dei 520 battery backup

2001 chevy silverado, viper 5901 and remote start currently installing...

Hello.  i have the 520t brain backup and the install instructions tell you to ground the module, hook up to 12v constant positve fused and then it tells you to connect the GREY positive output to the brain only.

A friend of mine is an installer and he told me it's fine to hook up the 520t's red + constant AND the GREY wire together to 12v constant vs just the grey wire to the brain.  also, the 520t says not to use parking lights via the viper 5901 to run the truck's parking lights as the battery backup doesn't have enough juice. 

i'm torn whether or not to install this now.  i have a batter backup siren, so i know i don't REALLY need the 520t, but i like to cover all my bases.  Should i leave it out of the equation as i intend to use parking lights for remote start.  Or can i hook it up the way my install buddy says?  i'm afraid to make a mistake.

please help me all.  THANK YOU MUCH!!!

Bill

I would leave out the equation and hook it up to DEI specs. Just make sure the grey wire powers the alarm brain and siren only..and is not connected to power other devices or relays.  If your parking lights draw to many amps (juice), you will want to switch program jumper to a neg setting and use a relay. I will be honest though, I am not impressed with the 520Ts. I have had a few in the past year and they don't hold a charge very long and the current that charges the battery is not regulated via the diode box..thus prematurely wearing down these batteries.  I have decided to scrap the 520t and bought a UB1250 universal backup recharg battery for my alarm system. While it is somewhat bigger and might be harder to conceal, these last up to 3 years and can supply more amps...thus if you want your park lights to flash or even a second siren, this should get the job done. I bought a 12v 4ah battery. The reason for this is my alarm system draws just under 4amps during full activation, light flash and 2 sirens. So the way I look at it is it will supply 4amps for an hour  if a thief cuts my power supply.  I use the same diode box but added a resistor to limit the charging current into the backup battery. I cut the plug off the original backup battery and connected it to the new larger backup batt, and plugged it into the original harness that leads to the diode box.  I know this is a little of the subject, but just thought I would share my thoughts.

ACTUALLY, it's a PERFECT response.  unluss i do the mod  you mention, i'll leave it out altogether.  i was thinking along the same lines of the shortened life of the battery.  and i'm also in the AZ desert heat, so it'll only die that much quicker.

thank you.

eh, can't edit yet...

how does the 520t work anyway?  should seem straight-forward, but things hardly ever are.  does the 520t module ONLY use its battery power when the vehicle's battery is disconnected and otherwise it's using the vehicle's battery?  if so, then it will run all the parking lights and what not without an issue as it takes its own battery out of the equation.

i ask this because the manual says not to use parking lights with the 520t hooked up.  OR, is it referring to never using the power features while only being powered by the 520t's battery?  i don't know why this thing is so tough for me to figure out???

The resistor used here is a 1/2 watt carbon composition resistor..1100ohms. Carbon or metal composition will work and can range between 1000 and 1500 ohms.  This resistor will limit charging current to between 14.5 and 14.9 volts to the UB1250 backup battery and at no more than 1.7ah. The average discharge current under normal conditions will be between 13.6 and 13.8 volts. These figures and other stats relating to discharge characteristics and  duration of discharge vs duration of current related to temperature can be found at www.upg.com  and search model #UB1250.  Looking at the picture I took of the circuitry.. I snipped the diode off CR2 and attached it to backup battery+ pin C2.  This serves as the blocking diode for the current from the 12v battery of the car. The resistor which is soldered in parellel with the diode, allows a controlled current to charge the backup battery.  So this is my little project and I hope to get the install done this week. I more or less posted to benefit anyone curious that enjoys electronics as much as I do.  This project just gets down to the more technical aspects of my needs and alarm system which draws a little more amps than the average system. But at the same time trouble shoots the problem I have been having with the 520t. This is in no means to disrespect DEI products or those who use the 520t.