battery charging from tow vehicle

[John in Santa Cruz]

hair dryers are quite typically 1200-1500 watt devices.

[CarlD]

John, I was thinking along the lines of SpaceBalls.

[CarlD]

Originally Posted by Travellers

Hi folks. Woohoo. First contribution to the forum.

We built (or more assembled) a 10 amp DC to DC converter so the tow vehicle would charge the trailer battery at a better charge voltage. So 14.4 instead of 12.1 or whatever voltage was on the end of the charge line from the tow vehicle. The voltage drop is significant. The current is a little less but the voltage (or pressure) is a more appropriate voltage. We got a couple of meters off of amazon so we could see the voltage coming in and going out. We mounted it all in a little craftsman toolbox and it goes nicely in a cubby close to the AGM batteries (which is under the bed).

Anyway, just an idea. I'm a tinkerer so it was a fun little project. We like short travel days but even after a couple or three hours we are able to restore a reasonable amount to the 2 X 6 volt AGM's.

Here is a pic or two. It's on the bench here but tow vehicle 12 volts comes in the left, corrected charge voltage headed for the 2 X 6 volt AGM.s heads out the right.





Safe travels all.

I have a concern with your design. The Victron DC-DC is what is known in the industry as a constant current, constant voltage power supply. If the load on the power supply is greater than it's maximum output capability the device will reduce the voltage until maximum current is output. As the load decreases the voltage will rise until the voltage setpoint is reached. It is ok to charge a LFP battery this way, however you can damage a lead acid battery by overcharging it, because the voltage will not reduce like a battery charger does. What you really need is a DC-DC battery charger. I suggest you investigate something similar to this.
https://www.renogy.com/12v-20a-dc-to...YaAiS2EALw_wcB

[John in Santa Cruz]

Hmm? My Victron Orion Tr 12/12-18 has modes for lithium charger, lead acid charger, and simple power supply. See the manual here,
https://www.victronenergy.com/upload...Charger-en.pdf

[CarlD]

Jon,

He has the 12-12 9 amp unit, same as me. It is not a battery charger. The 18 amp version obviously is.

Carl

[Travellers]

Yah. It has to be operated manually. But in the application where we have it, that is essentially how we operate it. Our tow vehicle is a Tesla. When our trailer vehicle gets low we are able to just plug into an auxiliary port on the Tesla and bring the battery up to a reasonable charge. The aux ports stay active when in Sentry mode. The problem is the aux ports can only provide 16 amps peak and 12 amps avg. so a 20 amp charger is not an options. Works well though. It’s kind of like having an 82 kWh trailer battery. Lol ��.

[John in Santa Cruz]

ahhh, there's an Orion-Tr *converter* and an Orion-Tr *charger*, and each of these comes in Isolated and non-Isolated versions each of these 4 combinations comes in different capacities.

edit, oh, and not all of them are 'smart' with the bluetooth interface.

[Travellers]

Originally Posted by John in Santa Cruz

ahhh, there's an Orion-Tr *converter* and an Orion-Tr *charger*, and each of these comes in Isolated and non-Isolated versions each of these 4 combinations comes in different capacities.

They really do have lots of cool stuff for tinkerers like me.

[John in Santa Cruz]

Originally Posted by Travellers

They really do have lots of cool stuff for tinkerers like me.

yeah. sadly a lot of the AC inverter kinda stuff is 240V 50Hz only. :-/

[Travellers]

Originally Posted by John in Santa Cruz

yeah. sadly a lot of the AC inverter kinda stuff is 240V 50Hz only. :-/

Yah I noticed that. Bigger market maybe?

[John in Santa Cruz]

Originally Posted by Travellers

Yah I noticed that. Bigger market maybe?

They are a Dutch company. They have some cool stuff like an all-in-one inverter/solar controller/charge controller that would make an awesome home battery/solar off grid system

[Travellers]

Originally Posted by John in Santa Cruz

They are a Dutch company. They have some cool stuff like an all-in-one inverter/solar controller/charge controller that would make an awesome home battery/solar off grid system

Yah. Some neat tech. We are thinking of adding a second 165 watt panel to the roof of our T@B as well as a lithium battery upgrade from the two 6 volt AGM’s the trailer came with. But it’s hard to justify for a couple reasons.

1. Half of the time we camp we are in BC forested campgrounds. So, in the shade. .

2. When we travel we tend to look for serviced sites for easy overnight charging of our tow vehicle. We only plug one thing into the pedestal at a time but plugging the trailer in for an hour gets a substantial charge.

3. Even when we are dry camping and the trailer batteries run down we can simply leach off the tesla battery pack via the 12 volt aux port.

Anyway, hard to justify spending money on lithium batteries and solar equipment.

Cheers.

[John in Santa Cruz]

after replacing my 160W factory polycrystalline with a 360W mono panel, I'm toying with mounting the 160W and adding it. since the two panels are different voltages, I'll probably have to use a 2nd controller for the 160W.

OTOH, the 360W has provided all the power I need easily so far.

[Travellers]

Originally Posted by John in Santa Cruz

after replacing my 160W factory polycrystalline with a 360W mono panel, I'm toying with mounting the 160W and adding it. since the two panels are different voltages, I'll probably have to use a 2nd controller for the 160W.

OTOH, the 360W has provided all the power I need easily so far.

It’s the shady days that make the greater capacity nice. We carry a 47 pound genny and it comes in handy sometimes. Mostly for running the microwave though. Lol. .

[beardrum]

Wow, this thread has sure wandered far afield...

Just as an update, I thought I'd circle back around to say that I sprang for a Renogy 200 watt suitcase solar panel (2 100 watt panels hinged together), with a PWM charge controller and a pair of extra 20 foot cables, and an SAE battery box connector. On a 5 day stay camped in Eastern Washington without power, I observed up to 7 amps of charging for an hour or two, in bright light, with the panel more or less oriented to the sun (48 degree north lattitude) and the battery was topped off everyday by mid-afternoon. The biggest electrical load was the Suburban furnace running mornings and evenings, along with a few LED's and a small inverter charging the laptop. With that size of panel, I noticed the battery was charging even when the panels were in shade or dappled sunlight. The things weigh over 40 lbs, and it takes a bit of fussing, but I'm pretty pleased to be able to be off-grid pretty much indefinitely. Water and black water seem to be the long poles in the tent now.

So, no more need to worry about charging from the tow vehicle!

Thanks!

Chuck

[Eggcentric]

Since we started full time in our 5th wheel (1998) we pretty quickly realized that water was the number one problem. I was given a new 40 gallon water tank that came with a park model and was in their way. I picked up a shurflo pump & used this so that we could get water and bring it back. We have had a system such as this (usually 20 gallons) until we stopped RV'ing. In Mexico on the beach I rigged it to be an after swim shower with a switch on the stand for the outdoor shower.