Community Forums

dca81 · 07-19-2019, 03:10 PM

Alternator light is red. After a while it stayed on often for 10-15 minutes then would go off. Initially I had a load on it to run the chassis AC on high (ambient temp just below 100). When I saw the check engine light come on I figured it was a warning that the batteries were getting to low and turned off all the 12v load and started the generator. The generator was running so why I saw the house batteries slowly deplete???? I was not holding the boost switch down, but it appears the batteries were connected. Also, as soon as the alternator kicked back in you could see the vehicle and house batteries immediately increase in voltage. Thanks for the input.
Bob

wackymac · 07-19-2019, 03:18 PM

A while back I had what I thought was a bad alternator but it turned out that the negative terminal was loose on the battery.

dca81 · 07-22-2019, 05:50 AM

Removed my alternator yesterday. I disconnected the engine batteries and was still getting current flow to the positive post on the alternator. I then disconnected the house batteries and was still getting current flow to alternator. Huh???? Found the source was a small wire attached to a terminal in the wiring panel. I assume this is coming from the solar panel. It is protected by only an in-line 5 amp fuse. Pulled fuse and all current is gone.
Then I cleaned the terminals on the house batteries and saw two pads glued to the side of the batteries. One pad was next to a positive terminal on one battery, and another pad next to a negative terminal on another battery. Looks like they are held on by a combination of glue and tape. Does anybody know what these PADS are for? Each pad has a separate wire running into the wiring loom.

twinboat · 07-22-2019, 06:11 AM

Possably Battery temp sensors for the inverter/charger.

Chargerman · 07-22-2019, 06:11 AM

Those pads are the temp sensors. They are tied into the charging system to prevent overheating/boiling the batteries when charging

dca81 · 07-22-2019, 06:35 AM

Thanks, this form is great. So when I change batteries I remove these and silicon/tape on to the replacement batteries?
Thanks
Bob

CountryB · 07-22-2019, 07:55 AM

you don't want to use anything that may act as an insulator and prevent a correct temperature reading. I just have my sensor wedged in between two batteries with nothing else holding it in place.

If the gap was too wide between your batteries to hold sensor in place you could insert a plastic carpenters shim or such against the top side of sensor and second battery (keeping battery sensing side of sensor in tight contact with battery case on first battery).

Chargerman · 07-22-2019, 08:43 AM

Maybe Gorilla tape might work also

dca81 · 07-23-2019, 05:58 AM

What is the specific Delco Si alternator number that will replace the LN alternator in my ISL?
Alternator rebuild shop said my alternator tested good. Recommended I check all my grounds. All my grounds on the battery terminal are good so I guess I try to find frame/engine grounds next. They also indicated that an alternator will not operate intermittently (kick on and off). Although I have talked to two mechanics who disagreed and say an alternator with an internal voltage regulator will kick on and off intermittently. Like I wasn't confused enough already

. Also, looked at the maintenance invoices and saw that alternator was previously replaced twice. Once at 60K miles in 2012 (costs $1159) and again in 2015 cost($960). Mileage on 2nd change is not indicated but unit now has 89K. The invoice for first alternator change at 60 K indicates po complained about an intermittent alternator light. Tech tested and found an intermittent over charge by a couple of volts and changed the alternator.
So I think I need to change something. I thought I would check chassis grounds that I can find. Also, based on comments on this form I think I should change to the Delco 28 Si 200 amp alternator. When I look on-line for the 28 Si there are several different models and casing configurations. Can anyone provide me with the specific model number 28Si that will fit the mounting configuration and pulley on my ISL.
Thanks
Bob

CountryB · 07-23-2019, 08:21 AM

Bob, you didn't say what year or model coach you have. If it is older than 2004 it probably has a DUVAC battery isolater.

That design requires a sensing terminal on the alternator to read battery voltage so the alternator knows how much to charge. If you have the style, I would check the "sensing wire" and make sure it is in good condition and its connection is good.

So any alternator you get (if you have the DUVAC) will need to have the sensing terminal (the Delco 28SI has it, on the Delco 24SI its an option). If you dont have a DUVAC then it wont matter if the alternate has the sensing terminal or not.

You need to also know whether you have the "Pad" style mount (like my CAT C13) or if you have a "Hinge" style mount (hinge style is more like a car style with a pivot bolt at the bottom).

If you have a newer model coach (you would probably have the Intellitec Big Boy battery isolater (or similar device), in which case the alternator reads battery voltage directly off its output terminal which is connected to chassis battery.

dca81 · 07-23-2019, 10:08 AM

2004 Windsor ISL. The L-N alternator on it does have a Duvac connection/wire. I think I need a 28Si, Jmount, long hinge by comparing the specs to the measurements of my current L-N alternator. I am not sure how to check pulley shaft diameter, or ensure pulley /belt alignment is correct.
Thanks
Bob

dca81 · 07-27-2019, 11:30 AM

I installed a 28si started it up and had perfect voltage,. However, key would not turn the motor home off. I had to go out and flip the chassis switch to turn the engine off (fuel pump). Check for similar problems on this site, found at least two (changed alternator, engine would not shut off), BUT neither indicated why (wiring wrong??) or a resolution. So changed back to a L-N alternator. When I installed the L-N alternator ignition key works fine but I get no current (alternator light is on and no voltage per Aladdin). Both alternators are new.
When I removed the 28si I thought I may have reversed the Remote sense (unknown purpose) and Duvac wires (battery isolator, identified as S terminal on diagram from this site). Also before removing the first alternator I checked all terminals for positive electric flow. The + terminal and S terminal both had positive flow (light up test light). These are the two terminals closest to the engine on the L-N alternator. However after doing the switch the S terminal (second from the engine) does not have a positive flow(will not light test light).
Is there a fuse hidden somewhere for the S terminal? Any suggestion? The only good thing with this exercise so far is that I am getting reasonably proficient at removing the alternator

Thanks
Bob

veraken · 07-28-2019, 06:29 AM

The DR 28SI is self igniting and does NOT need to be connected to the start switch

https://cdn.shopify.com/s/files/1/14...87673606426245

86 Cavalcade · 07-28-2019, 12:15 PM

I installed a 28si on my Diplomat and after it was installed I started the engine and it charged great but would not shut off. I called Delco & an engineer said to disconnect the ignition wire from the back of the alternator which I did and it worked great from then on. George