Bounder: Coach Batteries not Charging While Driving 99 Bounder

[harmonybrew]

99 Bounder - Ford F53 Chassis

I am not getting juice to my coach batteries when the engine is running.

There is a relay in the fuse box under the hood. I have tested this by flipping the aux start switch while using my multi-meter on the relays pos. and neg. posts with shore power plugged in. When the switch is held, i get a little over 12 volts to the relay, I hear a pop sound. I think it must be working.

With the vehicle running, I do not get a reading on the relay (other than about 3.4V). No popping sound, nothing.

I did have my house batteries unhooked at this point. Not sure if that would change anything. Wouldn't the relay still pop? Regardless. When driving, there is no extra voltage to the coach batteries from the motor. I have checked.

I have read in the forums that with shore power plugged in, the house batteries will charge up, then when they reach a certain point the selenoid will open (or close - not sure) and the chasis battery will start to charge as well. Is that true?.

Sound confusing? It is! To simplify, if the selenoid were working properly, what could else could prohibit juice from getting to the coach batteries? Or does the charge go directly from the alternator to the coach batteries?

Thanks in advance!!

Marcus

PS. I have included a few pics to clarify my system. I am not sure where these attachments will shop up. The pics are self explanatory, other than the one of the outside of the fuse box that show where the two bars lead to that are connected to the solenoid.

[twinboat]

Not sure about the 3 volt reading, may be 12 actavate and 3 volt hold BUT the selonoid clunking is not proof of internal connection.

Test voltage on both sides of the solenoid with and without the boost switch on.

Off, it should be different and on it should be the same.

[ga traveler]

The silver relay in the picture is the relay that is supposed to close and charge the batteries. Check the small connectors for 12 volts while the coach is running. If you have 12 volts on the small connectors, Check the voltage on both sides of the large connectors. If you have 13+ volts on one side and 12 volts or less on the other, The relay is bad.

[nothermark]

The short answer so far is we don't know. The relay could do the job but how it is implemented depends on the electronics that control the relay and the relay itself.

At this point my inclination would be to make sure both battery banks are connected and start the motor home and check the voltage on either side of the charging relay. If they match then something else is going on. IF they do not match then have somebody push the aux start button and see if they become the same showing the relay is closed. If they do not become the same then the relay is not closing and the question is whether it's the relay or electronics. At that point I would check the small terminals to ground when the button is pushed. One should go high. That is around battery voltage. If neither go high then there is a problem with the electronics. If one goes high then the problem is probably the relay. Get past that and see what happens.

[Waiter21]

Your BCC should be the same as mine..

I had a bad solenoid. It was energizing, but the internal contacts were not making..

When the BCC sees either house or coach battery voltage go above 13.2 volts, it will delay about 30 seconds, then energize.. It will deenergize when the voltages drop below about 13.0

Carefully measure the voltage on both sides of the solenoid. If your plugged into shore power the solenoid should energize after the short delay. Same if the engine is running..

Here is an article I wrote when I changed the solenoid...

Replace battery isolator solenoid in the BCC – 1999 Southwind 35S

..

[winniman]

Have you tested the alternator. You should test the alternator while the motor is running. You should be getting close to 14 volts coming off the alternator. If not, the alternator is shot. If you are getting proper voltage at the alternator, follow it upstream. We blew two alternators this winter. The second one we suspect was a defect as it only lasted 800 miles. The next replacement lasted the remainder of the trip. We were not getting proper voltage at the alternator, and had to run a jumper cable from the house batteries to the engine batteries, and run the generator just to get us to a campsite. We changed the alternator ourselves.

[harmonybrew]

Originally Posted by Waiter21

Your BCC should be the same as mine..

I had a bad solenoid. It was energizing, but the internal contacts were not making..

When the BCC sees either house or coach battery voltage go above 13.2 volts, it will delay about 30 seconds, then energize.. It will deenergize when the voltages drop below about 13.0

Carefully measure the voltage on both sides of the solenoid. If your plugged into shore power the solenoid should energize after the short delay. Same if the engine is running..

Here is an article I wrote when I changed the solenoid...

Replace battery isolator solenoid in the BCC – 1999 Southwind 35S

..

Great work! Time definitely not wasted! Me and many others included are benefiting from your work! Thanks!

And, this is the exact BCC that I have. Great pictures, great descriptions!!

