 | Home > Technical > [Electronic Engineer: Mode On] Advise for Dual Battery Sys |
 
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| Cupboard Member Since: 21 Mar 2014 Location: Suffolk Posts: 2971   
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Yes, you just need a double pole switch.
You don't actually need two voltmeters, a single pole, double throw switch would mean you could use the same voltmeter for both batteries. Option 1: one switch, two meters. One battery in to one side of the switch, voltmeter out the same side. Other battery in to the second side, voltmeter out the second side. Option 2: one switch, one meter. Bear in mind you need a three way switch for this instead of a two way, so you have centre off. Battery 1 in to one side, voltmeter out of the middle, battery 2 in to the other side. I've just used a couple of these switches: http://cpc.farnell.com/unbranded/abrr003/s...dp/SW02926 for a similar purpose - my rear work light is either off, on or controlled from the front, same as a socket I've got next to it. Make sure you fuse the the cables from the batteries to the switch/meters. It may not be taking any current but it can still go wrong  |
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21st Jan 2016 1:16pm |
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| DEF_Jam Member Since: 17 Jul 2011 Location: Milan Posts: 59  
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So guys, I collected a part of the shopping list for the dual battery system and now I'm bringing this back because it's the wiring time and I need to get all the connectors, wires, battery and cables terminals.
This is what I ended up drawing:  Click image to enlarge I'm going to use a 50mm2 from here http://www.ebay.it/itm/281217301497 to connect the batteries to the IBS relay and the two andersons. My questions are now about the cable sizes and connectors to use for the wiring. I would like the rear left worklamp to switch on when I insert the reverse gear and the two of them to switch on when I use the fron panel switch. I would need a solution like this one found on this forum for the connector that will bring the power to the 4 front lights and a 12V socket mounted on the roof rack that I will keep close when the roof rack it's not on. They come from here http://www.bulgin.com/products/circular-po...ndard.html but I don't know which one to get for my setup on the roof rack. Click image to enlarge I'm going to place an order at mobilecentre website because I need the tray for the two Odyssey and I also know they read this forum so if by any chance they are reading this I would like to discuss what do I need out of their kit since I've already something with me. https://www.mobilecentre.co.uk/index.php?m...cts_id=909 Admin note: this post has had its images recovered from a money grabbing photo hosting site and reinstated  Last edited by DEF_Jam on 2nd Feb 2016 10:50pm. Edited 1 time in total |
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2nd Feb 2016 9:23pm |
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| DEF_Jam Member Since: 17 Jul 2011 Location: Milan Posts: 59
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You are correct. I would just say the two anderson connectors (edited and corrected on the post).
One will be placed under the wing and connected to the starter battery only for emergency. Any idea where to pass? The other one I'm thinking of a sort of panel with two 12v sockets (water pump and fridge) and switch (for the "switch services") behind the cubby box also because I feel like I'm going to use the under cubby box safe I have to place the fusebox and the battery charger. |
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2nd Feb 2016 10:49pm |
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| redline Member Since: 28 Jun 2015 Location: Mountains and Lakes Posts: 221 
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DefJam: I suggest that give mobile centre a call. They are very helpful, and "modified" their kit to suit my own particular requirements.
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3rd Feb 2016 5:10am |
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| Peter Td4 Member Since: 23 Oct 2010 Location: Antwerp, Belgium Posts: 227  
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Fuses definitely have to go on the positive wires, not the negative
 Peter,
Defender 110 StaWa - Td5 Defender 110 HCPU - Puma Defender 90 Soft Top - Td5 |
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3rd Feb 2016 8:53am |
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| DEF_Jam Member Since: 17 Jul 2011 Location: Milan Posts: 59
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Sure Peter
I ended up learning that it's quite impossible to use an Anderson connector with the cables I have. They are special very flexible 50mm2 cable for welding but they are about 13,5mm diameter. http://www.ebay.it/itm/Cavo-saldatura-EXTR...1603679402 So I'm going to use the proper connectors from the same italian factory. http://www.ebay.it/itm/Presa-fissa-femmina...SwxH1T~0cd http://www.ebay.it/itm/Connettore-rapido-m...Swl9BWKjm9 My big doubt it's about the back socket/plug to bring power to the roof rack. If I'm correct I'm going to have 10 wires out from the fuse box (2 wires from each front light x4=8 + 2 wires for the roof rack 12v socket to have power inside the tent) and they are going to be running from the under cubby box space to the top rear corner of the car (as the picture I posted with the work lamp) where they are going to meet a connector. I will keep that sealed when the roof rack it's not on and plug in the connector with the cable coming from the roof rack when it's on. Is this too long for those wires? How big the cable should be in relation to how many Ampere I should consider to have for the 12v socket up there? |
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3rd Feb 2016 3:47pm |
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| Peter Td4 Member Since: 23 Oct 2010 Location: Antwerp, Belgium Posts: 227
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I would definitely not use welding connectors.
