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Old 12-29-2018, 12:11 PM   #1
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Batteries won't recharge during tow.

Anyone know why my batteries in my Landmark are not recharging during towing. I have power to the outlet in the truck but don't know where it goes from there. Where do I look to check the power going to the batteries. Does anyone know where I can get a wiring schematic for 2014 Heartland Landmark?
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Old 12-29-2018, 12:15 PM   #2
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I think its important to set some expectations here: what are you expecting to happen to your batteries while towing?

At best you can get mild topping off on relatively charged batteries- I've only ever seen about 12amps coming over the wire from the truck using OEM wiring(i can watch this on my Trimetric). If the batteries are flat, there is simply not enough current available to charge the batteries by any meaningful amount during a average length trip..... If you have 100-200ah of batteries and do some basic math...you can see the problem. There is also quite a bit of voltage drop over the 20'+ foot of wire which slows down the charging rate from what most people expect.

If your not getting anything at ALL - The 7 pin charging circuit will terminate in fuse box on the tongue or just inside the basement usually - you can check there, and then will also connect to the main DC fusebox - check to see if those fuses are blown.
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Old 12-29-2018, 02:07 PM   #3
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Take a meter reading on trailer battery(s).....hook up cord to truck, take another reading....that'll tell you if the circuit is capable.......you could always run a larger wire or two....of course you'll have to start tow rig.......and try at different rpm's..
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Old 12-29-2018, 02:25 PM   #4
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Does the Landmark have a residential refrigerator?
As mentioned, best you can hope for is keeping charged batteries at current level. If you have the RR, it probably is using as much or more than the truck is furnishing.
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Old 12-29-2018, 02:32 PM   #5
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Is the tow vehicle a Ford truck? Some years Ford didn't ship the trucks with a relay or a fuse installed even with a trailer brake controller. Without the fuse you won't be passing 12v through the 7 pin connector. My former 2008 F150 didn't have either installed when I bought it...
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Old 12-29-2018, 10:28 PM   #6
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Quote:
Originally Posted by RoadDogYVR View Post
Is the tow vehicle a Ford truck? Some years Ford didn't ship the trucks with a relay or a fuse installed even with a trailer brake controller. Without the fuse you won't be passing 12v through the 7 pin connector. My former 2008 F150 didn't have either installed when I bought it...


Same with GM, had to manually hookup the charge line at the fuse box, same with the brake controller...and fuses
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Old 12-29-2018, 10:46 PM   #7
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Quote:
Originally Posted by bob caldwell View Post
Take a meter reading on trailer battery(s).....hook up cord to truck, take another reading....that'll tell you if the circuit is capable.......you could always run a larger wire or two....of course you'll have to start tow rig.......and try at different rpm's..
Increasing the size of the hot lead may help some, but keep in mind you must also replace the ground wire with the same size as the hot lead. I do not think you'll ever get enough volt and amps to do much recharging. IMO the math does not work out too well.

I have 1050 watts of solar on the roof and that keeps the batteries charged. I don't even use the converter anymore.
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Old 12-30-2018, 02:27 AM   #8
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[QUOTE=Pete Menges;4564421]Anyone know why my batteries in my Landmark are not recharging during towing. I have power to the outlet in the truck but don't know where it goes from there. Where do I look to check the power going to the batteries. Does anyone know where I can get a wiring schematic for 2014 Heartland Landmark?


If you have a Residential fridge, youíre inverter is using a lot of battery keeping the fridge running on the road. On my Ď17 LM after a long day driving the inverter has used up the batteries to where theyíre ready to be plugged in and recharged when we stop!
I hear some of the newer trucks are set up to charge the RV batts. Mine, a 2015, is not, yet anyway.
If youíre in the Heartland Owners Group you can search that question in the group and there is plenty of discussion on it!
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Old 12-30-2018, 04:43 AM   #9
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Of course, all of the responses are valid. However, you indicated that you do have 12 volt power on the 7-Way and that is a good start. The question is whether that power is making it to your batteries. How much power and what it will do for you batteries is a question for another day.

