Deep Cycle Batteries

Submitted: Saturday, Feb 04, 2006 at 15:28
ThreadID: 30416 Views:7505 Replies:8 FollowUps:3
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Hi all,

I currently have a 75AMP hour deep cycle on my camper trailer and frnkly it doesnt quite last the distance when you get three days of rain and the solar isnt charging.

It is used for running, fridges, the laptop, lights and other stuff the wife makes you take away. Plus i would like to be abelt o hook up an invertor to it as well of some 600 watts.

I am lookign to replace it with the biggest capacity deep cycle i can find that will fit in the standard black battery boxes you get form pretty much any auto store.

Any advice on brands and capacities would be greatly appreciated.


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Reply By: Member - Reiner G (QLD) - Saturday, Feb 04, 2006 at 16:00

Saturday, Feb 04, 2006 at 16:00
Hi Mark
I didn't understand much about 12 volt and batteries but I found reading this very helpful. Collyn Rivers has soem great Info on Batteries and cable sizes too.
I had to read it a few times since the grey matter is getting a bit worn, but before you spend more money on equipment and find that wont work either have a read.

AnswerID: 152954

Reply By: Mulga Bill - Saturday, Feb 04, 2006 at 16:05

Saturday, Feb 04, 2006 at 16:05
Maybe a second battery of the same size connected parallel, if you have a spot to put it ? That might collectively be larger than a big replacement - thinking of doing that with my camper (1 X 70AH at present). Not surprised the current (he he) unit doesn't last - you folks do inconvenience a lot of electrons !
AnswerID: 152956

Reply By: Member - Norm C (QLD) - Saturday, Feb 04, 2006 at 18:38

Saturday, Feb 04, 2006 at 18:38
OMN, if I understand the black battery boxes you are talking about, you can get a 120AH Fullriver AGM into one. I was looking to do this with two AGM's, but ended up mounting a lockable metal box on the drawer bar (bolted to to the side of the storage box). It houses the two AGMs. Bought the batteries from Fridge and Solar on the Gold Coast. Reiner has provided a link to their web site.

If you don't know much about AGMs, there is good info on the Fridge and solar web site. Great batteries. Charge quickly and hold their charge well (don't ned to on trickle charge when not in use).

AnswerID: 152987

Reply By: bouncer - Saturday, Feb 04, 2006 at 18:42

Saturday, Feb 04, 2006 at 18:42
I have a trojan 130ah battery that fits in one of the black box's you are talking about.
AnswerID: 152989

Reply By: Crackles - Saturday, Feb 04, 2006 at 19:52

Saturday, Feb 04, 2006 at 19:52
Mark you seem to have the cart before the horse. You don't fit the biggest battery you can first rather add up all the expected loads you intend to run, add a 10 to 15% buffer then calculate what size solar panels you'll need. With all this imfo you'll then be able to calculate the battery size you actually NEED. Putting a bigger battery in may not necessarily fix all you problems if the solar panel is too small as well. Solar retailers would be the best to calculate your requirements as everyones setup will be different.
All that said the 130 AH Trojan battery is good quality & should just fit in your box.
Cheers Craig.......
Twin 115AH Trojan batts.
AnswerID: 152998

Follow Up By: Mike DiD - Sunday, Feb 05, 2006 at 14:41

Sunday, Feb 05, 2006 at 14:41
If you are limited in budget (its all relative !) then work out how much solar panel you can afford.

e,g, two 80 watt panels will give you 9 amps so in good conditions you will be able to put 72 amphours into your batteries each day. This will fully charge a 60 amp hour battery, though you should never PLAN to discharge your battery below 50%. Therefore you could put in a MINIMUM of a 120 amphour battery.

If there is no sun for two days your battery will be fully discharged - this will SHORTEN its life, not kill it.

With this setup YOU HAVE TO ACCEPT that you only have AVAILABLE 60 amphours every day. In REALLY HOT conditions, this may only be enough to run a fridge.

