Magical Battery Charger

Topic: Magical Battery Charger (Read 1192 times) previous topic - next topic

Magical Battery Charger

July 08, 2011, 11:30:22 am

Once again I need help from the electrical experts.

This morning I started to install my new Ultra Trick-L-Charger. I was checking to make sure which post on the Boost Switch went to the starting batteries and which post went to the house batteries. Per Mark Harvey's suggestion I checked to see which post had the greater charge. He said and it makes sense that with the Boost Switch off the House post that is getting charged by the Xantex 3000 would have a slightly higher voltage than the post powered by stating batteries. When I checked it the voltage was the same on both posts with the Boost Switch either off or on.

I then disconnected both battery cables for the starting batteries and found that the cables were still getting 13.76 volts from the coach system. Remember the Boost Switch is off. With the engine not running and the Boost Switch off, I don't think there should be any voltage on the starting battery cables unless there is already something like a Trick L Charger on line. Am I correct?

If there is an auxiliary charger like a Trick L Charger installed somewhere on the coach, does anyone have any idea of how to find it. I have looked in the obvious places like behind the white fuse panel in the bay, under the bed and on the plate where the isolater and boost switch are located.

My presumption is that I don't need a Trick-L-Charger if the stating batteries are being charged with the boost switch off. Any Comments?

Re: Magical Battery Charger

Reply #1 – July 08, 2011, 11:41:21 am

This is from a non-electrician, but is it possible the boost switch is stuck in the boost position??

Re: Magical Battery Charger

Reply #2 – July 08, 2011, 11:48:51 am

Quote from: Bob McGee – July 08, 2011, 11:41:21 am

This is from a non-electrician, but is it possible the boost switch is stuck in the boost position??

I guess that's possible. I will disconnect the starting battery cable from the switch and see if the Boost switch is functioning.

Thanks for the thought, expert or not common sense works most of the time.

Re: Magical Battery Charger

Reply #3 – July 08, 2011, 12:04:02 pm

I just disconnected the starting battery cables from the Boost Switch. It is working properly. No voltage on the starting battery post when the boost switch is off and 13.36 volts when on just like the other house post.

Re: Magical Battery Charger

Reply #4 – July 08, 2011, 12:06:41 pm

Kent,

You could also have a failure of your isolator. If both diodes have failed in a "short" mode, the alternator, house, and chassis connectors will all show the same voltage, even if the engine is not running. Other failure modes on the isolator might show different results.

Your description indicates some kind of connection between the 12VDC circuits for the chassis and the 12VDC circuits for the house. Normally, the boost switch should be the only connection. The Trik-L-Start is designed to provide a one-way connection from house to chassis. There will be about 0.5 volt drop across the Trik-L-Start from the house batteries to the chassis batteries. That drop will be evident after the coach has been parked for a while.

Re: Magical Battery Charger

Reply #5 – July 08, 2011, 12:11:42 pm

JD, I checked the isolater while I was on the phone with Mark Harvey. With the key off, I only have voltage on the left and right post. With the engine on, all three posts are hot. I don't know how it could be malfunctioning to cause the starting batteries to be charged when the key is off. Am I missing something?

Re: Magical Battery Charger

Reply #6 – July 08, 2011, 12:24:55 pm

Maybe, because the refer is now working so well, you are getting magic reverse power into the system due to the high airflow rate over the coils and increased insulation raising, even your MPG!

Re: Magical Battery Charger

Reply #7 – July 08, 2011, 12:39:37 pm

Quote from: Kent Speers – July 08, 2011, 12:11:42 pm

... With the key off, I only have voltage on the left and right post. With the engine on, all three posts are hot. ...

It seems like the isolator must be OK. You have demonstrated that there is 12VDC on the chassis circuit with the chassis battery disconnected and the boost switch disconnected. What would be supplying that voltage? I assume any solar panels would be connected on the house side.

On our coach, the previous owner installed a small charger in the engine compartment that was connected to the chassis circuit. It was plugged into the outlet for the block heater. You might look for something like that.

What happens when shore power is removed, the inverter is off, and the generator is off? Can you measure any differential voltage between the chassis voltage and the house voltage?

Re: Magical Battery Charger

Reply #8 – July 08, 2011, 12:44:56 pm

With a good isolator hooked up correctly to both house and chassis batteries, both of those posts should have a voltage reading as you would be reading that battery's voltage. The reading could be identical. The alternator post should not have a voltage reading; it might show a voltage reading though if the ignition switch is on, I have never checked that. The purpose of the boost switch and solenoid is to defeat the function of the isolator, and connect the batteries together. A good fully charged battery can not charge a discharged battery when connected together, the weak battery will pull down the fully charged battery though. It takes 13.5 or more volts to charge a battery. A fully charged battery at rest is about 12.8 volts or less. The trickle charger can only do its thing when the house battery is being charged.

Re: Magical Battery Charger

Reply #9 – July 08, 2011, 01:04:22 pm

Jerry, I think I understand. What I found is that with the key off, the boost switch off and the cables removed from the starting batteries, there is still voltage equal to that of the house batteries on the starting side of the Boost Switch. When I disconnect the starting battery cables from the boost switch, that post is dead as it should be. With the starting cables removed and the boost switch on, the post is hot.

