Free 7 Day Trial RV GPS App RV Trip Planner Campground Reviews RV Maintenance Free 7 Day Trial ×
RV Trip Planning Discussions

Go Back   iRV2 Forums > MOTORHOME FORUMS > Toads and Motorhome Related Towing
Click Here to Login
Join iRV2 Today

Mission Statement: Supporting thoughtful exchange of knowledge, values and experience among RV enthusiasts.
Reply
 
Thread Tools Search this Thread Display Modes
 
Old 05-08-2021, 05:20 PM   #1
Senior Member
 
jarwiebe's Avatar


 
Newmar Owners Club
Spartan Chassis
Join Date: Jul 2012
Location: Manitoba, Canada
Posts: 424
Toad Charge Line

I just finished installing a charge line between my RV and Toad and am puzzled by the voltage readings I am getting when hooked up. Readings as I expected them to be with either end open but I'm not getting the readings I expected when hooked up at both ends.

I bought the diode (rated for 60 amps) at "Start & Charge" a local business that rebuilds starters and alternators.

Any thoughts on why this would be?
Attached Thumbnails
Click image for larger version

Name:	Toad charge line.jpg
Views:	8
Size:	18.3 KB
ID:	327704  
__________________
Jake
2005 DSDP 4024, Cummins ISL 370, Spartan MM Chassis / 2018 Ford Taurus, Roadmaster Base Plate, Aventa LX Tow Bar, RVI 2 Brakes / 1996 Mariah Shabah Z210 - 5.7L Alpha 1 Gen 2
jarwiebe is offline   Reply With Quote
Join the #1 RV Forum Today - It's Totally Free!

iRV2.com RV Community - Are you about to start a new improvement on your RV or need some help with some maintenance? Do you need advice on what products to buy? Or maybe you can give others some advice? No matter where you fit in you'll find that iRV2 is a great community to join. Best of all it's totally FREE!

You are currently viewing our boards as a guest so you have limited access to our community. Please take the time to register and you will gain a lot of great new features including; the ability to participate in discussions, network with other RV owners, see fewer ads, upload photographs, create an RV blog, send private messages and so much, much more!

Old 05-08-2021, 05:39 PM   #2
Senior Member
 
Join Date: Jul 2014
Posts: 27,527
Diodes have a voltage drop thru them. The one your using seems high.

Replace the diode with a relay, controlled by the RV key.
twinboat is offline   Reply With Quote
Old 05-09-2021, 12:28 PM   #3
NXR
Senior Member
 
NXR's Avatar
 
Join Date: Mar 2019
Posts: 2,665
Quote:
Originally Posted by jarwiebe View Post
I just finished installing a charge line between my RV and Toad and am puzzled by the voltage readings I am getting when hooked up. Readings as I expected them to be with either end open but I'm not getting the readings I expected when hooked up at both ends.
The standard voltage drop for a silicon diode is 0.6 to 0.7 volts so your readings are right where they should be. Most people never check so they assume a diode is like a wire but only passing current in one direction. Not so.

Are you actually measuring the voltage on both ends? If so, put one probe on each side of the diode when it's all hooked up and you'll see the actual voltage drop through the diode.

Ray
__________________
2020 Forest River Georgetown GT5 34H5
NXR is offline   Reply With Quote
Old 05-09-2021, 12:49 PM   #4
Senior Member
 
Bigd9's Avatar


 
Join Date: Jun 2012
Location: The Bluegrass State
Posts: 7,012
It is my thought that using a diode isn't necessary in most situations especially if you or the chassis builder uses a relay that is only activated when the coach ignition is on. Current will only flow from the higher voltage to the lower voltage batteries.
__________________
Good Luck, Be Safe and Above All, Don't Forget To Have Fun
Pete
Central Kentucky
2006 Fleetwood Discovery 35H, 2014 Honda CR-V, M&G Engineering Braking System
Bigd9 is offline   Reply With Quote
Old 05-09-2021, 01:09 PM   #5
Senior Member
 
jarwiebe's Avatar


 
Newmar Owners Club
Spartan Chassis
Join Date: Jul 2012
Location: Manitoba, Canada
Posts: 424
Quote:
Originally Posted by NXR View Post
The standard voltage drop for a silicon diode is 0.6 to 0.7 volts so your readings are right where they should be. Most people never check so they assume a diode is like a wire but only passing current in one direction. Not so.

Are you actually measuring the voltage on both ends? If so, put one probe on each side of the diode when it's all hooked up and you'll see the actual voltage drop through the diode.

