Does Size Matter?

[boxcarOkie]

"Last week I replaced my start batteries (2 8D monsters) for two Group 31 start batteries. They fire up the motor really fine when the house and start batteries are connected via a switch in the battery compartment. When the motor starts on its own start batteries, it kicks but I concur with Clifford that having 4 Group 31 offers a lot more CCA to kick the motor over. I'm going to keep things as is for now as it works fine having the house back up the starts."

If it is wired correctly you do not need house batteries at all.  It is not easy being frustrated beyond belief.  I would pull my hair out, but I don't seem to have any to spare.  I will buy the beer if all of the free advice he gets is to replace those 8D batteries with two more 8Ds or 4 group 31.

Instead there will be people who will say the 2 group 31 are all you need, some will say you need 4 and some will give him a round of applause for tying the house to the start batteries.

The house is not backing up the starts. The house has become the starts and I will buy you two beers when at some point this guy ends up with 15 year old batteries for his house and chassis and wonders why his bus won't start or he is stuck in the back of the lot in Tucumcari.

After reading the thread about the guy who thought cold temps made his tires lose pressure I am further convinced that trying to post valid information on BCM and BNO is the equivalent of trying to cross breed a goat with a fifty-year old bus owner ... it just produces a weed eater that won't work.

Two things leaped out at me.

Not a single soul mentioned how if those tires had been driven on with low pressure they are junk. Not a single tire manufacturer disagrees with the policy that tires that have been driven at 20% less pressure than what was required based on weight should be removed from service. Driving on low pressure converts a good tire to scrap.

Nobody said that and one guy even said when he had low pressure he just put air back in his tires and he was good to go.

The second thing that got my attention is the Windy guy stating how he thinks valve stem caps are a pain in the a** and that he was OK just screwing a valve cap on a tire if the Schrader valve is leaking.

I should not have high expectations because these are the type of folks that will justify driving on 10 year old tires because they still haven't had a blowout that tore up a brake chamber or body panels.

Now here is MY problem in a nutshell.

I am going to polish my wheels this weekend and I always put a small nut inside the plastic container to break up the material inside.  I think this is called "viscosity" but I am not all that sure, as I have not stayed in a Holiday Inn for a long time.

But I was told by the guy down the street who owns the Winnebago that NEVER goes anywhere.  When you shake the vessel vigorously it breaks down the material on the inside that is sticking to the walls, and therefore, efficiently improves product flow to the rag.  Using this method and huge amounts of elbow-grease, will produce the desired impact on the driving public at large ... and of course ... shiny wheels.

So using a 1/4" or 3/8" nut, which would be better?  I have some ball bearings I have been using to shoot the neighbor's cat with, would they work just as well?

Watch those Right-handers. *

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* No actual cats were harmed in the fabrication of this post Dave.  Please do not send me any letters.

[belfert]

The guy with the low tire never said he drove on it with low pressure.

[boxcarOkie]

"The guy with the low tire never said he drove on it with low pressure."

Okay, I stand corrected, thanks for pointing that out.

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[TomC]

Big rig trucks with sleepers always use 4-31 batteries. And most all are 12v (no 24v starters-unless custom ordered). Now what they do is to have a low volt cut off of the cab lights at 12.2 volts so you can still start the truck. Another truck manufacturer, isolated one 12v battery just for cab lights leaving 3 batts for starting.
I still believe in separate starting and deep cycle batteries. The two are completely different strains on the batteries. I also believe in a jumper solenoid that you can control from the driver's seat to either charge both sets or jump if the starting batteries are low. But-do it your way-that's why we have our buses. Good Luck, TomC

[lvmci]

Larger nuts would produce greater flow!

[Dave5Cs]

Yes they do!

[Lin]

Larger nuts would produce greater flow!

But only up to the point that they are too large

[niles500]

I'm now pondering if I am a 1/4 or 3/8 nut  I'm always mixed up

[windtrader]

@Tom

I still believe in separate starting and deep cycle batteries. The two are completely different strains on the batteries. I also believe in a jumper solenoid that you can control from the driver's seat to either charge both sets or jump if the starting batteries are low

I have a manual switch for that same thing. I'm fine with leaving the house/start disconnected but that means my house battery bank will not charge via the bus alternator.

And that may be a good thing. I've just replaced the house battery bank and reviewing the inverter/charger calibration. While doing this, it made me reflect on how the bus' alternator regulation is nothing like a 3 stage bulk/absorption/float function offered when charging via the Vanner. In fact, it makes me wonder if charging directly off the alternator does damage (long term) to the house bank since it is not being charged and maintained as recommended.

