Big Boy isolator or Bird relay problem?

[Bryan Beamon]

Background: while driving I experienced alternator voltage fluctuations from 13.2 to13.7. Steve Huber suggested to tighten the ANL cables in the rear run bay  and that did cure the issue temporarily. Also while driving I noticed that the house batteries were not being charged when the alternator was showing 13.2 to 13.4 I then tried the battery booster switch and it re-engage the house batteries and the alternator voltage returned to 13.7 In addition the Big  Boy and Bird function correctly while on shore power. Any suggestions on how to correct this problem?

[Bill Lampkin]

You can take the big boy apart and clean the copper washers inside.

[Steve Huber]

Bryan,
Next time it occurs (before hitting the Battery Boost) check the voltage on the Solenoid pin on the Bird. It should read about 3-4v. This is the holding voltage for the Big Boy as keeping 12v on it constantly would cause an overheat condition. If the correct voltage is there and at the Big Boy (other end of the wire) the Bird is working. Also check that the House battery voltage is present on the Coach Battery pin of the Bird. Note the Solenoid pin will have 12v of it just  after energizing to close the big Boy but after few minutes it drops to the holding voltage.
Steve

[Bryan Beamon]

Follow up: after arriving in camp today and hooking up to shore power I found my chassis batteries were not being charged and showing 12.7 volts. I checked the bird solenoid as you suggested and in read 3.4 volts as you stated was a good holding voltage. I then checked the house batteries on the bird and it showed 13.4 volts. Next  checked the Big Boy and found 12.7 on one side and 13.4 on the other terminal.
Then activated the booster switch and it brought  the chassis batteries back to 13.3 volts.
I last replaced my current Big Boy 12 years ago and the current  Bird is 7 years old. If I replace both do you think this is the cause of my alternator voltage fluctuations?

[Steve Huber]

Bryan,
The Bird is OK and doing its job. The problem is the Big Boy. Before spending the $ to replace it, try cleaning the contacts as Bill suggested. They can become corroded or pitted over time resulting in intermittent contact. This is a link to the Common Problem article on cleaning the Big Boy contacts. You will have to log on to the club website to access it. https://www.beaveramb.org/resources/Documents/Technical%20Forum/Common%20Problems/Big-Boy-Cleaning.pdf
Steve

[Bryan Beamon]

Steve, thanks again for your support

[Lee Welbanks]

You can tell if the Bird relay is working traveling down the road, check you house batteries voltage and if it is discharging your relay needs cleaned, start you generator to charge the house batteries. When you stop remove your relay and take it apart and clean the contacts, they will be a pretty green color instead of copper. Just be careful not to short yourself out on a live circuit in the run box. Even with my batteries turned off there a a couple circuits live in my run box.
I  clean mine at least once or twice a year just to stay in practice lol!

[Steve Huber]

If you only turn off 1 of the 2 battery disconnects, the BIRD will keep the Big Boy closed for about 1 minute before opening the Big Boy. Thus both battery circuits will remain hot during that time.
Steve

[Steve Huber]

My previous post re Bird/Big Boy was incorrect. The Bird will keep the Big Boy solenoid closed, tying house and chassis batteries together until it senses that the battery voltage has dropped below 12.5 volts for over 1 minute.
So if you turn off one of the battery cutoff switches it will little effect as the Big Boy will continue to supply voltage from the other battery set. The Bird won't open the Big Boy until the voltage drops below 12.5 volts, which could take a considerable amount of time if the batteries are fully charged. The Salesman Switch will kill coach battery power to the 12v circuits in the coach interior but will not affect the voltage in the rear run box.
To get around this problem turn off both battery cutoff switches or if you need one of the battery sets to stay on, remove the Solenoid wire on the Bird. Either will cause the  Big Boy to open.
Sorry if my confusion led anyone down the wrong path.
Steve