Forum Discussion

Newbiecampers's avatar
Newbiecampers
Explorer
Feb 02, 2018

The various batteries and their charging sources

Hi all,

Looked through the various manuals that came with our '18 Coachmen freelander 21qb class C but could not find all the answers.

I have 2 12v house (coach) batteries, and I know that they are charged by the converter (wfco 8900 series). Are they also charged by the vehicle's alternator while driving (research points to yes)? To the opposite: Is the vehicle's battery (chassis battery) charged by the converter like the house batteries are when connected to shore power or onboard generator? I have been going out on occasion to plug the RV in to an outlet in our winter storage bay to charge the house batteries via the converter, and was curious if the chassis battery was also getting a charge.

Regarding the starting of the generator: In the fall while under the RV looking for holes mice may be able get in through I saw a battery box behind the Onan generator. The house batteries are under the entry stair, and the chassis battery is in the engine compartment. Does the generator have it's own battery for starting? If so, how does that battery receive a charge? Only when the generator is running/via the converter/via the vehicle's alternator/all three??

I did not actually look inside the battery box behind the generator, so maybe it is just a standard box for various chassis configurations. Not sure, though I have a vague recollection of seeing wires coming out of it. Thought somebody here may know definitively.

Thanks
Class C
  • Lwiddis's avatar
    Lwiddis
    Explorer II
    Feb 02, 2018
    “I did not actually look inside the battery box behind the generator,“ Look! Why speculate? Let us know what you find.

    “I have been going out on occasion to plug the RV in to an outlet in our winter storage bay to charge the house batteries via the converter” Why? Does a meter of some type indicate charging is necessary? While in storage are the house batteries disconnected?
  • DrewE's avatar
    DrewE
    Explorer II
    Feb 03, 2018
    Usually (as in nearly always) the generator does not have a dedicated battery; it typically cranks from either the chassis or house battery. On my '98 Coachmen, it's the house battery.

    The house battery charges from the converter and from the engine when it's running, provided everything is working properly. The chassis battery charges from the engine, of course. Sometimes the chassis battery is charged from the converter via a bidirectional isolator or some other device, but that's comparatively uncommon on class C's I believe. If you want it to charge that way, you can install a Trik-L-Start (which is not a super expensive gizmo); it sends a few amps to the chassis battery when the converter is operating or something else (such as solar) is charging the house battery.

    The generator charges the same things that charge from shore power, through the same mechanisms.

    Have you verified that there actually is a battery in the battery box by the generator, and it's not just an enclosure for some other electrical equipment?

    If you have a voltmeter, it's easy to check what batteries are charging under different conditions. If the voltage is above 13V, usually 13.5V or higher, it's charging or was just charged and still has a surface charge. If it's less than 13V, usually 12.6V or less, it's not being charged.
  • Newbiecampers's avatar
    Newbiecampers
    Explorer
    Feb 03, 2018
    Thanks for the info DrewE.

    Being a bit of a "budget" type class C I am guessing it does not have the equipment you mentioned to charge the chassis battery from the converter if that is an uncommon trait on class C's. I'll look into that Trik-L-Start you mentioned.

    Did not actually look into the battery box behind the generator, so there may not be one in there. Was concentrated on trying to get it winterized and verifying the "mouse-proofness" of the underside before the cold hit. Good point on the other electrical equipment. Maybe just a relay or something in that box.

    Next time I head to the storage lot to plug it in I'll take a voltmeter and check the chassis battery before and while the converter is on. Checking that battery box on the underside might have to wait until the temperature gets above the usual frigid winter temp.. ha ha
  • midnightsadie's avatar
    midnightsadie
    Explorer II
    Feb 03, 2018
    take couple bottles a water with you and check the water level in those batteries .a must thing to do about five times a year. a charged battery won,t freeze.
  • SidecarFlip's avatar
    SidecarFlip
    Explorer III
    Feb 03, 2018
    Batteries are the most neglected items on any unit, until they fail. Just like your car battery, they all need maintenance. Water (distilled) needs to be checked...often as does the connections.
  • TreeSeeker's avatar
    TreeSeeker
    Explorer
    Feb 03, 2018
    You will definitely have parasitic drains on your chassis battery caused by the radio, alarms, and the onboard engine computer among others. So, you will need some method of maintaining it’s charge while in storage. The Trik-L-Start is one way but I don’t trust it. It only charges the chassis battery when the house battery is above a certain voltage. So, if your chassis battery is discharging at a faster rate than the house battery, the chassis battery will never get charged enough.

