Alternator charge pulses 50 Amps

[wsmurdoch]

Originally Posted by pcmm

Given that the regulator is a Xantrex, and Xantrex is know for producing just crap product quality... Don't rule out that the regulator has died!

Guess who made the Xantrex XAR regulator:

I stripped off the potting material to see what name was on the circuit board.

Also see post #23 of http://www.cruisersforum.com/forums/...ure-64346.html

[Maine Sail]

Don,

You forgot to mention this..

Originally Posted by Capt.Don

I have an old 70 watt panel that I've been experimenting with. I ended up going with a mid-priced 10 Amp PWM controller that supports battery selection (I have AGMs), Renogy Viewstar. Many of the cheap eBay controllers don't have the selection options for different types of batteries and charge voltages etc. I didn't want some cheapo controller to cook my batteries.

You may be having a game of voltage ping-pong. With the alternator booted up the solar can drive sensed voltage above regulator sense and the reg shuts down. Without the alt current the battery voltage decays and the reg fires back up only to repeat..... Disconnect the PV after you've tested all the connections and see if that helps.

[Capt.Don]

Originally Posted by Maine Sail

Don,

You forgot to mention this..



You may be having a game of voltage ping-pong. With the alternator booted up the solar can drive sensed voltage above regulator sense and the reg shuts down. Without the alt current the battery voltage decays and the reg fires back up only to repeat..... Disconnect the PV after you've tested all the connections and see if that helps.

Maine Sail - My solar is not yet connected to the boat. My solar experiments were conducted in my back yard, so that I could learn more about how all this works. I plan on adding solar to the boat and I'm waiting for the new generation of Renogy flexible panels. I also did see a post where a guy added a cutoff switch to the solar to prevent the situation you describe. Makes sense, with all these charging options.

Thanks for looking into this in more detail.

[RaymondR]

Sounds like some sort of thermal overload switching is kicking in.


Low batteries = high ampage = high heat = thermal overload limit ampage, then cools down, high ampage =high heat and the cycle repeats.

[nigelmercier]

Originally Posted by wsmurdoch

Guess who made the Xantrex XAR regulator: [Balmar]...

In which case, try the small engine mode I mentioned above.

Small Engine Mode
The MC-612 can be switched to provide a half-power setting by installing a toggle switch between the positive and negative terminals of the alternator temperature sensor circuit. When activated by closing the switch, the regulator reduces the alternator output by a maximum 50%. This mode is ideal for smaller engines that are not capable of providing suitable horsepower to drive both the alternator and propeller at full output. When in Small Engine Mode, the regulator will send a signal to the Auxiliary #1 Status Output.

[a64pilot]

Originally Posted by RaymondR

Sounds like some sort of thermal overload switching is kicking in.


Low batteries = high ampage = high heat = thermal overload limit ampage, then cools down, high ampage =high heat and the cycle repeats.

I thought that too, but 5 sec is an awful short interval to heat and cool, mine acts this way, but it's a minute or two minutes per cycle I believe.
Bumping the engine to a much higher RPM lengthens the interval and makes it stop sooner too, I assume of course increased cooling, so if RPM affects it, you may be normal?


Sent from my iPad Pro using Cruisers Sailing Forum

[smac999]

Remove the field cable from the alt. connect 12v direct to field post of alt

Run engine. if you get full charging it's not the alt or batteries. But a regulator issue. Don't leave it like this for too long. If it still does it it's an issue with alt or batteries or between.

[Capt.Don]

Unplugged the boat from shore power and running down the house bank. I plan to duplicate the pulsing behavior and checking batteries, temps, etc. I think I mentioned earlier the battery connections were a bit corroded, so I hope cleaning them helps.

One thing I noticed today -- after disconnecting the shore power, the house voltage dropped to 12.6v, while the start stayed above 13v. I was surprised at the drop. I'm thinking batteries.....

smac999 - thanks for the idea on checking the regulator.

I'll keep you posted.
Don

[smac999]

if you had house loads on that is pretty normal. as the start battery won't have any loads.

[Capt.Don]

An update -- I haven't posted in a few days waiting for the house bank to burn down sufficiently to test. As suggested, I first cleaned contacts and made sure all the battery connections were tight. Batteries finally at 1/2 capacity; ran engine -- NO PULSING!!! Interestingly enough - there must have been enough corrosion on the positive terminal to cause the pulsing.

Today the alternator was putting 60+ amps back into the house. This will become an annual maintenance item. Thanks again for all your suggestions.
Don

[wsmurdoch]

The Xantrex XAR regulator uses a single red wire to sense the battery voltage, draw the power to operate the regulator, and to supply up to 5A to the blue alternator field wire. Any voltage drop in the red wire is a bad thing. I have a feeling that the cycling caused by a bad contact has steps something like this:

1. The regulator starts up with no field current being provided to the alternator. The current flow in the red wire is low (just enough to power the regulator electronics), thus the voltage drop in the red wire is also low. The regulator has enough voltage to supply its electronics and begins to charge the battery.

2. As increasing amounts of current flow to the regulator, in thru the red wire and out to the alternator in the blue wire, the alternator output rises. At the same time the resistance in the red wire's bad contact causes the voltage sensed at the regulator to fall as the red wire current increases. The regulator reacts by increasing the current to the alternator field in an attempt to increase the battery charging rate.

3. At some point the voltage at the regulator falls to the point that the electronics in the regulator shut down. The current to the alternator stops, and the alternator output stops.

4. With little current flowing in the red wire the voltage at the regulator rises, the regulator restarts, and it all begins again...

I have never measured all this while it was happening, but it is my guess.