To Plug or Not to Plug

[vlamgat]

Originally Posted by flyfisher

I have a 2005 SMB with a Lifeline AGM for the house battery. I talked to the folks at Lifeline and they recommend keeping the battery plugged in and charged if possible.

Thats been the advice I have had from manufacturers for over 30 years. No matter whether it was boats, planes, RVs, cars or ships. Batteries must be kept full charges or their lives are shortened for various reasons. However this requires sophisticated management or microprocessor controlled. Solar chargers do not do this especially if there are residual demands on the batteries for memories or stand-by features. These are often hard to isolate and some get around this by disconnecting the batteries. On my SMB this is not easy to do so I also paid the $250 to add a 30 amp outlet and I keep it plugged in to my Tripplite controlled system.

[daveb]

Originally Posted by DocMP

Forgive if this is a silly question: How important is it to keep the house battery in my 2012 Ford SMB fully charged at all times? The former owner had a sweet garage with 220v outlet just for the van. Right now my rig is on the driveway, and the solar panels are getting sun most days, but the van is not plugged into shore power. Thinking about renting a garage for it (won't fit in current garage, of course), but difficult finding a garage rental with power access. So do I need to plug it in?

In storage it's always best to isolate the batteries and use a trickle charger. At a minimum, open the separator so the starting system and house system are isolated from each other. But both system usually have items that pull low amps. Detectors draw down the house battery over time and the radio does the same to the starting battery. On some builds SMB installed a master switch that killed most of the items that pull a parasitic draw SMB installs. You can do the same with a high amp disconnect switch so you don't have to actually pull out the battery or reach the cables. A good AGM battery can generally last a month of two without a charge. You'd just have to make it a point to visit the vehicle every month or so to close the switch and run the engine to top it off. I'm a fan of keeping tabs on the status of your vehicle anyway. My inverter has a maintenance mode so I plug in at home. If the fridge is on (running), the maintenance mode is enough to keep the batteries above 13 volts at night as it cycles on and off. IMO leaving the inverter set to auto charge (high amp taper charge) can get you in trouble if you don't monitor the charging session. More than once I've had a bad battery (in my case it was a wet cell starting battery) trick the charger into thinking the battery system was at a low state of charge. The result was the inverter ramping up to about 40 amps and cooking the battery. The battery off gassed, spewed acid and got so hot I couldn't touch it. You don't want that to happen in a storage facility. And as mentioned, most SMB's are 30 amp 120 volt.

[urbanfood]

it's my understanding that solar won't quite top them off so i tested it and i've found that to be true in my new to me 2004 E350 that has solar. i had it parked in the driveway in the vegas sun and batteries were hanging around 13 consistently for several weeks. i decided to plug in and it shot up another .5-.7, can't recall exactly but it definitely took it higher than the solar panels could go. i read it on some solar website which is why i tried it.

just get a 15 AMP adapter for your 30 AMP plug and you can plug it into your normal garage outlet via your shower power cord and keep it outside in the driveway (same setup i have mine). perfect for keeping them topped off.

[DocMP]

Thanks. I'm sure you're right. It's that weird looking plug with three prongs that are in a circle, not the usual two prongs that are parallel with the third ground prong.

[DocMP]

Originally Posted by rionapo

Can you run an extension cord to it? My understanding is battery life is determined by recharge cycles but there are others on the forum who know if this is correct.

Don

Yes, so I have it in a garage now that has an outlet, so I guess I'm going to figure out how to plug it in every once in a while, but not all the time. I emailed Peter at SMB about this and his reply was, "You can go ahead and store it just be prepared for the house battery to be drained when you take it out. In which case you can plug it in after to recharge it."

[DocMP]

Originally Posted by AdventureDave

You don't say what type of batteries you have. I will assume they are AGM. You definitely want to keep the batteries fully charged while not in use. You should check the specs on your solar charge controller. It may or may not be a smart charger that monitors the charge state and changes the charge voltage input accordingly. Most importantly does it have a trickle charge mode? You definitely do not want to keep a full charge voltage going to the batteries all the time either.

Yes, AGM. The van is in a garage now that has a 110v outlet, so I think what I'll do is just check on it monthly if we're not taking it out, drive it for a bit, plug it in for a bit, and hopefully all will be well. Thanks for your help!

[rob277]

The stock battery only lasted two years before it wouldn't recharge. I replaced it with two golf cart batteries that are built for constant discharge and recharge and haven't had a problem since. I have solar but live in Oregon so recharge with plugin when needed. I found that the propane detector would go off when charge got low. I plug in to 120v in garage via the shore power cable overnight. That lasts for about a month before it beeps again.













2011 Ford RB 50

[daveb]

Originally Posted by DocMP

Thanks. I'm sure you're right. It's that weird looking plug with three prongs that are in a circle, not the usual two prongs that are parallel with the third ground prong.

Called a twist lock. Its got a ground, a hot leg and a neutral just like a typical house socket. But it doesn't mean you need to have a 30 amp shore power circuit. SMB gave me an adapter to use a standard extension cord. The inverter itself does not use much to warrant a 30 amp draw. In other words the inverter in a high charge mode usually draws less than what a standard 15A house circuit delivers. The 30 amp service is for larger loads or combined loads such as running a air conditioner while you run another item like a heater or microwave.

