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Old 01-26-2012, 08:32 PM   #1
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House Battery Isolation

Have a Class A DP with a 4 house battery arrangement with a general isolation switch. Use my DP 1 to 2 weeks per month. Where I store the unit has no external power. I engage the islation switch when the the unit is in storage but I still need to start the generator at least once per week or my batteries will drop below 70% charge. Besides finding out where my apparently excess phantom drain is coming from, are there any battery special isolation equipment or procedures to stop the phantom drain that you employ. Thanks!

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Old 01-26-2012, 08:48 PM   #2
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1. Year, make , model?

2. Your "isolation switch" may be for the chassis battery only. Make sure that ALL house battery loads turn off.

3. To find parasitic draw, install an ammeter in the house battery feed, then shut off one circuit at a time.

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Old 01-27-2012, 04:37 AM   #3
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Battery Isolation

I have a 2008 Newmar Kountry Star model 3916.The chassis batteries are on a seperate general islation switch in the engine compartment and that plus the solar panel on the roof keep those charged with no premature decrease.The house general isolation switch is on a panel above the the passenger seat. I think I've turned everything I can even that is covered by the general switch. When I metered the phantom I believe I got .2 amps. I say I believe because I've been unable to replicate on my multimeter. I possibly blew out my multimeter?
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Old 01-27-2012, 04:58 AM   #4
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Our Newmar has a chassis battery disconnect switch, a coach battery disconnect relay and a BIRD isolator relay between the 2 battery systems.

In addition on the control panel there is a switch to turn off the propane detector which is fed from the chassis battery and a switch for the antenna booster fed from the coach battery. When checking for phantom loads don't forget if you have an inverter it may be pulling a small load even if switched off and may have to have a power wire disconnected if its upstream of the isolator relay/switch.

Intellitech uses a coach battery disconnect relay that needs no power to hold it in either position. My BIRD isolator relay does require power when both battery systems are full charge to hold the relay in to connect the 2 systems together (so both are charged) even when the coach battery disconnect relay is in the store position. I simply pull the red wire going into the BIRD control board to de-energize the isolator relay.

Note- if you disconnect the chassis switch you may loose any fault codes associated with the engine and/or tranny. We have not had a problem disconnecting it.

As stated below, measuring the battery current while shutting off the loads, pulling fuses and/or circuit breakers will isolate most phantom loads.

It may be easier to just disconnect one of the feed leads from the battery bank during storage to be sure its not the batteries self discharging due to age and temp. - your call.
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Old 01-27-2012, 06:05 AM   #5
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0.2 amps would not be unusual phantom draw for a large, modern coach. Lots of things draw a tiny amount of power, even when turned off. That's because they have circuit boards that stay alive, waiting for you to press the On switch. But 0.2 amps shouldn't drop the batteries to 70% in one week if the bats were fully charged and in good shape. 7 days x 24 hours x 0.2A = 33.6 Amp-hours, which is less than 10% of your total amp hours with 4 batteries.

Have you checked the water in the battery cells? Are you sure they are charging to 100%? Running the genset for 30 minutes may make the meter on the coach say 100%, but it probably isn't over 80% actual. The charge is mostly a "surface charge" and quickly disappears.
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Old 01-27-2012, 07:45 AM   #6
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Battery Isolation

Thanks for the info. The batteries are brand new and I check the water level regularly. Might be I'm not running the gen long enough to reach "float".
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Old 01-27-2012, 03:14 PM   #7
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Hi glemo81540,
Back to the OP question, consider installing a blade type switch on the coach batteries. Install on the lead that goes to the coach. Positive or negative post, it does not matter. This will definitely isolate the batteries from all drains.
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Old 01-29-2012, 07:06 AM   #8
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house battery isolation

Thanks for the info. Is the switch you mention the type carried at Camping World (which seems more appropriate for a chassis battery bank-pole vs screw on bolt type on my deep cycle) or is another type available somewhere else. Again thanks!
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Old 01-30-2012, 07:07 AM   #9
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Originally Posted by glemo81540 View Post
I have a 2008 Newmar Kountry Star model 3916.The chassis batteries are on a seperate general islation switch in the engine compartment and that plus the solar panel on the roof keep those charged with no premature decrease.
Or, consider making a small gauge jumper wire with alligator clips on ea end and attaching it to the pos+ terminals of the chassis and house batteries. This way the solar will trikL charge both batt banks?

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