Auxillary Battery - Deep Cycle ? or not

Thanks Mainey for your comment. I have a bit of an interest in this subject at the moment & was wondering if you could elaborate a bit further.

In particular relating to Brians query at the end of his post, which I interpreted as how long would it take for the vehicle alternator to stick 45 amps back in the battery after having used 45 amps out of the battery?

I realise that probably alternators differ in output & that the answer to such a question would be dependant upon many variables such as cable size & length etc.

But as a rule of thumb, how long would it take for an alternator to stick 45A in after taking 45A out & would it differ from a deep cycle battery as opposed to a cranking battery? Thanks & cheers

barry,
Various batteries charge at different rates, there is no correlation between two different *technology* DEEP CYCLE batteries, ie; when comparing a wetcell Calcium battery to a conventional lead/acid wetcell battery, they will accept charge at different levels depending on their condition and state of charge.

However, *AGM Deep Cycle* batteries will charge more fully and much faster than any wetcell DC.

my fridge draws ~10 Amps (~33% duty cycle)
it's *tested* consumption is: 2.8 ah x 12 hours = 33.6 Amps (indisputable)
some brands claim <1 ah ( therefore: 1 ah x 12 hours = 12 Amps )

100 Amp Alternator does NOT put 100 Amps into battery continuously
The vehicle *regulator* adjusts the charge going into the battery to what is 'required'
To attempt correctly estimate the time to (fully) charge a battery with "45" Amps is dependant on just too many factors to state here and what-ever is posted will be disputed anyway :) :) :)

I will suggest a few hours, that's the reason I use Solar power, it's continuously maintaining the battery fully charged during the day, (as my profile pics show) but that's not relevant.

Maîneÿ . . .

Lionel,

Why the need for two heavy crankers???
I believe you would be wasting your money.

Both the winch and the spotties are usually only used while the engine is running and therefore the alternator is feeding the Cranker with power as it is being used.
The winch is only ever used for relatively short durations and therefore will not drain the battery when used as above.

A deep cycle battery is best used in a dual battery configuration, regardless of whether it is portable, remote or whatever. In this configuration it is also charged by the vehicle alternator when travelling, or if removed from the vehicle, by a solar panel or other power source.

Bill.

Thanks Bill, does seem a little over kill now that I think about it.

Cheers....Lionel.

I have a 100ah AGM, and bought this DC digital amp current meter thing from Jaycar.
I ran the battery down a little then connected this gadget inline of a 15amp 3 stage charger. and it was pumping the full 15amps into the battery.

Col

That is very good advice, I two run two starter battery's in the Troopy.

I'm not sure if a deep cycle battery can start the 4.2 TD Troopy if the main crank battery craps itself, but I would rather drink hot beer them not to be able to start her out in the desert

Cheers

Richard

Col,
I won't suggest your talking rubbish, it would be just soo unkind, but you must understand two Cranking batteries are the same price as a GOOD Deep Cycle battery, yes based on your own numbers.

I use AGM's with a two (2) year warranty, so I don't have any problems, they retail @ ~$360 (same as your 2 batteries) and they do fully charge from an Alternator.

They have a stated service life of 10 years, that equates to only $36 per year.
Your Cranking batteries cost you $120 per year, again using your own numbers.

I'm sure most people would rather spend $36 per year on batteries, than the $120 per year your paying.

With 2 AGM's it's only $72 per year, which is still less than what you are (happily) paying, and with three (3) AGM's it will still cost less than you have to pay per year.

They will also get superior performance from AGM's.


There is not a *web site* on the net that will even suggest a Cranking battery is superior to an AGM Deep Cycle battery for running a fridge or accessories, if you honestly believe there is, then please post the link and prove me wrong.

Richard, yes AGM DC's will crank a diesel, I've used mine to jump start my GF's troopy.

Maîneÿ . . .

Hi Mainy, for the price you pay for one battery i get two, and they to have 2 year warranty.
As for charging from your alt, no battery can be fully charged to 100% of its capacity by your vehicles alt, this is proven science. This is where deep cycle batterys fail because they are designed to be fully charged from discharge.
I never suggested cranking batterys are better than deep cycle, but i do say for the average joe and his 4by the cranking batterys are a better way to go.
Try reading the Rivers books on this exact subject and you may learn some interesting facts, as i did.
If you have a smart charger try fully charging your battery, then go for a days drive just using your normal power usage in your vehicle, when you get home put the charger back on and see how long it takes to get the battery back to 100%, This is a simple way of seeing that the alt doesnt fully charge the battery.
I also never stated that a deep cycle battery wouldnt start a vehicle.
In my travels i have met several people who have got rid of the deep cycle and gone back to normal batterys as they havent been able to fully charge the deep cycle.

Cheers Col

who says you can't charge your AGM fully from the alternator?

