Charging while towing

Anything electric, AC or DC

Re: Charging while towing

Postby wincrasher » Sat Feb 14, 2015 7:25 pm

Well, the smart charger was only $20, so I wouldn't characterize that as spendy. But it's going to top out at .75 amps, which I don't think is enough to do the job.
2015 Little Guy T@G Max
Follow my blog: http://www.wincrasher.blogspot.com
wincrasher
Teardrop Master
 
Posts: 218
Images: 88
Joined: Thu Jul 21, 2011 8:07 am
Location: South Carolina

Re: Charging while towing

Postby capnTelescope » Sat Feb 14, 2015 7:37 pm

wincrasher wrote:But it's going to top out at .75 amps, which I don't think is enough to do the job.

Exactly right. :thumbsup: You will need a bigger charger. That's the spendy part. :(
I'll burn that bridge when I come to it.

Brad
ImageImage

My Build
User avatar
capnTelescope
Lifetime member
 
Posts: 1089
Images: 360
Joined: Sun Jun 27, 2004 3:44 pm
Location: Round Rock, TX

Re: Charging while towing

Postby Wishno » Wed Apr 29, 2015 12:18 pm

Is this what I'm looking for as far as an isolator?

http://www.amazon.com/Stinger-SGP38-80- ... v+isolator
Wishno
Teardrop Builder
 
Posts: 32
Joined: Fri Aug 22, 2014 6:06 am
Top

Re: Charging while towing

Postby Dale M. » Wed Apr 29, 2015 9:06 pm

Wishno wrote:Is this what I'm looking for as far as an isolator?

http://www.amazon.com/Stinger-SGP38-80- ... v+isolator


Yes its one form of isolator.... It disconnects tow vehicle system for trailer system when TV ignition is switched off....

Dale
Lives his life vicariously through his own self.

Any statement made by me are strictly my own opinion.
You are free to ignore anything I say if you do not agree.

Image
User avatar
Dale M.
2000 Club
2000 Club
 
Posts: 2636
Images: 18
Joined: Thu Jun 09, 2005 8:50 pm
Location: Just a tiny bit west of Yosemite National Park
Top

Re: Charging while towing

Postby Wishno » Thu Apr 30, 2015 2:30 pm

Dale M. wrote:
Wishno wrote:Is this what I'm looking for as far as an isolator?

http://www.amazon.com/Stinger-SGP38-80- ... v+isolator


Yes its one form of isolator.... It disconnects tow vehicle system for trailer system when TV ignition is switched off....

Dale


Is 80amps going to be enough? Or do I need to match it to my alts output? (140)
Wishno
Teardrop Builder
 
Posts: 32
Joined: Fri Aug 22, 2014 6:06 am
Top

Re: Charging while towing

Postby capnTelescope » Thu Apr 30, 2015 6:23 pm

Wishno wrote:Is 80amps going to be enough? Or do I need to match it to my alts output? (140)

You need to size the isolator to the maximum amount of current the trailer will draw, which must be less than the alternator can put out. 80 amps should be plenty for most purposes. 20-30 amps should be sufficient, I would think. Other than spending more money, no problem with with a higher rated isolator.

I'm using this $10 one.
I'll burn that bridge when I come to it.

Brad
ImageImage

My Build
User avatar
capnTelescope
Lifetime member
 
Posts: 1089
Images: 360
Joined: Sun Jun 27, 2004 3:44 pm
Location: Round Rock, TX
Top

Re: Charging while towing

Postby ukewarrior » Thu Apr 30, 2015 6:42 pm

Is there a reference hookup diagram for these units?
capnTelescope wrote:
Wishno wrote:Is 80amps going to be enough? Or do I need to match it to my alts output? (140)

You need to size the isolator to the maximum amount of current the trailer will draw, which must be less than the alternator can put out. 80 amps should be plenty for most purposes. 20-30 amps should be sufficient, I would think. Other than spending more money, no problem with with a higher rated isolator.