[Scalf77]

Originally Posted by DocMP

I emailed Peter at SMB about this and his reply was, "You can go ahead and store it just be prepared for the house battery to be drained when you take it out. In which case you can plug it in after to recharge it."

Wow, that is pretty much the most uninformed advice I have ever seen.






We have probably all seen the Cycle versus Lifespan Chart. And most try to adhere to the 50% rule, but the fact is that there are other important things that also affect the lifespan of our batteries.

Temperature, unless we all live in a perfect temperature of 77°F (25°C), temperature will have an impact on the life of our batteries. While higher temperatures result in higher capacity, this comes at a price to lifespan. For every 15°F increase in battery temperature the lifespan is cut in half. At 122°F the capacity is increased by 12%. Fortunately, or unfortunately the opposite can be said of low temperature. At freezing battery capacity can be reduced by 20%. At -22°F the capacity is reduced by 50%, the lifespan however has increased by 60%. Hopefully for most of us this will average out.


The other area where temperature comes into play, is charging setpoints. Our Absorption and Float values are also listed at 77°F (25°C), those will increase or decrease with temperature. The general value use is 0.030 (0.005 per cell) volts per °C. So, for every degree over 25°C the voltage setpoint will be reduced by 0.030 volts. Of course, the inverse is also true, for every degree below 25°C the voltage setpoint will be increased by 0.030 volts. This is where having a charger that can compensate for battery temperature comes in. Every decent battery charger can add a temperature probe, so that it can compensate to the correct voltage. This also includes your solar charger if you rely heavily on it

The time between discharge and full charge is another crucial input. In the normal process of discharging a battery lead sulfate forms, the sulfate is converted to lead and lead oxide during the charge process. Unfortunately, some of it never reconverts and is left behind. The deeper the discharge and longer time between recharging increases the amount left behind. Performing an equalization charge can get back some of the lost capacity caused by sulfation, unfortunately most AGM batteries don’t even have a procedure for this, and if they do it generally more complicated than flooded lead acid equivalent batteries.

This brings us to our next problem, and probably the number one item in decreasing the lifespan of our batteries, Partial State of Charge. If leaving our batteries in a discharged state for longer periods of time before fully charging is bad, the only thing worse is to provide some charge but not a full charge. That sounds reasonable, but who really treats our batteries like that. Unfortunately, the answer is most of us. If you rely on your alternator to charge your battery to full capacity, you are never getting there. Remember the absorption phase, we increase the voltage and gradually bring down the current to force the last amount of current into the battery. A normally regulated alternator just can’t do that.

The second misnomer is Solar, oh my solar controller brings it to a full charge. In many cases this is true, but it is very easy to get behind the curve. The thing that worries me when people talk about solar is that I am charged back up by noon. Did your charge controller go through a full cycle of absorption and then into float? But it is up around 13 something volts it must have, well not necessarily. Another misconception is I used 60 Amp hours since last charge. My two panels put out 10 amps of power, so I need six hours of good sunlight to charge back up. Never mind that you need to put more back in than you took out, that absorption phase gets us again. Once you hit the absorption phase, you begin gradually decreasing charge rate, so that 10-amp value doesn’t work. Many times, we will run out of sunlight before we complete the absorption phase.

Of course, we want to use are vans as intended, there is no way that we can guarantee to charge it back up every day. I generally shoot for at least a full charge once a week, if I’m out camping. The key will be to come home and put your rig on a good plug in charger and go through a full charge cycle. After that maybe solar will be able to keep you charge up, or you can disconnect the battery. A lot depends on how much current is being used while it sits in your driveway or garage. I like to leave my refrigerator on, in the winter this draw can be minimal, while in the summer it can be a big impact.

Unfortunately, all things never work as people design it. One of the problems of the float stage is when things come on and off. There are some reports of chargers being tricked into thinking they are not in float, and start the absorption phase again. This creates a classic over charging situation, so it is good to monitor your charger to see what the impacts are of current surges like the refrigerator or other low current devices coming on and off are. I probably monitor my rig more than most, I have never seen this happened on my rig. Another possible area of confusion is the solar charger, care must be made that they can work together. If unsure it is better to just leave the solar off.

My solar charger is more accurate than my Magnum Inverter/Charger, thus when my inverter/charger was in float mode, the solar charger would see it below the float mode set point that it monitored. After a set time from below float it would kick into absorption. Every morning it would come up end up going into an absorption phase. Luckily for me both chargers had programmable settings and I was able to find a spot where both are happy. If that wasn’t the case, turning off the solar charger would have been the easy solution.
With all that you may want to know what the easiest way to know, if the battery is full or 100% SOC. I recommend Balmar SG200 to keep track of your battery. You can read about it here http://www.sportsmobileforum.com/for...mar-22688.html

-greg

[Orv]

The 15A to 30A adapters daveb mentioned are common items at RV supply stores, and you can often find them at "big box" home improvement stores too. I carry one to use at campgrounds that don't have 30A service. They're fine as long as you don't try to run heavy-duty loads like air conditioners.