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We all know that the ultimate battery for the p38 is the ginormous Hankook MF31-1000 (the one that just fits in the hole) but the last time anyone checked, they were being shown as no longer available. Well thankfully, now the weather is about to get colder and batteries are going to start to show their age, they are back. https://www.batterymegastore.co.uk/hankook-mf31-1000.html

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Joined: Jan 16 2016
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I am 99% certain that it is the same battery as the Lucas MF31 which is more readily available.
Made in South Korea. Looks the same with a Lucas badge on. Same spec anyway @ 1000 CCA.
I got a 3 yr warranty on mine.

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Where from? I just Googled Lucas MF31 and came up with nobody wanting to sell me one.

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Joined: Sep 14 2016
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Are we sure these are for vehicle applications?

Various makes show ---31MF as a leisure battery (whatever that means) where --- is the makers letter code. Lucas version is LX31MF. Quite a few of the usual mail order suspects list it.

Link here https://advancedbatterysupplies.co.uk/news/2012/04/what-is-the-difference-between-a-car-battery-and-a-leisure-battery/ purports to explain the difference but the electrochemistry sounds suspect to me.

Clive

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They do look very similar except for the terminals. My understanding, having been involved with them a little at work, is that a leisure battery doesn't mind being left fully discharged but is designed to give a constant output over a long period but doesn't like being asked to supply very high current for short peroiods. Whereas a starter battery, as the Hankook is described, will quite happily give maximum output for cranking a starter. I'm sure Bolt will be able to give us chapter and verse though. All I know is that the hankook I put on mine about 3 years ago will still happily crank the engine over at a decent rate and the one I took down to my mates place in France for his P38, fired it up instantly even after the car had been left for 5 weeks.

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I'm on my second Hankook, but that's after 3 years of total abuse and several deep discharges. They're great batteries!

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Joined: Jan 16 2016
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I bought my Lucas LX31MF from Eurobatt. It says dual purpose and 1000 CCA. I have taken dual purpose to mean leisure ie. deep cycle and engine starting.

My experience has been good with them. Diesel starting is a lot more demanding and it has been OK.

I went through a period when my BECM kept being woken up (before I fitted the latest receiver) and the battery was completely flattened on more than one occasion. Because the battery is deep cycle I got away with it I think.

I have actually got 3 Lucas LX31MF batteries. Two old ones are in my caravan and a newer one in my diesel p38. The caravan is quite heavy and has a motor mover fitted. It pulls 85 amps when in use and I fitted twin batteries and a marine change over switch so I don't get stuck. I also changed the connections so they are the same as the car. It didn't make sense buying different batteries. I am also a tight git.

From experience, the car battery starts to play up after 3 years, usually when the warranty runs out. I then put a new one on the car and the old one goes on the caravan. I think the car battery is coming up to two years old. The caravan batteries are probably 5 years and 8 or 9 years old.
The older one is not holding a charge as well as the other so I will probably buy a new one for the car soon.

https://www.eurobatt.co.uk/type/marine/lucas-marine-1870054143/lucas-xv-dual-purpose/lucas-lx31mf-leisure-marine-battery-110ah-xv31

https://www.ebay.co.uk/itm/12V-105AH-Lucas-LX31-XV31MF-HD-Ultra-Deep-Cycle-Leisure-Battery-3Yrs-Wrnty/201697662185?epid=9034024974&hash=item2ef61e14e9:g:9f8AAOSwdjha3bos

https://www.ebay.co.uk/itm/12V-105AH-LUCAS-LX31-Deep-Cycle-Leisure-Marine-Battery-Dual-Posts-Terminals/192991775864?epid=1525084115&hash=item2cef34cc78:g:k4gAAOSwGvhT2N~Y

The case looks the same as the Hankook I think or maybe I am wrong. I also notice it now has a 4 year warranty.

I have also noticed that other manufacturers are pedalling the same battery with their badge on it:

https://www.ebay.co.uk/itm/12V-105AH-Numax-XV31MF-Ultra-Deep-Cycle-Leisure-Marine-Battery-3-years-Wrnty/190603406688?hash=item2c60d92d60:g:zsIAAOSw3fpapqH3

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All more expensive than a Hankook from battery Megastore though. I must admit, I'm considering getting a second one. The Ascot needs a battery so I figured I'd get a new one for my car and fit the one that's been on mine in the Ascot.

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We had put to replace the Hankook MF31 on the red one unfortunately not long back :( Though since replacement along with one of the prototype RF filters (okay so it was quite a while ago now) - it has been fine when left since. Still rocking the prototype filter too.

I think multiple discharges through lack of use and RF interference just took its toll.

Mine has been down to 3v prior to obtaining a 3rd gen receiver a couple of years back now, and bounced back just fine. Actually discharged a couple of times through other reasons (fridge...whoops) and it has recovered.

Wouldn't bother with anything else - either the MF31 or perhaps the dual use variety. For the price too... I mean, you can't really beat it.

