dual battery system with main and auxiliary batteries
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- lost2
- Posts: 67
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- Vehicle: Delica L300 Exceed 1990 4wd RHD
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- Location: Amqui (Quebec) Canada
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dual battery system with main and auxiliary batteries
Hi everybody!
I finally had a chance to install a dual battery system in our L300. It has a brand new 1060 CCA starting battery and a deep cycle auxiliary battery. I choose batteries for their similar sizes to be able to fit them it teh space available under passenger seat.
I also found a battery isolator in a marine shop in Nova Scotia. It is rated 70 amp. Since my alternator is a 75 amp, the isolator is a bit under rated, but it shouldn't be a problem unless a let the auxiliary drain entirely... I added marine fuses between the isolator and both batteries (positive wires only).
And finally put a master switch to use as a manual "antirobbery" system... :)
Here are some pics
Davy
I finally had a chance to install a dual battery system in our L300. It has a brand new 1060 CCA starting battery and a deep cycle auxiliary battery. I choose batteries for their similar sizes to be able to fit them it teh space available under passenger seat.
I also found a battery isolator in a marine shop in Nova Scotia. It is rated 70 amp. Since my alternator is a 75 amp, the isolator is a bit under rated, but it shouldn't be a problem unless a let the auxiliary drain entirely... I added marine fuses between the isolator and both batteries (positive wires only).
And finally put a master switch to use as a manual "antirobbery" system... :)
Here are some pics
Davy
- Rising Sun Auto Import
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Re: dual battery system with main and auxiliary batteries
Very nice, Davy.
Steven

Steven
Rising Sun Auto Import Inc.
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- jessef
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Re: dual battery system with main and auxiliary batteries
I can't see the battery hold down cross section. Did you put it back ? If your batteries are loose and the positive connections are as in the pictures (bare/open), there is a possibility of them touching the frame if you go over a bump,etc.. and causing some not so good things.
100A is the minimum what I was recommended by an electronic shop/alternator place for our rigs in a aux/dual setup.
Looks tight though
100A is the minimum what I was recommended by an electronic shop/alternator place for our rigs in a aux/dual setup.
Looks tight though

- lost2
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Re: dual battery system with main and auxiliary batteries
jfarsang wrote:I can't see the battery hold down cross section. Did you put it back ? If your batteries are loose and the positive connections are as in the pictures (bare/open), there is a possibility of them touching the frame if you go over a bump,etc.. and causing some not so good things.
You are right (and thanx for the reminder), there is no hold down cross section (and there has never been any since I own the car...). I wanted to finish the setup before fixing everything in place, and I will soon (although it is funny how tight and how difficult it already is to move the batteries in any possible direction...)
When you say 100A, are you talking about the isolator? Or the alternator?jfarsang wrote:100A is the minimum what I was recommended by an electronic shop/alternator place for our rigs in a aux/dual setup.
I am not an electrical geek, so here is what I understand about the necessities for a bigger alternator (and in the meantime of a bigger isolator): if you have lots of components drawing much power out of the battery or if you stand still for a long period of time using continuisly small appliances, you will need bigger rig to sustain your consumption.
In my case: I have no winch, no fridge, no extra sound amplifier, and not planning on having such voracious appliances. I also got rid of the a/c system. The auxiliary battery will run an inverter for our portable computer and mp3 readers, regular car accessories (lights, radio and so on). I bought 3 low consumption led for inside lighting.
I think the emptier a battery is the more power it draws out of an alternator. As long as the charge of the auxiliary battery stays a "regular maintenance charge", it should never get even close to the capacity of the alternator or of the isolator.
The more important purpose of this dual battery system is to keep the starting battery as full as possible to prevent any cranking problem in our cold north-easthern climate, our to avoid having it half emptied because a door was badly closed while hiking all day in a remote area.
And,well ... they didn't have any bigger isolator where I bought it ...

- nxski
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Re: dual battery system with main and auxiliary batteries
I think that was in reference to the isolator since there are many delica's out there running 2 batteries on smaller alternators. If you've wired in a fuse I can't imagine there would be a problem although. I would keep some spare fuses on hand.
Looking good!
Looking good!

Live the life you love, love the life you live...
Had: 1991 Mitsubishi Delica L300 SuperExceed, heavily modified (totalled by a drunk driver)
Have: 2011 Acura CSX manual, lightly modified
Want: Mitsubishi Pajero Evo
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Nicola Spurling
Had: 1991 Mitsubishi Delica L300 SuperExceed, heavily modified (totalled by a drunk driver)
Have: 2011 Acura CSX manual, lightly modified
Want: Mitsubishi Pajero Evo
http://nes-design-construction.com
http://ca.linkedin.com/pub/nicolas-spurling/46/b48/924
Nicola Spurling
- jessef
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Re: dual battery system with main and auxiliary batteries
correct - 100A isolator
The price difference is minimal but the safety gain is high.
The price difference is minimal but the safety gain is high.
- lost2
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Re: dual battery system with main and auxiliary batteries
As stated previously, it is not money that was the concern about buying a bigger isolator rather than the availability. I do things on my own and can't always find the best suitable solution right away. There is place for improvement, I agree.
But I'll let you know how it goes with the 70A isolator. For now on, everything is find (and I got a few extra fuses ;) )
Thanks jfarsang for your good advices.
Also thanks Steven and Nxski for your good words
Davy
But I'll let you know how it goes with the 70A isolator. For now on, everything is find (and I got a few extra fuses ;) )
Thanks jfarsang for your good advices.
Also thanks Steven and Nxski for your good words