There is a simple test. Connect your cable, start your TV and look at your tank/battery monitor panel. When you press the battery button, ALL 4 LEDS should light. The rightmost LED indicates a voltage over 13 volts and if you look carefully it says "C" for charging, NOT "C" FOR CHARGED! If it doesn't light, the TV voltage is not reaching the batteries and you are going to have to trace the umbilical from the entry point to the batteries.

Most good umbilical cord has 14 ga for signal lights and brakes, but #10 for the ground and charge line (white and black). #10 should give you 10 or 15 amps at a decent voltage on your round trip from the alternator to the batteries. Even if you have a residential reefer, that should keep you up to charge on average, but, as others have said, it won't take a flat bank and recharge it unless you drive a very, very long time!
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Old 01-03-2019, 12:04 AM   #10
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To expand a little on my prior post.

If your trailer battery requires bulk/absorption charging you'll need to see something above 14.4 to 14.8 volts, float level charging is around 13.2 to 13.4 volts. The tow vehicle's alternator output is controlled only by the vehicle's engine charging system. The trailer's batteries are seen only as another 12 volt load. On my truck typical running voltage is 14.4v. There will be a significant voltage drop from the front to rear in most installs.

Using a voltage drop calculator like: https://www.rapidtables.com/calc/wir...alculator.html
using 14.4 volts, a 30ft one-way cable run of 10 gauge wire we get about a 0.9 volt drop, not counting losses at the connections. That means you see about 13.5 volts at the trailer's battery on the hot lead. Well below what's needed for any serious charging and just above the float level. It should keep things running in the trailer if you don't need lots of amperage. But, don't expect it will add much charge to your battery. A quick look at DC cable sizing chart you see to maintain a 2% voltage drop for a 10-15 amp load over 30 ft run you'll need like a #4 to 6 wire for both hot and ground. Long shot from common 10 gauge wire used for the hot and ground leads.

Just the math...
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Old 01-03-2019, 06:14 AM   #11
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Rarebear's post got me thinking (sometimes a dangerous thing.) We constantly hear that charge lines do not work for low SOC batteries in a TT. In other words, they will charge if you don't need any, but if you are low...they do nothing! His numbers are completely accurate! Looking at the data that I have measured on charge cycles for my 4x12v bank, 13.3 is plenty to bring it up from 66% to 90% or so in 4 hours...driving or when connected to shore power. Actually my alternator gets me a higher charging voltage than my converter (all measured at the batteries.)

This isn't simple circuit analysis. You know, current, voltage, E=IR stuff. Batteries are funny things. They are not simple resistive loads. Put four of them them in parallel at 66% SOC, give them 13.3 volts or so...and they will suck 30+ amps. But give them 12.3 at the same SOC and they will draw virtually NOTHING! That is because they have a back voltage and if you cannot overcome that voltage no current will flow and in order to get them to re-charge you have to drive current through the cells.

Now, back to the analysis. A nice 14.4 volt alternator with a 60 foot round trip of #10 at say 15 amps and you will get 13.5 volts at the batteries. Great, but 4 batteries in parallel at 13.5 volts will try to draw more than 30 amps and if you put that into the numbers, the voltage will drop to 12.6 and they will draw almost nothing!

You give them what they want...or they will take nothing. The problem, in my example, is that there are too many batteries in parallel. If there were only one, at a voltage of 13.3, it would draw no more than 10 or 12 amps, the voltage would hold and the battery would recharge.

So, if you have a bunch of batteries on a charge line...they won't charge. If you have one...it will charge, like it does in my TOAD connected to my coach alternator.

Now...does this mean that if you want 2 batteries in a TT it is better to use 2-6 volt batteries in series rather than 2-12 volt batteries in parallel (roughly the same storage capacity.) I think the answer is yes, but thinking about it kinda makes my head hurt.