May be a moot issue for me as my next project is to size a solar panel array for charging the house bank, hoping to eliminate the need for the generator to supply the charge. I'll be OK if I use it for the bulk charging and let the solar do the rest but will see how it goes.

[Lin]

I'm now pondering if I am a 1/4 or 3/8 nut  I'm always mixed up

Easy to measure with a caliper

[bevans6]

If the bus alternator has the regulator adjusted appropriately, it won't damage the house batteries.  I discussed this with an engineer at US Batteries when I was setting up my house/start combiner system.  The alternator puts out a constant voltage but current flow varies with load and battery charge state.  It's a constant high current charge that fries batteries.  Also, you don't typically drive the bus for days and weeks without stopping.  Charging the house batteries at alternator voltage for 4 or 5 hours is actually very good for them.  I start the bus first thing in the morning with two gp 31 batteries, and throw the bridge switch after the alternator has turned on and has charged the start batteries for a few minutes.  For starts all day, I leave the bridge switch on.  At the end of the day, I open it so inverter and house use doesn't draw down the starts.  If my starts are low or go bad, I throw the bridge and boost them with the house bank.  I had a start battery completely fail on the first day of a trip, I just disconnected the starts with the master switch, threw the bridge switch and ran off the house bank for a few days until I could buy and install new batteries.  It's good to design in a lot of flexibility and redundancy.

I call the valve stem cap a dust cap.  For me, it's there to keep spiders and crap out of the valve stem.  The schrader valve seals the air in, although I admit a good cap will help keep air in just fine.  Anecdotally, I just moved my car hauler trailer for the first time in two years, so I checked the air pressure in the tires.  All four were exactly where I set them two years ago, within the accuracy of my air gauge.  Not what I was expecting, to be honest.

Good to hear from you again, BCO

[Jon]

@Tom I have a manual switch for that same thing. I'm fine with leaving the house/start disconnected but that means my house battery bank will not charge via the bus alternator.

And that may be a good thing. I've just replaced the house battery bank and reviewing the inverter/charger calibration. While doing this, it made me reflect on how the bus' alternator regulation is nothing like a 3 stage bulk/absorption/float function offered when charging via the Vanner. In fact, it makes me wonder if charging directly off the alternator does damage (long term) to the house bank since it is not being charged and maintained as recommended.

May be a moot issue for me as my next project is to size a solar panel array for charging the house bank, hoping to eliminate the need for the generator to supply the charge. I'll be OK if I use it for the bulk charging and let the solar do the rest but will see how it goes.

There are a lot of points you need to understand based on what you state above.

You can charge both the chassis and house simultaneously automatically by the use of an isolator or a circuit with a solenoid (relay) that opens the circuit when there is no alternator output. Having a manual switch is the same thing and does the same right up until you forget to close the circuit and the house batteries don't get recharged by driving.

Assuming 24 volts, most chassis alternators with a voltage regulator that is adjustable charge at about 27.7 volts which is perfectly fine. even on excessively hot days. It is not the ideal charge like you get from an inverter, but it does keep your house batteries adequately charged. The inverter connected to shore or generator power is the ideal way to charge but not always desired or practical.

What is important is to understand the correct batteries and charging protocol for the application with deep discharge being the type required for the house and start batteries for the chassis. Keep temperatures in mind and don't plan on anything other than flooded lead acid for high temp locations and if gel or AGm are used for the house try to keep temps within a range in which you will be comfortable. Also the type of house batteries will determine the charging protocol the inverters will be set to provide, and learn what the inverter cycle will be and if it is satisfactory for the type of batteries.

[luvrbus]

27.7 volts is good for a float charge on the LifeLine AGM batteries,LifeLine is telling me to reach 100% of rated amp hours of their deep cycle 8D's  the absorption (bulk) charge rate needs to be 28.4v or higher,now I am more confused since paying big bucks for a new Balmar multi stage regulator  

[Jon]

I think the redeeming factor relative to alternator charging of Lifeline (or any AGM batteries) is the 27.7 volt typical alternator regulator setting is it is a safe value with respect to temperature variations. At that voltage level even hot temperatures are not going to make it too high.

But no AGM batteries should remain in bulk such as for a day of driving so the lesser value is unlikely to cook them.

Further, at least for motor homes with inverters when shore or generator power is available the batteries are going to receive the correct voltage for a charge and then drop to float which is somewhere around 27.2 (13.6)

[Road Dawg]

What in the world are these peope talking about?