Another 3rd battery charging question

Submitted: Friday, Dec 19, 2008 at 18:19
ThreadID: 64411 Views:14193 Replies:6 FollowUps:21
This Thread has been Archived
Hi all,
a question regarding charging the caravan AGM 105 ah battery from tow vehicle via anderson plug.
I have seen the diagrams in the electrical part of this site explaining how to wire the anderson plug at rear of car to charge van batt.
Firstly I have a 100 series t/d Cruiser that comes from the factory with twin batteries hooked up together. I had an auto leccy split them using a redarc 100 amp smart solenoid. They momentarily join together when I hit the start key and disconnect when I let the key go once engine has fired. The diagram I have seen to wire the anderson plug says to join the wire at the redarc solenoid which feeds tha aux batt. My question is if the batt in the van collapses or whatever what stops it draining the aux batt in the vehicle? Should I not have another redarc after the aux batt and connect the wires for the rear of vehicle to that?

Hope I explained the question well enough.

Regards

Gary
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Reply By: ABR - SIDEWINDER - Friday, Dec 19, 2008 at 18:37

Friday, Dec 19, 2008 at 18:37
Yes fit another isolator to protect the caravan wiring from starting current.

You could disconnect the start facility you have if the main battery is big enough to start the engine.

Regards

Derek from ABR
AnswerID: 340536

Reply By: Member - Roachie (SA) - Friday, Dec 19, 2008 at 18:38

Friday, Dec 19, 2008 at 18:38
Gary,
IMHO you'd be best off sticking with the KISS priciple. (ie: Keep It Simple).

After all, what's the worst that can happen if you keep an eye on your batteries you will know pretty quickly if one or other of your batteries has developed a fault etc.

I wouldn't bother with a 2nd Redarc.

However, you could do away with the really heavy cabling needed when using a direct wiring method, by fitting something like a Arrid Twin Charge (which is a DC to DC battery charger). There are other brands as well; but I use 2 Arrids (one in the back of the Patrol for the 3rd battery plus another in the camper trailer for the 2 SLA batteries back there).

Roachie
AnswerID: 340537

Follow Up By: Featherfoot - Friday, Dec 19, 2008 at 19:37

Friday, Dec 19, 2008 at 19:37
G'day Roachie

Havn't heard of the twin chargers before. Have bought the wiring now so has better use it.
Thanks

Gary
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FollowupID: 608191

Reply By: Member - Mel D (NSW) - Friday, Dec 19, 2008 at 18:38

Friday, Dec 19, 2008 at 18:38
You do not need another redarc. The redarc is there to ensure that your starter battery is fully charged before any other battery gets charged. Batteries do not suddenly collapse so dont worry about that. I have my two auxiliary batteries (one in the trailer) connected in parallel on the same side of the redarc. In fact I wonder if it mightnt be better to have both your starting batteries in parallel and the auxiliary on the other side of the redarc.
AnswerID: 340538

Follow Up By: Featherfoot - Friday, Dec 19, 2008 at 20:10

Friday, Dec 19, 2008 at 20:10
Thanks for your input Mel. I have not seen a battery collapse myself but have heard it mentioned so thought it may be something to take into account.
Cheers

Gary
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FollowupID: 608197

Reply By: Maîneÿ (wa) - Friday, Dec 19, 2008 at 19:01

Friday, Dec 19, 2008 at 19:01
Featherfoot,
You say:
your Cruiser comes with twin batteries hooked up together.
An auto leccy split them, using a Redarc smart solenoid.

They momentarily join together when you hit the start key and disconnect once engine has fired.

My question is: how does the Cranking battery that is "disconnected" when the engine starts, get to be charged by the alternator ???

Mainey . . .
AnswerID: 340541

Follow Up By: ABR - SIDEWINDER - Friday, Dec 19, 2008 at 19:05

Friday, Dec 19, 2008 at 19:05
The Redarc is a VSR
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FollowupID: 608177

Follow Up By: Maîneÿ (wa) - Friday, Dec 19, 2008 at 19:10

Friday, Dec 19, 2008 at 19:10
So what's the logical reason to place a Redarc between two Cranking batteries ??

Have Toyota made a technical error keeping the two batteries wired together ??