Wire up/plug in your 12/240 inverter to the main batt and run your AGM charger off it while cruising along....
Just keep the VA rating of your inverter twice that of your max charger rating and your all set. E.g if your charger can deliver a max 15A, you want an inverter of 400VA or greater.

best, mr.batteryvalue

Col,
What brand and capacity are these Cranking batteries you use ?

As to people not being able to fully charge a Deep Cycle battery don't you think it's the fault of the charging system ?

Maîneÿ . . .

Mainy, They are yuasa made by century in australia, of hand not sure of the cca, and from memory they are 13 platers.

Its just not deep cycle batterys, but all batterys that will not charge to 100% of the batterys capacity. You are partially right it is tha fault of the chargeing system, by design only. The alt cannot read when a battery is full so by design the are made to put out heaps of charge after starting, to put back what the starter took out, then tapers of to put out a very small % of what the alt can deliver. This is to stop overcharging, which means the battrery doesnt get charged to its absolute capacity.

Deep cycle batterys are designed to be slowly charged, and the best way is with either a smart charger, or a solar pannel with a regulator. You will be suprised how much longer your fridge will run of the battery if charged by one of these methods.

Another good charger is the christy generator, it has a car alt fitted, but has a manual switch for low charge or the full 55amps for as long as the genny is running, in this mode you can overcharge your battery if you dont use the led read out fitted, or a multi meter to check battery capacity.

The Rivers books are very good reading and explain it better than i ever can.

Another good investment i found, is the c- tek smart charger, i got the 2500 and leave it connected to the 4by 24/7 when not using it, i also have the fridge connected all the time.

Col

Hello, would you care to comment on the suitability of a Powertech intelligent Full Automatic Battery charger, Model # MB 3612 for the charging of a deep cycle 120ah/20hr AGM cyclic.

The charger was bought from Jaycar. Many thanks

Hi Barry, sorry i dont know any thing about them, it sounds like a smart charger. The c-tek i have has 8 different stages, and can be left on indeffiantly and will handle having draw on the battery while charging. Col

Col,
from what I understand they may be N53's, is that correct ?
( 225 x 170 x 220 )

Maîneÿ . . .

Damian,
You say-> " If it were me and I needed a DUAL PURPOSE battery, A marine Battery is probably the best for this use. It's designed to take a lot of punishment. I'm not sure but I think a marine battery has fiberglass seperators in order to make them tough "

The original question is: "Auxillary Battery - Deep Cycle or not ?"
This battery is N0T going to be used as a Cranking and also a Storage battery, it's only a dedicated DEEP CYCLE storage battery, used for running Auxiliaries like fridge etc.


My question to you because you've "been in the trade now for 20 odd years" would be:
is an *AGM Deep Cycle* battery more suitable as a *DEDICATED AUXILILLARY* Battery, than either a wetcell Deep Cycle battery or wetcell Marine battery ?

Maîneÿ . .

Actually, the head of the thread is what you say but the question explained is "Deep Cycle or Hybrid Battery".

Also, I wasn't actually replying only to the Original poster as I was to everyone who posted a comment. I mean, You have one person stating that a Vehicles Alternator cannot charge a Wet Cell battery to it's fully charged state. Well, I beg to differ.

Years Ago, (When I started my first Shop) I looked at batteries for this very use, I looked at all types of batteries for all sorts of uses.

Marine batteries used Fiberglass separators then and I'm not so sure they do now (Could be Plastic) I can only guess they still do. The reason for Fibreglass is to handle the Vibration, heat and other sorts of knocks etc.

In Answer to your second question: An AGM battery needs to be carefully looked after. For one, you cannot leave an AGM battery in it's discharged rate for too long or it will deteriorate very quickly. You must charge an AGM Battery as soon as you can, even it's been used to 75% of it's charge. If you want to get the best life out of a AGM you need to take in it's special charging characteristics. 14.4v all the way to 15.5 volts for some.

I have a an N70z Type Wet Cell Marine battery in my Caravan, It's been in and out of Boats and Caravans for the past five years but in saying that, I do take care of it. Specific Gravity for each cell shows it's still in good nick. Although I wouldn't take it as gospel. Any Battery can fail just when you need it the most.

An AGM Battery will last a long time too if you look after it. But Personally, I prefer the Marine Battery because I know it will allow me to Crank a 200hp Mercury or will last me the weekend out in the bush.

If you were using Solar Panels to charge batteries, then I would have to go with an AGM as it is charging and discharging everyday.

The main problem when using a "Cranking Battery" is everytime you crank a car with it and Charge it, it sheds some lead of it's plates and therefore will sooner or later fail because of lead build-up in the bottom of it's casing (Shorted Cells) or Plate Buckling.
I do know of people getting 7 years out of their car battery in a car. Doesn't everybody?

Anyhow, Thats my 2 cents worth.

PS, When I spoke to the Battery Rep about batteries he had the same opinion as me. I can't mention the company.