Boondocking on lithium batteries?

[jeffb831]

Originally Posted by Troutboy

Has anyone tried this. Interesting concept. Use your tow vehicle as a backup generator…

https://www.cargenerator.com/

The pros and cons have been discussed here:
https://www.airforums.com/forums/f38...or-230220.html

and here:
https://www.airforums.com/forums/f44...or-227281.html

[pteck]

Originally Posted by tusocks

We will be receiving our 2023 27 GT in two months and was hoping to install 2 SOKs batteries. Originally I thought about installing two of the 100 Ah batteries but there is no way that they will fit into the battery box that comes from the factory. Therefore I was thinking about installing two of the 206 Ah batteries and I assume that you installed those in the baggage compartment that is directly behind the battery box on the outside of the trailer. Is that correct?
Two other questions: have you had much “wobble” in your dinette table and if so have you done anything to try to lessen that question? Also, how is the 27 GT been working out for you?
Thanking you in advance for your response
Mark & Jeannie

Lithium batteries, because of their more limited temperature handling, are better suited inside. Both winter and summer can push outside of their thermal boundaries where they won't like to charge and may have diminished power output. They like temps that people like, so are aligned to interior temps. Putting them in the battery box may also limit your ability to expand the bank, as batteries should ideally be wired together with similar wire lengths.

Originally Posted by Troutboy

Has anyone tried this. Interesting concept. Use your tow vehicle as a backup generator…

https://www.cargenerator.com/

It wouldn't be my first choice.

Rarely talked about, but if you need an alternative, backup, or expanded power capacity, I'd look into a portable lithium battery. Something in the 1000Wh/100Ah range. These can be charged in the car when towing via cig lighter adapters. Or there's more powerful options. When the trailer needs power, these can charge the trailer via an inverter and 120V, to the trailer converter. That can be done quietly without firing up the TV to idle for hours. Or use the battery more directly for luxuries such as blender, coffee maker, charging cell phones/laptops. That'll make the existing trailer battery capacity go farther.

Goal Zero, Jackery, Bluetti, there's tons of great options these days.

[uncle_bob]

Hi

There is no single answer to any of this. If you are careful about it, you can indeed put part of the battery bank indoors and the other part outdoors. There's only so much room for things in an RV. Is it optimum? Probably not. We've been running that way for 5 years of pretty heavy usage. It all runs fine for us.

Lithiums do not like to charge below freezing. They are fine at discharge. Their capacity loss at cold actually is less than a lead acid battery (yes, that's really weird). If you plan to camp a lot in the snow, there are a number of things to consider. Batteries are on that list, but far from the only item. I would suggest that an AS is not the perfect snow camping RV ....

Unmentioned so far is matching batteries. Best practice is to build the entire bank up out of same / same batteries. Same brand, same model, same capacity, same manufacture date. Mixing brands is probably the worst error. There are a number of examples of this or that brand / model not playing nice with other brands.

Bob

[Winder119]

(I’ve subscribed to this thread, as this is an interesting thread)

On a practical note.

- these type of batteries in my research appear to *very* expensive. Putting inside might add an element of security that a locked battery box won’t.

- would putting them inside remove some tongue weight, or would that be marginal?

Thanks all for your marvellous insights!

[foobar]

Originally Posted by Winder119

(I’ve subscribed to this thread, as this is an interesting thread)



On a practical note.



- these type of batteries in my research appear to *very* expensive. Putting inside might add an element of security that a locked battery box won’t.



- would putting them inside remove some tongue weight, or would that be marginal?



Thanks all for your marvellous insights!

Deep cycle group 27 batteries (for example) weigh as much as 60 - 70lbs or so.

Airstream uses 2 batteries.

So you are looking at 120-140lb reduction in tongue weight. This is definitely significant if you are challenged in terms of tongue weight and/or tow vehicle cargo capacity.

[field & stream]

Originally Posted by Winder119

(I’ve subscribed to this thread, as this is an interesting thread)

On a practical note.

- these type of batteries in my research appear to *very* expensive. Putting inside might add an element of security that a locked battery box won’t.

- would putting them inside remove some tongue weight, or would that be marginal?

Thanks all for your marvellous insights!

Simply replacing lead acid with lithium will reduce tongue weight by 60-70 pounds. Moving them inside to the front of the trailer will reduce a little more, moving them to behind the axle(s) will have more effect. Is it “marginal”? Yes, but since many of us are on the margin it could still be significant.

An inside location adds security and some shelter from the cold.

[tusocks]

Originally Posted by uncle_bob

Hi

I believe you will find that there are a number of 100AH lithium batteries that fit in the factory battery box. No, you aren't going to get more than 200AH of lithium in there. If you are after 400AH or more, it's gotta go someplace else ( or at least part of it does).

