2000 Savana 2500 5.7L 3/4 ton clicks, won't start

[rpdm]

Van has needed 'jumped' in mornings for a few days, then wouldn't last all day. Has only been reading at 9 on the gauge recently, but battery is 12.5. Clicks, but won't start. Replaced starter. When applied extra voltage, 40 amps, using battery charger it will almost turn over, but won't quite, loses power. Have had 17 volts coming out of it to try to start and barely turns over, but won't start.

 

[cubicinches]

Clean the battery terminals of any corrosion. The alternator might be bad. Check the battery for amps, not volts. If there are next to no amps the battery is bad as it's not holding a proper charge. Or, the alternator needs to be replaced. Most HD batteries are in the 700amp hour range, and if you can't get more than 50 amps or more out of the battery, you won't have enough power to turn the starter over as the starter motor will drain power fast

As you had mentioned upwards of 17 volts, it sounds like the relay(?) or whatever that piece on the alternator is called to keep voltage in check is shot...so the alternator itself might be OK. On the alternator there should be a small piece covered with a plastic or metal panel. Anyway, I'm not too well versed in the matters but get it checked out!