Ray
Thats good to hear. Yes, I checked voltage at both ends. I'll check voltage across the diode next time I hookup.
__________________
Jake
2005 DSDP 4024, Cummins ISL 370, Spartan MM Chassis / 2018 Ford Taurus, Roadmaster Base Plate, Aventa LX Tow Bar, RVI 2 Brakes / 1996 Mariah Shabah Z210 - 5.7L Alpha 1 Gen 2
jarwiebe is offline   Reply With Quote
Old 05-09-2021, 02:06 PM   #6
NXR
Senior Member
 
NXR's Avatar
 
Join Date: Mar 2019
Posts: 2,665
Quote:
Originally Posted by jarwiebe View Post
Thats good to hear. Yes, I checked voltage at both ends. I'll check voltage across the diode next time I hookup.
The way you did it is OK but an undersized ground wire or charge wire can cause low voltage at the car side as well, if the car actually needs amps from the motorhome at the time of measurement.

An Equinox probably is the poster child for that. My 2020 draws almost 8 amps out of the battery when configured for towing, far more than other cars. Unless the charge and ground wire are at least 14 AWG and preferably 12 AWG, the Equinox will actually slowly discharge while being towed.

Ray
__________________
2020 Forest River Georgetown GT5 34H5
NXR is offline   Reply With Quote
Old 05-09-2021, 04:38 PM   #7
Senior Member
 
jarwiebe's Avatar


 
Newmar Owners Club
Spartan Chassis
Join Date: Jul 2012
Location: Manitoba, Canada
Posts: 424
Both my positive and negative wires are 12 gauge so wouldn't expect any significant loss there.
__________________
Jake
2005 DSDP 4024, Cummins ISL 370, Spartan MM Chassis / 2018 Ford Taurus, Roadmaster Base Plate, Aventa LX Tow Bar, RVI 2 Brakes / 1996 Mariah Shabah Z210 - 5.7L Alpha 1 Gen 2
jarwiebe is offline   Reply With Quote
Old 05-09-2021, 08:29 PM   #8
Member
 
Kevin_D's Avatar
 
Join Date: Oct 2020
Posts: 62
Quote:
Originally Posted by Bigd9 View Post
It is my thought that using a diode isn't necessary in most situations especially if you or the chassis builder uses a relay that is only activated when the coach ignition is on. Current will only flow from the higher voltage to the lower voltage batteries.
I didn't put a diode in mine.
I did, however, add a 15A circuit breaker.
__________________
2015 Fleetwood Bounder 35K
2021 Jeep Gladiator toad
Kevin_D is offline   Reply With Quote
Old 05-09-2021, 09:07 PM   #9
Senior Member
 
jarwiebe's Avatar


 
Newmar Owners Club
Spartan Chassis
Join Date: Jul 2012
Location: Manitoba, Canada
Posts: 424
I put in a 20 amp auto reset breaker at the RV battery end and the diode at the toad battery end of the charge line.
__________________
Jake
2005 DSDP 4024, Cummins ISL 370, Spartan MM Chassis / 2018 Ford Taurus, Roadmaster Base Plate, Aventa LX Tow Bar, RVI 2 Brakes / 1996 Mariah Shabah Z210 - 5.7L Alpha 1 Gen 2
jarwiebe is offline   Reply With Quote
Old 05-09-2021, 09:27 PM   #10
Senior Member
 
Isaac-1's Avatar
 
Join Date: Jun 2016
Location: SW Louisiana
Posts: 6,086
I have both a diode and a 15 amp auto reset breaker on mine, partly the diode is insurance to keep the pins on the 6 way connector at the front bumper from potentially shorting out if exposed to mud, etc. and draining the Jeeps battery. Also the diode will lower voltage and therefore lower battery charge rate on the TOAD if the battery were to be partly drained before connecting, and therefore limiting the chances of tripping the 15 amp auto reset breaker. I am not trying to charge the TOAD battery with the Charge line, just maintain it at a reasonable level.
__________________
2002 Safari Trek 2830 on P32 Chassis with 8.1L w/ 400 watts solar
2017 Jeep Cherokee Overland TOAD with Even Brake,
Demco Commander tow bar and Blue Ox base plate
Isaac-1 is offline   Reply With Quote
Old 05-10-2021, 04:51 AM   #11
Senior Member
 
Winemaker2's Avatar
 
Join Date: Nov 2006
Location: Western NY
Posts: 4,142
I'm not a fan of auto reset CBS.
See
https://www.irv2.com/forums/f85/battery-charging-wire-to-toad-535618.html
Post #3 for details why.
Manual resets work in most cases and I've never had a trip. Worst that happens you have a low batty but with auto resets it can bevfar worse.
__________________
Don & Marge
'13 Newmar Ventana 3433 - '14 CR-V TOAD
'03 Winnebago Adventurer 31Y - SOLD
Winemaker2 is offline   Reply With Quote
Old 05-10-2021, 08:58 AM   #12
NXR
Senior Member
 
NXR's Avatar
 
Join Date: Mar 2019
Posts: 2,665
Quote:
Originally Posted by Bigd9 View Post
It is my thought that using a diode isn't necessary in most situations especially if you or the chassis builder uses a relay that is only activated when the coach ignition is on. Current will only flow from the higher voltage to the lower voltage batteries.
You're right, it depends. The Ford F-53 gasser chassis (mine is a 2019 chassis) has the charge line available 24x7 on the 7-pin connector whether the motorhome is running, turned off and parked in the desert for a month, or whatever.

