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Topic: Batteries  (Read 507 times) previous topic - next topic

Batteries

Two part question...1994 280 Cummins 8.3..

1) are the "house batteries" normally charged by the engine alternator? Or in "boost"?

2 is it possible to overload the engine alternator with a large "house" battery bank
1994 U280 Unihome Grand Villa aka "Lazy Dayzz"                                              Cummins 300hp
    Allison 6 speed

Previous coaches:
1984 Revcon Duke 29 aka: "The General"
1984 VW Westfalia
1976 VW Westfalia

Re: Batteries

Reply #1 –
Quote from: Tomibach –
Two part question...1994 280 Cummins 8.3..

1) are the "house batteries" normally charged by the engine alternator? Or in "boost"? Yes,the alternator, through the diode-based battery isolator charges both house and chassis batteries (yes, if everything is working as it should).

2 is it possible to overload the engine alternator with a large "house" battery bank. Yes, particularly with Li batteries.  Alternators are not designed to run at full rated capacity for very long. Obviously, more of an issue if the batteries are deeply discharged.
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: Batteries

Reply #2 –
Thanks, was hoping you would answer, and no Lion batteries just yet, pair of Renogy 200a AGM
1994 U280 Unihome Grand Villa aka "Lazy Dayzz"                                              Cummins 300hp
    Allison 6 speed

Previous coaches:
1984 Revcon Duke 29 aka: "The General"
1984 VW Westfalia
1976 VW Westfalia

Re: Batteries

Reply #3 –
Quote from: Tomibach –
Thanks, was hoping you would answer, and no Lion batteries just yet, pair of Renogy 200a AGM
I want to ad just a little more detail to Brett's answer.

When the engine driven alternator reaches its maximum power out put, when it is delivering its maximum rating in Amperes. the voltage regulator rolls back the output voltage to keep the current flow from cooking the alternator.  Automotive alternators, at least in the past would not tolerate this for very long.  Truck alternators, I would hope, have more robust construction.

When we can't comfortable make an out and back trip in one day, we take the house with us, use the generator to run the microwave/convection oven and rely on the battery for everything else.  Then charge the house battery on the way home.  When the dash mounted voltmeter reaches 14.5 volts I know that the alternator is no longer running flat out.

TMI?
1992 Foretravel Grand Villa
U225 SBID Build No. 4134
1986 Rockwood Driftwood
1968 S.I.A.T.A. Spring
1962 Studebaker Lark
1986 Honda VF700C
1983 Honda VF750C
Charlie, the Dog was broken out of jail 24 Oct 2023
N1RPN
AA1OH (H)e who must be obeyed.

Re: Batteries

Reply #4 –
Few dash voltmeters will read over 14 volt. Most common is 13.5, without lights on and 13.2 or so with full lights.
Modern , post 2010 vintage are using higher voltage , early crap like my 88 will show lower.

Re: Batteries

Reply #5 –
Reading voltage on a circuit will usually read lower than battery post voltage, because of other loads on the circuit and wire size.

We don't use dash lighter for accurate voltage readings.

Running a dedicated wire from battery to a convenient interior place will not have much of a voltage drop. We bring separate wires from each battery bank to interior monitor panel that has two volt-meters.

BTW, we also have separate shunts on each house battery and measure current flow in & out.  Interesting on how multiple parallel connected house batteries do not equally share loads and charging current. Monitor panel also has two millivolt meters to read shunt amps.

23 years ago, when we purchased our Foretravel that has two 8D GEL house batteries, we quickly learned that one battery must have had an open cell as that battery was showing ZERO amps. On this discovery, Foretravel replaced both 8D batteries. Ignorance (about separate batteries in a bank) is not bliss.
 

Re: Batteries

Reply #6 –
The extra wires that run from the engine compartment to the dash can be used for a dedicated voltage reading. With nothing running and the solar panels on or off,  our lighter plug voltage is exactly the same as the battery voltage at the back with a digital multimeter. With the headlights on and/or the heater blower running. the voltage up front will be lower. When I turned on the old Taytronics inverter, the idle voltage dropped over a volt up front. Our new sine wave inverters don't change it much at idle. So, nothing like checking the voltage right at the batteries.

Pierce
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)