Here is my basic data for a bank of 4 12 volt batteries. Note that the feed lines are 33 feet round trip and they are #8 and not #10!
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Old 01-03-2019, 12:35 PM   #12
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Scott thanks for adding the additional material. I did not attempt to run my example for various amperage loads or complexities of battery configuration and chemistry. Different kinds of batteries will behave differently, etc, etc. Scott, nice find on that graph.

In a MH where the distance is short between alternator and house batteries and possibly use of much larger cable you may see very different results. This thread is about trailers under tow, I think. As shown in my signature we have both a 5th and a small MH so I experience it both ways and my observations are different.

I think my main point and perhaps that of Scott is to properly set your expectations as to what the tow vehicle's charging system can and can not do for house batteries in a trailer. This can get fairly complex before someone can truly get their head wrapped around the subject. As always your milage may vary in this issue.

Just get out there, enjoy and be safe...
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Old 01-03-2019, 03:21 PM   #13
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12V 'Charge' line goes from truck receptacle (1 O'clock position) to trailer plug (11 O'clock position) to fused connection (in 5vr overhang/pin box area) to Battery POS Post.
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Old 01-03-2019, 03:37 PM   #14
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RAREBEAR, now that I have had some time to think about it, the problem is really quite simple. Of course I knew we were talking about TTs, but this is equally applicable for motorhomes as well. Today's RVs are getting more and more electrical with inverters, residential reefers, satellite dishes and all. When one battery isn't enough, manufacturers and owners just add a second, then a 3rd...even a 4th. What no one takes into consideration is charging these things as that second battery doubles the charge load and so on.

As I said, batteries are not resistive loads, they fight recharging and the higher the SOC the harder they fight. Flooded lead acid batteries need a MINIMUM of 2.15 volts per cell and a MAXIMUM of 2.35 volts per cell (AGM is even a little higher). For a 12 volt battery (6 cells) this translates to 12.9 and 14.1 volts respectively. Below 12.9 literally no charging will occur and above 14.1, they will boil electrolyte. Batteries in parallel increase the load current directly in proportion to the number of batteries connected. Of course, as this load increases, the voltage drop in the feed will also increase in proportion to the current and the voltage at the bank will continue to drop until it hits that magic 12.9 level, after which no charging at all will occur.

So, the operative question is "how much current can you provide...and still keep the applied voltage high enough to actually do anything to increase the SOC?" Lower SOC batteries will draw more and exacerbate the issue.

Take the numbers that you provided, that is a 60 foot round trip of #10 wire with an alternator output voltage of 14.4 will supply a maximum of 25 amps before hitting 12.9 volts. Now, at even 20 amps, the resulting voltage will still be so low as to only provide "float" charging. A safer number is more like 13 amps or so which will still read 13.6 volts at the battery, which is the "normal" slow charge mode of a converter. So, how many batteries can we connect in parallel and still stay below 13 amps. I am afraid that number is...ONE! With one 12 volt battery, the charge line you described will (eventually) bring the battery to full charge, albeit slower than a system that has a "boost" mode. With TWO it may never get very far at all and if it does, it will never get above 70 or 80 percent SOC since that takes a higher finishing voltage than you will have. So, if the TT has a residential reefer, the charge line should be OK if there is only one battery installed.

Now, this brings up a very interesting issue. We are talking about ONE 12 volt battery, which means 6 separate cells. The numbers don't care how big the cells are, although the bigger they are, the longer it will take to fill them...but fill them it will! This means that if you have a TT with a charge line as described and need more capacity than a single 12 volt battery can supply, you should install TWO 6 volt batteries in series. All this does is make the cells higher capacity and it does not affect the currents that will be drawn at any given SOC.

There are threads every day about 2 6 Volt batteries vs 2 12 volt batteries and they focus on capacity (if the batteries are of equal size, 2-6s is always better.) However, no one ever discusses the issue outlined here, which is far more important than total capacity. Even in the graph that I supplied for my RV with 4 12 volt units, bigger wire and a 3 level converter, 4 6 volt units would still charge faster and better than 4 12s.

My head is finally better. This is pretty simple.
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