Alante 26Battery idiot light in dash lit

Iam2alan · 03-18-2023, 12:23 PM

I just changed the battery that starts the engine of my Alante 26x with a new one that has slightly more amp hours than the original.
The battery was installed just fine but now after starting the engine, the battery idiot light in the dash comes on and does not go out.
Any ideas on what the issue might be? Of course this happens just days before our first trip! Any help would be appreciated.

craigav · 03-18-2023, 07:30 PM

Were you connected to shore power or have the generator running when you restarted and saw the battery light on? If so, disconnect all other power and try again and see if the light goes out. Otherwise, it is likely that your alternator is not working. Do you have a voltage meter? ~CA

Iam2alan · 03-19-2023, 08:32 AM

Craig, I was not hooked up to shore power and did not have the generator running when I started up the motorhome. Yes, I do have a volt meter. Thank you for your response.

craigav · 03-19-2023, 09:21 AM

The idiot light doesn't tell you much other than the system is not charging. Most likely is a failed alternator that perhaps was having problems that caused your previous battery to run down. You could check the voltage at the battery prior to starting the engine and then afterwards and you should notice a rise in voltage.

However, even with a rise in voltage the alternator could still be bad due to failed diodes internal to the alternator. When the diodes go out, often the battery will run down overnight (or perhaps a day or two) and the alternator can appear to still be working. Diodes can be tested and the alternator often will output a low voltage AC voltage when there is a bad diode(s) which can be detected with a voltage meter set to AC (and a low voltage setting), however replacing the diodes isn't a common repair as they are internal to the alternator.

Before I replaced the alternator, I would check the connections, grounds, belts, etc. just to make sure that there isn't another problem. ~CA

Iam2alan · 03-19-2023, 10:50 AM

Thank you so much for your help. I will check the voltage before and after start and see what I get. I will also check the connections again to be sure.
There is one cable attached to the negative terminal that has red tape on it which seems suspicious me. I have never seen anyone using red tape to mark something that would attach to the negative terminal.
This stuff always happens right before the first trip, last year it was the bad spark plug wires that was causing misfiring! I truly appreciate your suggestions, I will let you know what I find out.

Iam2alan · 03-19-2023, 11:25 AM

Checked connections, all clean and tight. Checked one wire with red tape going to negative terminal. I was wrong, it is only the red plastic in the connector.
The key is sitting battery had 12.6v, when started it still read 12.6v. There was no increase in voltage coming from the alternator. I tried this test in my pick up and had 12.8v sitting that jumped to 14.5v upon starting.
Based on what you mentioned earlier, the alternator is the likely culprit. I will try getting an appointment with our Ford dealer, hopefully they can fit me in and our trip can go forward. I appreciate all your help.

RustyA · 03-19-2023, 08:15 PM

If the battery light was not on prior to installing new battery I have a suggestion for you to check. Had a customer install their own battery and instantly their battery light came on. They insisted over the phone that all connections were installed correctly. When we inspected and removed battery the charge wire from alternator was laying under new battery and not connected. Trying to help save you time and money of a trip to the dealer.

Iam2alan · 03-20-2023, 06:57 PM

Thank you Rusty for your feedback. Today I went out, disconnected everything and cleaned thoroughly using a wire brush. Reinstalled everything, I started it up and battery light came on after 30 seconds or so. We has to cancel our trip with the motorhome and will take our pickup! Dealer appointment set for April 4th for this issue and rear stabilizer recall. I appreciate your help and will report back on the cause of my issue. Thanks again.

RustyA · 04-10-2023, 08:13 PM

What was the result of your repair visit? Others may want to know what the fix was. It's always nice to share the fix after asking for help.

Iam2alan · 04-14-2023, 12:47 PM

Rusty, I haven’t forgotten to get back to you. I have been waiting to get the results and get the motorhome back.
Picked up my motorhome today and found that when the positive cable inadvertently touched the negative terminal while changing out the battery it blew a fuse. The new circuit breaker assembly ($63.82) was replaced all was well during our 75 mile trip home.
The motorhome did do well on the trip to the dealer by using the onboard generator to keep the battery charged while driving. Thanks for all your help.

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