Portable Dual Battery Success!

Submitted: Friday, Apr 18, 2014 at 22:07
ThreadID: 107354 Views:1970 Replies:1 FollowUps:11
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Good day and Happy Easter to all!

Finally got around to installing a dual battery in my Mazda Tribute. Some may say 'how'? but I did it.
First I put the paranha system in, connected to my main and ran the auxiliary positive under my car. I had to drill a hole in the wheel arch and take the back left plastic covering off in the car, so the cable ran flush. connected the earth to the chassis.
Then went and put the anderson plug on the end of the auxiliary positive cable. That's the main part done.
Bought a 110ah deep cycle battery, battery box, low voltage 2 pin plug and went away! The cable from the main battery was 8-10mm. from the Anderson plugs to the second battery was 6mm. Should be fine. Enough to charge the battery.
Cant attach pictures? For people who pay? Bit disappointing.

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Reply By: John and Regina M - Friday, Apr 18, 2014 at 22:48

Friday, Apr 18, 2014 at 22:48
Hi misha_boi
Sounds good.

Did you insulate all the underbody cabling?
Use heat resistant and uv stabilised cable ties or clamps?
Is the main battery feed to the aux battery fused both ends?
Are all connections soldered and insulated?
Are all panel intrusions insulated and sealed as well?
Did you fuse the low voltage 2 pin plug?
6mm from the Anderson plugs to the second battery sounds very light for a cable that is charging?

Curious about your last 2 statements 'For people who pay? Bit disappointing.' though. What do you mean?
AnswerID: 530840

Follow Up By: misha_boi - Friday, Apr 18, 2014 at 23:18

Friday, Apr 18, 2014 at 23:18
How I have set it up was exactly how it was in my old mans hilux, it's the same system but took it out before I sold it. There is no fuse between the main and the anderson plug. There never was to start with. Should there be?
I definitely wouldn't install the 2 pin plug without an inline fuse.
Between the main and anderson plug is 8mm lead. Then from the other anderson plug is the smaller lead connected to the battery.
When I first wrote the thread I couldn't upload any pics? It said "for paying members only" or something similar. As I wanted to upload a picture.
FollowupID: 813820

Follow Up By: KevinE - Saturday, Apr 19, 2014 at 09:37

Saturday, Apr 19, 2014 at 09:37
Upload your pics to a hosting site such as tinypic first, copy their msg board ink to your pic & put it in your post via the insert images & files button down below the submit button. Clear as mud?

With your dual battery system; I'm no expert, but I'm informed you should run both cables all the way between both batteries in case of the earth shorting out on the chassis & causing catastrophic engine problems via the cooling system.
FollowupID: 813829

Follow Up By: The Bantam - Sunday, Apr 20, 2014 at 13:41

Sunday, Apr 20, 2014 at 13:41
I Disagree in the strongest terms that all connections should be soldered.
It is proven that properly made crimp connections are more reliable than soldered connections.

I do agree that the cabling should be well mechanically protected and all pentrations should have gromets or such to prevent chaffing

For anything other than cranking or winching circuits there should be fuses or circuit breakers, as close to the batteries as possible.

As for running the negative all the way back to the battery.....yes preferable, but there are many wives tales about not doing this.

If you are earthing to the chassis, make sure the paint was scraped away under the earthing bolts, preferably add some never seeze or at lest grease to the threads, bolt heads and washers and use two nuts ot a locking nut.

Don't forget to secure that battery well, and to provide some ventilation even if it is a so called sealed battery...there is no such thing as a completly sealed battery.

FollowupID: 813896

Follow Up By: misha_boi - Sunday, Apr 20, 2014 at 20:33

Sunday, Apr 20, 2014 at 20:33
Hey guys,
I did both. I crimped a couple as well as soldered. Nothing a vice isn't capable of.
I'm assuming you guys are talking about a maxi fuse? These were never used before so do I need them? It worked fine before without them.
Yes the paint was scraped away, but to test it I just touched the negative wire with positive if you get sparks it that means current is passing well.
I did hear about ventilation, it's not a sealed battery , but it's not in the car all the time so should be fine.
Link to the pics
FollowupID: 813935

Follow Up By: misha_boi - Sunday, Apr 20, 2014 at 20:35

Sunday, Apr 20, 2014 at 20:35
FollowupID: 813937

Follow Up By: The Bantam - Sunday, Apr 20, 2014 at 22:54

Sunday, Apr 20, 2014 at 22:54
if that is not a sealed battery you need to be well aware that it will release significant amounts of explosive gasses and acid mist while being charged.

you need to be damn sure you have plenty of ventilation.....better still get a sealed battery.

secondly, remember what you have there is a 15 to 20 KG plastic box full of lead and acid....if that gets free in an accident or rollover it could do some real damage.

seriouilsy it needs to tied down well and you need a selaed battery.

FollowupID: 813944

Follow Up By: KevinE - Monday, Apr 21, 2014 at 09:00

Monday, Apr 21, 2014 at 09:00
The wives tale I heard came from a retired TAFE lecturer who had also worked as a trainer for the RAA; apparently, according to him, earth leakage can react with engine coolant to completely wreck the internals of the vehicle cooling system. But hey, what would he know lol!
FollowupID: 813952

Follow Up By: The Bantam - Monday, Apr 21, 2014 at 10:14

Monday, Apr 21, 2014 at 10:14
Yeh there are some very interesting leaps of logic arround.

The biggest issue with grounding to the chasis is the adequacy of the return circuit.
many cars have a chassis bonding strap from the negative battery that is simply not up to the demands of a second battery.

If you are going to ground to the chassis, best to check the size of the bonding strap from the battery negative to the chassis.....hell...just upgrade it anyway....I have seen a few fail without a second battery.

then realise that some parts of the chassis or body may not be properly grounded if at all.

Most ute trays for example are not properly grounded to the chassis.

this is whay it is best to home run you negative all the way back to the battery.

FollowupID: 813958

Follow Up By: misha_boi - Monday, Apr 21, 2014 at 16:02

Monday, Apr 21, 2014 at 16:02
Hi John and Regina,

The cable to the auxiliary is actually 6B&S not 6mm. My bad.

I have looked into this for some months now, and some people said, you can't have a battery in the car due to a gas, bit in speaking to the guy at the battery shop all should be fine. His exact words were 'if your not sleeping in the car, and as long as that battery isn't smothered, you should be fine. They emit the smallest amount.' He also said it isn't illegal to have them in you car, so with these questions answered, away I went!

That's a new one KevinE. Haven't heard that one before!
The trick is, how do you find out if the battery is actually charging? Obviously the isolator LED lights up but.. Now sure.

FollowupID: 813978

Follow Up By: The Bantam - Monday, Apr 21, 2014 at 19:08

Monday, Apr 21, 2014 at 19:08
Maaate..if its a screw top wet cell battery......not sealed..they emit quite a bit of gas.


FollowupID: 813979

Follow Up By: The Explorer - Monday, Apr 21, 2014 at 20:52

Monday, Apr 21, 2014 at 20:52
..So do I..:)

VW Beetle I had 30 years ago had battery under the back seat. All good. Only caught fire once when springs under the seat shorted on battery due to a little bit of "off road" driving + passenger bouncing.

So probably best to avoid one in the confines of the car if you can but probability of an issue pretty low under normal conditions.


I sent one final shout after him to stick to the track, to which he replied “All right,” That was the last ever seen of Gibson - E Giles 23 April 1874

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