Lead acid to Lithium Help and Recs?

[backcountry birds]

I bought a used off-road teardrop a few years ago that currently has two 6V Interstate GC-2 Deep cycle extreme lead acid batteries rigged to be 12V (think that is series but get them confused).

The power capacity has been sufficient for my setup: small fridge, lights, fan and water pump. The batteries are at the end of their useful life and I am intrigued by lithium due to increased life and ability to run them down lower as many of my trips are multi day and even multi-week at times.

I have a victron controller and 2 - 100W solar panels on the roof. No invertor is on the trailer but it does have a plug where I can hook up to shore power if in a camp site.

Can I just drop in a 200ah lithium battery in the lead acid space and not look back?

Is their anything I need to alter or be concerned with before going lithium?

I use it as a hunting rig too so often camp in below freezing temps, I have read that charging lithium below freezing damages the battery. Is that true and what can I install or do to prevent that?

If lithium will work, any recommendations on lithium batteries both capacity and brand?

Would a jackery type setup work or is a standard lithium battery better?

Thanks in advance!

 

[DiploStrat]

The short answer is "no" but the longer answer is "yes" you want to move to lithium. It isn't that hard.

Can I just drop in a 200ah lithium battery in the lead acid space and not look back? - No, but pretty close.

Is there anything I need to alter or be concerned with before going lithium? - Yes, see linked slides.

I use it as a hunting rig too so often camp in below freezing temps, I have read that charging lithium below freezing damages the battery. Is that true and what can I install or do to prevent that? - You cannot charge below freezing, but is the interior of your camper below freezing? If the battery is mounted outside, you can buy heated batteries. The power drain is not usually the problem some fear is you usually only run the heater from the charging source.

If lithium will work, any recommendations on lithium batteries both capacity and brand? - People I trust like Battle Born and Lithionics.

Would a jackery type setup work or is a standard lithium battery better? - Don't waste your time and money. You already have most of the infrastructure, you can build a better, less expensive system on your own. Do consider adding a nice shore power charger, like a Victon.

You may find this useful.

https://cookfb.files.wordpress.com/2022/10/move-to-lifepo4-2022.pdf

 

[jonyjoe101]

If you can keep the battery inside your trailer it will be best. You can use any controller as long as you can adjust the bulk setting manually.
Depending on how full the battery is you might have to adjust the bulk setting up or down. If the battery is full most of the time set the bulk to 14.0 volts, if the battery is low than you might go with 14.4 volts or even 14.6 volts. That's if its lifepo4 (max 14.6 volts). The higher the bulk voltage the more amps go into the battery.
One thing about lithium that I learned the hard way is that you don't want the BMS to ever activate. If the BMS activates ( battery fully charged) the solar charge controller will produce voltage surges, these surges will destroy any 12 volt devices connected to the battery. I destroyed many fans and 12 volt water pumps/lights due to the surges, which can reach over 20 volts. I encountered these surges with both pwm and mppt controllers. What happens is when the BMS activates it uses electronic mosfets to disconnect the battery from the controller, but these mosfets leak voltage and the controller still reads a low battery and tries to forcibly charge the battery, thats where the surges come from.
Thats why some people recommend the battery bulk voltage be set to 13.8 volts, but at such low voltage the battery charges very slow since it gets low amps. We are talking charging at 1 to 2 amps, when your panel is capable of putting out 10 amps.
I've been using a makeskyblue 60amp mppt controller that is suppose to prevent voltage surges and I also run any valuable 12 volt devices through a 12 volt voltage stabilizer just in case. Haven't encountered voltage surges in several years.
Even if the solar controller has a lithium setting, it won't be a plug and play situation. On my 220ah lifepo4, I just adjust the bulk voltage manually (even though the makeskyblue mppt has a lithium setting) ,in the winter the bulk voltage is set higher than in summer.
To me that is the biggest hazard of lithium is the voltage surges. Through trial and error I was finally able to avoid them.
If you go with lifepo4, you will need a coulombcounter to keep track of the amps used. Lifepo4 reads 13.1 volts between 20 and 90 percent. You won't know if its full or empty by reading the voltage until its fully charge or fully discharged.
If you go with a jackery all you need is one in the 1000 watt hour ( about 100ah) to replace your 200ah of lead acid. The ecoflow power stations in the 1000 watt hour range you can find them refurbish for 600 dollars on ebay. Those have built in mppt controllers.
That might be one way to avoid voltage surges.

 

[backcountry birds]

Thank you for the input. I just checked and I have the Victron Smart Solar MPPT 100/20. So believe that is compatible with lithium batteries so my solar should still work.

It looks like most the lithium batteries do not have cold weather shutoff. I have read that perhaps my solar charger can be programmed to not charge at cold temps. Any thoughts on that or should I just ensure the BMS has that cold weather shut-off feature.

Should I get a 12V 100ah or 200ah? Looks like price is essentially the same per ah. If my understanding is correct the 100ah would more than double my old lead acid capacity, so likely would be plenty but since it can't charge in cold weather leaning towards the 200ah. Would two 100ah, be preferred over one 200ah? Price appears about the same.

Main things I am worried about besides the cold weather charging:

1. How do I not ruin my truck alternator when towing?

2. If I'm plugged into shore power how does that impact my battery? Any concerns there?

I assume I would need to install some kind of isolator or dc to dc controllers to alleviate the above concerns, could I just install a battery cutoff switch and not have it charging while driving or plugged into shore power? Worried about forgetting, but seems the simplest.

Would the bare minimum be the following:

1. Lithium battery swap
2. Battery cutoff switch turned off when towing or when on shore power
3. Try to get temp prope and program Victron to not charge below freezing

Then I can longer term work to upgrade to where I can charge battery from shore power and truck alternator?

Just saw the above post about surges. Now I'm hesitant. Don't want to ruin a bunch of stuff.