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Mine wasn't really dead, but after a day or so of sitting in the car it would fail to crank. I took it from 8V to about 12.3V eventually on my little charger but it never came back to being a reliable battery. Maybe a really long journey or a decent CTek or similar conditioning charger would do it, but I was starting to fear for the alternator and decided to get a new battery.

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Joined: Jan 16 2016
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https://www.ebay.co.uk/itm/MF31-1000-Heavy-Duty-Battery-12V-115AH-Tractor-Lorry-Truck-Taxi-Van-Leisure-Boat/272291607351

https://batteryfactory.co.uk/products/hankook-mf31-1000-643-644-heavy-duty-starter-battery-12v-ah115-cold-cranking-1000amps?variant=21372257435707

Prices seem to be all in the same range.

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It's gone up. When I posted the first link just over a week ago, they were in stock at £81, now Battery Megastore are showing them out of stock (again) and the price has gone up by a tenner to £91! But they'll still sell you one via eBay for £97. Bugger, should have got one last week.....

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Joined: Sep 14 2016
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I'm surprised that folk are only getting 3 or so years useful life from a battery. Mine is over 6 years old and still working fine despite lots of standing around and charge ups "when I think about it". Dunno what brand it is. Just whatever the local independent tyre & exhaust place was selling back then as a decent mid range choice.

Don't think I've ever put two batteries on a car but as I've had the P38 since 2011 it may be the first.

Clive

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Joined: Mar 14 2017
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Just received one. It certainly fills the hole and is quite tall (I may modify the strap a bit to fit better) and the leads had to be stretched a bit to reach the posts but it does fit. Starting the diesel is now almost instantaneous! It spins the diesel 6-pot over as if it were a Ford Fiesta!

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Joined: Jan 16 2016
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This is an old post but I have just found out some new info.

My p38 is presently sorned. Has been for a few months while I have been ticking off occasional jobs on it.
I thought I had been keeping and eye on the battery but just found it flat as a pancake. It was down to 11.6v.
However after 24 hrs on charge it has bounced back. Now up to 12.4v. Not quite there yet. Taking an age to charge with a small 3 amp Cetek charger.
It is a Lucas LX31MF which is described as a leisure/marine dual purpose battery. I thought it was a rebadged Hankook as the cases look the same. Eurobatt, who I bought it off, have just said it is not a rebadged Hankook but they are made in the same factory in Korea and use the same case along with some other brands.
The spec also isn't the same. It is 105 Ah and 740 CCA. They actually said it is 1000 MCA. Not sure what the difference is CCA vs MCA.
Also said Hankook do not make batteries themselves. They are a tyre company.

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Joined: Jan 05 2016
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I've seen lots of batteries using the same casing as the Hankook one - either way, I have no qualms with it. I have had to recently replace my first MF31-1000, but it had seen some serious abuse in its 3 years or so, including being discharged down to 3v. In the end, a cell went short.

For the price and performance, I wasn't hesitant about buying another. Last night with the M57 immobiliser issues, it must have been cranking that thing over without any signs of deterioration for a good 5 minutes total while we tried to figure out what the hell was going on.

At the same time, I also ordered a 'Hankook' AGM battery for my E60 530D - also so far no issues.

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Joined: Jan 15 2016
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Clive603 wrote:

I'm surprised that folk are only getting 3 or so years useful life from a battery. Mine is over 6 years old and still working fine despite lots of standing around and charge ups "when I think about it". Dunno what brand it is. Just whatever the local independent tyre & exhaust place was selling back then as a decent mid range choice.

Don't think I've ever put two batteries on a car but as I've had the P38 since 2011 it may be the first.

Clive

I've had my '38 for seven or so years now and on battery number four!

The heat kills them and after two years, you're on borrowed time. A pal of mine in KL moved his battery to the back, away from the engine heat but still only got another 12 months or so out of them.

The one good thing here is an outfit called Motorlite, who'll have a new one with you in around 20 minutes from calling them. Their number's on my mobile speed dial!

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Joined: Dec 29 2016
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It's for the warranty that I buy my batteries from Halfords. With a trade card they're no more expensive then any of the other batteries online. Halfords own Calcium batteries have a 4 year warranty and Yuasa come with a 5 year warranty.

If they fail, you walk into Halfords, they clip it to a machine and as long as it's dead you walk straight out with a new one. I've not once had them question it or refuse to change it.

The Yuasa battery isn't quite as big as the Hankook ones are but I've never had any problems with them on any of the P38's I've owned over the years.

David.

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How do you get a Halfords trade card?

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I recently committed the heresy of ordering a Varta 069 - 75 pounds delivered - 4 year warranty. It's a V8- capacity battery 70Ah - my last battery was the Bosch equivalent. Although there's something to be said for the Halfords warranty, if they're that good at honouring it, as DHallworth notes. I've always bought Bosch (Varta make Bosch), but last time I tried to get the motor factor/ Bosch to stand behind their warranty I got nothing...so I figured I may as well not pay a Bosch premium this time