Back up batteries for boon docking

Thanks CincyGus, yes that is very helpful, as has everyone else on this fantastic forum. We are not getting into all the nitty gritty until we arrive in April so just researching & gathering as much info as possible in the mean time. Solar sounds like a great idea with these deep cycle batteries you & Woodglue have mentioned.

Mik68,

Woodglue points you in the right direction. Since you say you are inexperienced and you mentioned "12v car batteries" I'm going to repeat a significant point. You want deep cycle batteries, not car batteries. They are built to take the charging/discharging much better and will last significantly longer.

So regular car batteries are < 12v deep cycle batteries which are < 6v batteries in ability to take discharge and last longer.

The class of battery (or group such as 24, 27, 29, 32, etc.) refers to how much power they can hold with bigger numbers indicating more power and generally larger size.

As mentioned, charging by driving is going to be very ineffective due to the length of the wire run from the vehicles alternator and the size of the wire. Your choices are going to be buy a genny and feed it gas to recharge every 2-4 days (depending on what size and how many batteries you end up going with and your power usage) or adding enough solar to recover your batteries back up to 90%-95% each day from the usage you had the previous day.

Use the search to read some fantastic posts about both Solar and batteries as both have been covered in much greater detail than I have above, I just wanted to get you some basic info before you went out and bought a couple car batteries that you would have been very disappointed in their performance.

enblethen wrote:
The truck will charge the batteries. It will take sometime to get a full charge. Plugging in overnight should do the trick.
Have you thought about a small genset? A 2000 watt inverter style( Honda or Yamaha) will charge the batteries while dry camping and allow you to use things like the microwave.
You could pick one up at many locations and be on the road right away.

Yes, this is another posting subject for me. I equally know nothing about genset's? How much are they, roughly? And how does it compare to solar pricing? The only negative I can see in going solar is having to park in the sun all the time. Not something we do here in Oz especially as I have worked out in our baking hot sun for the last 20+ years.

The truck will charge the batteries. It will take sometime to get a full charge. Plugging in overnight should do the trick.
Have you thought about a small genset? A 2000 watt inverter style( Honda or Yamaha) will charge the batteries while dry camping and allow you to use things like the microwave.
You could pick one up at many locations and be on the road right away.

So the only way to charge the batteries is from being hooked up using normal AC power or going the solar route? As we are flying into Dallas, purchasing a truck & FW & wanting to hit the road ASAP, there are possibly companies in or around Dallas that could install a system for me?

Get two AGM 12v Deep Cycle Marine batteries (probably group 34) and you should be good to go for 3 days. Just be judicious on the use of lights, etc.

WoodGlue

12 volt or 6 volt is always an issue. It depends on your needs and wishes. For my desires 12 volt is a better fit.

Do an energy audit.

Here is a link to the rather special spreadsheet that N8GS has created to help size solar battery charging systems!
Solar Spread Sheet N8GS

For a nice explanation of solar, try this link: Golden rules of solar

Mik68 wrote:

pianotuna wrote:
Hi,

Plan on adding a modest solar system. That way every trip will start with the battery bank brimming full.

I didn't wanna go down the solar route until I got it back to Oz. Wouldn't the batteries be 'brimming full' from a descent amount of driving most days?

No, it could take 24 to 48 hours of driving to fully charge three low batteries due to the long thin wire from alternator to batteries on any trailer.

Depending on the converter (that does the actual charging) it could take just as long with a generator. You need to get 14.4+ volts on the battery if you expect 95% charged in four hours. Many converters will just slow charge at 13.6 volts. WFCO "3 stage" converter is notorious for this.

Since this is temporary I would buy a Honda 2000 generator and get on the road. If the converter proves to be a slow charge you can buy a portable 40 amp charger from an autoparts store. Honda is an easy resell at the end of the trip.

Get in the rig and post these questions. It might be set up just fine.

Solar will be fairly expensive fully installed with enough power to do what you expect. Could kill a week or two to get it all scheduled, fitted and finished.

Honda 2000 msrp $1,150 http://powerequipment.honda.com/generators
Can be had for less by mail order from places like wisesales.com/Honda

Solar will have very little residual value. Honda 2000 will easily sell for 75%+ of what you pay. So the real cost of a Honda will be about $300 + fuel.

Hi Mik68,

The charging path is generally too long and so there is lots of voltage drop which leads directly to almost no charging while traveling.

Solar is about $2 per watt for materials.

Mik68 wrote:

I didn't wanna go down the solar route until I got it back to Oz. Wouldn't the batteries be 'brimming full' from a descent amount of driving most days?

enblethen wrote:
One battery with minimal loads will last a day or two. Two six volt batteries in series should last 4-5 days.
Minimal loads I consider as refer, lights and some TV. Does not include furnace running for 6-8 hours.

Awesome, thanks! Not 12v batteries? Definitely only 6v? And the vehicle will charge these batteries? I told you I was inexperienced about all this.