Charging your battery from your tow vehicle - R-pod Owners Forum

Author

Share Topic

Topic Search

Topic Options

Post Reply

Create New Topic

WillThrill View Drop Down

Senior Member

Joined: 04 Jul 2014
Online Status: Offline
Posts: 298

Topic: Charging your battery from your tow vehicle
Posted: 05 Dec 2017 at 1:21pm

Originally posted by Olddawgsrule

Will, I thought about this as well. My intention is to add a power outlet in the bed of my Tacoma. One reason is the hopes of running a solar charge controller on it for recharge when traveling.

My case, I will probably run a 12g wire back (should be over-kill) and see just what I have back there for voltage.

I have both PWM & MPPT charge controllers at the house from my house solar experiments. Which I use will depend on the voltage I read.

I have to dis-agree with using 'jumper cables' battery to battery. Yes through a charge controller. I personally don't like un-controlled charging.

MHO on the matter.

I'm glad to hear that someone else has had similar ideas! Smile

I plan to post some pictures of me doing this with a deep cycle battery within the next few days as a tutorial and demonstration for those interested.

"Not all those who wander are lost." Tolkien

2014 Hood River 177
2005 GMC Envoy XL

Olddawgsrule View Drop Down

Senior Member

Joined: 20 Sep 2017
Location: New Hampshire
Online Status: Offline
Posts: 1014

Posted: 05 Dec 2017 at 2:51pm

Please do! Also record voltages, battery and outlet (source) and time it takes. All good info for those reading.

My MPPT (downstairs) will run Float charge unless the under 13.4v. Below that will run full charge (this one being a 10a rating) to 14.4v.

My PWM is close to the same cycles but only a 5a rating.

We all have 'our' own reasons or uses, but all info is good and should be balanced to our individual requirements.

I'm looking forward to your results!

Byways no Highways
2017 Tacoma
Truck Camper Build
2004 F150 My Overlander

Keith-N-Dar View Drop Down

podders Helping podders - pHp

Joined: 03 Apr 2011
Location: Mayville, WI
Online Status: Offline
Posts: 1447

Posted: 05 Dec 2017 at 4:06pm

How is charging from the TV uncontrolled? All vehicles have a charge controller built in to properly charge the vehicle battery.

Keith-N-Dar
Boris & Betty (Boston Terriers)
2011 R-Pod 177
2010 Ford F-150

Olddawgsrule View Drop Down

Senior Member

Joined: 20 Sep 2017
Location: New Hampshire
Online Status: Offline
Posts: 1014

Posted: 05 Dec 2017 at 4:44pm

Originally posted by Keith-N-Dar

How is charging from the TV uncontrolled? All vehicles have a charge controller built in to properly charge the vehicle battery.

A starter battery, not a deep cell battery. There are no stages involved. Vehicles have not reached this point yet.. sorry to say.

Cars have huge draw to start the vehicle, so have large returns to recover. Not what you wish to do to your Deep cell Battery.

That's the quick answer or my opinion on this.

I have a de-sulfator circuit that I use on my vehicle batteries. It helps and extends their life by twice, but reality is... Too much juice drawn vs. recovery. sulfate builds.

Sorry... longer answer...

Byways no Highways
2017 Tacoma
Truck Camper Build
2004 F150 My Overlander

GlueGuy

Senior Member

Joined: 15 May 2017
Location: N. California
Online Status: Offline
Posts: 2629

Posted: 06 Dec 2017 at 1:43pm

Originally posted by Keith-N-Dar

How is charging from the TV uncontrolled? All vehicles have a charge controller built in to properly charge the vehicle battery.

That's true. The TV alternator plus voltage controller will prevent the voltage from getting too high. It is not "uncontrolled", but it's not a 3-stage charger either. Assuming that you don't leave it on for hours and hours, it will provide a good charge relatively quickly.

The WFCO charger is going to provide > 50 amps if it is in bulk mode. That's a lot more than you will probably get from your TV alternator/voltage control while it's in idle.

It's not something that I would worry about.

bp
2017 R-Pod 179 Hood River
2015 Ford F150 SuperCrew 4WD 3.5L Ecoboost

Olddawgsrule View Drop Down

Senior Member

Joined: 20 Sep 2017
Location: New Hampshire
Online Status: Offline
Posts: 1014

Posted: 06 Dec 2017 at 4:07pm

Originally posted by GlueGuy

Originally posted by Keith-N-Dar

How is charging from the TV uncontrolled? All vehicles have a charge controller built in to properly charge the vehicle battery.

Okay, let's get into this a bit further.

The WFCO puts out 50a, but that's not necessarily what is going back to the battery.Those spec's I have not seen. That seems to be what it will (or can) deliver to the unit to use. Again correct me if understanding what I reading is wrong.

Battery recharge should be slightly higher than battery draw. Ratio can be argued but reality is slightly higher. This indeed is to remove the sulfate from the plates that built up when dis-charging without doing harm to the battery.

High fast charging can do as much damage as charging too slowly or letting the battery sit for too long at time.

To me, and MHO, is why it is so important to have a controlled circuit 'meant' for recharging our deep cell batteries.

I'm a strong proponent for a good 'wall wort' charger. I do see how a solar charge controller can work as well.

I have one in mind and still researching it. Looking forawrd to the OP's results of his his idea.

