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mxw1 · 07-05-2020, 10:46 PM

Hi,
I have a 2004 National Seabreeze on a Ford F53.
This problem just started recently.
While my RV is in storage I go there to connect to shore power for 24 hours, every 3 weeks. I can't just leave the shore power connected at all times because the storage place had a huge fire a few years ago. They have a one day limit to connect.

When I went to disconnect the shore power I always check both batterie's voltage before leaving. My engine battery did not charge up (about 12.3 volts), but the house batteries did; they were at about 13.3 volts.
I brought the motorhome and started checking more closely and suspect the battery isolator or disconnect is not connecting the two batteries. I know this worked in the past. I put a charger on the engine battery and brought it to a full charge, but the two battery voltages don't match.

My question is this; I'm thinking it's either the electronic board that senses both battery voltages and triggers has failed or the disconnect solenoid has failed. When I measure the voltages on the large terminals of the solenoid I see the house battery voltage on the left terminal and engine battery voltage on the right. There are also two small terminals on the solenoid, one near the house battery connection and the other near the engine battery connection, both small terminals are connected to the sensing board; one has 12 volts on it and the other does not. Does anyone know what these two small terminal voltages should be if the solenoid should be connecting the two batteries and vice versa?

I believe I once saw a description on the workings of this system but I don't know if I can find it again. Does someone have this info?

Thanks,
Mike

HarryStone · 07-05-2020, 10:56 PM

If you have 12 volts on the left small terminal, the solenoid is activated. The other small terminal is ground, thru your BCC. The BCC senses a charging condition, and then activates the solenoid, to enable charging both batteries. Also, when you press your aux, or emer start button in the cab, it supplies 12 volts to the left small terminal. The Aux start button won't do anything as long as you have 12 volts on the left small terminal, since that has already activated the solenoid. You can test this by carefully removing the nut on the right small terminal, then removing the wire. You should hear the solenoid disengage. If it does, check the two large terminals on each side of the solenoid with a volt meter. You should read 2 different battery voltages, one from chassis, and one from house. Put the small wire back on the right terminal, and if the solenoid energizes again, retest the large terminals, they should read the same now. If not, your solenoid is bad. Also, the BCC should not be putting 12 volts on the solenoid all the time. Only when it's sensing a charging condition, with either the house or chassis battery. Hope this helps.

twinboat · 07-06-2020, 03:45 AM

Very common for the solenoid to activate but not make the connection internally.

mxw1 · 07-06-2020, 09:38 AM

Thanks to both of your posts. That seems what is happening, the solenoid is activated, but not making internal connections to the large battery terminals.

I'd rather change the solenoid than the BCC anyway.

Are these solenoids easy to find?

Mike

HarryStone · 07-06-2020, 01:28 PM

Post a pic of your solenoid. If it's the normal one, they are available on Amazon.
https://smile.amazon.com/tekonsha-70...063684&sr=8-14

HarryStone · 07-06-2020, 01:30 PM

Please remember, the solenoid should only activate if it senses a charging condition i.e. engine running, generator running, or on shore power, or, possibly, if one battery is extremely low, but I don't know that for sure.

edit; or if you engage the aux or emer start button in the cab.

Sbrownstein · 07-06-2020, 02:06 PM

Quote:

Originally Posted by mxw1

Thanks to both of your posts. That seems what is happening, the solenoid is activated, but not making internal connections to the large battery terminals.

I'd rather change the solenoid than the BCC anyway.

Are these solenoids easy to find?

Mike

Most RV stores stock replacements. Look for a continuous duty 12 volt solenoid switch. They often go bad since when plugged in for months they are energized for months!

mxw1 · 07-09-2020, 08:06 AM

I,m out of town at the moment, but will let you know what I find when I get back and make the repairs.
Thanks again for the help and replies.
Mike

chboone · 07-09-2020, 11:45 PM

RV Custom Product is the manufacturer of the Battery Control Center (BCC). Seems they have upgraded to a web site never had one before. Use to have to call and they would email the documentation for the BCC. This link has the troubleshooting guide and diagrams for National RV BCC. If you need additional help try calling them use to be very friendly. I'm sure things changed with the COVID-19.
https://rvcustomproducts.com/111979