The various batteries and their charging sources

[Newbiecampers]

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

[Newbiecampers]

Wanted to bring this subject back from the dead. I finally got the chance to bring the RV home from the winter storage lot and get under it with a creeper to check things out again regarding this:

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??

There is indeed a third battery mounted on the left frame rail (driver side), forward of the generator. It is an AcDelco battery, says GM, so I am guessing it came from the factory. The negative cable goes to ground on the frame, and the positive goes forward and disappears into a hole in the driver door footwell.

Called coachmen but no answer. Prelimanary research Here shows this might be the GM option : "Isolated 2nd Battery — allows 2nd battery to be used when the vehicle is not running without affecting ability to start the vehicle"

Anybody know anything about this feature? I apparently have three sets of batteries: One in the engine compartment, the house batteries under the stairs, and this third battery mounted on the frame rail under the RV. I'm wondering if this third battery is connected in with the house at all, or how it can potentially be capitalized on for RV use.

I found it funny that this extra battery actually has more CCA (770) than the battery in the engine compartment (600).

And FYI for anybody with a Chevy-based RV, you may have this extra battery as well. Bonus!! ??

[Bordercollie]

I installed a Trik-l-Start a few years ago and it has worked fine to keep the engine starter battery charged when rig is connected to 110 vac shore power. Installation was not quick and easy on our 2004 Tioga 26Q. I had to run a long heavy gage hot wire along the frame and up into the engine compartment, through a 15 amp circuit breaker, and finally to the positive engine battery terminal. Your installation may be easier if you can find/have the solenoid device mentioned in the instructions.

[TreeSeeker]

DrewE,

So it seems, that you are agreeing with me, that the Trik-L-Start does not do as good of a job charging the engine battery as a dedicated multi-stage charger would?

You can get a dedicated multi-stage smart charger for about the same price as the Trik-L-Start.

The question remains, how much better would a multi-stage charger be?

For many people the Trik-L-Start still is probably a better choice, since once it is installed you don't have to remember to hook up a dedicated charger. Any charger is better than none.

Harvey51, thanks for the link to the Trik-L-Start discussion. Good info.

[DrewE]

As I understand it, the Trik-L-Start amounts to a current limited (to 5A) voltage controlled diode. If the house electrical system is at a higher voltage than the chassis, and the house system voltage above 13.x volts, it turns on and allows up to around 5A to flow, though it could be less current if that's all the chassis battery will accept at whatever voltage is applied (the house voltage minus any wiring losses and whatever drop there is in the Trik-L-Start circuitry).

It does not implement a multi-stage charging regimen independent of the house battery. At a 5A limit, I'm not sure how useful that would be anyhow. If the house converter or charger has a periodic equalizing charge (or something vaguely similar), such as e.g. the PD converters with the charge wizard attempt, that higher voltage would be reflected across the Trik-L-Start, but not independently.

[CharlesinGA]

Trick-L-Start will not charge chassis batteries until the coach batteries are well above their resting voltage (which is usually about 12.8 or so, and "well above" is around 13.6 or so).

Charles

[Harvey51]

Trick-L-Start discussion

Looks like it only charges the engine battery when the house batteries are being charged. Nice idea.

I have a pretty simple Motorhome - the built in Ford engine has a fuse and relay to provide charging to an "auxiliary battery", and this is used to charge the house batteries while driving. The relay connects the engine battery to the house battery when the engine alternator is charging. Trick-L-start in reverse. When parked at home I wanted to have the batteries connected so the solar panel could charge both house and engine batteries. I unplugged the relay in the fuse box and put a piece of wire in its place.

I never intended to use that connection in other situations but it was nice when camping and of course made no difference when driving so the batteries have been left connected for a couple of years now, except in winter when all the batteries are disconnected. The solar panel has kept the house batteries over 80% charged all the time so no worries about the house draining the engine battery when camping.

[TreeSeeker]

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.

[DrewE]

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.

[Harvey51]

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

[TreeSeeker]

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.

[Newbiecampers]

Thanks.

I'll bring some distilled water and check the levels as well.

[SidecarFlip]

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.

[midnightsadie]

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.

[Newbiecampers]

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