Too much battery?

[RandyDaytona]

Is there such a thing? Disclaimer: I’m a fairly non-tech-savvy person regarding batteries. I’m looking at the EcoFlow batteries and similar and seeing how everyone uses them. I’m thinking I may not need that much power.

I have recently set up my fridge in the back of my 200. It previously lived in my work truck and was plugged into a socket that was always on, and since I drove it every day, it was a non-issue.

But now, for the first time, I’m considering adding a battery to the mix. I figured I would plug my fridge into a small battery, which would then be plugged into the DC socket in the LC cargo area and would charge when the vehicle runs. When I stop for the night, the battery would run the fridge until morning, soon after which I’d hit the road again.

Is there a better-sized (or better suited) battery for this kind of application? Maybe one that takes up less space? Sorry if this seems like an ignorant question!

Edited to add: I would not be powering anything else. Just the fridge, which is admittedly probably older than most mud members , if that has any bearing on power requirements.

 

[Mike6158]

Nope. All you need to do is make sure the voltage is the same. Battery A/hr ratings are just that, a rating for how many amps per hour you can pull out of the battery before pulling the voltage too low. Renogy.com is a more wordy

Amp-hours, or Ah for short, are a unit of measure for a battery's energy capacity. This rating tells us how much current a battery can provide at a specific rate for a certain period. So, for example, if you have a fully-charged 5-Ah battery, it can provide five amps of current for one hour.

I have a LiFePO4 battery that I carry with me that is 70Ah. I can run 7 hours at 10A (but I wouldn't) and longer if I connect it to a solar panel.

 

[sdnative]

If all you are powering is a fridge overnight, and you are able to recharge the battery fully every day (whether driving with DC/DC or stationary with solar), you won't need much capacity. I would think 40Ah/500Wh of usable capacity (probably even less than that) should be more than sufficient. I am assuming you are considering LiFePO4 batteries.

Fridge power consumption varies, but my insulated ARB consumes less than 1 Ah / hr when full and contents have reached temperature equilibrium.

 

[e9999]

If your current setup of one battery works for you, there may not be a need to do anything different. Now, is it a good approach? I don't think so, mostly because I would not want to take a chance on the only battery getting discharged and being stranded. But if yours won't get discharged too much, then it works. What is your rationale for going the new way?

As to adding another battery, there are some complications, such as mixing different types like lead acid and lithium, isolation, charging schemes, etc, but this a bit more complicated than looking at just basic capacity issues. Otherwise, then, just from an energy point of view based on your scenario, adding another battery is equivalent to having a bigger one under the hood. So, figure out what is the longer period you expect to experience without charging, calculate fridge use for that period, give it a bit of safety margin, and you'll know how to size it, given how much you want to discharge it. (If you don't, there are plenty of info on that out there that is worth getting familiar with.)

As to the type, if it were me, I'd start by looking at the newer small size 100Ah LiFeP batteries. Pricier than lead AGM probably but much lighter and way longer life expectancy so I suspect it may be a toss up or -likelier I think- cheaper long term. But you should not just connect Lithium and lead directly. You would not want to put a flooded lead acid in the back, either, though, cuz of fumes, spilling etc, but having an AGM in the back would make things much simpler than lithium in terms of connections.

Don't just put any battery in the back, connect it in parallel and call it a day, there are issues like I mentioned above that have to be addressed. And make sure it is held in place properly cuz a loose heavy battery may barrel through the seats and through you if you ever have a serious frontal hit. Or would become a blender if you were to roll over.

Also, rereading your OP, and to be clear, keep in mind that with the setup you described, you would not have just the back battery running the fridge, it would always be both.

 

[Mike6158]

This is an example of a good way to protect your ability to start. There are quite a few out there.

 

[LandLocked93]

Is there such a thing?

No, actually.
The key is charge/re-charge abiltity.

I have recently set up my fridge in the back of my 200.

So...in terms of current draw, what does the fridge you have draw? (with voltage drop included)
And I'm talking max current draw. (startup mainly)
Design the wiring to that.
This ensures all other current draw amounts are covered.

But now, for the first time, I’m considering adding a battery to the mix. I figured I would plug my fridge into a small battery, which would then be plugged into the DC socket in the LC cargo area and would charge when the vehicle runs. When I stop for the night, the battery would run the fridge until morning, soon after which I’d hit the road again.

Ok. But ensure that the "small battery" has the capacity to run your fridge over the night hours.
And that capability is calculated relative to the max and min current draw of your fridge.

Is there a better-sized (or better suited) battery for this kind of application?

Beyond the capacity calculations, re-charging said battery is the next concern.
There are probably only 2 ways to do this, depending on batt chemistry and charge-wire length.

 

[RandyDaytona]

Wow - awesome information guys!

I actually carry around a commercial-grade jump pack. Bigger than necessary and a long story, but I’m not too worried about being stranded.

The reason for the change is that my old govt truck had a DC plug that was always on. And even if I didn’t drive it the next couple of days, the fridge would keep going and the truck would *usually* start anyway. In my LC, however, the rear/cargo DC plug is not always on, so when I stop, it stops. And I’d like it to keep chilling. I know there are ways to change it so it’s always in, but I’d prefer not to go that route.