I'm using this $10 one.
ukewarrior
Donating Member
 
Posts: 103
Joined: Tue Apr 21, 2015 3:19 pm
Top

Re: Charging while towing

Postby capnTelescope » Thu Apr 30, 2015 7:17 pm

It's not too difficult. One small terminal goes to ground, the other small one to a wire that's hot when running. The large terminals have one through a fuse to battery positive and one to the trailer.
I'll burn that bridge when I come to it.

Brad
ImageImage

My Build
User avatar
capnTelescope
Lifetime member
 
Posts: 1089
Images: 360
Joined: Sun Jun 27, 2004 3:44 pm
Location: Round Rock, TX
Top

Re: Charging while towing

Postby Hal W » Tue Jun 09, 2015 3:37 am

First post here, and I know this is an ancient thread, but I read through the 13 pages and want to add something that has been missed here. I have 30 years experience in auto tech so I have a little background with this subject, at least as far as auxiliary batteries on vehicles. Two very different batteries will have a slightly different charging requirement. That being said, if they are in parallel the alternator will see them as a single load, or in effect, a single battery. Think about it this way; if you connect a fully charged battery with jumper cables to a dead battery the 2 batteries will equalize, the dead battery will come up and the charged battery goes down. The gauge of wire that the jumper cables are made from prescribes the amount of amps that will flow between the batteries, (or, the speed that it takes to equalize them). This is why a set of cheap jumper cables get hot when you are trying to jump your neighbors stone dead battery with your fully charged car, the cable size is too small and they become a resistor as too many amps are trying to flow at once. I could go much deeper into this but if you're still with me...

The "Simple" RV system talked about here is fine, but there needs to be a couple of things in the system. There does need to be a heavy relay and a MANUAL switch. You do not want to have a dead battery on the TD and a full one on the TV that connect at the moment that you turn on the ignition to start the TV. Remember the cheap jumper cables. The cable size should be a minimum of 6 gauge and 4 would be better. (Think; full-sized battery cables are best). So now you are thinking "that is waaayy overkill". Yes, unless you have the above condition happen... Then it is properly sized to not smoke the 10 gauge typical charge wire running through your TV and TD. The way to avoid this problem is to install a resistor on the TV battery end to "slow down" the rate of charge to meet a smaller cable's capacity.

OK, so a "Simple RV system" set up like this will work great and be safe: TV Batt + to a Mega Fuse to a heavy relay run from a switched ignition source THROUGH a manual switch (to switch it off for starting the TV) to fire the relay, Then through a heavy resistor (50 amp 2 ohm? You need to wire it and check the voltage at the TD batt as you are wanting about 14.5 when charging). This is the only way I can see this type of system working properly and safely.

I think a Battery isolator system would be better in the long run if the cable size to the TD doesn't drop the voltage too low. I like the inverter to smart charger even better as the voltage step up eliminates the cable size problem and the charger is on-board the TD to plug into shore power anytime. There is no worries about efficiency here, a typical drive to and from your camp will take way more time then it will take to charge your TD battery fully. Think of that like "I have a 50 gallon bucket to fill up a 5 gallon bucket, who cares if I spill some?"
Hal W
Teardrop Inspector
 
Posts: 2
Joined: Mon Jun 01, 2015 3:12 pm
Location: Sunriver, Oregon
Top

Re: Charging while towing

Postby capnTelescope » Tue Jun 09, 2015 9:04 am

Hal W wrote:I like the inverter to smart charger even better as the voltage step up eliminates the cable size problem and the charger is on-board the TD to plug into shore power anytime. There is no worries about efficiency here, a typical drive to and from your camp will take way more time then it will take to charge your TD battery fully. Think of that like "I have a 50 gallon bucket to fill up a 5 gallon bucket, who cares if I spill some?"


Well said, Hal. :thumbsup: :applause:

As the original proponent of the inverter to smart charger method, thank you. :beer:
I'll burn that bridge when I come to it.

