Measuring battery performance

[Mcalvert]

Hi,

 

The battery in my 1700SS seems to down on charge - I'm not getting the same enthousiasm on starting (althoug it does still succeed), and I have had some misrires at high revs which I feel may be down to poor spark?

 

Can someone please provide some guidance re. how I should go about diagnosing whether it is the battery at fault, or the alternator down on efficiency. I have a multimeter, but would appreciate advice on what to look for, and what readings I should be looking for at different points.

 

Thanks - Michael.

[Nigel Riches]

Michael, if you have some decent sharp pointed probes with your multi-meter measure the volts at the battery terminals with the engine turning sufficiently fast to extinguish the ignition / charge warning light, battery volts should be some where around 14 volts (13.5 14.5), if this is not so, clip the negative terminal of the multi-meter to the battery neg post, and probe the volts directly at the alternator output terminal, (the large terminal, probably a brown wire, about 4 mm in diameter), if the charge volts are O.K.(13.5 14.5) there is some resistance in the charge lead, this is not good, O.K. if the volts at the alternator are good and the volts at the battery are lower, then stop the motor, disconect the battery (neg lead first) and measure the resistance from the battery positive connector to the output terminal of the alternator, ( which you also disconnect) with your meter, this should be in the order of nil ohms, if it's not then a replacement wire of same size from battery to alternator should see you right, also check for high resistance earths at the battery post and "neg" of the cars various earth points , i.e engine block , chassis etc, make sure the battery terminals are clean and dry, and tight, other reasons for poor starting are numerous, low electrolyte in the battery, over filling when topping up the cells of the battery, poor earthing of the battery to the engine block and car frame, is your ignition timing correct? to much advance can cause the starter to strain against the firing of the cylinders, are the mixtures O.K., do you have "points" in the ignition? are they correctly set? how old is the the battery? does it stand idle for long periods? this causes the plates in the cells to sulphate and reduces the batteries ability to have any get up and go, could it be the starter motor is getting knackered, nothing lasts for ever, have fun, regards Nigel.

[Pierre Gillet]

What would be the time life of a Seven BARRIEN battery normally maintained?

 

Pierre

[Nigel Riches]

Michael, back again, just had another thought, check the battery volts when cranking the motor, at this point if the meter is indicating less than about 8 volts it's a bit marginal, and maybe in need of a closer looking at. cheers Nigel.

[EFA]

If the battery is not charged regularly its ability to hold a charge will be compromised. This seems to be the case particularly in the case of the Torque Start and Banner batteries in Sevens.

 

I have found that the life is very much prolonged if the battery is run on trickle charge for an hour a day throughout winter or periods of non use over 2 weeks.

 

If you run injection it is interesting that MBE's wasted spark system does not operate when the batt voltage drops below around 11v during cranking. The injectors however continue to trigger happily, flooding your engine beautifully!

 

 

 

Fat Arn

The NOW PROVEN R500 Eaterid=red>

See the Lotus Seven Club 4 Counties Area Website hereid=green>

 

[Pierre Gillet]

Thanks Arnie. I use my Seven at minimum once a week around the year, and have found that a 2-hour load each week compensate the consumption of the Rover "anti-thief" device (sorry, cannot remenber the right word!). So far, my BARRIEN is 4,5 year old with no problems.

Cheers,