Charging problem

[Boswell]

I have an 1983 lazydaze Chevy van 30 . I can't get the alternator to charge . Bought it from a private party. It has a 305
In it I ran the numbers . Anyway when we purchased it we noticed the chassis battery was dying. Not being charged by alternator. Took it to cowboys rv in lake Havasu to let them look at it and help as to what the problem was . They told us the battery was putting out 28 v . ?? Replaced the battery . Replaced the alternator . Discarded the alternator that it came with . ( Stupid ) I remember it was a bigger high performance alt. So now still not charging . Drove it to Laughlin parked in a RV park . The air pump for the smog emissions stopped working . I gutted it . Replaced it so now it just acts as a pulley . Deleted the smog stuff . ?? Purchased a new battery isolator the same model that it had a 702 . Installed it . Alternator still not exciting . So now I have went a got a altenator off a 454 thinking it's bigger higher output maybe what a RV would require . Installed it . I also grabbed the batt isolator that was on the pace arrow that the alt came from .. it's bigger than the 702 . Still has three terminals just longer . ?? Anyway the wiring on this thing is a nightmare . I'm about to lose myotorhome if I can't figure this out . It's sitting in my lady's sister's driveway and the husband wants it gone . I need help . I'm bout to try to rewire from scratch the chassis wiring . I understand the diagrams , it seems simple , I just can't figure what I'm not doing or doing wrong. I think it may need a fuse or diode somewhere in the wiring . If anybody has some common sense for me I need it like yesterday . Please help .

[twinboat]

Combine the 3 wires on the isolator to get it charging for now. It should work but remember that both batteries are going to discharge together while camping.

If that works, you'll need a battery sense wire and an alternator that uses one.

Standard alternators sense battery voltage thru the main wire. Isolators block that voltage. No sense no output.
The correct alternator will have a sense terminal that goes to the chassis battery to control charging.

[Winemaker2]

I think twinboat is right on target with your problem.
I had a similar issue on my boat when I bought it. First cruise no batty charging. I did essentially what twinboat suggested but used a batty switch to connect alt to batty cables so I could charge both underway and switch to house batty when without power and running on battys. That way I prevented running start batty down and having a problem starting. Worked fine with manual controls until I did a major upgrade.
There are much better technologies available today to replace those old diode isolators.
Note... I also had a sense wire issue that was a mfg issue but finally figured it out and I now have a reliable system.

[Mark_K5LXP]

Missing from the timeline of events are any voltage measurements made. One can replace parts based on logical assumptions but taking measurements removes all doubt. Doing so will quickly reveal a bad/missing connection, failed component or miswire.

Mark B.
Albuquerque, NM

[153stars]

Does the van use diode isolator mentioned.You could ditch diode isolator/combiner and go with a smart battery combine relay ACR. Then there's no need to have a battery sense alternator anymore ,so one you have will work. There are tough to kill but a slight chance isolator went bad and not original the alternator .Look up vid how to test diodes or you isolator with a meter. Would not want to see you buy both and still not get bidirectional charging that you would gain with smart combiner ACR.
A lot of us put Bluesea MTL-ACR in our DPs but you you need to run a few wires to dash to have switch there. Then it will work as boost too, and has a couple flashing diognostic codes. There's a couple stand alone ones as well. Basically looking at about $150 ish

[RossDinan6]

So Lazy Daze got lazy and threw parts at it if I read this correctly. They would not see 28 volts unless the OP has the one and only C30 van with a 24 volt electrical system. I haven't yet seen a 12 volt alternator drive the battery voltage that high when the regulator failed.

The air pump is not relevant, it is not an electrical part.

If you still have a problem with this, you need an individual that can troubleshoot. Do not throw parts at it until it is fixed.

Ross

[RealNiceTent]

If a delco alternator does not have battery voltage to the red wire in the 2 pin plug they will run away, I've personally seen this send output voltage over 20 Volts. the loss of battery sense can also happen internally at the voltage regulator.