Second Deep Cycle Options

[k3vin]

Hi Guys,

I thought best to post this here in case anyone in the future might have the same queries I did regarding running a second deep cycle battery.

I searched through threads but couldn't find out exactly what I was after, so I thought I'd ask the Guru himself "Old.Tony".

My original message to Tony:

I have a dual battery system setup now already and functioning correctly on my D40. I was thinking of whacking in a another deep cycle (same as my existing one) to purely run the fridge, and using my original deep cycle for all the accessories. The reason I'm thinking of doing this is the travel buddy drains alot of juice.

I would connect the 2nd deep cycling using another isolator. Would it be possible to do without upgrading alternator in your opinion? Just was not sure if the charging capacity would be okay still.

Cheers,
Kevin.


Tony's response:

The D40 alternator puts out a fair whack of power anyway and could probably handle the load without too much drama. When travelling with our caravan, ours has to supply about 40A to keep the fridge in the caravan operating and about 10A for the stuff in the tub. It does it just fine, I've kept an eye on the ECU voltage and it's remained around the 14V mark. If it fell below 13.5V I'd be concerned, that's a possible sign of the alternator struggling to deliver power.

The only drawback with cranker -> isolator1 -> cable -> auxbatt1 -> isolator2 -> auxbatt3 is that the voltage on isolator2 has to exceed 13.2V in order for it to switch on, which may take quite some time since "cable" will have some voltage drop in it and full power won't be delivered to auxbatt1 anyway. It means that auxbatt1 will pretty much have to charge first, before auxbatt2 will get much charge.

An alternative is to double the cables from front to rear and parallel the charging, so that there are two isolators connected to the cranking battery, and two sets of cables heading to the rear. This separates the two aux systems and ensures that both are charged at the same time, rather than one aux battery charging before the other.

Cheers
Tony

 

[benchrisfennell]

Let us know mate what you decide to do i was thinking the same thing and how to go about it. Cheers heaps Ben.. ��

 

[75 GRC]

http://www.aussiebatteries.com.au/batteries/deep-cycle-agm/280ah-12v-agm-deep-cycle-battery

Has anybody,
Looked into these batteries.Yes I know it's some serious amperage...

And a serious price tag!!!

Any feedback would be great thank you..

 

[benchrisfennell]

http://www.aussiebatteries.com.au/batteries/deep-cycle-agm/280ah-12v-agm-deep-cycle-battery

Has anybody,
Looked into these batteries.Yes I know it's some serious amperage...

And a serious price tag!!!

Any feedback would be great thank you..

That is some serious battery. I like it a fridge would last ages on that without starting the car

 

[HJ22]

But run it down to 50% and it will take ages to bring it back to full charge. And you would need a forklift to load it into the tray

 

[Old.Tony]

73Kg that sucker weighs. It's also 522mm long.

Allowing it to get to 30% SOC, you'd have used 196Ah. At a typical 4Ah draw on a 50% duty cycle a Waeco fridge would last 196/(12*4) = just over 4 days.

With that much weight and a $669 price tag (without delivery) I think a $300 battery plus $200 solar panel (with regulator) would probably be better and easier to manage for a small install like in our utes. It'd be bloody useful in a large RV though.

 

[75 GRC]

73Kg that sucker weighs. It's also 522mm long. Allowing it to get to 30% SOC, you'd have used 196Ah. At a typical 4Ah draw on a 50% duty cycle a Waeco fridge would last 196/(12*4) = just over 4 days. With that much weight and a $669 price tag (without delivery) I think a $300 battery plus $200 solar panel (with regulator) would probably be better and easier to manage for a small install like in our utes. It'd be bloody useful in a large RV though.

Yes Tony,
I am reassessing my thoughts atm. I do have 160watt solar panel. I'm now starting to think that it is just going to be way too much power for my needs.
And yes the 73kg of the battery does bother me.

I think I might just step back a little bit. And look at one between 165 amp hours to 200 amp hours.

But will stick with the same brand.

Thank you for the input that people have given.

And yes Tony I was hoping you would jump in and add some technical knowledge to it.
Which is always a great help when you are outlaying reasonable dollars on 12v gear.

Will keep use updated what I end up choosing.
And installing and how Giant perform as well.

Hooroo!!

 

[Old.Tony]

You're welcome.

For anyone considering a solar addition: remember to keep the regulator close to the battery. It's better to have longer leads from solar panel to regulator.

Here's why: the regulator takes whatever voltage it gets from the panel and converts it to a suitable voltage for charging the battery (like any smart charger would). If you have a long lead from solar panel to regulator, and a short lead from regulator to battery, the voltage drop experienced on long cables will only affect the regulator input - so the output is going to be perfect (unaltered) when it gets to the battery. Using a long cable from the regulator to the battery causes THAT side to have the voltage drop - definitely not what you want!

 

[benchrisfennell]

IM learning heaps from you tony.... �� Anyways what do you guys think about the AGM brand battery? They are on ebay for around $300.00 and the are 130 ah... Or do you guys or tony have any other recommendations? I have a super charge deep cycle battey now 105 ah. For my second battery but was thinking putting that in engine bay and turf the Nissan genuine battery and buy a better one for the second battery... Any thoughts???

