Charging from the alternator - Page 2

backdoctor · 02-22-2017, 06:52 PM

To revisit. I bought a crimping tool and made certain the lug was fastened securely.

When I measure voltage with the engine running at the chassis battery (the post, lug and wire beyond the lug) reads 14.2v. When I first start the rig, the lug and post at the BCC read 14.2v, and then the solenoid clicks to close the circuit between batteries of the chassis and coach and the voltage at both sides of the solenoid read 12.5v, the current state of the coach batteries. (I purposely let the coach batteries discharge to 82℅). But the chassis battery post and lug read 14.2. There is obviously going to be a small voltage drop over the 8' of cable from the chassis to the BCC. But I can't figure out why this is happening.

I also checked the red power cable under the driver's seat that is for some.of the FR accessories. When I disconnect the cable from the battery to the BCC it also disconnects the power to this cable. Where are they connected? There are a number of red positive cables coming from the chassis battery, but none of them are the same shade of red as the Forest River chassis to coach battery cable.

This is really ticking me off. I can usually find and fix this stuff. Not this time!

FFred · 02-23-2017, 07:11 AM

Sounds to me like the solenoid is disconnecting the eng alt ,and not connecting it to the house.

A jumper cable could bypass the solenoid and you should see the house begin to charge.

KatanaPilot · 02-23-2017, 07:35 AM

Quote:

Originally Posted by backdoctor

To revisit. I bought a crimping tool and made certain the lug was fastened securely.

When I measure voltage with the engine running at the chassis battery (the post, lug and wire beyond the lug) reads 14.2v. When I first start the rig, the lug and post at the BCC read 14.2v, and then the solenoid clicks to close the circuit between batteries of the chassis and coach and the voltage at both sides of the solenoid read 12.5v, the current state of the coach batteries. (I purposely let the coach batteries discharge to 82℅). But the chassis battery post and lug read 14.2. There is obviously going to be a small voltage drop over the 8' of cable from the chassis to the BCC. But I can't figure out why this is happening.

I also checked the red power cable under the driver's seat that is for some.of the FR accessories. When I disconnect the cable from the battery to the BCC it also disconnects the power to this cable. Where are they connected? There are a number of red positive cables coming from the chassis battery, but none of them are the same shade of red as the Forest River chassis to coach battery cable.

This is really ticking me off. I can usually find and fix this stuff. Not this time!

Assuming you have the same Battery Control Center as I do, give Precision Circuits a call or email. I have found them to be helpful and competent. If they have a troubleshooting guide, it would be good to post it here for all of us to have access to.

I'm not sure if the FR wiring schematics that have been posted before have any useful information on the 12 volt power leads to/from the batteries.

ScottBrownstein · 02-23-2017, 07:44 AM

There are some auxiliary fuses in the BCC for some things that RVs need but trucks don't. You can look there. Before the solenoid clicks, the voltage is 14.2 and then it clicks and it drops to 12.5? That is kinda strange since I think the BCC shouldn't fire the solenoid if the voltage is below 13. No way should the voltage drop in that cable be anything near 2 volts. Has to be a bad connection somewhere as 2 volts in 8 feet is absurd but it is kinda funny that the voltage magically drops to exactly the house voltage. If you short the solenoid does the voltage on the house rise to 14?

backdoctor · 02-23-2017, 07:58 AM

Nope. I installed the switch described by katana pilot that activates the solenoid and closes the coach and chassis battery circuits. Even at rest with no loads, the chassis circuit reads 12.7 and the coach reads 12.5. Then flip the switch, connect circuits and they both go to 12.5.

What I thought of last night as I lay in bed trying to sleep was to measure the amperage to see if there is a strong draw of the coach on the cable connecting the coach to the chassis. I'll try that this am, as I have a hall signal amp guage.

The other odd thing I noticed was that when starting the rig, and the two circuits (chassis and coach) separated by the open solenoid, there is a 5.5 amp draw registered breifly on my battery monitor. That's wierd! As katana pilot noted while installing his audio deck, there is some connection to the chassis that is allowing current to flow from the coach batteries, even when the solenoid is open. Where is the connection?

ScottBrownstein · 02-23-2017, 09:02 AM

Well, on my 335 (Ford chassis) there is a switch that connects the radio to either the chassis or the house. Not sure why they went to all that trouble, maybe if the radio is on the ACC position of the key switch and wouldn't work without it. My old 1995 Bounder had a switch like that as well.

Now, if your engine is running and the battery post on the chassis reads 14.5 or so, what does the lug and post on the solenoid from the chassis read before you fire the solenoid? If it drops back to 12.6 or so and read 14.5 before firing, it has to be that wire somewhere. My alternator puts about 20 to 35 amps into the house at 14.5 volts when the engine is running and the house is below 80% (on the Trimetric.)

