Lithium battery in Lil Snoozy

[buff30]

Looks good Doug! I think your battery longevity will be much better with that second battery. .6C is a lot even for a LIFEPO4. Have you ever figured out what your Truck Fridge averages for current draw per day?

[dleverton]

Originally Posted by CarlD

Doug, I have a question regarding the 30A fuse in line with the solar panels. I also have a fuse in this location, but I installed it blindly because the manufacture recommended it. I may be missing something here, but what scenario will cause this fuse to blow? The solar panels have a current limit that, I assume, is less than fuse value, so there is no scenario there that could blow the fuse. Is there some kind of back feed mechanism in the MPPT charger that could feed battery current to the panels? Do you have any insight?

Your right that if the short circuit current of the panel is less than the fuse value...what’s the point? Two points: fuses are to protect the wire and the amp rating is chosen accordingly, and the manufacture recommended it because UL does, and it’s still a bit of a grey area.

[John in Santa Cruz]

Originally Posted by dleverton

Your right that if the short circuit current of the panel is less than the fuse value...what’s the point? Two points: fuses are to protect the wire and the amp rating is chosen accordingly, and the manufacture recommended it because UL does, and it’s still a bit of a grey area.

fuses are there to prevent fires. they do this by keeping the wiring from burning up. they can protect a power supply, but they are not there to protect the load.

[Air Doug]

Originally Posted by buff30

Have you ever figured out what your Truck Fridge averages for current draw per day?

I don't have a good number for the Truck Fridge draw. Obviously it is easy to measure while it is running. But how often it runs varies by ambient temperature outside and setting inside. Plus, the upper door hinge mount broke and the fridge door was slowly falling apart without us noticing it. It caused some abnormally high draws until we figured out that the door wasn't closing all the way (condensation at the door seal was the tipoff). After I get that fixed I may be able to get a good number at various fridge settings and outside temperatures, or maybe not. I really would like to not worry about it so that was another reason to get a second battery: I don't have to worry so much about the fridge power budget.

[buff30]

Thanks Doug,

I will eventually figure it out my self. I have my four 60 AH LIFEPO4 cells and my SBMS 120 battery management system. I just need to get it installed and figure out what my actual usage before I buy my full size cells.

[Air Doug]

Gene, I have been paying more attention to the TruckFridge draw. I have a 3 amp charger that I can just leave on all the time if I want to. When I do, it basically keeps up with the fridge and minor light usage. It won't keep up if I am using fans or the water pump a lot.

[buff30]

Thanks for the update Doug! I am still without a fridge but I did get my battery installed.

[parmm]

Thanks for all the good reading info!! Am planning on installing a single Battle Born LiFePO4 in my Scamp 19. Would love to do 2 of them, but... The extent or our boondocking is occasional overnight parking at Walmart type stops on the way to Florida. I prefer someplace cheap where I can plug in. My biggest concern is the cold weather we can get in the winter here in Western NYS around the time we would leave to go south. I remember one winter when it was something like -20F when we left home. Think I prefer to relocate the battery to the inside of the trailer for some heat, maybe under the steps to the bedroom instead of on the outside front of the trailer. Was also planning on using a 12 volt to 12 volt charger, but the idea of a converter is intriguing.

[Air Doug]

Originally Posted by parmm

My biggest concern is the cold weather we can get in the winter here in Western NYS around the time we would leave to go south. I remember one winter when it was something like -20F when we left home. Think I prefer to relocate the battery to the inside of the trailer for some heat, maybe under the steps to the bedroom instead of on the outside front of the trailer. Was also planning on using a 12 volt to 12 volt charger, but the idea of a converter is intriguing.

In the Snoozy, the stock battery is inside and that is where I put the LiFePO4 batteries. In cold weather, I remove the doors to the battery area so they stay warmer. I take them into the garage for storage in the winter. I think that if I had -20F that I would use a space heater in the trailer while packing and install the battery before hitting the road to FL. Sounds like your idea to move the battery inside is sound. Also, several companies, including Battle Born, now make self-heating batteries.

