12 volt longevity and recharging??

With six 6 volt batteries you will just have more batteries to charge. The weak link is going to be the fact that your converter , depending on model, will not go over 13.6 volts. It will fully charge six 6 volts if plugged in long enough but it will probably take a week or so.

Your furnace will pull 5 amps or better plus lights, water pump, frig etc. If you are running incandescent bulbs it will be even worse.

I doubt if your vehicle is going to keep up with winter energy demand. I have four 6v and with full charge It could probably run my furnace and other things non stop all night but the next day it's going to need a serious charge. I would then run my PD4655 on boost mode (14.4) on one pack and my Quick Charge 1250 with a finish voltage of 15.3 or so on the other pack.


If your converter is only doing 13.6 and you hit the shore power, you will need to sit there for a couple days or more to charge 6 batteries. You need a source of top charging that can get the volts to at least 14.4 but preferably 14.8.
Some people like the Black and Decker 50 amp charger ($150) My separate Quick Charge battery charger was $450.00 and weighs 36 pounds. Some of us also use power supplies. I have a 30 amp model that will do over 15 volts. ($65.00)

Thanks for all your responses. Very helpful. We will stay in hotels if and when temps are below freezing which they will be for a couple of nights going down and coming back.

The model # of my "System Monitor" converter is a TNC 400 D.
Output 40 amps with a 5 amp charger. Serial # 74849.

I was assuming that because I use 4 of these batteries @ 24 volts to run a 24 volt water pump. Charged with two 64 watt panels and manage to water 300 heifers trouble free all summer I was equipped to do this with out the need for a generator etc. I will have a volt meter along and could always check the voltage with all 6 tied together and if we have drawn them down to far could unhook 4 until we can plug in to shore power.
Is this a valid strategy?

The truck will never 100% charge the batteries. You will be lucky to get over 80% IMO.

You need to plug in overnight periodically and/or install 200 to 500 watts solar.

Actually a 1990 trailer converter may not even charge overnight if the battery is a bit low. If you have a portable charger bring it along. Post the converter model number for best answers.

Hi,

You may need to beef up the charging system from the tow vehicle to the trailer. #4 wire with appropriate fuses or better yet a circuit breaker would be good.

Perhaps an automatic circuit breaker at 50 amps. You really do not wish to burn out the alternator. Monitor the voltage in the tow vehicle. Keep it above 13 volts and all should be well. Switch off the charging circuit if the voltage at the tow vehicle gets too low.

for this reason alone, i swapped my converter charger my trailer... I swapped to a boondocks 75amp model... worst case i plug in to my penny, and let the batteries get the 14.6v for a bit... I charge between 4 and 6 12v. group 27's...

ivbinconned wrote:
o I expect our furnace will run a lot when we park.

Up there, now? Yes, it will likely never stop running. No, your truck is not a good charger, at least not through the 7 pin.

I suspect your Truck Alternator system will keep your Trailer Battery Bank topped off just fine. The problem of course is when you run the Trailer Battery Bank down to their 50% charge state then they will be demanding a very large DC charge current for around 30 minutes and probably will exceed what is being provided by the trickle charge coming from the Truck Alternator system.

I know what I would do and that would be to run my 2KW Generator for at least an hour with the trailer shore power cable connected to the 2KW Honda 120VAC Receptacle to get past the initial high DC CURRENT demand from the trailer batteries.

When I run down my trailer batteries below their 50% charge state they will want to draw around 53-55 AMPS DC Current when they first see 14.4VDC Boost Charge mode. This DC Current will start tapering off and eventually will get down to around a 8AMP DC CURRENT charge state as the batteries are taking on charge. In an two hour run off my smart mode converter running from my 2KW Generator this will drop to around 6AMPS in a two hour 14.4VDC charge period before dropping back to 13.6VDC charge mode.

I don't think your truck alternator charging setup will do much of this with your trailer batteries so far away from the alternator. The Truck Alternator will be more controlled by the Truck Start Battery charge status then it will with the trailer battery bank charge status. The Truck Alternator will most likely sense the Truck start battery is charged up and stop sending 14.4VDC to charge the battery in only a few minutes time. This will mean you will only be 13.6VDC down the Trailer Charge lead instead of 14.4VDC.

Once your trailer batteries taper back to a lower DC CURRENT demand then the truck alternator charge system should keep them recharged ok.

People in the know here will MEX and Pianotuna and others that live and travel consistently in their motorhomes with the dual Truck Start and Trailer Battery banks.

I am being old school here and will not do things that I know will task my Truck Alternator Charging system if I can help it. Its only purpose is to maintain the Truck Start Battery, not the additional Batteries associated with the TRAILER Battery Bank. I only have one ALTERNATOR CHARGE system to get me home on...

I most definitely would run my 2KW Generator during the time I would get up and all during Breakfast before leaving my night camping location and hitting the road again.

This is what I do every morning when camping off the power grid and running my trailer battery banks down to their 50% charge by 8AM each morning. I charge them back up to at least 90% charge state using my on-board smart mode converter charger setup powered by my 2KW Generator. When I get 20AMPs worth of Solar Panels added to my trailer I will do the same thing except I will only need to charge my trailer batteries for at least one hour to get past the high DC CURRENT initial charge using the Generator and then let the Solar Panels continue the charge state until the high sun goes away. I will never start my nightly camping run off the battery bank unless I start out with at least a 90% charged battery bank.

In your case you might want to do this sitting in your drive way before you head out on your long trip. Dry runs duplicating what you expect to do on the trip might give you some very valuable information on how the Truck Alternator system is going to perform for you... I suspect your six eaxh 6VDC batteries connected in series/parallel will react like three 12VDC batteries connected in parallel. They will draw around 55AMPS DC Current when first hit with 14.4 Boost charge smart mode.

Your big question will be will your Truck alternator hold up to this big increase in DC CURRENT demand before blowing out your truck alternator charge circuit.

Sorry for long report
Roy Ken

The furnace blower uses a lot of 12 volt power, so plug in as often as possible or getting a small generator for charging batteries may be a better option.

Plug in when you can. Firnaces consume vast quantities of both has and 12VDC when running.