Gary Lewis Posted August 19, 2022 Share Posted August 19, 2022 For some reason Big Blue's battery was down a bit this morning. Like even the dome light didn't come on when I opened the door. But when I put the charger on it the headlights came on. So after 30 minutes of charging with my 30A charger I tried to start it and had to hit the parallel button to bring the aux battery into play. And with that it started fine. But on the 12 minute drive to load up some more of the lady's Ford parts (more of which later) the voltage didn't come up to 12.8 even when keeping the R's up around 2K the whole way and not running any accessories. And when I tried to start it 2 hours later to come home I had to hit parallel again. After the parallel timed out the voltage only got to 12.9 at best on the way home - still w/o any accessories. So my question to y'all is whether it is reasonable to expect that a 130A 3G should pull an 1150 CCA battery up faster than I'm seeing? It was down around 3v, so it was seriously discharged. And I have it on the charger again to see if it is going to come back up. But it just seems like the alternator isn't doing what I expected. Link to comment Share on other sites More sharing options...
Gsmblue Posted August 19, 2022 Share Posted August 19, 2022 Certainly sounds like the alternator has failed. At least it is a 3G and is easy to source. Link to comment Share on other sites More sharing options...
Gary Lewis Posted August 19, 2022 Author Share Posted August 19, 2022 Certainly sounds like the alternator has failed. At least it is a 3G and is easy to source. It hasn't completely failed as the battery voltage has now made it up to 13.5V after four trips and a one-hour charging stint. But it sure doesn't bring the voltage up as fast as I expected it to do. I'm thinking of replacing the one I have with the DB Electrical HO-7748-220Â Link to comment Share on other sites More sharing options...
mat in tn Posted August 20, 2022 Share Posted August 20, 2022 It hasn't completely failed as the battery voltage has now made it up to 13.5V after four trips and a one-hour charging stint. But it sure doesn't bring the voltage up as fast as I expected it to do. I'm thinking of replacing the one I have with the DB Electrical HO-7748-220 what caused the battery to be so low to begin with? on my last full build I had a 3g that was actually draining the battery by way of an internal short/ground. a real pain to figure out, probably because I trusted the new alternator which turned out to be bad. the odd part was that the way I found it was because as I was studying the wiring and scratching my head after checking every possible connection. I could hear a very faint yet high pitch "sing" coming from the alt. and it went away as soon as I disconnected the battery. the next alt did not sing, nor did it lose any measurable voltage even well over a month. Link to comment Share on other sites More sharing options...
Gary Lewis Posted August 20, 2022 Author Share Posted August 20, 2022 what caused the battery to be so low to begin with? on my last full build I had a 3g that was actually draining the battery by way of an internal short/ground. a real pain to figure out, probably because I trusted the new alternator which turned out to be bad. the odd part was that the way I found it was because as I was studying the wiring and scratching my head after checking every possible connection. I could hear a very faint yet high pitch "sing" coming from the alt. and it went away as soon as I disconnected the battery. the next alt did not sing, nor did it lose any measurable voltage even well over a month. Some idiot left the lights on. High beam and fog lights, no less. Link to comment Share on other sites More sharing options...
85lebaront2 Posted August 20, 2022 Share Posted August 20, 2022 Some idiot left the lights on. High beam and fog lights, no less. Sounds like that idiot needs a dinger or buzzer to remind he or she that the lights are on when the door is opened. Link to comment Share on other sites More sharing options...
Gary Lewis Posted August 20, 2022 Author Share Posted August 20, 2022 Sounds like that idiot needs a dinger or buzzer to remind he or she that the lights are on when the door is opened. Apparently said idiot is oblivious to dingers as there is one on the truck. 😩 Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted August 20, 2022 Share Posted August 20, 2022 Apparently said idiot is oblivious to dingers as there is one on the truck. 😩 Gary, Do you have an amp clamp you can put on the alternator output? I've never had one of those fancy batteries but if a lead acid battery gets too low it is going to take some time to bring it back (if it comes back 100% at all) The problem with deep discharge is sulfation. It won't all come off the cathodes at once. 30A is a trickle compared to alternator output. Remember 4 12 minute round trips is an hour and a half total with eight starts! (Yes, I know you had to use the aux) Link to comment Share on other sites More sharing options...
Gary Lewis Posted August 20, 2022 Author Share Posted August 20, 2022 Gary, Do you have an amp clamp you can put on the alternator output? I've never had one of those fancy batteries but if a lead acid battery gets too low it is going to take some time to bring it back (if it comes back 100% at all) The problem with deep discharge is sulfation. It won't all come off the cathodes at once. 30A is a trickle compared to alternator output. Remember 4 12 minute round trips is an hour and a half total with eight starts! (Yes, I know you had to use the aux) The voltage is running at about 13.5, but is coming up slowly. Very slowly while driving, with all accessories off. But I put the battery charger on it yesterday afternoon, so it should be up this morning when I drive it. (Making more runs to get parts out of the lady's shop before it sells, and today Steve/FoxFord33 and I are taking the trailer and getting an FE and an M-Block to sell.) So maybe it is just taking a lot longer to come up than I expected. I already have the green light from Janey to go with a new alternator, but haven't pulled the trigger yet as I want to see that the battery isn't bad and is the cause of the slow come back. If it is back up today then I think I'll buy the new, big alternator. Link to comment Share on other sites More sharing options...
Gary Lewis Posted August 20, 2022 Author Share Posted August 20, 2022 Gary, Do you have an amp clamp you can put on the alternator output? I've never had one of those fancy batteries but if a lead acid battery gets too low it is going to take some time to bring it back (if it comes back 100% at all) The problem with deep discharge is sulfation. It won't all come off the cathodes at once. 30A is a trickle compared to alternator output. Remember 4 12 minute round trips is an hour and a half total with eight starts! (Yes, I know you had to use the aux) Oops, I forgot about the clamp-on ammeter question. Jein. I have one but it doesn't work. So I'm assuming that the alternator is throwing the 115A that my nephew measured back in July. But I would have thought that those 12 minute trips would have brought it up faster since I kept the R's up to ~2000 by staying in a lower gear than normal. And, I didn't run any accessories at all. Link to comment Share on other sites More sharing options...
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