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MontyStory



Member Since: 07 Apr 2021
Location: UK
Posts: 1

United Kingdom 
Dual battery set up

I've been trawling through various websites and blogs, and still feel like I could do with some guidance.
I have a dual battery system set up in parallel with A, B, A+B, Isolation selection switch.
Defender is kitted out for overland with fridge, led flood lights, winch and inverter.
I need to replace the batteries.
Does AGM really suffer with overcharging? Is AGM that much better?
Will a deep cycle cope with winch use?
Does running a regular battery down harm the battery?
What battery, x2, should I go for?

Post #896401 7th Apr 2021 9:46am
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landy andy



Member Since: 15 Feb 2009
Location: Ware, Herts
Posts: 4459

2006 Defender 110 Td5 USW Zermatt Silver

The bits I know.
Running down a standard battery is much worse for it than running down a battery that is designed for it.
Why would you run the winch off the second battery? Are you planning on using when engine is off? I always run it off starter battery not leisure one, otherwise the split charge system gets a real hard time.
I run two Odyssey pc 1500 and have now done that in 3 defenders without any issues. They have fun fridges, inverters, lights and loads of other toys including a winch on each Defender.

https://www.tayna.co.uk/industrial-batteries/odyssey/pc1500dt/

Post #896510 7th Apr 2021 5:03pm
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leeloo



Member Since: 31 Mar 2021
Location: Bereldange
Posts: 6

Luxembourg 

I know quite a bit about dual batteries, I set them up myself in about 3 vehicles so far and I had all kinds of systems and did a lot of research.
You can use AGM both as a start and auxiliary battery, but you will have little added value.
You can have a normal start battery and put an AGM deep cycle as auxiliary.
For AGM deep cycle, the recommended charging voltage depends on the AGM type, it can be 14.V, 14.2-14,4. or even higher, and at float a little less.
Your alternator , if is not a smart alternator, should put out between 13.5 and 14.5 V. You need to measure and go for an AGM with higher charge voltage, to avoid overcharging. Perosnally I rarely seen older vehicles putting out more than 14V, mostly because of the age. Maybe new they were reaching 14.5, so get a multimeter and measure it.
Vehicles made after 2006 typically have smart alternator, and there the voltage is maybe 13.5 maximum even less very often.
It will help us to advise you if you can tell us what vehicle you have.

If you have a smart alternator, it is not a huge issue regarding the life of the battery but it will impact the size you need.
If you think you can get away with an 80 AMP deep cycle, considering it will not be full unless you top off with solar or shore power, you might need to redo the math and put in a bigger 90 or 100 AH battery, considering that it will never be full.

Post #896636 8th Apr 2021 11:57am
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Julie



Member Since: 07 Oct 2017
Location: Nantes
Posts: 290

France 2012 Defender 110 Puma 2.2 SW Keswick Green
Re: Dual battery set up

MontyStory wrote:
.
Does AGM really suffer with overcharging? Is AGM that much better?
Will a deep cycle cope with winch use?
Does running a regular battery down harm the battery?
What battery, x2, should I go for?


Dual batterie setup over here : sealed lead acid + AGM = 110 + 80 Amps
AGM do allow fast recharge rates, higher voltage, hnce faster charging of itms like portables laptops etc.

Your winch is on the starter battery - with the engine running - like your compressor - I hope so at least - no criteria for thé choice of a service battery though

I opted for a DC//DC charger with 20 Amps allowing for two different types of batteries : standard lead acid + AGM v Gel v Lithium as your service batterie.

Your choice dépend on :
- solar charging rate
- Service temperature
- life span estimated
- costs
And your consumption, of course, which is the most important detail to clarify

P.S.: Forget about lead acid batteries as service batteries.

Post #896763 8th Apr 2021 8:14pm
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jlpsmith



Member Since: 13 Apr 2021
Location: Buckinghamshire
Posts: 1

England 

Pretty much everything explained about dual battery systems here.

Post #898785 17th Apr 2021 6:05pm
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