These welding connectors have one side that is exposed and that is far too dangerous for making a short circuit. This is the beauty of the Anderson connector; it is really designed for high-current DC applications. So please be careful ! On the wire size, there are plenty of calculators. Please be aware that on a low voltage DC system you have to pay much more attention to voltage drop than on a domestic 230V installation. A 12V DC system is more critical in that sense. Take a look at this one: https://www.bluesea.com/resources/1437 It still uses feet as measure of length  , but that's easy to convert. Peter,
Defender 110 StaWa - Td5 Defender 110 HCPU - Puma Defender 90 Soft Top - Td5 |
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3rd Feb 2016 4:02pm |
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| DEF_Jam Member Since: 17 Jul 2011 Location: Milan Posts: 59
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Peter as you can see there is someone else that did this job and he's very pleased with that.
Click image to enlarge Click image to enlarge Click image to enlarge The only difference is that I'm going to have 2 of them on a panel behind the cubby box and two under the wing with a sealed mini panel as well. It's in consideration of voltage drop that I'm going for 50mm2 cables. |
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3rd Feb 2016 4:14pm |
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| Cupboard Member Since: 21 Mar 2014 Location: Suffolk Posts: 2971
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Whilst I'd agree that Anderson are the nicest way to do it, if you want to see slightly alarming design you should see the jump start posts on some tractors. It's just two post sticking out behind a plastic flap.
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3rd Feb 2016 5:01pm |
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| DEF_Jam Member Since: 17 Jul 2011 Location: Milan Posts: 59
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About the switch I have to use for the "switch" part of the fuse box do I have to calculate the full Ampere amount of the seriveces connected and go for a 50A switch?
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4th Feb 2016 11:48am |
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| Peter Td4 Member Since: 23 Oct 2010 Location: Antwerp, Belgium Posts: 227
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Def_Jam, it is all about safety.
Technically seen these welding connectors are certainly adequate, but with the exposed metal you can generate quite nice fireworks if you unintentionally touch a metal body part whilst you have a battery connected to the other side of the cable. Anyway, in case of jump starting, if you follow the golden rule to first connect the Plus sides on both vehicles, and only then the Minus sides, you will eliminate the biggest risks. For the switch you would rather want to use an oversized model. The key in low-voltage high-current installations is to keep the total resistance down, just to make it bulletproof and reliable. Peter, Defender 110 StaWa - Td5 Defender 110 HCPU - Puma Defender 90 Soft Top - Td5 |
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7th Feb 2016 9:57am |
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| DEF_Jam Member Since: 17 Jul 2011 Location: Milan Posts: 59
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Thanks Peter, I did change my mind on pulling such a big cable under the wing only for jump start.
I was doing it just because I meant to have them ready if I'm going to add a winch. I'm just going to pull a sealed anderson for now. About the switch, since the oversized ones are pretty ugly, what about to use a realy associate to the switch? |
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8th Feb 2016 4:30pm |
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| Peter Td4 Member Since: 23 Oct 2010 Location: Antwerp, Belgium Posts: 227
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You could use a relay for the purpose, but keep in mind this will have constant power consumption.
In stand-by use, meaning when the car is not being used frequently, you don't want to have this. Would a recessed switch not be a solution ? Click image to enlarge FCX, a site sponsor, is selling this and it really is good stuff. Matt showed it to me when I visited his place some time again and it would be my first choice if I needed a battery switch. Peter, Defender 110 StaWa - Td5 Defender 110 HCPU - Puma Defender 90 Soft Top - Td5 |
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8th Feb 2016 5:18pm |
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| DEF_Jam Member Since: 17 Jul 2011 Location: Milan Posts: 59
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I'm not sure I'm looking for a battery switch because it's going to be a fuse box switch.
It will turn on the sevices or sockets passing throught a dedicated space on the fuse box. I was thinking to keep that space in the fuse box for what concern the roofrack services (which they will be 4 spotlights and a socket for the tent not always mounted on the car) and the other two "camping" devices socket fridge and water pump. |
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8th Feb 2016 5:35pm |
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