 

[HJ22]

Just a thought, sealed AGM'S dislike heat. The temp in the engine bay can be high, perhaps check with the supplier first.

 

[Old.Tony]

I don't like the idea of any deep cycle battery exposed to the heat of an engine bay, particularly when it's on the hot side (exhaust/turbo). I'd never put a Gel battery in there period, that's just asking for trouble. AGM batteries might survive better because of their recombinant design, but there's another factor where heat is concerned - charging rate. It applies to any battery at all - even NiCds.

You could have the battery in the engine bay with fewer worries if you not only shielded it from the engine bay, but if you piped in cool air from the front of the car into the battery area. The obvious alternative is using the tub, underside ...

As for AGM batteries - they are the best of the lead-acid varieties. Here's a summary of the different types:

Cranker
Relatively thin walled plates immersed in a bath of sulphuric acid - they can't be discharged too deeply but they deliver a large amount of current without worry. Almost always flooded cell, sometimes built as VRLA ("sealed" or "zero maintenance"). Some might have a decent RC (reserve capacity) but discharging them below 50% is fairly bad for the battery.

Ordinary Deep Cycle
Same as a cranker - must be kept upright and refilled as needed - but with thicker plates to withstand a greater depth of discharge. Often cannot dump large amounts of power so they're not good as crankers. Must not be charged too quickly or the electrolyte will boil away.

Gel
A good idea in theory. Instead of a battery that MUST be kept upright so that the battery works, a gel battery contains the battery acid with some silica gel added to turn the acid into a jelly. Works upside down, on its side - it will keep your fridge going when your car is rolling sideways down a cliff without missing a beat. However, fast-charging causes bubbles to form in the jelly, and if that happens ... well, those bubbles never burst, so the acid stops touching the plates and the battery stops.

AGM
Take the jelly out of a gel battery and insert fibreglass matting (like ceiling insulation batts) and 95% saturate them with battery acid. Won't harm the insulation (most batts are made of glass) and the matting keeps the acid where it needs to be. Moreover, if a bubble forms it will easily burst allowing the battery acid to remain in contact with the plates. Use in any orientation. Spiral wound AGMs use plates that wrap around each other and thus become much stronger but the cost of manufacture is much higher. They aren't really worth the additional cost for recreational use.

 

[benchrisfennell]

Just a thought, sealed AGM'S dislike heat. The temp in the engine bay can be high, perhaps check with the supplier first.

I was asking about the AGM battery to be placed in my battery box in the tub where my AUX battery is now... And put the deep cycle i have in the tub, into the engine bay to replace the stock Nissan one......

 

[75 GRC]

I was asking about the AGM battery to be placed in my battery box in the tub where my AUX battery is now... And put the deep cycle i have in the tub, into the engine bay to replace the stock Nissan one......

Sorry to Jump in.
But an AGM deep cycle battery should not be used as your main cranking battery, I hope that is not what you intending on doing...

I apologise if that is incorrect. But that's the way I have just read it.????(?

Like I said I'm not here to start any arguments!
I am just looking out for a fellow forum member.
Deep cycle batteries should never be used as a cranking battery for your main battery!!

I do not believe I'm wrong in The statement I have said.

But if I am wrong feel free to jump in...

 

[Old.Tony]

Pocoyo is right - deep cycles generally shouldn't be used as crankers, because they aren't built to handle high transient loads. They're build for long hauls.

There are some manufacturers who allow for both. Optima is one. The D31A in my tub is onmly 75Ah, but it's 900CCA too. If yours doesn't have a CCA rating on it (and the CCA rating needs to be over 600 for a diesel, about 400 for a V8) then don't put the deep cycle under your bonnet. Chances are it'll work the first time, and the second, but it'll fail when you stop in a dry river to take some photos and see the water raging towards you in the distance.

 

[benchrisfennell]

Pocoyo all good for jumping in more input the better and you too for.your help old tony ����������

So tony the battery in my tub now is a supercharge deep cycle it is 105 ah and yes it is 770cca....
So will that be fine for my cranker in the engine bay? Turf the Nissan battery.

Then buy an AGM or better to put back into my tub for my aux battery? Hope this makes sense...

As above my now aux battery (the supercharge deep cycle is only few months old so is still new)
I just thought it would be better than a standard Nissan one. And i could buy a better quality one as my aux.

Cheers heaps guys ��

 

[Old.Tony]

Sounds like you have an MRV70 series. Haven't used one myself, but by its specs it should do the task.

 

[benchrisfennell]

Sounds like you have an MRV70 series. Haven't used one myself, but by its specs it should do the task.

So my deep cycle battery in the back.i have now will bo fine in the engine bay replacing the standard battery?

Cheers Old.Tony

 

[benchrisfennell]

Sounds like you have an MRV70 series. Haven't used one myself, but by its specs it should do the task.

Yes that is the one i have as my aux battery at the moment..

 

[Old.Tony]

It should be fine as a cranker.

 

[benchrisfennell]

Cheers old' mate �� that's the plan and two agm batteries in the tub ��