Davy
- nxski
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Re: dual battery system with main and auxiliary batteries
Live the life you love, love the life you live...
Had: 1991 Mitsubishi Delica L300 SuperExceed, heavily modified (totalled by a drunk driver)
Have: 2011 Acura CSX manual, lightly modified
Want: Mitsubishi Pajero Evo
http://nes-design-construction.com
http://ca.linkedin.com/pub/nicolas-spurling/46/b48/924
Nicola Spurling
Had: 1991 Mitsubishi Delica L300 SuperExceed, heavily modified (totalled by a drunk driver)
Have: 2011 Acura CSX manual, lightly modified
Want: Mitsubishi Pajero Evo
http://nes-design-construction.com
http://ca.linkedin.com/pub/nicolas-spurling/46/b48/924
Nicola Spurling
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Re: dual battery system with main and auxiliary batteries
Did you notice a voltage drop using the diode isolator?
- lost2
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Re: dual battery system with main and auxiliary batteries
To be honest I didn't monitorized anything before adding the system (I installed the inverter the same day than I installed the dual battery system). So if your question refer to some difference between BEFORE and AFTER the installation of the dual battery system, I have no real clue.Jordan wrote:Did you notice a voltage drop using the diode isolator?
Here are the caracteristics of the isolator I bought:
Optimized heat sink design for maximum performance
Minimized voltage drop across isolation barrier using Schottky type diodes
Fixed cable posts for secure connections
Waterproof components for harsh environment performance - year after year
2 Year Warranty
Right now, it ranges between 14.2 and 14.5v depending on the load (accessories used) when the engine is working. For what I read on other thread, it seems to be a proper voltage out of the alternator.
Hope it answer your question,
Davy
- Firesong
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Re: dual battery system with main and auxiliary batteries
Should work just fine! I set up something similar in my old Westy.
I like the disable switch.
Nice work!
I still have the dual setup for my L300 but it isn't powering anything
other than the stereo and normal motor components. No camping stuff.
FS
I like the disable switch.
Nice work!
I still have the dual setup for my L300 but it isn't powering anything
other than the stereo and normal motor components. No camping stuff.
FS
- FredVenne
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Re: dual battery system with main and auxiliary batteries
I don't know how to bring this up but... I see something ironic in this thread. And this is a reflection of the real world out there. The dealer sees the photos and says: Very nice! Now usually dealers only talk to sell something. So I don't know why he interacted here but anyway... And then there's the other guy that does not sell anything, that just want to help genuinely, for the love of these awesome vehicles, looks at the photos and, spot on, find something to help buddy here...
Maybe it's just because I'm tired...
Fred
Maybe it's just because I'm tired...
Fred
Why driving on well traveled route when you can beat your own path...
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-The Mighty Yeti
Fun Long Road Trip on road, dirt and ice - Delica L300 Pop-Top Camper
Fun playing around in the mud and work horse - Pajero GDI 3.5L 6cyl LWB
Best vehicle in all conditions - Subary Impreza WRX
- lost2
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Re: dual battery system with main and auxiliary batteries
Sorry Fred, I don't see why you are saying this (and that could be because english is a second language for me).FredVenne wrote:I don't know how to bring this up but... I see something ironic in this thread. And this is a reflection of the real world out there. The dealer sees the photos and says: Very nice! Now usually dealers only talk to sell something. So I don't know why he interacted here but anyway... And then there's the other guy that does not sell anything, that just want to help genuinely, for the love of these awesome vehicles, looks at the photos and, spot on, find something to help buddy here...
Maybe it's just because I'm tired...
Fred
I believe dealers are human beings, and despite their obvious interest to sell things, they can also have a spark of humanity ans say kind things.
OR
maybe this dealer wanted to put a silly comment to make sure his signature would be in this thread and that way he would do some advertising freely.
I don't konw for you guys, but I prefer seeing a glass of water half full rather than half empty: I love to give people my trust and confidence rather than starting with suspicion and distrust. Twice, I bought parts for my L300 at Rising Sun, and Steven have been very kind and helpful (it was not the case with all the dealers I spoke to...). (lets call it a bouquet for RS!) So maybe he just looked at the pictures and thought: that's nice, and decided to say it.
All interventions don't have to be smart and extraordinary technical to be a contribution to a thread . Good words are always nice to receive, especially when you live isolated from the rest of a community like the Delica's. In other words, it helps to feel "part of the family" although I can't come at Delica's meeting and meet you in person.
Cheers,
Davy
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Re: dual battery system with main and auxiliary batteries
How many amp/hour is your deep cycle? I am running a 105amp/hour battery right now. Just curious to see how your charging system is holding up. I am running a 100amp isolator.
- lost2
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Re: dual battery system with main and auxiliary batteries
Carquest deep cycle model DC24: 500CCA, 625CA, 150RCcruisn06 wrote:How many amp/hour is your deep cycle? I am running a 105amp/hour battery right now. Just curious to see how your charging system is holding up. I am running a 100amp isolator.
"RC - Rating in minutes a battery will carry a 25 amp load at 80ºF and maintain a minimum terminal voltage of 10.5 volts.
AH - (@ 20 hours) a battery having a 100 AH rating must carry a 5 amp load for 20 hours and maintain a terminal voltage of 10.5 volts at 80ºF (100 ÷ 20 = 5 amps).
Ratings Conversions: RC = 1.75 x AH AH = (RC ÷ 2) + 15.5"
Depending upon the conversion method list above, AH rating of the battery is between 86 and 90 amp/hour.