I’ll have to make sure of the power draw when I get back home, but I believe I read somewhere that it was something like 3.5 amps. It’s a Norcold Tek II. I believe it’s from the 1980’s. Maybe earlier. Got in on Craigslist around 2015 from a guy who used it solely for his annual Lake Michigan fishing trip and it was in mint condition.

Thanks everyone!

 

[LandLocked93]

Wow - awesome information guys!

I actually carry around a commercial-grade jump pack. Bigger than necessary and a long story, but I’m not too worried about being stranded.

The reason for the change is that my old govt truck had a DC plug that was always on. And even if I didn’t drive it the next couple of days, the fridge would keep going and the truck would *usually* start anyway. In my LC, however, the rear/cargo DC plug is not always on, so when I stop, it stops. And I’d like it to keep chilling. I know there are ways to change it so it’s always in, but I’d prefer not to go that route.

I’ll have to make sure of the power draw when I get back home, but I believe I read somewhere that it was something like 3.5 amps. It’s a Norcold Tek II. I believe it’s from the 1980’s. Maybe earlier. Got in on Craigslist around 2015 from a guy who used it solely for his annual Lake Michigan fishing trip and it was in mint condition.

Thanks everyone!

The "always on" DC outlet in the gov't truck is just a wiring thing.
Your 200 that switches off the DC outlet to which the fridge is connected is also just a wiring thing.

Recommend a DC to DC charger that contains charge profiles (Renogy, RedArc) or battery bank (Jackery, Zero, etc) to keep the small battery topped off while you drive. A direct wire from small batt to DC outlet can work but it's neither efficient nor fully effective. And could be dangerous in some situations.

 

[ntsqd]

Since the Power Port goes dead with the key off that's a pretty good battery separation method.

I would suggest looking into the lithium option too. It hits all of your bullet points. The charging of it is really the only question. An issue with any lead-acid battery is that you can only really use about 1/2 of it's rated capacity. Drawing more than that is good way to drastically shorten the life-span of the battery and even drawing down to a 50% State of Charge is not a great idea. So a 100 AHr rated lead-Acid battery is usefully really only about a 40 AHr battery. I'm reading that lithium batteries can be drawn dead flat, but I expect that's over exuberant marketing and the reality is somewhere in the 80%-90% range if you want the longest battery life.

Truth is that you could probably run the fridge off of that jump-starter that you carry. Not that I would, but that you can. If you can figure out a way to log how many amps it uses in a typical day I suspect that you'll find that such a battery won't need to be very big (physically or AHr capacity) to run the fridge w/o charging for a couple of days.

 

[AndrewHadji]

i have 400AH of 12 v in the troopy, it is too much battery for the manager 30.... limited to 30 amps recharge rate, it takes me 8-10 hours from 10 % abouts. @LandLocked93 has it right, you can have a huge bank, but if you cant recharge them fast enough, or at least fast enough to replenish demand.... yea... i really enjoy not having relying on propane for cooking or heat or hot water. a typical day of stay in a spot camping takes me down to 85% abouts.

 

[RandyDaytona]

Thanks guys.

I ended up ordering an EcoFlow Delta2, which arrived this week. I’m just starting to set it up (though everything is pretty well “set up” already, right out of the box).

Thanks again!

 

[RandyDaytona]

Follow up on EcoFlow and weighing other options:

Hi guys,

I received the EcoFlow Delta2, charged it up, and headed out on my second multi-week road trip immediately afterwards.

As I stated in the earlier post, I simply wanted it to run my fridge at night. Then I’d charge it while driving the next day.

Did it work? Yes and no. It ran the fridge fine at night. I added a small fan to the mix and it handled that, too. But recharging the next day was painfully slow. I mean like 6-8 hours of driving to recharge it from 40% back to full.

I did some more digging on EcoFlow batteries and even contacted their customer service folks. Apparently, this is normal. However, this really doesn’t work in an overlanding situation where you may want to camp somewhere for more than one night. And to my surprise, this was never fully addressed on EcoFlow’s website. They simply threw up the big splash screen that said “charges 80% in 50 minutes” without telling you that they were talking about charging that fast if using a wall plug.

So now I’m looking for options and soliciting suggestions from the IH8MUD brain trust.

Failing a way to charge the EcoFlow A LOT faster, I’m open to the dual battery option.

If I go that route, I’d like to have all the plug-ins connected to the second battery and have them be always on, even when the truck is off. Is that how it’s normally set up?

I was looking at the LC 200 second battery bundle on Slee’s website with the thought of ordering that and have my local shop install it, since it appears to include everything you need except the actual battery. But the rep I spoke with there said the setup might be too involved for a local shop (as an example, he said Slee normally charges 5K for that, with parts and labor). He also said the bundle doesn’t include the wiring. So that option may be a non-starter.

Any other options?

 

[ntsqd]

Might consider putting something like this wattmeter between your EcoFlow and everything else. Then you can see what your actual power use is.

From there you can make decisions on how much battery you need, what size it can be at max, etc.

