Prevosman, why a Vanner for a DDEC supply they don't care if they are 12V or 24V never saw a DDEC ran from a Vanner before ?
Clifford I have to ask are you sure?
I'm not challenging your vast knowledge. Just that I've been told the exact opposite.
I was told on our older DDEC's (8V92's an early 60 Series) that they are very picky about 12 V not getting below 12.1.
Now our newer buses have 24V DDEC units (or so I am told) and one of them is very finicky and if it ain't seeing 25+ volts it will crank all day and not start until I charge the batteries or put a booster box on it. Now the other will fire even if it gets down to 22 V so go figure.
Also not long ago we were experiencing HARD down shifts. (like throw ya outta the seat hard) And after the Allison dealer had it nearly 2 weeks and never found anything except low voltage codes.
Then about the same time we discovered one of the alternators was going/gone bad.
So I changed the alternator and it started shifting correctly again.
About a week later the other alternator went out. (yeah I know shoulda changed them both at the same time.)
SO when I mentioned the alternators going out to Allison they immediately said "uh huh that's exactly why you were experiencing those hard shifts!" They also told me that the ATEC'c were very very sensitive to correct voltage an if they didn't have 12.5 or 25 V for which ever unit you had they would act up.