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Topic: Boost Switch/battery Talk (Read 622 times) previous topic - next topic

Boost Switch/battery Talk

Just to confirm something about the boost switch...

When I dry camp, if I leave the boost switch on it could possibly give me some more watt hours through the night correct?
I've never done this before, but about to go to the desert next week and wanted to try it...

I understand being careful not to drain my chassis batteries to the point of not being able to start my coach, but I have 1100 watts of solar and a suitcase genny that I sometimes use in the evenings to top things off every day. I also have a separate monitoring system for the chassis batteries and watch it closely.

The problem is that although my 8D's are fairly new, I think they were abused some by the previous owner (drawn down below 50% multiple times and not kept on a trickle charge when not using the coach). They don't seem to hold a charge for how much wattage is outgoing on a day to day basis...which isn't much when I dry camp. I will eventually get lithium-ion batteries and this will be a mute point.

...I also understand that the chassis batteries are "starter" batteries designed for higher cold cranking amps and not for deep cycle duties like the coach batteries.

In the end, I don't think i'll draw much from the chassis batteries overnight, but I do have a 12v electric blanket that I wanted to try :)

Re: Boost Switch/battery Talk

Reply #1 –
Check the amp rating of the blanket. One zone of the AH to keep the bedroom warm might be more efficient.

Re: Boost Switch/battery Talk

Reply #2 –
Personally, I'd be afraid of drawing both banks down so low you won't be able to crank in the morning.

Re: Boost Switch/battery Talk

Reply #3 –
Quote from: craneman –
Check the amp rating of the blanket. One zone of the AH to keep the bedroom warm might be more efficient.
Very true, I keep the aqua hot on the whole trip anyway so not sure how much more diesel I would save if I didn't run the bedroom zone heat through the night...also depends on how cold it's going to be on a given trip I suppose.

Re: Boost Switch/battery Talk

Reply #4 –
Quote from: Moby –
Personally, I'd be afraid of drawing both banks down so low you won't be able to crank in the morning.
I'm actually not that worried, like I said...with the solar and running the little genny in the evenings I'm topped off when I go to sleep. Just trying to get a little bit more juice though the night.

Re: Boost Switch/battery Talk

Reply #5 –
Dylan,

Using the boost switch as you describe won't hurt anything, and will provide some additional battery capacity.  You seem to be well aware of the possible consequence of depleting your start batteries.  As long as you actively monitor the voltage you will be fine.

Our coach is set up to use our batteries in exactly the way you describe.  We have two AGM8D house batteries, and a single AGM8D start battery.  Coach starts just fine using the single AGM8D.
I replaced the factory boost solenoid with a Blue Sea 7701 ML (magnetic latching) Solenoid.  We have often used all 3 batteries combined to carry us through the night when dry camping.
Never had a "NO START" situation.....yet. 

ML Solenoid - 12V DC - Blue Sea Systems

'93 U280 Isolator Panel Upgrade

Re: Boost Switch/battery Talk

Reply #6 –
The nice thing about the Blue Sea is you get to use both batteries until they get to 12.8 volts
and then they separate so the chassis battery won't get discharged. 

Re: Boost Switch/battery Talk

Reply #7 –
Quote from: oldguy –
The nice thing about the Blue Sea is you get to use both batteries until they get to 12.8 volts and then they separate so the chassis battery won't get discharged.
That's a different device.  The ML7701 I used is a manual control (only) latching solenoid.

They also make several Automatic Charging Relays, of which you speak.

Automatic Charging Relays - Blue Sea Systems

Re: Boost Switch/battery Talk

Reply #8 –
Quote from: Chuck & Jeannie –
That's a different device.  The ML7701 I used is a manual control (only) latching solenoid.

They also make several Automatic Charging Relays, of which you speak.

Automatic Charging Relays - Blue Sea Systems
That is definitely something I need to do!
Why did you install the manual switch instead of the auto? Wanted more control just in case? I also noticed the auto switch was cheaper.

Re: Boost Switch/battery Talk

Reply #9 –
Quote from: dlkj07 –
Why did you install the manual switch instead of the auto? Wanted more control just in case?
I prefer manual control - KISS

Further clarification of why I did not use an automatic charging relay:  Following the mods I mentioned in Reply #5 (above) I continued my simplification of our coach battery charging system.  I eventually removed the battery isolator completely.  My upgraded Delco 28Si alternator is now connected directly to the AGM8D being used as my "start" battery.  Normally, going down the road, the "start" battery is charged by the alternator.  The "coach" batteries are charged as required by either rooftop solar panels OR (in hot weather) by the inverter/charger, which is powered by the generator, which is running to power the roof air conditioners.  Automatic combining of my batteries was a function that I neither needed nor desired.
 

Re: Boost Switch/battery Talk

Reply #10 –
Whatever way you go.  Electronics wise it may last for years but it will be obsolete in weeks.