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Topic: Wiring diagrams (Read 700 times) previous topic - next topic

Re: Wiring diagrams

Reply #20 –
To test diode-based isolator with three lugs:

Center lug is from Alternator B+ and with engine off, 0 VDC.  With engine running (and around 1,100 RPM) in the high 14's.

One outer lug to chassis battery and will read chassis battery voltage with engine off.  With engine on it should read in the lower 14's.

Other outer lug to house  bank and will read house bank voltage with engine off.  With engine on, it should read in the low 14's.

Yes, if batteries are deeply discharged and alternator output is insufficient to achieve target voltage, that is also OK-- just need to recheck when batteries charge rate is within the alternator's capability.

Let us know what you find.

Re: Wiring diagrams

Reply #21 –
Bats are fully chgd.

Need to test diodes

Re: Wiring diagrams

Reply #22 –
Quote from: TerryW –
Bats are fully chgd.

Need to test diodes

Then, my test immediately above should tell you what is going on.

Also a good idea to check the other/small wires/terminals on the alternator.  The sense wire is small-gauge and have seen some not connected, some wires broken.

Re: Wiring diagrams

Reply #23 –
Thank you very much for helping me with this issue!

Internal reg.  No sensing wire.

Alt will chg if there is 12v available at output post.  There isn't preaumably because of the diode.

Re: Wiring diagrams

Reply #24 –
Very likely you have an incorrect alternator for a system with diode-based battery isolator. OE, and with a diode-based isolator, you need a DUVAC alternator.

There is about a .7 VDC drop across the diodes (turned into heat, which is why the aluminum fins to get rid of the heat).

If the alternator is putting out, say 13.5 VDC, the "far side" of the diodes and hence both batteries will only be charged at 13.5 minus .7= 12.7 VDC.

If not a DUVAC, you can either change the diode-based isolator or get the correct alternator.

Short term, you can move all the terminals in the diode-based isolator to one lug to get you where you are going.