 | Home > In Car Electronics > Which batteries and split charge system with solar? |
 
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| dantastic Member Since: 04 May 2010 Location: London Posts: 367  
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I'd only require one of to 30s. If I can fit a 27 and a 30 I'd be really happy. Or one even bigger! 😃
Looking at the tray as well I don't think I need to buy anything. I will be able to fabricate whatever platform is needed to get them level. |
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7th Mar 2019 2:53pm |
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| Cupboard Member Since: 21 Mar 2014 Location: Suffolk Posts: 2971 
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I would have thought you'd struggle with a pair of the larger Numax batteries, based on what I've got I thought the largest you could fit was a pair of 019 sized batteries.
That being said, height is as much of a limiting factor in my seat box as anything and both of those Numax batteries are taller than a 019, so what do I know! Assuming there's enough height, and there must be otherwise jst wouldn't have managed it, then the larger Numax might fit because the footprint is smaller than a 019. Anyway. Just to give you another thing to think about... here's why you shouldn't bother with a split charge system at all and you should do what lorries do and use the starter batteries for house duties too. Cranking amps don't drop much until the state of charge goes below 50%. You shouldn't be cycling batteries below 50% because it substantially reduces their lifespan. So rather than have a start battery and a house battery, use the same two batteries but permanently connected. You'll have twice the starting capacity and twice the camping capacity whilst keeping the wiring simpler and not having to think about whether your interior lights are running form the correct source. The obvious disadvantage is if you're not paying attention and manage to flatten both batteries, but there are ways to solve that problem (low voltage cutouts etc) and you can inadvertently do it by leaving your lights on anyway. The Victron BMV 712 works well. I have one. There is no reason that a standard Defender alternator won't fully charge an AGM battery in a sensible timeframe, when you look at battery datasheets the alternator voltage falls well within the recommended charge voltages. Sure, a 14.4V alternator won't charge quite as quick as a 14.7V alternator but DC/DC chargers are so current limited anyway you are not going to get any noticeable advantage (and most like disadvantage) by using one. My aux battery will happily charge at 60A for quite a significant period and is over the capacity of most DC/DC chargers right up to 90-95% charged. The exception is when you've got a battery at the end of a long, thin wire, but the solution to that issue is to upgrade the wiring. |
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7th Mar 2019 11:40pm |
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| jst Member Since: 14 Jan 2008 Location: Taunton Posts: 7682 
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most dont run them in parallel for the exact reason you state, not wanting to be in a position where they cant start the vehicle. Cheers
James 110 XS Utility 130 Puma Station wagon/camper (in the making) 90 Puma Hardtop |
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8th Mar 2019 10:22am |
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| Cupboard Member Since: 21 Mar 2014 Location: Suffolk Posts: 2971
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me included
But the next time I redo my electrical system that's the way I'm going. There's a chap whose name I can't remember but I met at one your Big Outdoors events with a rather nice blue 90 and he just uses a massive great Odyssey battery for everything. |
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8th Mar 2019 7:17pm |
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| jst Member Since: 14 Jan 2008 Location: Taunton Posts: 7682
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Chris Pretty. He used to work for odyssey. Cheers
James 110 XS Utility 130 Puma Station wagon/camper (in the making) 90 Puma Hardtop |
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8th Mar 2019 7:38pm |
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