Switching between Lithium and Lead Acid in Winter?

Buckster

Our 2022 CSS has the lithium compatible converter which automatically detects the type of battery.  During the warmer camping season we use a LiFePO4 200ah battery.  I pulled it out of our T@B this past weekend when I winterized the camper due to the potential damage that can occur when charging a lithium battery during below freezing temps.  I am thinking about purchasing a cheap EverStart Lead Acid Marine & RV Deep Cycle battery to use the FEW times we camp during the winter.  We only camp in parks providing shore power, so the limited amp hours would not be an issue.

Has anyone else done this?  My converter should automatically detect the different battery, correct?  It seems to be the cheapest alternative when camping in the winter time without damaging our LiFePO4 battery.  Thoughts?

pthomas745

Did you check to see if your battery has "low temperature charging protection" built in?  Remember: that protection only is needed if you try to charge the battery under certain temps.  No charging? No problem.  If you are camping with shore power, if the battery switch is off while you are plugged into shore power, you can avoid the freezing issue that way.  The Victron controller charger can also be turned off if you happen to hit a day with below freezing temps. 

So, check those details.  It may be easier than you think to avoid the "charging when freezing" issue on the lithium, and avoid the cost of an extra battery.

But: yes.  Dropping in a new battery wouldn't be an issue at all.  You might need to reset your Victron for a lead acid battery.

Buckster

No, I'm certain that the battery does not have low temp charging protection. I did purchase a Victron Smart Battery Sense temp sensor and have/had it set up to shut off charging at 39 F, but was told that it only protected the battery from being charged by the solar panel.  In other words, if connected to shore power, the battery would still charge.  

Are you saying that if the battery switch is OFF (while connected to shore power) that the battery will not charge?  Do you know if the LED cabin lights would work if the battery switch is off (again, while connected to shore power)?

pthomas745

If you are connected to shore power, with the switch off, the shore power does all the work for the items in the trailer.  The battery will not be charged.

pthomas745

I'm a Will Prowse fan, and he has a video that discusses low temps and lithiums, etc.  His claim is that if the battery is protected by being inside, or even protected with some type of insulation, the battery itself can protect itself. 

As he says in the first comment:  "I know you all live in Antartica where Jet Fuel freezes....but many people don't!" 

https://www.youtube.com/watch?v=EaiwxDUY9ho

Slackers

@Buckster With your CS-S make sure you can fire up the galley stove with the shore power connection while the battery is off.  There's an electrically safety mechanism that cuts off propane flow if it is not powered.  I don't recall if the mechanism is strictly battery powered.

Sharon_is_SAM

The propane switch for the CSS galley hatch works with shorepower or battery.  

Buckster

Thanks for all the responses. @pthomas745 I'm a Will Prowse fan as well.  His videos helped influence the battery I ended up purchasing.

One other question: Does anyone know if connecting to shore power while having the battery switch off runs any risk of damaging my controller or converter (if I have one)?

techietab

Buckster said:

One other question: Does anyone know if connecting to shore power while having the battery switch off runs any risk of damaging my controller or converter (if I have one)?

There's no additional risk to connecting to shore power while the battery switch is in the 'off' position.

Denny16

Quite the contrary, if you are not using the TaB, turning off the battery full stop is a good idea.  If not connected to shore power, it prevents the battery from being discharged by the small current from TaB’s equipment (CO2 detector, radio, etc).  If connected to shore power, turning off the battery switch keeps the convert from overcharging The battery, as even in float mode the converter is still adding a significant bit of current to the battery.  

Our local TaB dealer recommends turning off the battery, if storing the TaB with or without shorepower, to keep the battery in good kit. Once every month or two, or when getting ready to go,out camping, you can turn on the battery to get a quick top off charge from shore power, then turn it off.  After all, batteries ( especially wet cell or AGM) are voltage storage devices, and can go several months without being recharged.

Solar charging with MPPT controllers like the Victron, can reduce the charge level a lot,lower, and are more effective at keeping a Battery charged, with out overcharging it, like the WaCo power converter can do.  

Cheers 

pthomas745

@Buckster I wanted to learn a little more about lithium batteries due to all the conversations about them.  I had been all ready to buy a new decent AGM to replace my aging stock battery.  After a few Will Prowse videos....I wound up with a lithium battery from Amazon on my front porch.  (AmpereTime).  Once I understood the "low temp charging" issue, and the general ways to charge a lithium, I was like..well.  I don't live or camp in the cold, and my solar controller can shut off charging by adding a temp sensor. (And...it was a toy to play with.)

gulfarea

If you have the Victron controller and solar, disconnecting the battery while the solar is still connected is a no no! Always disconnect the solar first then disconnect the battery. I wish I could remember where I read this. The battery proberaly prvides reference voltage for the solar controler to go by. Art

techietab

gulfarea said:

If you have the Victron controller and solar, disconnecting the battery while the solar is still connected is a no no! Always disconnect the solar first then disconnect the battery. I wish I could remember where I read this. The battery proberaly prvides reference voltage for the solar controler to go by. Art

This doesn't make sense. Aside from the fact that recent model years with the Sunflare panel + Victron controller are sold with the Victron wired in on the battery-side of the disconnect switch (why would they do that if it was unsafe?), what harm could possibly be done? The Victron controller will charge the battery when it's safe to do, and when the panel isn't producing sufficient voltage, it'll just idle and put a very, very small load on the battery/batteries.