There are a *lot* of choices about where to put lithiums. Since they don't have the venting issues that lead acid's do, they can go just about anywhere. Under this or under that, it all seems to work. We have 200AH under the center of the sofa in the Classic.

On a 2023 you will have a compressor fridge. They pull a non-trivial amount of power. It goes out while you are towing as well as when you are camping. Unless you put in a DC / DC converter for charging while towing, the "on route" power drain gets added to your drain at the campsite.

Some math:

If the fridge averages 3.5 AH an hour ( who knows ...) then you run 24 x 3.5 = 84 AH a day running the fridge. In 5 days, the fridge all by itself kills 400AH of batteries.

If you drive 4 hours a day and charge at 10A while doing so, you get 40AH a day back from the drive. You can now drive for almost 10 days before the fridge by itself kills your 400AH of battery.

Yes, this all is part of why many of us run solar .....

Bob

Appreciate your thoughts regarding my lithium concern.
I will have a total of 460w of solar power along with 3 to 400Ah of lithium batteries.
Regarding your comments of charging from my vehicle while driving I have a 2022 F250 diesel with max tow package & therefore I would assume that it would automatically be configured for DC/DC charging while driving. Am I wrong in that assumption?
Thanks once again for the info-
Mark

[uncle_bob]

Originally Posted by tusocks

Appreciate your thoughts regarding my lithium concern.
I will have a total of 460w of solar power along with 3 to 400Ah of lithium batteries.
Regarding your comments of charging from my vehicle while driving I have a 2022 F250 diesel with max tow package & therefore I would assume that it would automatically be configured for DC/DC charging while driving. Am I wrong in that assumption?
Thanks once again for the info-
Mark

Hi

Unless you have a DC/DC converter and it's properly configured, no you will not be charging lithiums as you go down the road.(even with an F250 ...).

There are a couple of things you run into:

1) The truck is set up to charge lead acid batteries. It does it's thing to keep the truck batteries happy and un-damaged. Lithiums want higher voltages than lead acid's.

2) The wires back to the trailer are pretty small. That gives you a pretty significant voltage drop as you pull current. If fractions of a volt matter, a drop of a volt or three is a really big deal.

So you put in a DC/DC converter. It takes the anemic voltage from the 7 pin and turns it into something the lithiums like. Problem solved right ? nope ....

You are right back to the voltage drop with current issue. That nice big 30A DC/DC you bought fires up. The voltage drops. The DC/DC shuts down. It times out and tries again. Net result is no charge to a battery that needs it. It will do a fine job for a battery that needs no current

The answer is a programable DC/DC that lets you tune the output voltage ( which you already had to match the lithiums ) *and* tune the current. The first is easy to find, the second may take a bit of looking. Tuning the input voltage limit also is possible.

On my F350 the DC/DC puts about 15A into the batteries. The voltage at the input to the converter is 11.5V most of the time. Since the output is at (maybe) 14V, the input current is quite a bit more than 15A. On the van, MB has a 15A fuse and even smaller wire. The DC/DC that goes with it is set much lower ....

Bob

[pteck]

Agreed with Bob. A DC-DC charger is key for lithiums. Actually, it's a boon to lead acids too, to get more meaningful charge at the trailer.

Lithiums really do need the DC-DC for charge, but also proper isolation from the tow vehicle electrical as some may cause the lithium to not fully charge or even reverse charge.

Popular 18A Victron or 20A Renogy DC-DC units generally work great for most stock 7-pin wiring.

[foobar]

Originally Posted by pteck

Agreed with Bob. A DC-DC charger is key for lithiums. Actually, it's a boon to lead acids too, to get more meaningful charge at the trailer.

Lithiums really do need the DC-DC for charge, but also proper isolation from the tow vehicle electrical as some may cause the lithium to not fully charge or even reverse charge.

Popular 18A Victron or 20A Renogy DC-DC units generally work great for most stock 7-pin wiring.

Agree with ptech and Bob.

I have 30amp 7pin charge capability on my Cayenne.

However, I installed the victron smart 18amp 12v - 12v DC-DC charger instead of the 30amp charger in order to avoid the cyclical reset problem that Bob described above.

[uncle_bob]

Originally Posted by foobar

Agree with ptech and Bob.

I have 30amp 7pin charge capability on my Cayenne.

However, I installed the victron smart 18amp 12v - 12v DC-DC charger instead of the 30amp charger in order to avoid the cyclical reset problem that Bob described above.

Hi

I started off with the 18A Victron Orion ( the one with no current programability ). It would not work with the wiring on the F250 or the wiring on the F350.

The fuse on the circuit is a 30A. You can pull 30A without anything catching fire. You will have near nothing for voltage when you do, but it's a 30A circuit .... weird .....