FollowupID: 407026

Reply By: Mitch of Bleakheath - Sunday, Feb 05, 2006 at 14:24

Sunday, Feb 05, 2006 at 14:24
I tow an Avan which came with an 85AH marine battery for lighting. Apart from the stupid location of the battery, it worked OK for about three years until the continual discharging/recharging caught up with it. Relocated and replaced it with a REMCO RM 105 (105AH) deep cycle battery. This battery technology also required an adjustment to the maximum charging voltage. That is, if you are replacing standard lead acid batteries with some types of deep cycle batteries you will need to check that the solar regulator and mains battery charger deliver the correct charging rates/voltages.

After weeks of wading through technical data sheets I decided to seek the advice of experts in remote area 12/24 volt systems. Their advice was to install the RM 105 battery and a replacement mains charger (YK 12 am auto charger).

Subsequently decided to replace the Electrolux three way (gas) fridge with something that will work in the tropics (Engel swing door model) which required an additional solar panel (Uni solar 165), a great regulator (which allows detail monitoring of charge rates and current consumption) and an additional YM 105 battery in parallel. Have never discharged the batteries below 50% of available capacity (approx 110AH) and no longer have to go into rapacious caravan parks to top up batteries.

The RM 105 batteries are physically smaller than the typical 85 AH marine batteries that get installed in Caravans and should fit inside a standard battery case. Be warned! - they are back-breakingly heavy (34kg) but very robust. They use a gel electrolyte which eliminates the risk of catastrophic leak if the outer case cracks (eg as a result of a pounding from corrugations).

It is not a cheap option. Each battery will set you back around $330. The matching charger is around $300, the regulator $165 and the panel about $650. Installation is additional if you want the professisonals to do it.

It was worth it for us because we are away for months on end, spending long periods in remote areas.


AnswerID: 153132

Follow Up By: Mike DiD - Sunday, Feb 05, 2006 at 14:48

Sunday, Feb 05, 2006 at 14:48
Whitworths sell the RM12-100 100amphour for $279.

I found by ringing around a few BatteryWorld stores I could save quite a bit more.

FollowupID: 407028

Follow Up By: Mike DiD - Sunday, Feb 05, 2006 at 14:51

Sunday, Feb 05, 2006 at 14:51
Jaycar sell a 12 amp Three stage switchmode charger with voltages compatible with these AGM batteries for $99 (currently out of stock).

FollowupID: 407031

Reply By: OMN - Sunday, Feb 05, 2006 at 16:14

Sunday, Feb 05, 2006 at 16:14
Thaks guys for all the info, the CT i have it in already has all of the regulators and solar panels to charge the battery no problems in quick time based on one issue, sunlight.

The panels are 190 watt in total and keep it charged no problem, i can check the charge rate, the drain and voltage on the battery and everythign with the system.

My main problem is that the last two times i have been camping we have had completely overcast and raining days for two to three days of the trip in succession while stationary both times and that is really testing out the life of the battery.

Both times have had to connect to the car and run the engine for a while to get some charge back into it.

My preference would simply be too put in a bigger battery and then i will no doubt go camping in the future and it will be sunny every day and i will have wasted my hard earned.

But very annoying when there is a choice of which fridge to turn off and the wife chooses the alcohol fridge over the food fridge every time.

Thanks again.


AnswerID: 153150

Reply By: Member - Collyn R (WA) - Sunday, Feb 05, 2006 at 16:26

Sunday, Feb 05, 2006 at 16:26

The important is to realise that you are unlikely (in practice) to be able to access much over 35% of any conventional battery's Ah capacity unless fully charged via solar or a really good three-stage charger.

They will not charge to much over 70% from most conventional charging systems (incl car alternators) - and cannot be realistically discharged much below 40% without drastically reducing their life.

AGMs are a better bet here. They will charge very close to 100% from a car alternator and can be taken down to 30% without undue concern. You thus have about 70% of the 100% you probably thought you were paying for. This goes a fair way to compensating for their higher cost.
Collyn Rivers
AnswerID: 153153

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