Re: Magical Battery Charger

Reply #10 – July 08, 2011, 01:19:52 pm

Try loading the house side down. Unplug 110, turn on inverter, turn on lights, TVs, reefer, etc. Then see if one side is down over the other. Take your readings at each battery bank.

Re: Magical Battery Charger

Reply #11 – July 08, 2011, 01:54:57 pm

Kent, If you have a solar panel on the roof and your coach is in the sun your system could back feed the system. Mine connects at the rear pf the refrigerator. I actually get 14+ volts into the system when in the sun... there is some loss by the time it gets to the isolator.

Re: Magical Battery Charger

Reply #12 – July 08, 2011, 02:01:32 pm

I think I understand Dave, but what will that show me?

Gerry, no Solar Panels are connected.

Re: Magical Battery Charger

Reply #13 – July 08, 2011, 02:03:13 pm

Quote

What I found is that with the key off, the boost switch off and the cables removed from the starting batteries, there is still voltage equal to that of the house batteries on the starting side of the Boost Switch. When I disconnect the starting battery cables from the boost switch, that post is dead as it should be. With the starting cables removed and the boost switch on, the post is hot.

Kent Speers

Kent,
Have you checked to see if the boost solenoid is stuck "on" - does it click when the dash switch is toggled? (probably takes two people) Or maybe the solenoid contacts are burned together from switching the boost switch when 'under load' or from one battery bank often being quite low (current surge), too many times. If it doesn't click on and off, disconnect the battery cables to the solenoid and test with an ohm meter. Obviously the solenoid's battery posts should not show continuity if the coil in not energized.
It also is possible that your dash switch is shorted "on" Look for constant voltage to the primary coil post on the solenoid regardless of the dash switch position.

Re: Magical Battery Charger

Reply #14 – July 08, 2011, 02:08:25 pm

Jim, already did all of that, please see previous post at 12:04PM and see if I missed anything. The boost solenoid seems to be functioning fine.

Re: Magical Battery Charger

Reply #15 – July 08, 2011, 02:17:14 pm

Quote from: Dave Cobb – July 08, 2011, 12:24:55 pm

Maybe, because the refer is now working so well, you are getting magic reverse power into the system due to the high airflow rate over the coils and increased insulation raising, even your MPG!

Dave,

You are gonna fit in very well here. Good response.

Re: Magical Battery Charger

Reply #16 – July 08, 2011, 02:19:11 pm

George, remember he spent three days with me when he picked up my U225. I'm afraid I tainted him.

Dolly is still OK. She hung with Peggy.

Re: Magical Battery Charger

Reply #17 – July 08, 2011, 02:20:46 pm

What is this world coming to?

Re: Magical Battery Charger

Reply #18 – July 08, 2011, 02:26:21 pm

What is surprising is that with that exposure, they are still great folks and a real valuable addition to the forum. Well at least Dolly is still great, school is still out on Dave after hanging out with me for that long.

Re: Magical Battery Charger

Reply #19 – July 08, 2011, 02:54:50 pm

If they banks are NOT truly paralleled you can determine that, then going to the boost solenoid it will be easy to determine which side is which.

Re: Magical Battery Charger

Reply #20 – July 09, 2011, 10:44:58 am

Dave, I did the test as you suggested. If I understand my data correctly I have proven the boost switch is working and that the starting batteries are being charged by something with the Xantrex 3000 charger on and the boost switch off. I still don't know what is charging the starting batteries with the boost switch off so I don't want or apparently need to install the Trick-L-Charge.

Does the following tell you anything I may be missing?

Xantrex On

Boost Switch Off
House = 13.27 V
Starting Batteries =12.88 V
Starting Battery Cable unhooked from starting batteries, Boost Switch Off = 13.33 V

Boost Switch On
House Batteries = 13.31 V
Starting Batteries = 12.76 V

Xantrex Off house under load

Boost Switch Off
House Batteries = 12.55 V
Starting Batteries = 12.77 V

Boost Switch On
House Batteries = 12.76 V
Starting Batteries = 12.52 V

Re: Magical Battery Charger

Reply #21 – July 09, 2011, 11:45:06 am

From where I sit, which is probably 450 miles away, it sounds like the house and chassis circuits are connected all the time. Perhaps someone wired something to both circuits causing them to be connected. Tracking it down will be challenging. Look for any wiring that looks like it was added after the coach was delivered new. The toad wiring might be a place to look early in your search.

Re: Magical Battery Charger

Reply #22 – July 09, 2011, 12:40:33 pm

If you read 13.27V on the start battery cable to ground with the boost switch off there is a bypass feed - AND its not running through a diode based system because it would drop half a volt. Wonder what it would read with the Xantrex off?

As such - if you run your engine, is the voltage the same on both banks? This would help determine if the banks are paralleled or there is a dual charging feed.

Re: Magical Battery Charger

Reply #23 – July 09, 2011, 01:24:19 pm

Remove the wires from your isolator and check it with an ohmmeter. Mine was shorted and gave funny results when trying to test it with voltage. Make sure you label the wires so you get them back on the right posts.

Re: Magical Battery Charger

Reply #24 – July 09, 2011, 03:01:05 pm

I had an 84 35 foot 0red and the boost solenoid had the contacts welded together and that would give you that kind of condition. I think that someone else had mentioned the boost solenoid. To test take off the lead from the solenoid to the chassis batteries and there should be no voltage on that terminal with the boost switch off good luck Ron

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