Secrets of the 92-96 Auxiliary Battery Set-Up
Posted: Thu May 05, 2011 10:10 pm
I have read all of the great posts in the electrical section and have not seen this issue discussed. Hopefully you will not run into this problem, but if you do, maybe this post will speed up the solution and fix. I recently "upgraded" from a perfectly fine 91 model(except for the rust around the bottom perimeter up about a foot) to a 1993 pretty rust free model 190. I traded in at a dealer and did not realize the extent of the house battery problems until we got home and I started going through the various systems. Anyway, it had 3 batteries, with the 3rd being added under the folding bed/seat which others have done. The strange part I discovered after getting home was that the vehicle battery was also tied into the house system, making 3 house batteries, one being shared to start and run the engine. Niether of the house batteries were any good, thus the reason for the jumper to the vehicle battery(see picture with jumper wire disconnected).
The Delco group 27 marine battery under the seat is dated 1999 and will not take a charge(no surprise there). The auxiliary battery under the hood is not a deep cell battery but a conventional lead acid that fits in the narrower space. There is no liquid in any of the cells. I have decided to go with just a sealed group 27 under the seat and eliminate the house battery under the hood. I have removed the jumper wire from the main vehicle battery that tapped into the house battery terminal(more on that in a minute). A disconnect switch had been added to the vehicle battery and I found out why after not disconnecting it. The battery will drain in about 4 days. Put an ammeter on the battery and it is drawing .25-.30 amps somewhere. I disconnected the house jumper and the amp draw dropped way down to what I would consider normal(radio time and pre-sets, etc.). So something in the house is drawing .25 amps all the time. Maybe a detector as in a previous post. I think it was the 12 year old group 27, because after removing it the current leak went away. I assumed someone(possibly dealer) tapped into vehicle battery to avoid needing to replace the house batteries. Further testing revealed no power to the house batteries with engine running.
Fortunately the first thing I did when I got home with this 93 unit was to order the 3 volume set of factory workshop manuals. Behind the drivers(left) headlight is a auxiliary battery relay(see picture).
After removing the headlight I tested this relay and it works when the engine is running. But there was no 12+ volts coming into the relay from the alternator with the engine running. Further review of my manuals(needed to go back and forth between two of them to get all the info) revealed that fuse T in the engine compartment fuse panel is between the alternator output and the auxiliary battery relay. Fuse T is a 60 amp fuse( a big blue jobbie)! I located the engine compartment fuse panel between the engine and master cylinder, under the coiled brake lines(see picture).
The cover is a little tricky to get off(had to pull up on the brake lines and move another larger hose out of the way). The fuse locations are identified and I quickly found slot T. Had to use a pair of soft nose pliers to pull it out. Sure enough, it was blown. So tomorrow I will head to local auto parts store in search of one of these big blue fuses.
It is now tomorrow and I have 2 new 60 amp fuses. Put one in slot T and now have charging power to both house batterie locations when engine is running.
I have also ordered the converter upgrade from BestRV to replace the Megatek unit and fuse panel.
Now I have a favor to ask of you 93-96 owners. Under the hood on the left fender well by the firewall is a two terminal block that the auxiliary(house) battery cable attaches to(see picture).
I assume this was added by Airstream. Does you 190 have this? My auxiliary battery cable attaches to the forward terminal(along with the main battery patch cable). There are two cable leaving the rear terminal going down under the firewall. One of these goes to the converter(in my case also to the house battery under the seat). I have not been able to determine where the other one goes. Anyone know where it goes? I checked the trailer connections and it did not go there.
I will add some more pictures showing how I removed the battery cables from the auxililary battery location under the hood, and ran the cable from the auxiliary relay directly to the terminal block. This way there is no chance of anything wearing and shorting out at the unused battery location.
So, now you may know a little more about how and where charging power gets to your house batteries, plus, in a pinch you can jumper to your engine battery to get house power.
And thanks to Skater for teaching me how to post pictures.
The Delco group 27 marine battery under the seat is dated 1999 and will not take a charge(no surprise there). The auxiliary battery under the hood is not a deep cell battery but a conventional lead acid that fits in the narrower space. There is no liquid in any of the cells. I have decided to go with just a sealed group 27 under the seat and eliminate the house battery under the hood. I have removed the jumper wire from the main vehicle battery that tapped into the house battery terminal(more on that in a minute). A disconnect switch had been added to the vehicle battery and I found out why after not disconnecting it. The battery will drain in about 4 days. Put an ammeter on the battery and it is drawing .25-.30 amps somewhere. I disconnected the house jumper and the amp draw dropped way down to what I would consider normal(radio time and pre-sets, etc.). So something in the house is drawing .25 amps all the time. Maybe a detector as in a previous post. I think it was the 12 year old group 27, because after removing it the current leak went away. I assumed someone(possibly dealer) tapped into vehicle battery to avoid needing to replace the house batteries. Further testing revealed no power to the house batteries with engine running.
Fortunately the first thing I did when I got home with this 93 unit was to order the 3 volume set of factory workshop manuals. Behind the drivers(left) headlight is a auxiliary battery relay(see picture).
After removing the headlight I tested this relay and it works when the engine is running. But there was no 12+ volts coming into the relay from the alternator with the engine running. Further review of my manuals(needed to go back and forth between two of them to get all the info) revealed that fuse T in the engine compartment fuse panel is between the alternator output and the auxiliary battery relay. Fuse T is a 60 amp fuse( a big blue jobbie)! I located the engine compartment fuse panel between the engine and master cylinder, under the coiled brake lines(see picture).
The cover is a little tricky to get off(had to pull up on the brake lines and move another larger hose out of the way). The fuse locations are identified and I quickly found slot T. Had to use a pair of soft nose pliers to pull it out. Sure enough, it was blown. So tomorrow I will head to local auto parts store in search of one of these big blue fuses.
It is now tomorrow and I have 2 new 60 amp fuses. Put one in slot T and now have charging power to both house batterie locations when engine is running.
I have also ordered the converter upgrade from BestRV to replace the Megatek unit and fuse panel.
Now I have a favor to ask of you 93-96 owners. Under the hood on the left fender well by the firewall is a two terminal block that the auxiliary(house) battery cable attaches to(see picture).
I assume this was added by Airstream. Does you 190 have this? My auxiliary battery cable attaches to the forward terminal(along with the main battery patch cable). There are two cable leaving the rear terminal going down under the firewall. One of these goes to the converter(in my case also to the house battery under the seat). I have not been able to determine where the other one goes. Anyone know where it goes? I checked the trailer connections and it did not go there.
I will add some more pictures showing how I removed the battery cables from the auxililary battery location under the hood, and ran the cable from the auxiliary relay directly to the terminal block. This way there is no chance of anything wearing and shorting out at the unused battery location.
So, now you may know a little more about how and where charging power gets to your house batteries, plus, in a pinch you can jumper to your engine battery to get house power.
And thanks to Skater for teaching me how to post pictures.