-methods of CHARGING your AUX BATTERY, your thoughts-

Mainey, I have a very simple system for charging my battery in my golf camper trailer. I have a standard heavy duty wet cell in the trailer. It is used to run my 12 volt flouros and occasionally charge up the laptop. My needs are minimal when there is no 240 volt, the fridge is a 3 way one so it runs on gas. This battery is wired to the car charging sytem, no solenoid, just good quality 6mm cabling and one of the those 12 way flat tralier plugs. This supplies lighting for up to 7 days (nights) on the Murray each year. When touring over several weeks I still prefer to use the 12 flouros for lighting - the drive between locations seems to top up the battery. I have a voltmeter in line and it allows me to keep an eye on its progress. I know many will poo poo my simple method, but this battery is now 5 years old and it still in top condition. When not travelling it is connected up to a battery conditioner all the time. I have once had to "boil" the battery with a three stage battery charger after leaving it to run the frige for a couple of days (probably only lasted 4 or 5 hours) while the van was stored. It's a kiss system. lol.

I have a pop top with 2x 64watt UniSolar panels mounted on top running to the battery located in the caravan boot through a 20watt regulator. I also run a 39 litre Engel on freeze and never have a problem up camping up north. Camping in the south is another thing with our main camping spot in the hills only receiving sun from about 10.00am to 2.00pm. The only problem I encounter is if the caravan battery is not isolated when driving, the 10amp fuse holder between the caravan battery and the caravan wiring is extremely hot. I am investigating running heavy guage wire back from the 2nd car battery via an anderson plug but as the wiring is all jointed under the van and then runs to various parts of the van I am still trying to find the correct method.

Good idea Mainey. Here's my personal experience.

I have owned 2 HZJ75 Series utes both with duel battery setups. Both set ups used one starter and one deep cycle. Both of the wet cell type.

The first ute I set up a "samrt charge system". It was not a big brand version but did place initial chrage into starter battery before joining batteries into paralel until the key was turned off at which point it would isolate starter battery. Appeared to work well while I had that vehicle (somebleepstole it). Only thing I didn't like was that you never really knew what was going on with the batteries. You just had to hope that it did its job and in the morning or the following day you could start the vehicle when the key was turned.

In my replacement ute I put in a simple Marine battery switch setup. Cost stuff all to set up. If say I've been camping over night with fridge and lights running from deep cycle battery (pos2) I simply start the vehicle from the starter batt. (pos1)and leave switch in Pos 1 for minimum of 20 minutes (depends on what length of driving I'm about to do) and then switch to Pos 2 for majority of trip until I know I will be stopping. Once I stop I have the habit of turning the batt selector straight to pos1 ready for me to start vehicle when I get back in. I have never had to use pos 1+2 yet. I never charge in pos 1+2 either.

Some say this system might be time consuming or take to much "human input". It works for me. I know exactly batt is being charged, what voltage is in it and can select what ever choice/combination of batt I want all by just turning the dial. No computers/electronics to fail. Because with this system the 2 batteries are never put into parallel (unless you use pos 1+2) then it rids all the problems of "diferent types of batteries" "joining batteries of different voltages" "slow charging" etc etc.

The one catch is that yes you have to be on the ball and remember to change the position switch. But its not that critical, if after you stop you run the fridge/lights from the starter batt before you remember to change to pos 2....... Hell in the event that you went all night on the starter and in the morning it didin't have enough juice to start the vehicle then simply switch to pos 2 (which has been isolated all night) and start it. Believe me it works.

Anyway my 2 cents worth.

Cheers,
Hughesy

Mainey,

No surprise, it's solar for me.

I've had great results from it so far and have posted my results.

We're going camping this weekend for two nights. This will be the first time I will give it a workout in the Melbourne Winter. I'll post the results next Monday.

Cheers,

Jim.

May I suggest that, if using a basic master switch that isolates the 'second' battery from the charging system - to set it up such that an LED warning light comes on when in that position. (The LED only _Affordable_Storage_Drawers.aspx a few thousands of an amp). This eliminates the risk of forgetting to set it back again to charge.

Re solenoid switching, be wary of simple solenoids that operate immediately the ignition is switched on. There, there is a risk of the starter battery discharging into a deeply-discharged house battery in the event the ignition is turned on but the engine is not started immediately - if for example you turn the key but then note a king brown heading your way.

There is also a real risk of the starter battery being flattened in the event that a large load (such as a microwave oven) is switched on before the starter battery is up to charge. (The latter normally takes only 1-2 minutes).