    However, to be fair I have never used one so I don’t have any practical experience with it. Maybe I don't understand exactly how it works (there is not much detail on this on their website).

    I use a separate battery maintainer on the chassis battery, so it has it’s own monitoring and maintaining system. The downside is that battery maintainers generally cannot be left connected so you have to remember to hook them up when the RV is not being used, and to disconnect them when it is being used.

    The Trik-L-Start is hardwired so you don’t have to do anything after that.
  • Harvey51's avatar
    Harvey51
    Explorer
    Feb 06, 2018
    If you disconnect a battery so those parasitic devices can't draw power from it, the battery can be left for at least a month without charging.

    Batteries need charging when their voltage falls below 12.5 after several hours without charging. (Charging causes a temporary higher voltage that makes it impossible to read the state of charge with a voltmeter.) This is confusing when charging. The charger or alternator will run the voltage up over 12.6 in a minute but it probably needs at least an hour to provide a lasting charge. You will need to read the voltage frequently to get the experience to be confident your battery is charged and will remain charged for a month while disconnected.

    A "smart charger" is supposed to feed current into a battery until it senses the battery is fully charged but my charger isn't all that smart in cold weather.

    I think a battery monitor is great for the house batteries. It counts the amp hours (energy) going into and out of the battery bank displaying the per cent of full charge all the time. The Trimetric battery monitor is the top of the line but my $20 Chinese one works very well.
    eBay battery monitor
  • DrewE's avatar
    DrewE
    Explorer II
    Feb 06, 2018
    TreeSeeker wrote:
    You will definitely have parasitic drains on your chassis battery caused by the radio, alarms, and the onboard engine computer among others. So, you will need some method of maintaining it’s charge while in storage. The Trik-L-Start is one way but I don’t trust it. It only charges the chassis battery when the house battery is above a certain voltage. So, if your chassis battery is discharging at a faster rate than the house battery, the chassis battery will never get charged enough.

    However, to be fair I have never used one so I don’t have any practical experience with it. Maybe I don't understand exactly how it works (there is not much detail on this on their website).

    ...

    The Trik-L-Start is hardwired so you don’t have to do anything after that.


    The Trik-L-Start will never work if you don't have some source of power charging the house battery, be it shore power (and the converter) or solar or whatever. That's not at all surprising, since the power to charge the chassis battery needs to come from somewhere, and the house battery can't supply that forever without discharging.

    A charger, even when in float/maintenance mode, holds the voltage above 13V on the battery being charged. The house battery when so connected isn't being discharged at all; the parasitic loads are powered by the charger, not the battery. This is pretty easy to verify if one has a battery ammeter installed.

    I don't have personal experience with the Trik-L-Start, but most everything I've read has been quite positive about how well it works for its designed use.
  • TreeSeeker's avatar
    TreeSeeker
    Explorer
    Feb 06, 2018
    DrewE wrote:
    The Trik-L-Start will never work if you don't have some source of power charging the house battery, be it shore power (and the converter) or solar or whatever. That's not at all surprising, since the power to charge the chassis battery needs to come from somewhere, and the house battery can't supply that forever without discharging.

    A charger, even when in float/maintenance mode, holds the voltage above 13V on the battery being charged. The house battery when so connected isn't being discharged at all; the parasitic loads are powered by the charger, not the battery. This is pretty easy to verify if one has a battery ammeter installed.


    Yes, I understand all that.

    The situation is complicated and I can't find any information that explains exactly how the Trik-L-Start works. This is all I can find:

    "Steals" DC power from your RV's house battery charger.


    OK, I am guessing that it monitors the voltage of the engine battery and when it gets too low it connects the engine battery to the house battery which then causes the house battery's voltage to drop causing the house battery's charger to come on.

    What happens next, we don't know. I am guessing from the device's size and price that it is just a relay that connects the two batteries when the engine battery's voltage is too low. Then the house battery's charger kicks off and does a multi-stage charge on the now connected "battery bank."

    As you may know, battery banks ideally consist of all the same type, size, age and state of charge batteries. The Trik-L-Start is making a battery bank of the starting and house batteries (I am guessing). This is not good. One battery will get charged too much and one not enough.

    Certainly, any charging is better than no charging, so the Trik-L-Start is much better than nothing, but I don't know that it is better than using two different chargers, one for each battery.

    I want to like the Trik-L-Start because it is inexpensive, small, and hardwired so it is install and forget. I like that. If it also somehow does a multi-stage charge independent of the house battery, then I would get one.

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