Will capacitor prevent inverter from overloading on car startup? Or anything else?

**clean customs** · 01-22-2005, 03:11 PM

My inverter will overload when I start the car, its a Vector 750 watt, 1400 max. It turns the computer off and then back on when I start the car, and I want to prevent that. Will one of those large capacitors in between the battery and the inverter do the trick? That is what the capacitors are made for right?
thanks,
Kenny

**KyferEz** · 01-22-2005, 04:23 PM

You need a tank. A cap even a very large one (15farad) will only supply power for a very short period of time, and likely will not help this issue. The reason is because cranking the car is a task that will take several seconds, in which time a cap will fully discharge.

Tank:
Car+12-----|>|----TankBatt+12-----Inverter or DC-DC PSU

KyferEz

**clean customs** · 01-22-2005, 04:29 PM

Originally Posted by KyferEz

You need a tank. A cap even a very large one (15farad) will only supply power for a very short period of time, and likely will not help this issue. The reason is because cranking the car is a task that will take several seconds, in which time a cap will fully discharge.

Tank:
Car+12-----|>|----TankBatt+12-----Inverter or DC-DC PSU

KyferEz

So are you recommending an inline battery?

**KyferEz** · 01-22-2005, 09:27 PM

So I am recommending a battery isolated by a diode. See thread power issues, will an inverter regulate? where I post about doing this.

KyferEz

**clean customs** · 01-22-2005, 09:48 PM

Ok, let me make sure I understand this in my lingo. There is the car battery, and a diode in between the car battery and the tank battery. This prevents draining the tank battery by the car battery, well maybe thats not the purpose, but that is actually what would happen. The tank battery can be supplied, but no power can be pulled from the tank battery to start the car, leaving the inverter always powered by the tank batter? That makes sense to me,and sounds good. can you recommend a suitable tank battery, I only run the computer. I looked up the diode, and is that really a few dollars? Or am I looking in the right place.
thanks for all the help,
Kenny

Originally Posted by KyferEz

So I am recommending a battery isolated by a diode. See thread power issues, will an inverter regulate? where I post about doing this.

KyferEz

**KyferEz** · 01-22-2005, 10:04 PM

The Digikey part number is MBR4045CT-ND, I didn't realize there are 2 parts with similar numbers... It is 1.46 for the diode. The heat sink is 1.83. When doing it with an inverter this big, go ahead and be safe with the heatsink.

You are correct in what you say that the diode prevents the tank battery from being drained by the car battery.

I recommend a SLA (sealed lead acid) battery. A 12volt 7AHr one is good. The 12AHr would be good, but is starting to get big. We carry them at www.thecarpcstore.com.

KyferEz