[harmonybrew]

Thank you for the great - and right - answers! Now it seams like common sense. If the solenoid is working correctly, I should have the same reading on both sides - clunk or no clunk.

Waiter21 - The way you describe its function would explain things. When I am running, the house batteries aren't charging. When I am stationary and plugged in, the chassis battery isn't charging. Bad solenoid? Makes sense.

I read your article. If it does turn out to be the solenoid, this is going to help me immensely! Thanks!

Winniman - If it is not the solenoid, I will definitely check the alternator next. Thanks!

Nothermark - As soon as the water level drops outside ( In NC, rain and wind all night ) I am going outside to run these tests. I am thinking, almost hoping, that the solenoid is bad.

ga traveller - It seams like everybody knew this except me! Live and learn!

twinboat - I think the 3 volts is just basically noise.

Again, thanks everyone! And, the fact that you all have pretty much the same diagnosis is reassuring that my problem isn't really too complicated at this point.

I am going to get this test done today and write back.

Marcus

[harmonybrew]

Okay, I have done the testing. Here are the results.

When I push the aux/start switch on the dash and test the solenoid, like before, I get juice and a click. When testing both sides of the solenoid with the button held down, I do indeed show close to the same voltage, 13.61 coach side 13.48 chassis side (this is with shore power plugged in) I also tried flipping and holding the aux/start switch without shore power and got similar results, but with lower voltage levels.

But, the solenoid is not working otherwise. It is not connecting the coach batteries with the chassis battery except when the switch is being held down. Whatever tells it that it needs to actuate (other than the dash switch) is not doing so.

??Next??

Thanks in advance!

Marcus

[twinboat]

Now you need to see if it has a voltage sensing control, that closes the solenoid when it senses charging voltage from the chassis battery and alternator, OR simply a fused wire that actavates it when the key is turned on.

If its voltage sensing, there should be a second wire, on the same small terminal that the boost switch wire is on, and goes to the control.

If its the basic ignition actavated solenoid, that wire could go to the fuse box OR, like mine, a 5 amp Ford fuse, I found near the alternator. From that fuse, the wire was aftermarket looking, not Ford, and ran to the solenoid.

[Waiter21]

Here is a theory of operation and a diagram of the BCC:

http://1999southwind.com/DOWNLOAD/RV...ucts%20BCC.pdf

Look on page 6..

Auxiliary Battery Not Charging from Engine Alternator

If the solenoid is energizing with the AUX START switch and the voltages on both sides of the solenoid are almost equal, That says that part of the circuit is working.

It seems like the electronic / delay circuit isn't functioning to pull the solenoid in when on shore power or with the engine running..

IDEAs

Remove the circuit board and inspect it closely for burns, lifted pads, broken solder joints.. This board is subject to a lot of vibrations and solder joints on the board fail..

If you don't see anything, its time for a new BCC board..

WARNING - Make sure to disconnect the chassis and coach batteries AND remove shore power before working in the BCC..

Amazon has a rev "P" board for $260. I'd also replace the isolator solenoid while you have everything torn apart..

[kennyrodgers]

Hi.
I had this on my 94 Southwind.
I managed to find the troubleshooting guide for my particular BCC. I went through the process and it turned out that the solenoid was fine but the board in my BCC was bad. Rather than buy the expensive replacement ( as is recommended in the guide )I put a 300amp isolator in between the two sets of batteries at the solenoids and can now join them manually and turn the connection off the same way when parked. It was a £18 option as opposed to a very expensive circuit board change...... or a hillbilly fix as you guys call it over there. Still, it works just fine though.

[twinboat]

If the board is bad and expensive you can control the solenoid with a Yandina battery combiner. $70. and three wires to hook up gets you back to what you had.

For bi-directional charging ( BIRD ) you can wire it to both sides of the solenoid and it will carry 75 amps either way. You will still have your boost function thru the original solenoid.

https://www.yandina.com/c100InfoR3.htm

[harmonybrew]

Okay, the board.

I want to make sure my initial tests were correct, but I am pretty sure they were.

There is only one wire going to the positve of the solenoid, so a separate voltage sensing unit is looking doubtful, but I will research this.

-Waiter 21

I read through the trouble shooting on page 6. It does seem to be very clear.

-Twinboat and Kennyrogers

Thanks for these alternatives. I will very likely go with one of these choices. Much appreciated!

Now if the rain would just let up!