid.

One possible solution is to add a battery and use the DC/DC as a charger.
 

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Discussion Starter #3
Thank you for your reply.
I do have a small gel battery in parallel with the DC to DC. So a solution might be to put it in series: DC to DC then battery then load?
 

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The parallel setup is OK. Bigger battery = especially high discharge rated (thicker plates)?

Now a 4 or 6Ah gel I presume? Not enough.
If low temps are taken into consideration I'd say at least 20Ah high discharge.
 

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Discussion Starter #5
Thanks Tony
I set up to test that theory with a 35AH gel cell. It works.

Here is the odd part though- I disconnected just the battery and the DC-DC shut down. After letting it reset it is now working with or without Battery and now even the small battery (7.5AH) works! I am confused but happy it is working for now.
 

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It's a bit more than just a theory. Common practice for boom box lovers (i'm not one of them) to put a big cap across the battery lines.:D
 
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