KatanaPilot · 02-23-2017, 10:32 AM

Unless the engine is well above idle, I think it's possible that once the solenoid closes, the coach batteries are pulling the system voltage down.

Maybe I'm reading your post wrong. If you run the engine up to 2000 rpm or so and still reading 12.5 volts or so, then not sure I can explain it. Not much output from the alternator at idle.

backdoctor · 02-23-2017, 11:14 AM

My thought as well. But even on the hwy, there is no current running into the coach batteries, at night when solar isn't contributing. And there is some evidence of excessive charging on the chassis battery. I'm getting some evaporated acid on the deck of the battery and some corrosion of the positive pole indicating there is some evaporation happening. I've never had that previously when I've checked the chassis battery. Leads me to believe an excess draw is happening to the coach somehow. Just can't figure out how and where.

backdoctor · 02-23-2017, 11:47 AM

Where is the third positive cable on the main battery post going to/coming from? It's running through a hi amp (50amp) buss fuse. Ideas? The other two fun to the BCC and connecting the second battery...

backdoctor · 02-23-2017, 11:55 AM

backdoctor · 02-23-2017, 11:56 AM

It's the one katana pilot found to be poorly crimped, I believe.

Sagecoachdriver · 02-23-2017, 01:16 PM

This may help, if you have the Precision Circuits Battery Isolation manager located in your step well.
http://www.precisioncircuitsinc.com/...anual-RevA.pdf
It manages your batteries, all of your batteries! It's bi-directional and puts it where it needs it. Takes a few minutes to analyze once you start engine or plug into shoreline.
Note that it will only charge house batteries for 1 hour while driving unless the voltage drops below a set level.
I have solar and it seems to drive the BIM crazy at times.
Also here is the troubleshooting guide:http://www.precisioncircuitsinc.com/...e-Shooting.pdf
Here's my battery compartment labeled:

KatanaPilot · 02-23-2017, 04:11 PM

My bet, given the symptoms is one or more of the coach batteries are bad. One of mine failed within 6 months because of the bad crimp that you mentioned.

ScottBrownstein · 02-23-2017, 06:12 PM

Solar panels have always driven these BCCs nuts. Voltage goes above 13.5 and the solenoid closes and brings on the chassis battery. Sun goes behind a cloud or whatever, voltage drops and the solenoid drops out. Happens constantly. Some have put in toggle switches to turn off the boost solenoid when solar charging.

backdoctor · 02-23-2017, 06:52 PM

Thanks for the ideas. I did call George at precision circuits. Great guy! He spent 15 minutes with me understanding the situation and pronounce the BCC good but said to check the connection on the outside of the box where the cable comes in from the battery! YES! That was the problem. You see in the great white north we use lots of salt. Causes corrosion. Add to that the fact the the lock nut out on at the factory was between the lug and the post, as opposed to between the lug and the nut. Wrong side of the connection. This allowed buildup of rust to impairment the connection to the solenoid. When there was no load, all measured normally, but there was such a poor connection that it wouldn't conduct much juice and the voltage falls to the level on the coach side. Yippee! Thanks for all the ideas and encouragement.

KatanaPilot · 02-23-2017, 08:53 PM

Thanks for passing along the solution.

Highly recommend Corrosion X spray to help prevent this in the future. It has many uses and several formulations.

backdoctor · 02-23-2017, 09:47 PM

Where would I find this product? What formulation would you suggest?

KatanaPilot · 02-23-2017, 09:52 PM

https://www.amazon.com/Corrosion-X-9.../dp/B0009H1AMG

FFred · 02-24-2017, 06:38 AM

"Add to that the fact the the lock nut out on at the factory was between the lug and the post, as opposed to between the lug and the nut."

Many DC circuits have a star washer between the lock nut and the cable terminal.

The purpose is to keep the terminal end under contact pressure , after repeated heat and cold cycles as the wiring carries current.

An elastic stop lock nut or similar is fixed and can not aid the contact pressure after a few cycles.

These star washers are cheap at the hardware store and should be on ALL DC terminal ends , not just the heavy charge cabling.

A great rainy day project that will pay for decades .

backdoctor · 03-04-2017, 06:02 PM

I bought corrosionX from Grainger's in Jacksonville before I headed home. I gave all the exposed electrical cables nnections on the back of the battery management centre a blast. And since I was having a little hesitation starting the Genny, I sprayed the solenoid connections there too. They were corroded, and the problem with starting disappeared. Amazing stuff. I've never read such positive reviews on Amazon! Like they say, this stuff rocks! Thanks katana pilot.

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