Brad
ImageImage

My Build
User avatar
capnTelescope
Lifetime member
 
Posts: 1089
Images: 360
Joined: Sun Jun 27, 2004 3:44 pm
Location: Round Rock, TX
Top

Re: Charging while towing

Postby Gunguy05 » Tue Jun 09, 2015 9:20 am

I might have missed it so excuse me if it was mentioned. What is a descent smart charger for the dc-ac-DC method?
Brian


Checkout my buildThe Regal Eagle Bow front for 4
Image
Also my teardrop updates from blog on Dad Rambles
User avatar
Gunguy05
The 300 Club
 
Posts: 385
Images: 6
Joined: Mon Dec 02, 2013 4:45 pm
Location: South GA
Top

Re: Charging while towing

Postby capnTelescope » Tue Jun 09, 2015 9:56 am

I'm quite happy with the NOCO Genius G7200 12V/24V 7.2A UltraSafe Smart Battery Charger, which is 7.2 amps, but I'm not running a fridge, just LED lights & a FanFan. Generally, any AC charger will work. I'd recommend one that has a float/maintenance mode, as you can use it to keep the TD battery charged between camping trips. 5 amps is probably enough for most purposes. Definately get one that is more than a .75A maintainer-only.
Last edited by capnTelescope on Tue Jun 09, 2015 10:07 am, edited 1 time in total.
I'll burn that bridge when I come to it.

Brad
ImageImage

My Build
User avatar
capnTelescope
Lifetime member
 
Posts: 1089
Images: 360
Joined: Sun Jun 27, 2004 3:44 pm
Location: Round Rock, TX
Top

Re: Charging while towing

Postby Gunguy05 » Tue Jun 09, 2015 9:58 am

capnTelescope wrote:I'm quite happy with this charger, which is 7.2 amps, but I'm not running a fridge, just LED lights & a FanFan. Generally, any AC charger will work. I'd recommend one that has a float/maintenance mode, as you can use it to keep the TD battery charged between camping trips. 5 amps is probably enough for most purposes. Definately get one that is more than a .75A maintainer-only.


What about inverter? What would be the minimum needed there?

I'm starting to see the beginning of a solar system here. I'm just weighing do I hook this up, or save up fora 100W solar panel as my trickle charger.

Thanks!

Brian
Brian


Checkout my buildThe Regal Eagle Bow front for 4
Image
Also my teardrop updates from blog on Dad Rambles
User avatar
Gunguy05
The 300 Club
 
Posts: 385
Images: 6
Joined: Mon Dec 02, 2013 4:45 pm
Location: South GA
Top

Re: Charging while towing

Postby capnTelescope » Tue Jun 09, 2015 10:19 am

I'm using a 300 watt inverter. 7.2 Amps * 12 volts = 86 watts. About 40 bucks. Understand that you'll pull more than 86 watts due to charger inefficiencies. I couldn't say how much actual watts, but a 3X margin should be plenty.

This leaves a coupla hunnert watts reserve for other tow power uses. You don't need a big'un. :D
I'll burn that bridge when I come to it.

Brad
ImageImage

My Build
User avatar
capnTelescope
Lifetime member
 
Posts: 1089
Images: 360
Joined: Sun Jun 27, 2004 3:44 pm
Location: Round Rock, TX
Top

Re: Charging while towing

Postby capnTelescope » Tue Jun 09, 2015 12:40 pm

Gunguy05 wrote:I'm just weighing do I hook this up, or save up fora 100W solar panel as my trickle charger.


Brian, my take is that if you usually boondock for more than a couple of days in the same spot, solar will give you the "staying power" you need without burning a bunch of gasoline.

OTOH, if you mostly drive-camp-drive, I think the dc-ac-dc setup will better meet your need.

:beer:
I'll burn that bridge when I come to it.

Brad
ImageImage

My Build
User avatar
capnTelescope
Lifetime member
 
Posts: 1089
Images: 360
Joined: Sun Jun 27, 2004 3:44 pm
Location: Round Rock, TX
Top

PreviousNext

Return to Electrical Secrets

Who is online

Users browsing this forum: No registered users and 3 guests