Given that you're working with a 200 series I am reasonably sure that it has a "Smart Alternator", which means that you will need a DC-DC converter to charge the second battery.

Generally, where are you located? 5K sounds like a LOT for a second battery install. I'd have guessed it at roughly 1/2 that for a reputable shop to do the work.

 

[e9999]

well, how fast your aux house battery / Ecoflow charges is a function of 1) what it can accept and 2) what you can provide. 1) should be in the specs. 2) will be a function of the hardware you use for charging and the wiring size. Now, say, your Ecoflow battery is 1kWh, and say you use a DC-DC that can provide 30A, you should be able to charge it fully from zero in about 4 hrs or so, but that's only if the Ecoflow can handle 30A. If it will only accept 10A like many, and you use a cigarette lighter plug, say, then yes it will take 10+ hrs.

Note that if the Ecoflow will accept a higher input power in AC mode than in DC mode, you could always use an inverter to go between your main battery and your Ecoflow, charging would then be faster, but there will be additional losses and expenses.

 

[ntsqd]

I gave some thought to suggesting the inverter route. It just rattles my OCD to do something like that and passed.

 

[FrazzledHunter]

Follow up on EcoFlow and weighing other options:

Hi guys,

I received the EcoFlow Delta2, charged it up, and headed out on my second multi-week road trip immediately afterwards.

As I stated in the earlier post, I simply wanted it to run my fridge at night. Then I’d charge it while driving the next day.

Did it work? Yes and no. It ran the fridge fine at night. I added a small fan to the mix and it handled that, too. But recharging the next day was painfully slow. I mean like 6-8 hours of driving to recharge it from 40% back to full.

I did some more digging on EcoFlow batteries and even contacted their customer service folks. Apparently, this is normal. However, this really doesn’t work in an overlanding situation where you may want to camp somewhere for more than one night. And to my surprise, this was never fully addressed on EcoFlow’s website. They simply threw up the big splash screen that said “charges 80% in 50 minutes” without telling you that they were talking about charging that fast if using a wall plug.

So now I’m looking for options and soliciting suggestions from the IH8MUD brain trust.

Failing a way to charge the EcoFlow A LOT faster, I’m open to the dual battery option.

If I go that route, I’d like to have all the plug-ins connected to the second battery and have them be always on, even when the truck is off. Is that how it’s normally set up?

I was looking at the LC 200 second battery bundle on Slee’s website with the thought of ordering that and have my local shop install it, since it appears to include everything you need except the actual battery. But the rep I spoke with there said the setup might be too involved for a local shop (as an example, he said Slee normally charges 5K for that, with parts and labor). He also said the bundle doesn’t include the wiring. So that option may be a non-starter.

Any other options?

Possible thread derail but I totally get what you're saying:
" They simply threw up the big splash screen that said “charges 80% in 50 minutes” without telling you that they were talking about charging that fast if using a wall plug. "

This is the great sleeper on these portable batteries. The vendors of the batteries just don't get it. It's as if they think off grid folks have on grid AC power to charge their batteries while off grid!!!

Goal Zero is the only vendor AFAIK that can charge at high wattage directly from DC.

On a Goal Zero ALL charging* is done via the solar input which is max 600W. The plug in the wall chargers emulate a solar panel and plug onto the solar dc input. I charge it from my vehicle via a Victron 12|24-15 at the rate of 360W. But, if you have the DC wattage to charge it from any source then so be it.

*Goal Zero has a separate car charger that is an add on accessory that doesn't use the solar input and can charge at the rate of 600W.

 

[e9999]

The big issue overall with all this kind of stuff is that if you work with only 12V DC, you do need big amps to get any sort of reasonable power available. And that means bigger wires. (All of the former highly subjective of course.)

 

[FrazzledHunter]

The big issue overall with all this kind of stuff is that if you work with only 12V DC, you do need big amps to get any sort of reasonable power available. And that means bigger wires. (All of the former highly subjective of course.)

With my setup I have 100+ A at the bumper so I could in theory have 2 Victron 12|24-15 chargers in parallel charging the Goal Zero 1500X.

 

[ntsqd]

I wired the truck battery to camper battery circuit before DC-DC converters were common in high(er) amperages. Charging the camper batteries directly meant that I had to pay attention to voltage drop over the whole circuit length. Which including the ground cable ended up being 25-30 feet. After a bunch of research I concluded that the max charging current that I could ever expect was 80 amps. I used the Ancor Marine resources page to help with sizing the cables for 80A over that circuit length with a 3% or less voltage drop. 6 gauge cable is what was called for. Any smaller gauge would have throttled the charging and resulted in a lot of heat.

 

[RandyDaytona]

Might consider putting something like this wattmeter between your EcoFlow and everything else. Then you can see what your actual power use is.

From there you can make decisions on how much battery you need, what size it can be at max, etc.

Given that you're working with a 200 series I am reasonably sure that it has a "Smart Alternator", which means that you will need a DC-DC converter to charge the second battery.

Generally, where are you located? 5K sounds like a LOT for a second battery install. I'd have guessed it at roughly 1/2 that for a reputable shop to do the work.

Good info - thanks. I’m in MN, but the price was in CO.