Bi-Directional Relay Anyone ever intall one?

[steve258]

Intellitec's Bi-Directional Isolator Relay Delay
Bi-Directional Isolator Relay Delay
offers a new approach to charging batteries in an
RV application. Unlike prior systems that only
allowed charging the RV battery from the engine's
alternator, the Bi-Directional Isolator Relay Delay
charges both batteries when either one is
being charged. When the coach is being driven both batteries will be charged from the engine's alternator. When the coach is plugged into shore
power, both batteries will be charged from the
converter. If neither battery is being charged, the
batteries are fully isolated. The controller also
senses heavy loads on either battery to prevent
the wrong battery from being inadvertently
discharged.

[AFChap]

My coach came with the B.I.R.D. ...works great!

[tompen]

Do a search on the site for B.I.R.D
There is a TON of information already here. The answer to your question is yes.
I replaced my failing factory installed B.I.R.D with this.
100

larger image
$61.95

Bi-Directional Isolator Relay Delay by INTELLITEC
Intellitec’s Bi-Directional Isolator Relay Delay™ offers a new approach to charging batteries in an RV application. Unlike prior systems that only allowed charging the RV battery from the engine’s alternator, the Bi-Directional Isolator Relay Delay™ charges both batteries when either one is being charged. When the coach is being driven, both batteries will be charged from the engine’s alternator. When the coach is plugged into shore power, both batteries will be charged from the converter. If neither battery is being charged, the batteries are fully isolated. The controller also senses heavy loads on either battery to prevent the wrong battery from being inadvertently discharged.
It operates by sensing the voltage on both batteries. When either of these volts exceeds 13.3 volts for approximately 12 seconds, which happens when either battery is being charged, the control will close the isolator solenoid, connecting the two batteries together, charging them both. (Normal charging voltages are from approximately 13.8 to 14.4 volts.)
After the solenoid has been closed, the system continues to sense the voltage. If the ignition switch is off and the battery voltage drops below 12.8 volts for approximately 5 seconds, which might occur when the converter is heavily loaded, the solenoid is opened to prevent the chassis battery from being discharged by the coach loads. When the voltage goes above 13.3 volts again for approximately 5 seconds, the solenoid closes again.
If the ignition switch is on, the control allows the voltage to drop below 12.0 volts for approximately 5 seconds, before the solenoid is opened to insure the alternators full output is available for important chassis functions. When the voltage goes above 13.3 volts again for approximately 5 seconds, the solenoid will close.

[distaff]

Mine came with one, but since I had to do some work on it I can tell you that the wiring is far from trivial, and I can't really tell you why. It has to have a continuous relay, mine came with a Big Boy that can also provide cross over boost from the coach to the starting batteries (I have 6 coach and 2 starting batteries, and on occasion I have needed to extra boost from the coach side). If you are not going the extra mile and adding a cross over boost, you can get away with a much smaller relay, if not, the Big Boy is around $300 but it can handle 1,500 amps.

I think the biggest problem will be figuring out what you want, and figuring out the wiring. In addition to the Big Boy mine has at least 3 other relays to tie all the systems together.

You might find it cheaper and easier to just add a charger that plugs into your 110 and put a charge on your starter batteries that way.

[tompen]

Steve:
I see from your profile you have an Itaska MH. Could we get a little more info. What year, gas or diesel, are you having a problem ? Do you have an emergency start switch ? If you have an emergency start switch that hooks the coach batteries and chassis battery togeather, and it works, it would be fairly straight forward to install the B.I.R.D that I pictured. Are you sure you don't have one and it just doesn't work. As was stated, it would be easier to just add a battery charger/maintainer to keep the chassis battery charged. Also some folks have had good luck with a Trick-L-Start. Again you can search the site for lots of info.
The more specific your question and the more info you give us, the better the answers will be. Some pretty smart folks here.

Tom