Byways no Highways
2017 Tacoma
Truck Camper Build
2004 F150 My Overlander

Keith-N-Dar View Drop Down

podders Helping podders - pHp

Joined: 03 Apr 2011
Location: Mayville, WI
Online Status: Offline
Posts: 1447

Posted: 06 Dec 2017 at 4:41pm

To each their own. The internal charger in the Pod has served well for six years maintaining my deep cycle battery. If it gets low and I am away from power I have acceptable jumper cables and can get it going in an hour. I can't see idling for even that long. To each their own, but this seems to me like lots of hand wringing for nothing.

Keith-N-Dar
Boris & Betty (Boston Terriers)
2011 R-Pod 177
2010 Ford F-150

WillThrill View Drop Down

Senior Member

Joined: 04 Jul 2014
Online Status: Offline
Posts: 298

Posted: 06 Dec 2017 at 6:00pm

I've just finished my test (although I already knew this would work) and the results are in. The short version: it works!

Here's the long version, with pictures.

In the picture below, you see a Sunforce 10 amp PWM charge controller wired directly up to the battery of my tow vehicle (2005 GMC Envoy XL, 4.3L). I just used the 18 gauge wire that came with the charge controller. If I were doing this on a regular basis with this charge controller, I would use 16 gauge wire, but over a run that's less than three feet, 18 gauge is fine for this test at least. I just wrapped the wire around the battery terminals; this is a terrible electrical connection, but again, it's just a test.

In this picture, the vehicle is not running. The controller powered up as soon I connected to the battery (red light in upper left). While the controller indicated that it was maintaining a float charge on the 75 amp hour battery (barely visible on the bottom right) that I had just taken off of a wall charger. However, my voltage reading on this battery was just over 13 volts, indicating that there is no charging actually occurring.

In this picture, the vehicle is now running. The voltage reading shown on the charge controller is the same as that of the vehicle's battery, 14.08 volts. You can see that the blue charging light is now lit.

In this picture, you can see the alligator clamps from the charge controller attached to the battery and my multimeter measuring the voltage of the battery. The voltage is 13.58, .5 less than the voltage on the battery. As such, it is clear that the charge controller is charging the battery.

So why am I putting forward this method of recharging your Pod's battery when you can just use jumper cables, which certainly does work? For reasons beyond the scope of this thread, the jumper cable method is just raw current from the vehicle's battery into the Pod's battery. It is not a controlled charge because if the Pod's battery is low when the jumper cables are connected, power from the charged vehicle's battery will quickly flow at a very high rate into the Pod's battery in order to 'equalize' the charges (like two water tanks connected to each other with a pipe will naturally seek their own level). This is not good for deep cycle batteries, which are best charged from a multi-stage charger, which solar charge controllers like this one are.

For those who are dry camping (i.e. boondocking) on a regular basis with their Pod, they need to have means of charging their Pod's battery. If they aren't interested in running their air conditioner or microwave, then they don't really need a generator. Many of these people opt for solar panels to do this, which is perfectly fine. However, solar panels don't work when it's cloudy, shady, or dark. By simply connecting their charge controller up to their tow vehicle, they can recharge their Pod's battery in a controlled, healthy manner.

For those that already have solar panels, all they need for this method is a set of alligator clamps to connect their charge controller to their vehicle (these alligator clamps could be wired into a pair of MC4 connectors if that is what is already being used to connect their solar panels to their charge controller). Those that don't have solar panels can just purchase a charge controller (10-30 amps would be appropriate; I like the one in the OP that's just $18) and a set of alligator clamps to attach it to their vehicle's battery.

Honestly, as little power as we've gotten from our 100 watt solar panel in our time camping (we usually have hookups, and when we dry camp, we usually park in forests with lots of shade), I would personally not recommend that the 'occasional boondocker' bother with the expense and space of solar panels. Most vehicles can idle 1-2 hours on a gallon of gasoline, equating to $1.25-$3.00 at current prices per hour of charging. Considering that a rigid Renogy 100 watt monocrystalline panel is currently $130 plus tax, that means you could get around 45-100 hours of vehicle charging for the same price as the solar panel, and you aren't dependent on sunshine for that power.

So I consider this to be a very viable approach for either those who do occasional boondocking, can't get power from their solar panels for whatever reason, or else just need to recharge their Pod's battery but can't or don't want to do so from shore power or generator power.

"Not all those who wander are lost." Tolkien

2014 Hood River 177
2005 GMC Envoy XL

Olddawgsrule View Drop Down

Senior Member

Joined: 20 Sep 2017
Location: New Hampshire
Online Status: Offline
Posts: 1014

Posted: 07 Dec 2017 at 6:34am

Nicely done!

Byways no Highways
2017 Tacoma
Truck Camper Build
2004 F150 My Overlander

henryv

Senior Member

Joined: 09 Feb 2017
Online Status: Offline
Posts: 259

Posted: 07 Dec 2017 at 2:36pm

This is all very confusing to the average layman like myself and the lady who just wanted to know what to do. The arguing between experts doesn't help, but adds to the confusion. We are seeking simple answers to make our camping experience more pleasant. My R-pod is solar-prepped, but I won't get much use out of it unless I live in the desert somebody said. I could use jumper cables from the tow vehicle to the camper in a pinch. The best charging system off grid is from a generator. Now, at the risk of stirring up a bee's nest, is this a fair final assessment?