To avoid these situations it is safer to use a voltage sensing relay (such as the Redarc). This gives the starting battery automatic charging priority.

This is especially true if using an AGM second battery because AGM's very high charge acceptance may 'starve' the starter battery.

Most interesting thread!

I totally support the alternator charging charging plus solar approach where demand applies - but if there's ample space for solar modules and demand is light then solar alone is much simpler and works just fine.

My OKA has been set ujp like this since 1996 - and has not once run out of 12-volt power. I describe this method in some of my writings.
Collyn Rivers

My setup.

As its almost impossible to run a dual batt system on my Petrol Patrol , my dual batt is on the trailer.

Twin 6mm cable from starter battery to redarc isolator , then to the rear of the Patrol , to Anderson plug , onto the Trailer Battery.

The Battery is a Marshall Batteries 55 amp hour Deep Cycle.

I can run my Fridge and several Halogen lights for 2 days. It then runs out of puff.

As I dont have a 3 stage charger , and the battery is mostly charged by either a cheap charger or altenator , I'm not doing the battery any favours , but , its not really big enough capacity.

I'm about to change to a large cranking battery so it can be charged by the Altenator properly when moving. This should give me 2 to 3 days easily.

I use solidnoids on my system for charging second battery but have it activated on engine running only. Engine stops solidnoid shut down. on new prado have installed rediarc, interesting to see how it goes compared to last 2 setups that I had in previous vehicles
Cheers
Charlie

On previous vehicle [97TD cruiser] i used 2 x 700cca overlanders through a 150amp solonoid, system worked ok running a 60lt engel but i think it could have been better.

My new vehicle [100TD cruiser] will have 2 x 40lt engels [the thinking is combined they use slightly less amps than the old 60lt and gives me options of using one/both/fridge/freezer etc] I intend using a Redarc VSR and a AGM battery around 120ah [brand unsure] for the Aux and high CCA battery for starter. Looking at a 3 stage battery charger, CTEK or the new REDARC smart charger that Collyn mentioned and running that off my Honda genny as required, if funds permit i will get a 120w solar to supplement.

few in our club go with the christie system
http://www.christieengineering.com.au/

works very well

80 series turbo diesel auto ,standard alternator , 80amp hr Fullriver AGM as start batt , AUX batt 80amp Fullriver AGM through Rotronics weekender RA100H , 8mmsq +and - wire from aux to 50amp anderson at rear of vehicle , also 3x waeco style +1 engle style socket feed thru separate fuse/s from same wire ,,,,,,anderson plug to camper trailer feeding 3x 80amp hr Fullriver AGM batts supplying 3x3 banks of waeco style sockets ,,, ,,, 1x64 UNISOLAR +1x 120 KYOCERA solar panels free standing up to 30mtr from camp thru 8mmsq cable to Steca 2020 controller to anderson plug ,, Scorpion 950 2stroke generator + CTEC XS7000 charger for when the sun dosnt want to play ,,,,,,, USAGE = 1X 80LT Waeco fridge/freezer set to run at -10 in freezer and 3-4 in fridge ,, 1x 15lt Engle set to run at 2-3deg for beer ,, up to 5x 12v fluro , occasional cd/radio used for weather reports ,, have never run out of power "yet" ,,always leave home with batts fully charged and always get home with batts fully charged , works for me.

* * * * It’s good to read so many positive responsive * * * *

When you read my original opening statement it can be assertained that's what I wanted from guy’s and girls that have aux battery systems that they themselves use, have tested even to some small degree and know they work because they actively use them without problems!

The various reviews for the AGM batteries are good to see as even though I don’t use them, when my Delkors eventually die AGM’s are my replacement batteries of choice simply due to their technical features which give them the ability to accept a solar charge far quicker than a Wet DC battery.
Is a pity they were not so prevalent four years ago, but that is what technology is all about… change and technical improvements with the change!

Mainey....

Jimbo wrote -
"I've found in my testing that the AGM absorbs about an amp per minute from the alternator. "

I assume you mean 1 AmpHour per minute which means it is taking 60 Amps. This seems to be the charging current for a discharged AGM, although I haven't seen too many actual test measurements !!!

What size and brand is your AGM ?

What voltage does your Alternator put out ?

The Charging graphs for this AGM http://www.absorbedpower.com/battery/pdf/AP-GT12-100C-01Sep05.pdf
make it clear that you can charge it fully even if the Alternator is only putting out 13.8volts.

Jimbo

"Having said all that, the best reading I get from it in the car is 12.78 volts"

- is it the Auxiliary battery connected via an Isolator ?
- are any loads conected to it at all in the car ?