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Topic: Keeping start batterys charged from house battery. (Read 643 times) previous topic - next topic

Keeping start batterys charged from house battery.

Would a  diode, connected(proper polarity) between the positive posts work? If the start battery dropped below the house battery, wouldn't that forward bias the diode and tie the two banks together just as does the boost switch?  Except for the drop across th' diode. Help me out here...

Jim
'92 Grand Villa 36' w/8.3Cummins mechanical
ORED
Build#4062

Re: Keeping start batterys charged from house battery.

Reply #1 –
Good idea. The diode would have to be rated at 100+ amps, and a circuit breaker would be a good idea. This is because if the engine battery is at 12 volts and the house is at 13.3 volts, there could be a huge surge in current. Maybe a resistor or a light bulb would limit the current.
1997 U270 34FT Build 5140 Cummins 8.3 Allison 3060R
Solar 1920Watts, 14KWH lithium. Orion BMS.

Re: Keeping start batterys charged from house battery.

Reply #3 –
OR - we could just install a 12v solenoid and use a switch(name it "Boost")If we just didn't leave it switched on all the time...! I'm gone to bed...

Jim
'92 Grand Villa 36' w/8.3Cummins mechanical
ORED
Build#4062

Re: Keeping start batterys charged from house battery.

Reply #4 –
I use a Yandina combiner between the start and house battery.  It works for me.

wantabe

Re: Keeping start batterys charged from house battery.

Reply #5 –
Diode based Trik L Start takes care of it all with current limiting.  Simple, inexpensive and it works.

Re: Keeping start batterys charged from house battery.

Reply #6 –
Was not aware that the Trik L Start was diode-based, as there is no voltage drop. 
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Keeping start batterys charged from house battery.

Reply #7 –
List me as another one with a Yandina combiner 160. Yandina Marine Electronics This combiner also replaces the diode based battery isolator that is wasteful of energy and creates heat and voltage drop during driving when house bank is being charged by engine alternator.

I've had it for several years, it's set and forget.  I did wire in an extra switch that I can manually control it with (forced closed, auto, forced open).

After just checking their site now, I see they have some cool new devices, like a 24VDC and 36VDC combiner that charges a bank from 12VDC.
1998 U270 34'

Re: Keeping start batterys charged from house battery.

Reply #8 –
Trik L Start is diode-based and there is always a voltage drop. This product has been around for decades.  This morning our two meters show a voltage drop of 0.2. 

LSL's newer Amp L Start uses a relay with voltage circuit board and does not have a voltage drop, but the close and open pre-programmed voltage reading may not charge start bank when house batteries are real warm.

LSL Products / LSLProducts.com - Problem-Solving Gear & Gadgets

I just read that Amp L Start now has an optional close / open profile for hot house batteries.  This revision shows how responsive LSL is to real-world usage issues:

"The Revision F2 version also includes a user-selectable "HIGH TEMPERATURE" mode that reduces the turn-on and turn-off voltages to 12.7 and 12.5 volts, respectively, for compatibility with some temperature-compensated house battery chargers. This mode is enabled by installing a jumper across two pins on the back of the unit. Removing the jumper instantly restores the "NORMAL"  13.2/12.8 volt turn-on/turn-off settings."