Winter Storage MBS chassis battery

[MarsMan]

FR recommends not to use the onboard converter/charger to "maintain" the coach batteries during storage. They suggest disconnecting by removing the +ive terminal (too many things causing a discharge and thereby causing discharge cycles) and either bring indoors and float charge or leave in coach and float charge.

I am wondering what you MBS owners do with your chassis battery during storage? I was thinking of disconnecting the ground, and putting a charge on the battery. We will only need to worry about storage for 2 months since we are using the MH in Jan.

Always appreciate everyone's opinions

[khocke]

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[Still Kickin]

Procedure time tested three years running on the OE bats in Solera. Charge bats to full, check water levels, turn coach main connect off, remove the step cover, fish your supply power cord either through your hood vent or bat compartment vent hole, hook up trickle charger to one bat pos/neg. There is sufficient voltage on trickle to maintain all three batteries for the winter storage period, assuming all are in good working order and full charged. They are connected through the battery manager in the lower left stairwell. Longest duration tested with this procedure, four months.

[SSmbs]

Still Kickin - Curious about your charger on the house battery charging the chassis battery.My dealers explanation is that the connection between the chassis battery and house battery as a one way connection - the chassis will charge the house batteries but the house batteries will not discharge/charge the chassis battery. If that is the case would a charger on the chassis battery charge the house battery?? I was also told to use a float charger rather than a trickle charger.

[jdyson]

Originally Posted by SSmbs

Still Kickin - Curious about your charger on the house battery charging the chassis battery.My dealers explanation is that the connection between the chassis battery and house battery as a one way connection - the chassis will charge the house batteries but the house batteries will not discharge/charge the chassis battery. If that is the case would a charger on the chassis battery charge the house battery?? I was also told to use a float charger rather than a trickle charger.

I'm interested in this answer also, as I assumed there might be a one-way diode between the chassis battery and the house batteries as you state. i'm using two Battery Minder brand 4-stage float units. One I have hooked to the MBS chassis battery and the other to the two house batteries on the Forester MBS. This has worked well so far.

[Still Kickin]

My understanding of the terms; Trickle charging means charging a fully charged battery under no-load at a rate equal to its self-discharge rate, thus enabling the battery to remain at its fully charged level. [1][2] A battery under continuous float voltage charging is said to be under float-charging. Upon further review I employ a float charger.

Now, as to if the battery manager is: one or two way, I'd ask others to chime in, (i.e. FR EE's) on the statement made by one poster it might be one way. I can tell you that it has worked for me, three winter storage seasons. Last winter was a doozie, in the eastern US and I came away unscathed. I vote it's two way. But, i'm sure others will have specific knowledge to comment on that.

I have read from B Clemens in the past, that MB will not allow FR to tie into the house batteries as a jumping circuit, in the event the chassis bat crapped out to start the engine. But that is an entirely different issue.

[Nats]

I put in a disconnect in the battery compartment to remove the house batteries from ground. When I put in storage, I disconnect the ground, then I pull the Mercedes coach disconnect.

I've done this for 3 years now, goes in storage in October, comes out in April. Follow the Mercedes reconnect procedure and it has started every time.

[camaraderie]

NO charging should be necessary at all for at least 3 months IF you fully 100% charge the batts before storing and remove one of the terminal wires...either positive or negative. Cold weather loss of charge should not be even 10% a month for a fully charged and disconnected battery and they will not freeze even at -20 below if the charge level is above 60% (voltage 12.3).

[Total Loss]

I have a Battery Tender lead attached to the chassis battery.
Will this also charge the coach batteries if the battery switch is in the "off" position?
Seems to be conflicting answers to this.
I have the advantage of also plugging in the coach as I store it on the side of my house but the trickle charger to the chassis is easy.

[MarsMan]

Good question.. Seems like we all have questions.. you could check the voltage the charger is putting on the chassis batteries and see what the reading is on the coach batteries to see if charging

[SSmbs]

I was hoping someone with knowledge of the chassis and house batteries connect would chime in. I did a little research and this is what I came up with- the chassis and house batteries are isolated (not connected) to each other when the vehicle is not running through a battery isolator/management system. When the vehicle starts up it "charges" the system and allows the chassis to charge both house and chassis batteries. Without this isolator the house could draw down the chassis battery leading to a no start situation. I found my isolator/management system behind a cover to the left of the steps as you walk in to the MBS.

