Best battery - Deep Cycle or Stop/Start???

Looks like my battery is starting to give up. On 2 occasions following cold nights it has failed to turn over my 300TDi. Following a jump of short charge it works fine.
Due to this I feel I may well be in need of a new battery as I have yet to have to replace it since ownership (7 years+) so I can't really complain. However, what battery should i opt for?
Long term I wish to install a twin battery set-up for expedition/camping use and hence part of me thinks an AGM deep cycle battery would be the best option and then in a year or so add a 2nd AGM with split charge system.
What are your thoughts and recommendations?

Standard battery for starting,biggest that will fit in the box with most CCA, [ Cold cranking amps.] £1100 squid for a battery!!!

It sounds as if you are proposing to use a deep cycle battery as a conventional car battery. If not forgive the following.
Car batteries and deep cycle/leisure batteries are very different beasts. The car battery is designed to give a very high discharge (Cold Crank Amps) in order to start the car. The alternator then takes over provides electrical power and quickly recharges the battery to cope with stop start motoring. It is designed to cope with a great many rapid shallow recharge cycles, but fully discharging it can cause damage. The deep cycle battery is designed to cope with a great many full discharges, but does not charge quickly and will not deliver the same Cold Cranking Amps (CCA) you get out of a car battery.
A conventional car charging system would damage a deep cycle battery, it would struggle to start the car and not recharge quickly enough if you are doing short journeys. Install a decent sized car battery with at least 100 CCA and put in a deep cycle battery to power your fridge, lights, heaters, chargers etc when parked up. As you have said you need a split charge system to deal with the two very different requirements.

Si Click said:

As you have said you need a split charge system to deal with the two very different requirements.

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Like he ^ said. You can't cheat on this.

ogb said:

Like he ^ said. You can't cheat on this.

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Well you say that, but I'm tempted by the Ark Pack 730P Power Pack which gives a de-mountable system complete with its own charging system. It almost feels like cheating. https://tuff-trek.com/solar--electrical.html

I have a marine battery in mine. It is a sort of half way house
Good CCA but also will give a slow drain without damage apparently

Si Click said:

Well you say that, but I'm tempted by the Ark Pack 730P Power Pack which gives a de-mountable system complete with its own charging system. It almost feels like cheating. https://tuff-trek.com/solar--electrical.html

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Can I have your lottery numbers?- you don't need 'em now you've won!

Yeah, it's not cheap, but by the time you buy a D2 additional battery tray for the engine bay, buy a leisure battery, buy a split charge system and then pay someone who knows what they are doing to install it, I'm not sure the costs are so far apart. This takes up space in the load area, but could be removed when not needed. If it would fit into the space left by removing one of the third row seats, it could be a player.

_Stingrey_ said:

Looks like my battery is starting to give up. On 2 occasions following cold nights it has failed to turn over my 300TDi. Following a jump of short charge it works fine.
Due to this I feel I may well be in need of a new battery as I have yet to have to replace it since ownership (7 years+) so I can't really complain. However, what battery should i opt for?
Long term I wish to install a twin battery set-up for expedition/camping use and hence part of me thinks an AGM deep cycle battery would be the best option and then in a year or so add a 2nd AGM with split charge system.
What are your thoughts and recommendations?

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I just got one of these for my 300tdi Fender.

https://www.halfords.com/motoring/b...art-stop-agm-12v-car-battery-4-year-guarantee

£112 with a trade card, so far so good. Someone else was recommending another one from Halfords the other week, but it was a lot longer.

Cheers

Stop Start? I had no idea 300TDis were so advanced. Trouble with own brand batteries is you don't know the manufacturer.
I put one of these in my son's D90 TD5 over the summer
https://www.halfords.com/motoring/b...sb019-silver-12v-car-battery-5-year-guarantee
CCA 900 Amps, 100 Ah, a 5 yr warranty and £105 with a trade card.

Si Click said:

Stop Start? I had no idea 300TDis were so advanced. Trouble with own brand batteries is you don't know the manufacturer.
I put one of these in my son's D90 TD5 over the summer
https://www.halfords.com/motoring/b...sb019-silver-12v-car-battery-5-year-guarantee
CCA 900 Amps, 100 Ah, a 5 yr warranty and £105 with a trade card.

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I was specifically after an AGM battery. Which is why I chose the Halfords one, why does your son need you to put a battery in his defender??

Cheers

neilly said:

why does your son need you to put a battery in his defender??
View attachment 168043

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Technically he fitted it, but I went to buy it while he was fitting a new crank sensor.
Yup deffo him that fitted it, and he won't connect a battery up the wrong way round again. The ECU survived, but it needed a new alternator.

Si Click said:

Technically he fitted it, but I went to buy it while he was fitting a new crank sensor.
Yup deffo him that fitted it, and he won't connect a battery up the wrong way round again. The ECU survived, but it needed a new alternator.

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Ouuch, not so good....

Cheers

What about these batteries????

https://www.devon4x4.com/twin-battery-package-defender-up-to-2006.html

with this connected into the system.....

https://www.paddockspares.com/gwardar-dual-battery-management-system.html

Looks like a bit of a halfway house with two identical batteries giving a huge 1500 CCA (way more than needed), but a fairly low output of only 68 Ah.
It is similar to marine setups where you have two batteries, one of which is dedicated to starting the engine, while the other runs everything else. That way if you flatten the battery using your ancilliaries you can always still start the engine. They use the same type of battery so that if the starter battery goes bad, you can use the leisure battery to start the engine. That all makes for a very robust starting system (hence the military spec comment in the ad), but it comes at the expense of the leisure set up. It works well on a yacht because the batteries are huge, but if you are planning on running something as power hungry as a fridge, you may find that you would be better off with a full sized deep cycle battery rather than a smaller hybrid one.