Flat battery

[sorcerer]

The car is a 52-plate Nissan Maxima QX 3.0SE Plus Auto and the battery let me down today - closer inspection shows two cells are shot, so it's new battery time. The existing battery is currently on charge in the garage in the hope that it'll be good enough to get me to the battery shop tomorrow but in the meantime two questions come to mind:

1) Does anyone know anything about batteries? Looking at the website of a battery place just a couple of miles away from me brings up four choices for my car:

(a) Exide Premium 096 @ £89.95
(b) Varta Blue Dynamic 096 @ £89.99
(c) Varta Silver Dynamic 096 @ £99.99
(d) Varta AGM 096 @ £139.99

Why is the most expensive one £50 more than the cheapest? Is it worth it? This is a car that we intend to keep until it dies a natural death so if the more expensive battery is worth it and will give us the longest life and best value for money I'll happily pay the price because it's not a 'bung a cheapie on and sell it quick' situation. How do you know which is best?

2) When I come to reconnect the battery tomorrow (and then do it again when I get the new one), will I have any problems with the OMVL Dream XXI N LPG system or will it just find all its settings and values straight away as if nothing had happened?

Thanks.

[Allan1010]

Hi Sorcerer

I can give you a heads-up on the batteries you've quoted; The 096 is the industru standard designation for the size, shape and rating of the battery. All 096's from all manufacturers SHOULD be the same size, shape and capacity more-or-less give or take a few cold cranking amps or millimeters of case size.
I know that the zero or a one at the start of the size refers to which way around the terminals are, ie a 196 wil be identical to your 096, but with "wrong handed" terminals. The other 2 digits will refer to other parameters; case size, capacity, terminal type (round post or bolt-through) etc.

The most expensive one is an AGM, or "absorbed glass mat" battery. This is a more expensive construction, and newer design of battery although not brand new (they've been around since the 70's I think but are now becoming more popular). The electrolyte on these is, as it says on the tin, absorbed into a glass mat separator so the cells are not "flooded" as they are on conventional batteries where you top them up over the level of the plates.

They have to be made with purer lead plates (conventional batteries use a lead alloy as the plates have to be able to support their own weight) and are therefore generally more durable with a lifespan "up to" 10 years depending of course on how you use them.
They can be discharged deeper than conventional batteries which suffer a shortened life if they're regularly discharged past 50% capacity. AGM batteries can be discharged to 20% of their capacity regularly without a problem.

They don't tolerate overcharging very well, though but as long as your alternator is working properly they sound like a good alternative to me.

If you decide to go the conventional route, Euro Car Parts have branches nationwide and offer free delivery from your nearest depot, same day if they have the bits in and sell only premium parts such as Bosch and the like.

I hope this helps you to decide.

[Gilbertd]

See here http://www.autoexpress.co.uk/products/p ... eries.html which may give you a pointer. I've always looked at the warranty offered on a battery, if it has a warranty of 3 years, it'll last just over before the internal warranty fuse blows, whereas one with a 2 year warranty will almost certainly die earlier.

I had a Bosch Silver battery on my Saab and that had been there for at least 8 years and held a charge for well over 5 months (through the winter) when I wasn't using it before I sold it. There's a silver battery on the P38 too and that has never let me down (despite the huge amount of electronics that Mr Land Rover chose to fit). I've seen somewhere that you have to be careful with charging silver batteries and can't just whack a non-regulated cheapie on them and expect them to last a long time. If I were you I wouldn't go for the cheapest or the most expensive, c seems the best bet.

It is highly unlikely that the gas ECU will lose any settings, I've got a spare AEB Leonardo ECU (and the Dream is an AEB manufactured ECU) that still has the settings for the car it was fitted to and that was last used 2 years ago!

Probably teaching you to suck eggs but make sure you always connect the earth last and disconnect it first. Nothing to do with some of the b*llocks written about surges damaging electronics (because until you connect both, you've no circuit and it matters not which is connected first) but for safety reasons. Think about it, if you connect the earth first and then touch any metalwork with your spanner while doing up the positive, you've got a dead short across the battery. Not good for the battery and can weld a spanner to the car if you are unlucky (or blow a big chunk off it if you aren't).

[binder4]

.3GilbertD, if you mean disconnect battery earth first, reconnect it last, I agree, for the same reasons. Not fun touching the bodywork with the spanner whilst working on the positive terminal!

[Gilbertd]

Oops, well spotted. It should have read disconnect the earth (negative) first and connect it last. Original post now edited.

[sorcerer]

Thanks very much folks