What battery(s) I should get, and charge?

Hi to all, Ive been reading thru old threads on what battery's I should be buying and have become a bit bamboozled by it all.
At the moment I have (cant recall) starter battery which isn't very old, A MRV70 battery for winching/fridge/aux, which is 5 years old and no longer holds charge and due for replacement, and lastly, a deep cycle battery (sdc something)that came in the van I just purchased which also doesn't seem hold charge either, age unknown.

Question is, what should I be replacing them with?
The aux battery will be under bonnet on the Turbo side (105 cruiser), the other battery will be in the van, plan being when the van not in use, be plugged into a power source and charging via a smart charger(what type?).
I also have 120w solar panels for use when away to help top up battery's.

I'm reading conflicting info with regards to putting AGM's under the bonnet which is why I'm unsure about their suitability, but seem to be the logical choice for the van.
looking forward to more sensory inundation :)

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Reply By: Allan B (Member, SunCoast) - Wednesday, Apr 25, 2012 at 16:57

Wednesday, Apr 25, 2012 at 16:57
Hi Shane, I thought it was universally agreed that putting AGM batteries under the bonnet was perilous, although some do it and get away with it.

For my own part, I have prematurely destroyed a couple of flooded deep-cycle batteries in the engine bay even though they were away from the exhaust. It is possible that charging regimes may have played a part.

So now I have fitted an AGM in the engine bay with a heat shield and good cool air flow so we will see how that goes. At the same time I fitted an identical AGM in the cabin and each is charged via an Redarc DC to DC charger from the alternator which cares better for the batteries than brute-force charging. Time will tell if this is an improved setup.


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AnswerID: 484177

Follow Up By: walwffoeg - Wednesday, Apr 25, 2012 at 19:49

Wednesday, Apr 25, 2012 at 19:49
Putting a second battery in my Hiace, instead of a deep cycle type, I chose exactly the same type as the one which cranks over the diesel, in case of one day ever being caught with a flat battery having left the lights on or something silly like that, I will be able to just swap them over. The second battery is kept up with a Waeco DC to DC charger which supplies 14.2v, also a 90 watt solar panel. It is used to run a 50 litre Waeco fridge.
FollowupID: 759431

Reply By: The Bantam - Wednesday, Apr 25, 2012 at 21:49

Wednesday, Apr 25, 2012 at 21:49
Personally I think while AGM is a great technology and there are some very nice batteries out there, BUT it is oversold particularly in non-marine applications.

Likewise I believe deep cycle is often specified without a good understanding of its strengths and weakness.

a combination of both will often fail without people undertsanding why.

Many Deep cycle AGMs have very low maximum initial charge rates.
I have seen reputable N70 size batteries with maximum charge rates of 20 amps, people also fail to look at the recommended temperature ranges on AGM batteries..some quoted as low as 45C in charging cycles.
Put one of these under the bonnet connected by a simple solenoid and you have a guaranteed failure.

Deep cycle batteries are no mirricle and realy are strong where they are charged and discharged slowly.
Cycle them hard every day and you are realy more into a cyclic application rather than a deep cycle application.

personally after a great amount of thaught and looking at the specs and the prices I have standardised on good quality sealed marine cranking battery for all applications.

I can buy twice as much capacity in standard sealed wet marine batteries as I could in AGM, and that is a game changer.

Double the capacity you halve the drian on each battery making it perform better and give more capacity, for the same load and duration you cycle half as deep, that will extend the life of the battery no end.

Personally I like the Supercharge Seamaster Gold, because I have had a good trot with Supercharge..and although a "sealed" battery, once out of warranty, the top sticker can be removed and the vent valves unscrew and the battery can be topped up just like a basic screw top battery.

so my recoendation for what it is worth is go with as many N70 sized marine batteries as fits your need.

If you are going to paralell 2 up for more capacty make sure you buy them at the same time and periodiclay charge them seperately.

Oh and a good multistage charger is a great investment, but there is no need to leave a battery on them all the time..a good heathy battey should hold its charge if treated right for 2 months if leaft in peace.

AnswerID: 484218

Follow Up By: The Bantam - Friday, Apr 27, 2012 at 11:42

Friday, Apr 27, 2012 at 11:42
OH BTW..regardless of the type of battery make sure it is adequately ventilated.

There is no such thing as a completly sealed battery, all batteries can and will vent explosive gasses and possibly acid mist.

FollowupID: 759620

Reply By: Member - Shane D (QLD) - Friday, Apr 27, 2012 at 16:22

Friday, Apr 27, 2012 at 16:22
Thanks for the replies,

AnswerID: 484386

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