Combining AGM and Cranking batteries

Submitted: Wednesday, Jan 28, 2009 at 08:26

ThreadID: 65477 Views:3190 Replies:5 FollowUps:9

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Battery Power

In this article we explain why you might need an additional power source independent of the starting battery installed into your vehicle and we look in detail at types of batteries,

madcow

Well my Delkor M27 Deep Cycle battery has just about died. I've only recently replaced the cranking battery with a Supercharge Gold in my GU 4.2tdi 03. I looking at possibly slotting in an AGM bettery to run the fridge/s. Battery management is via a Pirahana system. With an extended trip coming up I'd like to gether everyones thoughts on either an AGM or Traditional Deep Cycle Battery. Given that an AGM will charge more quickly I'm leaning that way.

Thoughts , Ideas?

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Reply By: Member - Norm C (QLD) - Wednesday, Jan 28, 2009 at 09:38

Wednesday, Jan 28, 2009 at 09:38

AGM is certainly the way to go in my opinion. No problem connecting to cranking battery via isolator.

Some say AGMs are no good in the engine bay due to heat. I had a 90 AH AGM in the engine bay of my Hilux for close to three years. I took it out last August and it is now in the engine bay of my 70 Series Toyota. As long as it is not right against the exhaust manifold or turbo, my experience says they are fine in engine bay.

I have a second AGM (120 AH) in the back of the ute, connected in parallel with the one in the engine bay with 50 Amp circuit breakers at each battery. All works fine.

Norm C

AnswerID: 346290

Follow Up By: Member -Signman - Wednesday, Jan 28, 2009 at 11:27

Wednesday, Jan 28, 2009 at 11:27

Are both your aux. batterys of the same capacity??

FollowupID: 614295

Follow Up By: Member - Norm C (QLD) - Wednesday, Jan 28, 2009 at 12:05

Wednesday, Jan 28, 2009 at 12:05

90 AH in engine bay, 120 AH in back, Signman

FollowupID: 614306

Follow Up By: Member -Signman - Wednesday, Jan 28, 2009 at 12:34

Wednesday, Jan 28, 2009 at 12:34

Hi Norm
I thought there was some issue having dissimilar capacity batterys hooked up for a parallel charge??
Please correct me if I'm wrong !!!

FollowupID: 614312

Follow Up By: Member - Norm C (QLD) - Thursday, Jan 29, 2009 at 14:25

Thursday, Jan 29, 2009 at 14:25

That's a view expressed by some, but I don't think many subscribe to it any more.

Certainly, I have had no problem with it. Both batteries get close to a full charge on a long drive. My measure of this is that on returning from a camping trip, I put the batteries (separately) on a CTek smart charger. On most occasions they go straight to 'float' within a couple of minutes.

The current batteries have been used this way for close to 3 years, with no sign of trouble.

That's my experience. If in doubt, put a post on a separate thread. You will get lots of different views, but I think you know the people you can trust on 12 Volt issues so you can sort the wheat from the chaff.

Norm C

FollowupID: 614572

Follow Up By: Member - Mike DID - Thursday, Jan 29, 2009 at 16:46

Thursday, Jan 29, 2009 at 16:46

It's not a good idea to connect two different types of batteries in parallel - but if you're using an Isolator, then the batteries are not in parallel.

e.g. while the Starting battery remains fully charged, you're discharging the Auxiliary !!!

So if each battery (Starting, Auxiliary) is capable of being charged correctly by the Alternator, then they will charge as well when both are connected to the Alternator.

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Reply By: Member - Beatit (QLD) - Wednesday, Jan 28, 2009 at 09:47

Wednesday, Jan 28, 2009 at 09:47

I concur with Norm. I have had an AGM as a second battery for over 3 years also isolated by a pirahna isolator. Mine has always been in the cabin of the car and this system has served me well.

Kind regards

AnswerID: 346291

Reply By: madcow - Wednesday, Jan 28, 2009 at 11:19

Wednesday, Jan 28, 2009 at 11:19

Thanks for that fellas, Although my main reason is for quicker charging. I have put some heat sheilding to deflect heat from the turbo on it in the past and have had no dramas. Ideally it will be a 120 ah battery but A Fullriver battery in a Pirahana tray just misses out due to being too long but only just. will investigate other brands.

AnswerID: 346304

Follow Up By: Rolly - Wednesday, Jan 28, 2009 at 11:36

Wednesday, Jan 28, 2009 at 11:36

My choice would be one of those spiral wound AGMs which are smaller physically for the same capacity and have an enviable record for longevity and vibration resistance.

FollowupID: 614300

Follow Up By: Leroy - Wednesday, Jan 28, 2009 at 11:54

Wednesday, Jan 28, 2009 at 11:54

I have a couple of nice AGM batteries and they miss out on fitting in the battery tray by 10mm.

Leroy

FollowupID: 614303

Follow Up By: madcow - Wednesday, Jan 28, 2009 at 12:29

Wednesday, Jan 28, 2009 at 12:29

Thats about what the difference in mine is. I might pull out the other one and have a better look. It may mean relocating the canister that would interfere with it i at the present with a longer battery. Whne and if I go down this road time will tell. I'm still doing some homework at this stage.

FollowupID: 614311

Reply By: Sigmund - Wednesday, Jan 28, 2009 at 12:51

Wednesday, Jan 28, 2009 at 12:51

As an all-things-electric ignoramus, all I can report is advice I've taken from a local guy who builds camper trailers, mods 4bies and motorhomes, does auto-electrics and is a camper himself.

He's a fan of lead calcium batts - claims they are a good hybrid of cranking and deep cycle. They have a broader operating voltage range than deep cycle without being damaged. Can be used for cranking as well when nec.

I've reason to trust his credibility, and will have 2 x 96 amp hour batts fitted to the newly acquired CT.

...

Then lithium ion is available for aux batts too. Anyone had any experience? 'spect they'll cost a bomb.

AnswerID: 346319

Reply By: Member - Geoff C (QLD) - Wednesday, Jan 28, 2009 at 12:57

Wednesday, Jan 28, 2009 at 12:57

On a recent trip accross Aust by 4000km of dirt (a lot of corrugations) we had 3 deep cycle batteries die. None of them were over 12 months old and we use smart chargers off a Yamaha generator or via the Patrol generator to charge them. From what we've heard since corrugations are deadly for normal deep cycle batteries so we're replacing them with Agm as we can afford it. Hopefully this will solve our problem.
Geoff

AnswerID: 346322

Follow Up By: madcow - Wednesday, Jan 28, 2009 at 14:03

Wednesday, Jan 28, 2009 at 14:03

That was another reason as they seem to be tolerant to vibration. The kimberley region and thereabouts will test things out. Will be off work for 5 months woohoo

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