Mainey . . .
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FollowupID: 608180

Follow Up By: Featherfoot - Friday, Dec 19, 2008 at 19:24

Friday, Dec 19, 2008 at 19:24
One then becomes an aux.
Will replace with larger capacity batts when time comes

Gary
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FollowupID: 608186

Follow Up By: ABR - SIDEWINDER - Friday, Dec 19, 2008 at 19:25

Friday, Dec 19, 2008 at 19:25
So you can run the 2nd battery down and keep one battery fully charged. They simply connect a wire from the starter relay to the blue jump start wire on the Redarc.
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FollowupID: 608187

Reply By: ABR - SIDEWINDER - Friday, Dec 19, 2008 at 19:04

Friday, Dec 19, 2008 at 19:04
Gary have a look at this diagram, it should help understand the wiring.

My main concern with your current setup is the possible damage to cables and plugs if the cars batteries are lower in charge than the caravan.



Regards

Derek from ABR
AnswerID: 340542

Follow Up By: Featherfoot - Friday, Dec 19, 2008 at 19:33

Friday, Dec 19, 2008 at 19:33
Hi Derek
I have seen that drawing on this site and as you say the draw on startup would possibly pull on the van batt and also there is nothing to stop the current flow from the van to the car aux or visa versa without a redarc in place. That's why I was considering another redarc. Does that make sense?

Gary
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FollowupID: 608189

Follow Up By: ABR - SIDEWINDER - Friday, Dec 19, 2008 at 19:38

Friday, Dec 19, 2008 at 19:38
It would depend on your preference.

My own system is set so the van and cars aux are linked and I only have the one starting battery. You can split these two aux batteries with a 2nd isolator but I would rather disable your forced jump start feature that you have.

Perhaps rather buy a larger new cranking battery and disconnect the jump wire.

Regards

Derek.
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FollowupID: 608192

Follow Up By: Featherfoot - Friday, Dec 19, 2008 at 20:03

Friday, Dec 19, 2008 at 20:03
I see what you are saying. So the chance of something going wrong to cause unwanted current flow between the van batt and car aux batt is minimal and not really an issue. Get a bigger starting batt and disconnect the forced jump. Not sure how that was done will have to visit the sparky I guess, and save on a redarc to boot. I hope the starting batt dies tomorrow then I won't feel so bad pulling the Batt out and replacing it.

Thanks for your advice Derek,

Regards

Gary







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FollowupID: 608195

Follow Up By: Maîneÿ (wa) - Monday, Dec 22, 2008 at 21:53

Monday, Dec 22, 2008 at 21:53
Gary,
I'm not saying the diagram above is incorrect, that would be 'not nice' and yes it really does look nice :-))

But why not wire up your Redarc Isolator as Redarc specifies ?

Make sure the Auxiliary battery is independently grounded to the vehicle chassis, as is also the existing Cranking battery.

Connect the Redarc Smart Start (-) Ground lead to a good chassis ground. Remember to remove any paint/dirt at this grounding point to ensure a good electrical connection.



I would then connect the (+) & (-) cables from the (Van) Aux battery, via the Anderson plug and relevant fuses, only to the corresponding (Vehicle) Aux battery (+) terminal & earth point, definitely not onto your Cranking battery terminals !

Mainey . . .
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FollowupID: 608608

Follow Up By: ABR - SIDEWINDER - Monday, Dec 22, 2008 at 22:10

Monday, Dec 22, 2008 at 22:10
Mainey

Just the other day you did not understand how the Redarc worked in a LC100 with twin cranking batteries, now you are an expert.

Look at the drawing again.

There is an isolator and fuse between these connections. The drawing does not show any connection directly to the CRANKING battery.

What the !!!!!!

Are you feeling OK.

Regards

Derek
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FollowupID: 608611

Follow Up By: Maîneÿ (wa) - Monday, Dec 22, 2008 at 22:47

Monday, Dec 22, 2008 at 22:47
Derek,
On YOUR picture on the red (+) cable side there is NO fuse in the circuit between the Anderson plug and the Redarc isolator, as you can clearly see the Van (Aux) battery (+) charging cable joins into the (+) charging cable *BEFORE* the fuse, NOT after it, so the Anderson plug (+) cable in the Vehicle is NOT fused, now I believe that IS dangerous, obviously you do not !

Ok, it's embarrassing, that's why I didn't mention it earlier :-))
Image Could Not Be Found
On my screen the (-) black cable goes from the Aux (Van) battery via the Anderson plug, to the Vehicle (main) CRANKING battery (-) terminal, as in your picture.