Denny16

The only issue with connecting and reconnecting a battery with hot solar wire connection, is possible shorting out the cables.  You can turn off the solar power on the Victron App, thus removing any current going to the battery.  A good safety practice when disconnecting a battery, is to do’s connect the negative cable from the battery first, then the hot (positive) cable.
 Cheers 

Sharon_is_SAM

I think that @gulfarea is remembering the recommendation for using portable solar.  You should connect the controller to the battery first and disconnect the controller from the battery after the panels are disconnected.  I think the idea was to avoid the potential for current flow from the panels.  I agree, this has no bearing on the permanently attached solar panels and controller.

techietab

Sharon_is_SAM said:

I think that @gulfarea is remembering the recommendation for using portable solar.  You should connect the controller to the battery first and disconnect the controller from the battery after the panels are disconnected. 

That definitely would make more sense.

pthomas745

I think the idea of connecting the controller first is 1: the controller will have a chance to sense the battery state of charge before the solar panel is connected.  This would prevent the surge that Sharon_is_Sam mentions. 2: if you connect the solar panels to the controller first...and the controller is wired up, but not connected to the battery,  you basically have a hot wire in your hand. 

DBoondocker

So, am I understanding this correctly….if I turn the battery switch to off and turn off the Victron through the app, then I have done everything to protect my LiFePo4 battery and don’t have to pull it out of the box? Also, what would adding a smart shunt help with?

pthomas745

Correct.  The issue with a lithium battery and the cold is: if charging is applied when the battery is below freezing, it can be damaged and cannot be recovered.  The manufacturers can work around this by providing "low temperature charging" protection, usually in the form of sensors attached to the battery. (Not all batteries have this sensor).   Solar controllers also can be equipped with temperature sensors and be programmed to stop charging when temps get important.

You can avoid the whole issue in the method you describe:  Victron charger is off and there will be no solar input, the battery switch off would prevent shore power from charging the battery (if it happened to be plugged into shore power.)

The most important thing a shunt provides is a "countdown" of amps used by the battery.  At a glance, you can tell how many amps you would need to provide to bring your battery back to full charge.  Or, that you have plenty of capacity left to get you through the day or night.  My Victron shunt also provides information about the solar charging coming into the battery.  Combined with a Victron solar controller and the Victron app, you can get a complete picture of your battery status and the history of your charging and discharge cycles.

The difference in the shunt's information compared to any basic voltage measuring devices (a multimeter, or the readout on the Victron App from the solar controller) is that the shunt amp count is in real time  Any device measuring voltage (multimeter, the basic voltage from the Victron controller from the app) requires the battery to be "rested": no power coming in, no power going out.  Essentially, to get a decently accurate voltage measurement requires the battery switch to be off, and disconnected from shore power, and no solar coming in.  The shunt avoids the "false readings" of voltage of an unrested battery. 

The other advantage for lithium users is the way that a lithium state of charge using only voltage seems to drop very slowly.  Knowing the exact number of amps you have used/have left avoids the sometimes confusing readouts of the lithium voltage.

Sharon_is_SAM

@DBoondocker - a shunted battery monitor like the Victron provides a State of Charge - SOC (% of the battery available) and really simplifies your battery monitoring.  The SOC factors in amphr used as well as the voltage and charge efficiency.  For this reason, once you set up the monitor, Victron says to rely on the SOC.  There are caveats.  On occasion, the battery monitor must be synchronized because multiple sources of charging (shorepower vs TV vs solar) can alter the accuracy of the monitor.  Worth the effort.

DBoondocker

Thanks for everyone’s advise. I have one more question. We are having some frost warnings for tonight so I turned my battery switch to off an when I go to setting in the Victron add and disable the charger it says charger should be disabled during maintenance tasks only. Am I doing something wrong?

Denny16

No, you normally only turn off the solar charging when doing maintenance, like connecting or disconnecting a solar panel.  The Victron app is based on general use.  Turning of solar charging through the Victron App will not hurt anything, and is better than disconnecting wires.  

Cheers 

pthomas745

I would say that "protecting the battery from charging during freezing weather" is a "maintenance task"!