New "12V" battery with 4.9V....!

Michael · Post by **Michael** » Wed Feb 28, 2007 7:58 pm

Hi guys

this is weird!

About 2wks ago, i bought a brand new batt from nissan, 590cranking Amps, and just fitted it to Primera. Nothing registering on dash, and beeping noise coming from immobiliser.

There are no instructions for the immob. I have a fob with a coaxial connection which you hold against a similar connection linked to the immob. think this immob is after market - its in the boot!.

Have never used this immob before, just the cars normal NATS one, with the central locking. Replacing the car battery seems to have woken it!

Just out of interest, i tested new batt - 4.90V

Any chance my wee tester just isnt contacting it enough? Old battery is just over 12v.

Am i missing something here?!

Cheers for any hints!

battery has a two year guarantee btw.

robin · Post by **robin** » Wed Feb 28, 2007 8:14 pm

The problem is your new battery is f*cked, no?

Check out the date code on the battery and see how old it is - they do have a limited shelf life.

It should be 12-13V depending on state of charge.

4.9V is so low that I would guess it's just bust, not flat.

Cheers,
Robin

Michael · Post by **Michael** » Wed Feb 28, 2007 8:17 pm

strange!

Ill check the code...

Michael · Post by **Michael** » Wed Feb 28, 2007 8:24 pm

.

26-04-06....!

Think i'll need to just take it back...hmmf

The immob doesnt play up again when i put old one back in after dinner.....

Cheers,
Mike

r10crw · Post by **r10crw** » Thu Mar 01, 2007 9:15 am

As robin says the codes the first place to look, when I buy batteries for the caravans, usually in bulk, they come without charge and need an initial charge so might be worth charging it then see if it maintains it.

robin · Post by **robin** » Thu Mar 01, 2007 10:46 am

r10crw wrote:As robin says the codes the first place to look, when I buy batteries for the caravans, usually in bulk, they come without charge and need an initial charge so might be worth charging it then see if it maintains it.

Retail automotive Lead Acid batteries are stored charged as wet cell lead acid batteries don't tolerate deep discharge. If you buy one in a motor shop for your car it 100% must come charged - even if you can make it hold a charge now, starting with a dead flat battery means a reduced service life.

Marine Lead Acid batteries (typically Gel Cell construction) are designed to be deep discharged and are often stored discharged.

I am guessing that the caravans use Marine-type batteries because it's natural to run a caravan battery completely flat repeatedly (I guess you could run it flat every night if you run the TV, lights, some heating pumps, etc., off it). Of course you could use wet cell too, but I would expect to change them quite frequently.

Cheers,
Robin

r10crw · Post by **r10crw** » Thu Mar 01, 2007 10:57 am

Quite right robin, there deep cycle batteries, steady discharge for long period as opposed to car starting requiring high current for short periods.

hiscot · Post by **hiscot** » Thu Mar 01, 2007 11:21 am

most car batteries only have an inittal holding charge not sutiable for cranking the engine and after many months lying around a cold warehouse will discharge even further so should be fully charged before fitting at all , or it will be dammaged
you can get lead acid slow discharge batterys but they are expensive due to the lead plate used and are not ment to crank an engine but substain a very very low discharge, a 101 battery for example was desighned for battery lawnmower use and is very effective in its use , however most folk will try fitting a cheaper lighter std or leasuire ( caravan ) battery then complain it runs out
motor cycle batteries (and car i think) used to come dry and we used to put acid in in the pdi ( then charge ) however storage of acid is now more controlled hence inital fill from factory