Auxillery Battery

Submitted: Friday, Feb 11, 2011 at 19:03
ThreadID: 127206 Views:3757 Replies:5 FollowUps:1
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Our auxillery battery in our Troopy has just passed away after just over 2 years. Our auto electrican says that between 2 to 3 years is the life of them. This battery has never been below 11.9 amps,as we had a gadget set up that cuts the power off from it when it gets to 11.9amps,to give it a longer life As I've already had it taken out (not yet replaced) the only info I have is that it was a Century Marine Pro. When I had it put in,my A/E said that it would be the best one for the job,which was to run our Engil Fridge and our UHF radio. Have suggested to our A/E that I may look at a Ritar deep cycle battery as a replacement,but he reackons that it would take a lot to get it charged up again when it gets down to the 11.9amps.
Would welcome any feedback on what life others have had out of auxillery batteries under the same circumstances.
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Reply By: Umpire83 - Saturday, Feb 12, 2011 at 00:53

Saturday, Feb 12, 2011 at 00:53
Lawrie, Think you mean Volts not Amps when talking about a battery is this case. Our Waeco car fridge won't run when battery gets below 12 v, so we run the power lead to the Generator if we are parked up for a few days and not driving the car. Just on 12 months ago picked up a semi Deep Cycle (SuperCharge MRV 70, 105AH, 760CCA) for $199 and it also works well as a support cranking battery. Used it in the van in place of the usual 3 when they didn't go the distance to Cape York. Was a great support battery all round, no idea how long it will last.


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AnswerID: 582028

Reply By: Turist - Saturday, Feb 12, 2011 at 02:56

Saturday, Feb 12, 2011 at 02:56
I assume that you are using a splitter device to charge your aux battery.
This is the reason that an aux battery can take many hours to build up a full charge.
The alternator senses the voltage in the main system and as the main battery recovers charge (from starting etc) the voltage regulator in the alternator slows the charge.

The alternator is a voltage supply for the vehicle, not a battery charger.
It will increase/decrease charge dependent on the vehicle requirement, i.e., lights on or off, recovery from start load etc.

If you have the required instruments to measure volts and amps at the aux battery you will commonly find as little as 2 amps going into the aux battery, even when it is discharged.

To overcome this problem fit a DC/DC charger.
Depending on model/brand they will put 20-40 amps to the battery.

I have been using a Redarc model for some time and found that the aux battery recovery is very good.
The Redarc is a 3 stage DC/DC charger with settings foe sealed, flooded and AGM batteries.
I am using a Fullriver 120 amp AGM battery, similar to the Ritar you are looking at.

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AnswerID: 582029

Reply By: Bow & Nan - Saturday, Feb 12, 2011 at 03:51

Saturday, Feb 12, 2011 at 03:51
Auxiliary batteries in a Troopy are a real problem, the high under bonnet temperatures will kill the battery.

Try and construct a heat shield between the motor and the battery. It can also help if you run some ducting to pass fresh cool air over the battery.

AGM batteries do not like heat so be careful which battery you use under the bonnet.

As Bob said the DC / DC charges are the go. I use a 30 amp sidewinder DC/DC charger to charge my auxiliary battery and the 3 batteries in the caravan. I will never go back to a splitter charging system for auxiliary battery bank.

AnswerID: 582030

Reply By: Swanwood - Saturday, Feb 12, 2011 at 21:55

Saturday, Feb 12, 2011 at 21:55
I current have a Trojan 27 TMH as the auxillery battery in my Nissan Patrol to power the Engel Fridge. This battery is 5 years old and now needs replacing. I recently installed Ritar batteries in the caravan. I discussed the replacement for the Trojan with a Ritar and was strongly advised against using this type of battery in the hot engine bay. Alco Newcastle advised that in their opinion the Trojan was the only way to go to get reasonable life.
I will be replacing the battery with another Trojan even though they are more expensive and not a sealed battery.

Ian & Cheryl

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AnswerID: 582031

Reply By: TRB60 - Sunday, Feb 13, 2011 at 21:23

Sunday, Feb 13, 2011 at 21:23

Keep it simple, all you need is a solenoid that is activated by the ignition, and 2 batteries of the same brand and capacity, I have used this system for some 35 years on different vehicles, cheap but very effective. Lead acid batteries seem to last longer than deep cycle in this situation and are cheaper. A lot of installation use deep cycle and standard lead acid together this is a no no.

Regards Terry

AnswerID: 582032

Follow Up By: Bow & Nan - Monday, Feb 14, 2011 at 06:55

Monday, Feb 14, 2011 at 06:55
I liked the old solenoid system (KISS) but its day has passed. A solenoid is ok on old cars but be careful with the new cars. If the solenoid sends a spike through the system it can cost big dollars to repair. The solenoid must have spike protection.

On the newer cars the voltage can be to low (13.2v) to give full charge to the Aux battery. On my 200 series the voltage starts at 13.9 then after 5 minutes drops to 13.2v.

DC to DC chargers can be set up to separate the Aux circuit from the main circuit

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