Charging options

[george hirvela]

I have an old truck and Lance camper (80s) I added a 200ah lithium battery, two 100w solar panels with a charge controller, and a 3000w inverter. When I travel long distances with my fridge running off the inverter, it kills my battery. I'd like to add my truck's charging system while towing through the existing 7-pin connection that has a 10awg wire available in the engine compartment. It has a 120-amp alternator and dual AGM batteries. It needs to disconnect automatically when the truck is off. What do I need?

 

[sunshine_eggo]

Is it an absorption fridge that can run on propane?

 

[Suijkerbuijk]

A absorption fridge always run on power .
Trow it in a trash can. (If you use one)
And go for a fridge on a compressor base (12/24volt model)
Low power (35watts vs 120 watt max on a absorption model)

For the rest a dc to dc charger that have a function with a remote control.
That control you hook on your alternator wire (the wire that go to your light on the dashboard) or on switched plus from your starter key .
For a dc to dc see link.
The link is a 12 volt model .
If your alternator is 24volts you need a 24 volts model.

Battery Chargers, battery maintainers, trickle charger for Sale

Renogy provides DC to DC batteries chargers, AC and solar battery chargers, DCC30S 12V 30A Dual Input DC-DC On-Board battery maintainer, trickle charger

www.renogy.com

Or Victron

DC-DC converters - Victron Energy

Victron Energy's DC-DC converters are useful if you do not have a suitable voltage device. Ensure that voltage is converted now.

www.victronenergy.com

Personal go for a Victron

I use a fridge like this

https://www.amazon.nl/Alpicool-elektrische-vrachtwagen-stopcontact-USB-aansluiting/dp/B0C58D53SX/ref=mp_s_a_1_57?crid=1JN6Z39E5CN7N&dib=eyJ2IjoiMSJ9.ajVXjxmR2DoQ8nxAM0wWr15Hq4Q22J3lN8fgqLFGXpyA7znGNGceGDNUI1SwXWQ0ApgS4JLXOKLN3ttJDqrGg9vE_9yoc_jNCeaUgVMAkx8Uh1hJzoEEF_sl7PIZyg6Ce34MtWyDDoVCXWbQXo2IbP4rmO1mo_gPcn6BeH1rvTGl4DMJSI-yfY4hXczsB1ZKptAP6kntvgtHVN5Vlcp91Q.2fnKsgnfFDnmETqt76yYcley0Z9BL02hGsZH75r22JQ&dib_tag=se&keywords=compressor+koelkast+12v+24v&qid=1724957324&sprefix=compressor+koelkast+%2Caps%2C140&sr=8-57

 

[Bop]

Two ways- you can use a dual battery isolator (which is the system used in my ute) vast array of them available but require heavier leads running between the 'house battery' and the starter battery (you need heavier leads to prevent voltage drop- I used welding cable in the ute- for your camper, you might need to use a set of heavy Anderson connectors in the bed)

This is the model I used in my ute (the switch is handy if people leave the headlights on and flatten the start battery- pop the bonnet, flick the switch, wait a minute or so and you can 'jump start' yourself from the house batteries...

The alternative is use a 'DC to DC charger' which uses lighter cables but has a restricted charge current...

(some suggest using LPG/propane while driving- this is often illegal and very dangerous, it was banned in Australia after a spate of caravan fires started by LPG fridges blowing out the igniter flame while driving and filling the caravan (travel trailer for the yanks) full of LPG!!!- here its a fine in excess of $1000 if caught- and forget your insurance...)

Old L/A batts in the ute

Replaced by LYP- fraction of the size and weight- same run time for the fridge!!!

 

[george hirvela]

Is it an absorption fridge that can run on propane?

Yup, works great. I just ran around checking current draws and the fridge was not the problem, it was the inverter. I'm not wanting to run big cable back to the camper with dc to dc charger. Rather spend the money on another battery and more solar. Thanks

 

[sunshine_eggo]

Yup, works great. I just ran around checking current draws and the fridge was not the problem, it was the inverter. I'm not wanting to run big cable back to the camper with dc to dc charger. Rather spend the money on another battery and more solar. Thanks

Those heating elements tend to be 300-350W with a typical ~65% duty cycle depending on ambient conditions and use. You should be able to find the heating element spec for your unit.

I had a 7.6 cu-ft unit that would use 5kWh/day. Your Lithium battery only has 2.56kWh of total available energy, so you can run your fridge for about 12 hours before tapping out the battery.

Sure, your inverter likely uses a non-trivial amount of power, but I assure you, the fridge is the true bastard here.

Your proposed solution is workable, but if it can run on propane while on the road, that's a much better option. If you can't run on propane, I recommend an Orion XS DC to DC charger.

 

[Suijkerbuijk]

Yup, works great. I just ran around checking current draws and the fridge was not the problem, it was the inverter. I'm not wanting to run big cable back to the camper with dc to dc charger. Rather spend the money on another battery and more solar. Thanks

If you go for a dc to dc from Victron.
You can adjust the amps that can be sent.
So you can set it on 10/15 amps on that wire .

This way you can charge the battery with the alternator underway.

Solar panels are great but of you move them those panels will not operate full .

But its what you like to do .
Than do it.
Good luck.

 

[george hirvela]

Those heating elements tend to be 300-350W with a typical ~65% duty cycle depending on ambient conditions and use. You should be able to find the heating element spec for your unit.

I had a 7.6 cu-ft unit that would use 5kWh/day. Your Lithium battery only has 2.56kWh of total available energy, so you can run your fridge for about 12 hours before tapping out the battery.

Sure, your inverter likely uses a non-trivial amount of power, but I assure you, the fridge is the true bastard here.