The Victron DC/DC converter is cheap; I really like mine.

[thrifty bill]

Originally Posted by parmm

Thanks for all the good reading info!! Am planning on installing a single Battle Born LiFePO4 in my Scamp 19. Would love to do 2 of them, but... The extent or our boondocking is occasional overnight parking at Walmart type stops on the way to Florida. I prefer someplace cheap where I can plug in. My biggest concern is the cold weather we can get in the winter here in Western NYS around the time we would leave to go south. I remember one winter when it was something like -20F when we left home. Think I prefer to relocate the battery to the inside of the trailer for some heat, maybe under the steps to the bedroom instead of on the outside front of the trailer. Was also planning on using a 12 volt to 12 volt charger, but the idea of a converter is intriguing.

Depends what you are running, but for a single night dry camping, I have found my Group 29 Lead Acid battery in my Escape 19 more than adequate, and its cheap, and uses the original power center. To me, the BB battery starts making sense on longer stays of dry camping, say some National Parks. Even then, so far, my portable solar has worked to keep my battery well charged for week long NP stays.

[parmm]

Originally Posted by thrifty bill

Depends what you are running, but for a single night dry camping, I have found my Group 29 Lead Acid battery in my Escape 19 more than adequate, and its cheap, and uses the original power center. To me, the BB battery starts making sense on longer stays of dry camping, say some National Parks. Even then, so far, my portable solar has worked to keep my battery well charged for week long NP stays.

Ah yes - A Dreamstation CPAP with heated humidity. After many years of lead acid and AGM, the LiFePO4 batteries make all kinds of sense except for the With charging capabilities at temperatures below -4°F!

[thrifty bill]

Yes, if I was speccing a new trailer, I would go lithium for sure! I am not a big fan of lead acid batteries. But they do work OK for many. Once you add CPAP to your requirements, you have to add everything up to see how the load works out. Everything I have read adding heated humidification significantly increases electric use.

[Air Doug]

Update on conversion performance:

We just finished a month on the road and never had to worry much about battery status. One thing that works well is the 3 amp charger, which we run whenever plugged into shore power. That, on average, cancels out the TruckFridge draw and pretty much leaves the batteries at whatever charge they were at. And whenever driving, the DC/DC converter charges up the trailer batteries to full capacity. So, basically, there wasn't a capacity issue.

In one instance we parked the trailer and stayed at a cabin on the other side of a lake. We wanted to make sure that the batteries had enough capacity to run the fridge for three days in hot weathrer. The parking place was not secure so at first we didn't feel comfortable leaving a solar panel out to recharge the batteries. We have a separate panel and battery in the tow vehicle to run an ARB fridge when we are camping without the Snoozy. So we used a jumper from that battery to the 7-pin connector on the Snoozy, which feeds the trailer batteries through the DC/DC converter. That worked great and kept the Snoozy batteries topped off for three days while still running the fridge.

Bottom line, everything works fine and as designed.

[KJK]

Our 2016 Illinois based Lil Snoozy (currenty listed for sale on this forum) was upgraded to a 125ah Life Blue lithium ion Phosphate system in 2019 before taking the trailer to Alaska and back to the lower 48 (mid June - mid July), followed by hosting at a Wyoming campground without hook ups. Even though our 2019 system did not include DC to DC charging from the tow vehicle, we never had to worry about our 12 V truck fridge keeping food fresh.
A Bluetooth ap allowed monitoring our battery during the Alaska trip that consisted of dry camping overnights as well as 15amp electric service. No need for a generator. Instead when dry camping a 100W portable solar panel helped the battery maintain a sufficient 80% state of charge, which of course would have been dangerously low for a lead acid battery.
In 2020 we added a Victron DC to DC converter that allowed charging from the tow vehicle, which proved helpful when travelling during hot and sunny days through New Mexico.
A three way toggle switch allows selecting charging from any 110V source or a DC source (either from solar panel via Victron charge controller, or 7 pin tow vehicle connection via Victron DC to DC controller.
Best battery system we ever had. Unfortunately medical issues have us leave towing behind.