 | Home > In Car Electronics > Multiple battery setup help |
 
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| Cupboard Member Since: 21 Mar 2014 Location: Suffolk Posts: 2971   
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Read this thread:
http://www.defender2.net/forum/topic42887.html If you're going for a non-standard battery I'd use an Odyssey but as I explain in that thread I would just use cheaper batteries! Fuses close to the batteries as possible to protect the cables. If a cable has a battery at both ends (and is more than negligible length) then you'd need two fuses. You can use MCBs but they take up a lot more space than a standard automotive fuse box. Another option is something like this: http://www.beal.org.uk/electrical-products...00219.html Winching you almost certainly want both batteries joined together with a nice beefy link. No reason you couldn't just take a separate isolator on for that to do emergency jump starting of yourself too. |
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8th Feb 2016 10:49am |
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| itolond Member Since: 16 Jan 2016 Location: Singapore Posts: 193  
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Hi Cupboard,
appreciate the info, placement understood, what about fuse / breaker rating, any guides? |
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8th Feb 2016 10:58am |
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| Cupboard Member Since: 21 Mar 2014 Location: Suffolk Posts: 2971
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Do a power budget.
What loads are you supplying, what size cable are you using etc. Say you've got a 1A LED worklight, which you've wired using cable that's rated to take 16A because that's what you've got lying around. You could fuse that at 5A quite happily, but no reason you couldn't stick a 15A fuse on it either. I haven't seen it done much for automotive stuff, but for mains electrics one thing you can do is say "I have a 1A load so want to use X sized cable, but it's going to on a 16A plug so it needs to be rated for the fault current, so I'll use 0.75mm2 cable which you wouldn't use to supply a 16A load but can take enough current to trip the 16A breaker". If you look in the Defender wiring diagrams they do that a bit, have one fuse supplying multiple loads and the fuse is sized for the loads and not the cables. So long as if there's a fault in the cable the fuse will blow before there's a fire you're fine. Blue Sea do a neat little terminal mounted fuse block so you don't even need to think about the cable to the fuse box. You need to do an energy budget for sizing your batteries too. Say that your battery has 50Ah working capacity (see the other thread for more details) but you need to run a 3A load for two days, that's not going to work. Equally if all you're trying to do is charge a mobile overnight and will be driving again the next day then you'll be using more energy faffing around with your split charge system than the phone will ever take. |
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8th Feb 2016 1:11pm |
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| itolond Member Since: 16 Jan 2016 Location: Singapore Posts: 193
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Thanks,
I wil need to measure however i searched and found the TDI300 has a 300A cranking draw and the optima red has a CCA of 750... as for accessory load- not sure yet |
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8th Feb 2016 1:42pm |
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| Cupboard Member Since: 21 Mar 2014 Location: Suffolk Posts: 2971
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Sorry, what are you trying to fuse then?
Usually with an aux battery system you'd put a supplementary fusebox by the second battery to run the auxiliary loads off, things like work lights, fridge, radio or whatever you're putting the second battery in for. Not sure what that has to do with the cranking amps of a 300TDI? |
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8th Feb 2016 2:02pm |
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| itolond Member Since: 16 Jan 2016 Location: Singapore Posts: 193
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you need a fuse between the battery and the starter, correct?
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8th Feb 2016 2:03pm |
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| Cupboard Member Since: 21 Mar 2014 Location: Suffolk Posts: 2971
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There often isn't!
The Puma has a 400A mega fuse. But you shouldn't have to alter the starter circuit? That's already in and working I assume? All you're doing as adding a second battery and split charge system? |
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9th Feb 2016 12:40pm |
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| miker Member Since: 13 Sep 2015 Location: Surrey Posts: 1763 
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Generally you don't have a fuse between main battery, starter motor and alternator.
I wouldn't bother to change this unless you really need to! |
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9th Feb 2016 3:14pm |
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