Your proposed solution is workable, but if it can run on propane while on the road, that's a much better option. If you can't run on propane, I recommend an Orion XS DC to DC charger.

on an average I'm told a 3000w inverter uses 20amps, my fridge uses 2.78amps per my meter

 

[george hirvela]

Those heating elements tend to be 300-350W with a typical ~65% duty cycle depending on ambient conditions and use. You should be able to find the heating element spec for your unit.

I had a 7.6 cu-ft unit that would use 5kWh/day. Your Lithium battery only has 2.56kWh of total available energy, so you can run your fridge for about 12 hours before tapping out the battery.

Sure, your inverter likely uses a non-trivial amount of power, but I assure you, the fridge is the true bastard here.

Your proposed solution is workable, but if it can run on propane while on the road, that's a much better option. If you can't run on propane, I recommend an Orion XS DC to DC charger.

Using propane while driving they say is dangerous, I've done it often...

 

[sunshine_eggo]

on an average I'm told a 3000w inverter uses 20amps,

I suspect you meant 20W as that's pretty typical for a decent HF inverter. If it were a complete piece of garbage, it would only burn about 50W, so yes, your inverter is consuming power, but it's a very small portion.

my fridge uses 2.78amps per my meter

Your fridge is using 2.78A * 120V = 333.6W (sounds kinda familiar)

Using propane while driving they say is dangerous, I've done it often...

As have I.

So, you have two options... DC-DC charger or propane.

 

[Suijkerbuijk]

I suspect you meant 20W as that's pretty typical for a decent HF inverter. If it were a complete piece of garbage, it would only burn about 50W, so yes, your inverter is consuming power, but it's a very small portion.



Your fridge is using 2.78A * 120V = 333.6W (sounds kinda familiar)



As have I.

So, you have two options... DC-DC charger or propane.

330 watts lol.

My fridge use 35watts and deep freeze use 65watts.
50l freeze
65l fridge (15l freeze beult in)

 

[Bop]

on an average I'm told a 3000w inverter uses 20amps, my fridge uses 2.78amps per my meter

A 3000W inverter can put OUT over 20A- at 120v- when putting out to its maximum output...

It will draw (assuming your battery is a 12v one) approximately 250A from the battery while doing so... so it is 'using' 250A to make 25A' basically (W=VxA)
If your inverter is 'idling' at 20A coming in with no load- buy a new one (and a different brand!!!) thats a horrible idle draw... (240W at 12v)


Re 'propane' while traveling- lots of people say 'I dunnit no probs'- right up until the time they come online going 'my truck is alllll burned up and exploddeded- whhhyyyyy??????'

It's why it was banned from being used while mobile here- too many people lost their caravans because of using LPG while driving...

You can most certainly play Russian Roulette if you please- thats most certainly your right to do so...
Just don't complain when it goes pearshaped...
(and don't try and palm it off onto others by claiming insurance, rates are high enough already- claim that stupidity and wear it with pride...)

 

[sunshine_eggo]

330 watts lol.

Very typical for an absorption fridge.

My fridge use 35watts and deep freeze use 65watts.
50l freeze
65l fridge (15l freeze beult in)

LOL

You: 65L fridge, 65L Freezer for 100W total

Me: 210L (323%) fridge with 76L (17% more) freezer only uses 54W total

Off:



On:



.8-.9kWh/day

 

[sunshine_eggo]

A 3000W inverter can put OUT over 20A- at 120v- when putting out to its maximum output...

It will draw (assuming your battery is a 12v one) approximately 250A from the battery while doing so... so it is 'using' 250A to make 25A' basically (W=VxA)
If your inverter is 'idling' at 20A coming in with no load- buy a new one (and a different brand!!!) thats a horrible idle draw... (240W at 12v)


Re 'propane' while traveling- lots of people say 'I dunnit no probs'- right up until the time they come online going 'my truck is alllll burned up and exploddeded- whhhyyyyy??????'

It's why it was banned from being used while mobile here- too many people lost their caravans because of using LPG while driving...

You can most certainly play Russian Roulette if you please- thats most certainly your right to do so...
Just don't complain when it goes pearshaped...
(and don't try and palm it off onto others by claiming insurance, rates are high enough already- claim that stupidity and wear it with pride...)

View attachment 240126

How many absorption fridges have malfunctioned when completely stationary and burned down an RV? More than zero.

Where are the precautions against using in windy conditions? My propane fridge regularly experienced 20-50mph winds just sitting there. Why is that okay but use while driving isn't - where the wind is typically less of an issue than being broadsided @ 50mph?

Do you eat sausage or bacon or any other processed meat? Yeah? You have a 20% increased likelihood of pancreatic cancer. Oh Noez! Wait... okay, so even if you don't eat that, you have a 1.0% chance of pancreatic cancer vs. 1.2% if you do.

Didn't the government tell us that butter bad and margarine good/healthier? Oh... wait... now they're saying to avoid trans fats altogether.

Life is simply about risk management. The government's rules aren't always a good guideline for meaningful risk management decisions.

 

[RinVt]

You could use a solenoid and it can activate when your truck is running. I did that so I could have a hot lunch while flagging in the cold of winter.

 

[Suijkerbuijk]

Very typical for an absorption fridge.



LOL

You: 65L fridge, 65L Freezer for 100W total

Me: 210L (323%) fridge with 76L (17% more) freezer only uses 54W total

Off:

View attachment 240128

On:

View attachment 240129

.8-.9kWh/day

Can not set bigger in a boat .
And a boat fridge of 65l kost about 500euro.
Fridge for 100l cost about 800 euro.
But all run on 12/24 volts

The 65l and up to 120l.use the same compressor.
So it means 35watts for a 120l