Bob

[foobar]

Originally Posted by uncle_bob

Hi



I started off with the 18A Victron Orion ( the one with no current programability ). It would not work with the wiring on the F250 or the wiring on the F350.



The fuse on the circuit is a 30A. You can pull 30A without anything catching fire. You will have near nothing for voltage when you do, but it's a 30A circuit .... weird .....



Bob

Which one is programmable? In case my 18A doesn't work either and I need to swap it out for the one that is.

Dang it, I thought I was buying the programmable version.

[pteck]

Another couple possibilities is to spend the effort to upgrade the 7-pin wiring of the car. Or possibly bypass that to add an Anderson plug alongside. Aussies love the Anderson solution.

With ~25 amps or more, it's possible to run the fridge via electric on the road (either directly or via inverter depending on your fridge) , and still meaningful charge the battery bank

[richard5933]

Originally Posted by pteck

Another couple possibilities is to spend the effort to upgrade the 7-pin wiring of the car. Or possibly bypass that to add an Anderson plug alongside. Aussies love the Anderson solution.

With ~25 amps or more, it's possible to run the fridge via electric on the road (either directly or via inverter depending on your fridge) , and still meaningful charge the battery bank

I went with this option, running a pair of 6 ga wires from the battery to and Anderson on the back of the truck. Really didn't take too long to do this - took me longer to run them through the woven loom than to run the wires through the truck. Gives me lots of future proofing if I need to upsize me DC-to-DC.

[uncle_bob]

Originally Posted by foobar

Which one is programmable? In case my 18A doesn't work either and I need to swap it out for the one that is.

Dang it, I thought I was buying the programmable version.

Hi

They have an Orion Smart that looks like it can be programed for current:

https://shop.pkys.com/Victron-Energy...er_p_8042.html

The "king of the hill" ( and the one AS used in our van) is:

https://shop.pkys.com/Victron-Energy...er_p_7854.html

After the issues with the dumb one, I simply went with the one AS uses. No that's not the low cost approach.

For our "use case", the power from the 7 pin is plenty good enough. We stay topped off when in motion. No worries about frying alternators or any of that stuff ....

Bob

[richard5933]

Originally Posted by uncle_bob

Hi



They have an Orion Smart that looks like it can be programed for current:



https://shop.pkys.com/Victron-Energy...er_p_8042.html



The "king of the hill" ( and the one AS used in our van) is:



https://shop.pkys.com/Victron-Energy...er_p_7854.html



After the issues with the dumb one, I simply went with the one AS uses. No that's not the low cost approach.



For our "use case", the power from the 7 pin is plenty good enough. We stay topped off when in motion. No worries about frying alternators or any of that stuff ....



Bob

I've got one of these... Did you see a way to limit the current output? I've only found ways to set the charge voltages.

[foobar]

Originally Posted by uncle_bob

Hi

They have an Orion Smart that looks like it can be programed for current:

https://shop.pkys.com/Victron-Energy...er_p_8042.html

The "king of the hill" ( and the one AS used in our van) is:

https://shop.pkys.com/Victron-Energy...er_p_7854.html

After the issues with the dumb one, I simply went with the one AS uses. No that's not the low cost approach.

For our "use case", the power from the 7 pin is plenty good enough. We stay topped off when in motion. No worries about frying alternators or any of that stuff ....

Bob

Thanks. My installation uses the ORI121222120 Orion-Tr Smart charger. I'll find out if it is programmable when I pick up my trailer from A&P Vintage Trailer Works in a couple of weeks.

[foobar]

Originally Posted by richard5933

I've got one of these... Did you see a way to limit the current output? I've only found ways to set the charge voltages.

Which one of the two do you have richard5933?

[richard5933]

Originally Posted by foobar

Which one of the two do you have richard5933?

Victron Energy Orion-Tr Smart 12/12-Volt 18 amp 220-Watt DC-DC Charger, Isolated

This is what I have. Works well, currently set with the BB charging parameters. Didn't see any way to set a current limit. Not sure I need one now that I've got the 6 ga wires feeding it, but when I was using the 7-wire harness to feed I think it would have been ideal.

[OrangeCrush]

I am using the Orion Smart 12/12-18amp isolated with 2022 F250 stock 7 pin charge line which is 10 gauge charge/ground on a 30 amp circuit. It is working well for me but with Battleborn parameters but the Vin drops as low at 10-11V when charging at 18A in Bulk mode. Key to success for me was: 1) Drop the lock-out voltage down to 10V or lower and set restart to 10.5 or so. 2) Turn off the engine start detect algorithm if you have a smart TV plug as it will get confused and is unnecessary. I too can not find any way to throttle the max current with this device. The other thing that was a disappointment for me is that it will not work with VE smart networking so if you have solar charging simultaneously they will not coordinate states.