[MarsMan]

I did some further investigation and the system is isolated by the separator solenoid in the step by the house battery and a diode to prevent any power from going back toward the front. The solenoid is only activated when there is power on the ignition wire (starting or running the engine). Putting a charger on the chassis battery will not allow juice to the coach. I will go with my solar, disconnect the coach batteries from the coach and allow the solar charge the coach. I will put a DC Trik-L Charger on those and connect to the chassis. This will charge/maintain both systems. That Trik-L Charger is around $50

I appreciate all of the feedback

[Total Loss]

Originally Posted by MarsMan

Good question.. Seems like we all have questions.. you could check the voltage the charger is putting on the chassis batteries and see what the reading is on the coach batteries to see if charging

After I typed my post-I thought of just that.
Why not check it myself. DOH !

[MarsMan]

Originally Posted by Total Loss

After I typed my post-I thought of just that.
Why not check it myself. DOH !

Please let us know what you find

[Still Kickin]

Interesting stuff. Reading this I wonder can anyone point out the terminal connection coming into the Battery Manager, that goes to the chassis battery. Then you could connect there with a float charger to catch the chassis battery as well

[dukeboone]

I suppose I still don't understand why you couldn't leave the coach plugged in, especially with a 4-stage converter on board. For the chassis battery I plan to use a CTEK charger to maintain it during long storage periods. I actually figured I would just plug in the CTEK to a coach outlet so I didn't have to leave a window or door open to run the electrical wire to an exterior outlet.

[ipolyihh]

Originally Posted by dukeboone

I suppose I still don't understand why you couldn't leave the coach plugged in, especially with a 4-stage converter on board. For the chassis battery I plan to use a CTEK charger to maintain it during long storage periods. I actually figured I would just plug in the CTEK to a coach outlet so I didn't have to leave a window or door open to run the electrical wire to an exterior outlet.

If the the coach is plugged in, it will keep the chassis battery topped off.

for an experiment, turn on the headlights, you'll hear the charging start in the coach until a little after you turn them off again ( assumes you are plugged in )

[dukeboone]

OK, I'm thoroughly confused. Post #11 is consistent with my prior understanding the the coach and chassis batteries are isolated unless the engine is running. If the engine is running it will charge both the chassis and coach batteries. My understanding was that MB mandates this isolation and therefore prevents us from using the coach batteries to jump the chassis battery if ever needed. But you're saying if I'm plugged into shore power that will not only charge my coach batteries through my converter but also maintain my chassis battery?

On a different note I've read a lot of information from various online sources and there's some wildly different views on leaving the MH plugged into shore power for extended periods and relying on the converter to maintain the coach batteries. In dissecting all of this information there's a clear divide in the approach between those that have a single stage converter (battery boiler) and a multi-stage converter. That seems quite apparent to me. Reading further some argue that there's no point and simply disconnecting the coach batteries is sufficient. Many leave their MH plugged in 24/7 unless they're traveling or dry camping. And some argue that the prolonged use of the converter adversely shortens its lifespan.

[kandl]

Originally Posted by camaraderie

Cold weather loss of charge should not be even 10% a month for a fully charged and disconnected battery and they will not freeze even at -20 below if the charge level is above 60% (voltage 12.3).

Ditto. Been leaving LA batteries out in the cold (-20 to -30) for years. Check em every couple of weeks and charge as required. A good battery will go six weeks to two months before the charge drops below about 75 percent.

[Still Kickin]

Originally Posted by ipolyihh

If the the coach is plugged in, it will keep the chassis battery topped off.

for an experiment, turn on the headlights, you'll hear the charging start in the coach until a little after you turn them off again ( assumes you are plugged in )

So, according to your observation, the BCC (battery control center) must sense the load from the headlights draw, and call for juice from the converter to meet the demand. My question then would be; if that is the case, then does the BCC control current allow flow of current in both directions, as needed without the engine (alternator) entering this equation.

Wouldn't a volt meter test on the chassis battery, as the converter spoils up to supply juice to the demand, proff that assumption. I think if BbClemens could have an FR EE talk to this topic, it would be much appreciated.