Don't Connect impres™ Battery Chargers/XTVAs to “Switched+”!

[ASTROMODAT]

The impres™ battery has current flowing both IN and OUT during its charging cycle, so the OUT current may cause modern vehicle engine control computer systems to not allow engine start, if the RED lead is connected to a switched battery accessory point. In turn, the vehicle’s PC may detect this impress™ battery OUT current at the vehicle’s switched accessory power point junction during “engine off” conditions. Unfortunately, some vehicular PC control systems not “liking” this will subsequently not allow engine start to occur during such conditions.

The fix is to make sure to connect the RED lead of your vehicular impres™ charger, and/or XTVA, DIRECTLY to the car battery's positive lead. See SRN-1482.

This may seem a bit innocuous, but it is NOT! I know, ‘cause I recently got bit by this. My avionics tec had installed my XTVA in my new SL600 with the XTVA’s RED lead going to a switched point in the vehicle. The vehicle would not start. I thought he must have blown the MCS, or perhaps the vehicle’s micro, during the install and I was wondering what Mercedes was going to do. They towed my vehicle to their shop, and the Mercedes tec immediately started asking questions about the XTVA. He quickly disconnected it, and instantly, all was fine.

My tec called Elgin, and came back all red faced shortly thereafter, showing me SRN-1482.

Hope this helps!

larry

[Cam]

I'll had the same problem with my M3. If you still want the XTVA switched you can try the radio control (worked for me) or use a relay with the coil off the switched lead.


Edit: By radio control I mean the AM/FM CD headunit whatever you my have, this wire is in most cases red.

[Station House Products]

Excellent info Larry, and thanks for the update as well as the SRN #.

[wb4bsd]

Awesome. Now thats the kind of info i like to see on this board.

Great Info and thanks for sharing it.