jeffw Posted September 8, 2016 Report Share Posted September 8, 2016 We tow a car hauling trailer, and it's got a couple of batteries in it for the internal lighting, lifts and to start the generator. The trailer has a 120v minn-kota multiple battery charger installed. The batteries seem to go flat pretty quickly (I'm suspecting I've got a parasitic drain when the trailer is left connected to the truck). I'd like to be able to charge the trailer house batteries when we're traveling in the truck, so I was thinking of running an extension cord from the truck inverter to the trailer to power the battery charger (and 120V lights). What safety considerations do I need to be aware of? Suggestions for a nice 120V socket I can mount near the 5th wheel? Any other tips? Thanks! 2007 Volvo 780 Volvo D12D, 465hp, 1650 ft/lbs tq., ultrashift Link to comment Share on other sites More sharing options...
rpsinc Posted September 8, 2016 Report Share Posted September 8, 2016 Your idea has merit BUT it will only charge when you are traveling or plugged into S&B. Put a small solar panel and charge controller on it and you should be able to forget about it. Check that the charging is working occasionally and check the water in the batteries too. I have an enclosed trailer with a utility DC battery. I didnt go to the trouble of connectiing to tow vehicle circuit, just put on a panel and it stays in good condition, regularly exercising, which is more than I can say for myself. LOL Marcel Link to comment Share on other sites More sharing options...
Darryl&Rita Posted September 9, 2016 Report Share Posted September 9, 2016 We tow a car hauling trailer, and it's got a couple of batteries in it for the internal lighting, lifts and to start the generator. The trailer has a 120v minn-kota multiple battery charger installed. The batteries seem to go flat pretty quickly (I'm suspecting I've got a parasitic drain when the trailer is left connected to the truck). I'd like to be able to charge the trailer house batteries when we're traveling in the truck, so I was thinking of running an extension cord from the truck inverter to the trailer to power the battery charger (and 120V lights). What safety considerations do I need to be aware of? Nothing special, other than don't let the cord drag. Suggestions for a nice 120V socket I can mount near the 5th wheel? Any other tips? I've used the cord ends at the bottom of this page with good results, but they are limited to 15 amp connections. 20 amp ends will swap in their place, but they aren't UL or CSA approved, or NEC approved as an assembly. Use at your own risk. Thanks! I think Mark(DMBruss) uses the same idea, maybe he'll come in. I have been wrong before, I'll probably be wrong again. 2000 Kenworth T 2000 w/N-14 and 10 speed Gen1 Autoshift, deck built by Star Fabrication 2006 smart fourtwo cdi cabriolet 2007 32.5' Fleetwood QuantumPlease e-mail us here. Link to comment Share on other sites More sharing options...
rdickinson Posted September 9, 2016 Report Share Posted September 9, 2016 I installed a couple of cables from the truck alternator or battery bank to the trailer batteries with an isolator to prevent draining when truck is not running. Alternator is 135 amp, I'm told expect max 80% sufficiency so that is about 108 when going down the road. That way when I get to the destination the Inverter charger doesn't want to commandeer a whole circuit to charge the batteries at days end. I could tune the charge rate down though. Link to comment Share on other sites More sharing options...
Jack Mayer Posted September 9, 2016 Report Share Posted September 9, 2016 Installing a DC line between the truck and trailer - as Roger mentions above - is problematic. The voltage drop in most installations makes them of limited benefit. But there ARE things you can do to mitigate the issues with DC. Sending AC over to the trailer and using the charger already present works pretty well. Most of the chargers (certainly any converters) can handle very low voltage and dirty power just fine. So voltage drop issues in the AC circuit, and use of modified sine wave inverters to "generate" the power work OK. It's not real "efficient", but it will get a charge on your battery bank in the trailer, and in some sense the alternator in the truck provides "free" power to the truck battery bank - the source for the AC power going to the trailer. It "can" overwork the alternator in some scenarios, but that is relatively a minor issue. Safety is not something to be taken lightly. You are sending AC across while in motion and a very high quality twist lock plug is REQUIRED. Plus a high quality protected cord. And you have to route the AC power through your bed to the rear of the truck, and protect THAT as well. Overall, putting some solar on the trailer is a better solution, and it works when the trailer is "standalone" too. Jack & Danielle Mayer #60376 Lifetime Member Living on the road since 2000PLEASE no PM's. Email me. jackdanmayer AT gmail 2016 DRV Houston 44' 5er (we still have it) 2022 New Horizons 43' 5er 2016 Itasca 27N 28' motorhome 2019 Volvo 860, D13 455/1850, 236" wb, I-Shift, battery-based APU No truck at the moment - we use one of our demo units 2016 smart Passion, piggyback on the truck -------------------------------------------------------------------------See our website for info on New Horizons 5th wheels, HDTs as tow vehicles, communications on the road, and use of solar powerwww.jackdanmayer.com Principal in RVH Lifestyles. RVH-Lifestyles.com Link to comment Share on other sites More sharing options...
Darryl&Rita Posted September 9, 2016 Report Share Posted September 9, 2016 Jack, did you look at the link I provided? I have been wrong before, I'll probably be wrong again. 2000 Kenworth T 2000 w/N-14 and 10 speed Gen1 Autoshift, deck built by Star Fabrication 2006 smart fourtwo cdi cabriolet 2007 32.5' Fleetwood QuantumPlease e-mail us here. Link to comment Share on other sites More sharing options...
Jack Mayer Posted September 9, 2016 Report Share Posted September 9, 2016 Jack, did you look at the link I provided? Yes. That is great plug for non-moving applications, but it does not appear to be a twist lock. You want good retention in this application....but that does somewhat depend on the routing method. BTW Bill B does this exact thing being discussed. I'm sure he will eventually comment. Jack & Danielle Mayer #60376 Lifetime Member Living on the road since 2000PLEASE no PM's. Email me. jackdanmayer AT gmail 2016 DRV Houston 44' 5er (we still have it) 2022 New Horizons 43' 5er 2016 Itasca 27N 28' motorhome 2019 Volvo 860, D13 455/1850, 236" wb, I-Shift, battery-based APU No truck at the moment - we use one of our demo units 2016 smart Passion, piggyback on the truck -------------------------------------------------------------------------See our website for info on New Horizons 5th wheels, HDTs as tow vehicles, communications on the road, and use of solar powerwww.jackdanmayer.com Principal in RVH Lifestyles. RVH-Lifestyles.com Link to comment Share on other sites More sharing options...
Broncohauler Posted September 9, 2016 Report Share Posted September 9, 2016 Yes. That is great plug for non-moving applications, but it does not appear to be a twist lock. You want good retention in this application....but that does somewhat depend on the routing method. BTW Bill B does this exact thing being discussed. I'm sure he will eventually comment. I understand Wanting a twist lock to hold it secure. But then again I think if the plug was to hang up on anything, would it not be better for it to come unplugged rather than pull the wires out causing a possible dangling live wire?? Link to comment Share on other sites More sharing options...
Darryl&Rita Posted September 9, 2016 Report Share Posted September 9, 2016 The cord ends I linked to are straight blade, but use a locking ring to keep them together. They're used extensively on drilling rigs up here, and will fit any brand of cord ends on the market. The problem with Twist-Lok type ends, can be limited availability in case of damage. I have been wrong before, I'll probably be wrong again. 2000 Kenworth T 2000 w/N-14 and 10 speed Gen1 Autoshift, deck built by Star Fabrication 2006 smart fourtwo cdi cabriolet 2007 32.5' Fleetwood QuantumPlease e-mail us here. Link to comment Share on other sites More sharing options...
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