Yes, I'm feeling ok

Mainey . . .

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FollowupID: 608622

Follow Up By: ABR - SIDEWINDER - Monday, Dec 22, 2008 at 23:13

Monday, Dec 22, 2008 at 23:13
Mainey

You have missed it again !!

Check the diagram again !!!

There is a fuse at EVERY battery positive !!!!

Every wire is protected !!!!!

In every direction !!!!!!

I'm sure you are just tired as you are normally quite sharp (**)

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FollowupID: 608628

Follow Up By: Maîneÿ (wa) - Monday, Dec 22, 2008 at 23:27

Monday, Dec 22, 2008 at 23:27
Derek,
as can be very clearly seen in this section of your original picture there is *NO fuse* in the red (+) cable between the (+) terminal of the Redarc Isolator Aux battery post and the Anderson plug, as I have posted above.

Therefore the vehicle is obviously NOT protected by a fuse in this POSITIVE Battery charging cable.
Image Could Not Be FoundMainey . . .
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FollowupID: 608632

Follow Up By: ABR - SIDEWINDER - Monday, Dec 22, 2008 at 23:33

Monday, Dec 22, 2008 at 23:33
Mainey

I give up !

You need to look at the complete circuit, not one wire.
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FollowupID: 608633

Follow Up By: ABR - SIDEWINDER - Monday, Dec 22, 2008 at 23:42

Monday, Dec 22, 2008 at 23:42


Same circuit. Redarc instructions.
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FollowupID: 608637

Follow Up By: Maîneÿ (wa) - Monday, Dec 22, 2008 at 23:51

Monday, Dec 22, 2008 at 23:51
Derek,
I'm just pointing out the shortcomings of the diagram,
you say:
Every wire is protected !!!!!
In every direction !!!!!!

As can be clearly seen, the "one wire" NOT protected is a POSITIVE battery charging cable going from the Redarc isolator to the Anderson plug, probably the length of the vehicle!!

If it shorts out, it simply burns out the vehicle, that is the reason you should use a fuse on ALL POSITIVE cables.

Derek,
do you at least agree it is most probable if the (+) red UNPROTECTED cable shorted out, it WOULD burn down the vehicle ??

Mainey . .
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FollowupID: 608639

Follow Up By: ABR - SIDEWINDER - Tuesday, Dec 23, 2008 at 08:08

Tuesday, Dec 23, 2008 at 08:08
Sorry Mainey

That circuit is protected by the fuse between the Redarc and the main battery.

LOOK AGAIN !
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FollowupID: 608661

Follow Up By: Maîneÿ (wa) - Tuesday, Dec 23, 2008 at 18:52

Tuesday, Dec 23, 2008 at 18:52
Derek,
I humbly offer my apologies
The (+) cable IS protected :)

Mainey . . .
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FollowupID: 608803

Reply By: Maîneÿ (wa) - Friday, Dec 19, 2008 at 20:11

Friday, Dec 19, 2008 at 20:11
Yes. obviously Toyota have made a mistake putting two identical Cranking batteries in the 100 series TD cruiser, when they really only require one to operate safely and efficiently ??

Mainey . . .
AnswerID: 340546

Follow Up By: Member - Phil G (SA) - Saturday, Dec 20, 2008 at 00:01

Saturday, Dec 20, 2008 at 00:01
Mainey,
In the past, Toyota built their Landcruisers to suit individual markets. So the 60series and 80series LandCruisers were twin batteries in series (24V) for the Northern Hemisphere and single battery 12V for the warmer counties in the southern hemisphere.

When they built the 100series, they decide to build one vehicle that suits all - so they used twin 12V starting batteries. Typical Toyota overkill.

In Australia's warm climate, the 1HD-FTE starts nicely with a single battery, so owners here throw away the original twin N50's and fit twin N70's with an isolator so they can run the non-Toyota accessories like fridges.

The same motor appeared in the 78/79series and copped a single N70 battery. The HDJ78/79 were peculiar to the Australian market, so only came with a single battery.

Theres no reason why a 100series owner would not split the dual batteries in a warm climate.
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FollowupID: 608235

Follow Up By: Member - Mike DID - Monday, Dec 22, 2008 at 20:00

Monday, Dec 22, 2008 at 20:00
Mitsubishi do the same in their Diesels - two parallel 12 volt batteries in cold countries - one battery in Australia.
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FollowupID: 608585
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