My car had some weird OBDII codes once. The dealer in Nashville, where they work on a lot of toads for people passing through, said that is not uncommon for cars being towed. He suggested adding a diode if we start the motorhome with the car connected. That keeps the drop in the chassis battery of the motorhome during the start cycle from pulling the car battery down and then bouncing the car battery voltage up as the motorhome starts.

We do start the motorhome with the car connected at fuel stops, rest areas, and usually on one-nighter's.

If you're plugged into shore power overnight, having the 7-pin charge line powered up all the time can be good as it keeps the toad battery topped off.

I don't obsess over the toad battery charge line voltage. As long as the charge line is sufficient to keep the car battery from running down while towing, and 12.8 VDC does that, I'm happy. Even 12.5 or 12.6 VDC is fine with me.

I'm actually happier with the diode voltage drop because the motorhome's alternator voltage regulator has no idea what the car battery voltage is nor does it care, unlike the car's alternator voltage regulator.

Ray
__________________
2020 Forest River Georgetown GT5 34H5
NXR is offline   Reply With Quote
Old 05-10-2021, 03:08 PM   #13
Senior Member
 
Bigd9's Avatar


 
Join Date: Jun 2012
Location: The Bluegrass State
Posts: 7,012
Quote:
Originally Posted by NXR View Post
You're right, it depends. The Ford F-53 gasser chassis (mine is a 2019 chassis) has the charge line available 24x7 on the 7-pin connector whether the motorhome is running, turned off and parked in the desert for a month, or whatever.

My car had some weird OBDII codes once. The dealer in Nashville, where they work on a lot of toads for people passing through, said that is not uncommon for cars being towed. He suggested adding a diode if we start the motorhome with the car connected. That keeps the drop in the chassis battery of the motorhome during the start cycle from pulling the car battery down and then bouncing the car battery voltage up as the motorhome starts.

We do start the motorhome with the car connected at fuel stops, rest areas, and usually on one-nighter's.

If you're plugged into shore power overnight, having the 7-pin charge line powered up all the time can be good as it keeps the toad battery topped off.

I don't obsess over the toad battery charge line voltage. As long as the charge line is sufficient to keep the car battery from running down while towing, and 12.8 VDC does that, I'm happy. Even 12.5 or 12.6 VDC is fine with me.

I'm actually happier with the diode voltage drop because the motorhome's alternator voltage regulator has no idea what the car battery voltage is nor does it care, unlike the car's alternator voltage regulator.

Ray
Thanks for that information. I'll squirrel it away in my brain for future reference.

BTW, if someone (who will remain nameless since I'm married to her) accidentally leaves the toad ignition on while stopped for a overnight, and then try to start the toad the next morning to 'run it through the gears', well....... ...when one of us did that it popped the fuse because the Honda was trying to draw starting current from the motorhome batteries! Now I hate to say she is a slow learner, but twice in one trip OK, I better quit before she reads this or else
__________________
Good Luck, Be Safe and Above All, Don't Forget To Have Fun
Pete
Central Kentucky
2006 Fleetwood Discovery 35H, 2014 Honda CR-V, M&G Engineering Braking System
Bigd9 is offline   Reply With Quote
Old 05-10-2021, 03:17 PM   #14
Senior Member
 
sedaliaterry's Avatar
 
Join Date: Mar 2017
Location: Sedalia, CO
Posts: 290
This is the direction I took (used 10ga wire):
Attached Thumbnails
Click image for larger version

Name:	RV_ChargeLine.jpeg
Views:	14
Size:	162.3 KB
ID:	327889  
__________________
2017 3113 NewMar BayStar, Safe-T-Plus, RoadMaster SB, SuperSteer TB, Koni FSD shocks, CHF Rear, Sumo Springs, Centramatics, EEZ TPMS, King TailGater, LED Headlight kit, EMS-PT50X, Adjustable arm-rests, MagnaShade, 2017 Cherokee TrailHawk Toad...
And Tucker - [SIGPIC][/SIGPIC]
sedaliaterry is offline   Reply With Quote
Reply

Tags
toad



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Charge line to the toad Griffin379 Country Coach Owners Forum 7 09-20-2018 05:34 AM
Coachmen: toad charge line fuse Jack40 Toads and Motorhome Related Towing 9 07-13-2016 12:29 PM
Another Toad Charge Line Question USMCRET Toads and Motorhome Related Towing 5 11-18-2015 01:04 PM
Toad charge line artgpo Winnebago Industries Owner's Forum 3 10-29-2014 10:10 AM
Charge Line for toad Hrudey Toads and Motorhome Related Towing 19 03-08-2014 05:43 AM


All times are GMT -6. The time now is 10:40 PM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2021, vBulletin Solutions, Inc.