Thread: Discovery 4 "smart" charging system.

Hi GIL and those voltages are pretty good.

A suggestion, to get an even more accurate idea of your battery’s true state of charge.

Next time you do a long term non use voltage measurement, first take the voltage reading just before you need to use your vehicle.

Then turn your ignition on, BUT DO NOT START THE MOTOR.

Turn your headlights on and leave it that way for at least 5 minutes.

If the battery is in good condition, the voltage should drop no more than about 0.3v and SHOULD STABILISE.

IF the voltage continues to drop, time to get the battery checked.

Hi Tim,
Thank you for your input.
I will do this next time I need to use the car and post the results.
I have learnt much from your posts over quite some time.

Regards
GIL

Re a load test..eg. my new tractor batt seemed no good...engine slow to turn over...going flat etc..

So after charging...checked voltage. 13.6v.. then cranked engine with no start (disconnect fuel cut solonoid)..for a minute...till 'flat' ...voltage 13.0v.

Soooo...not the battery.

Turned out to be a short inside the starter motor..brush insulation worn thru..easy fix fortunately😚

Glad I did not cart it into town and complain to the seller🙄

Hi Folks,

Inter674
You just reinforced the idea to not get fixated on one possible cause for a symptom.
Good it was a cheap and simple fix.

update.
I had to use the car today. It has been only 3 days since last use after a short trip.
So, I tested the battery SOC using Drivesafe's method above.

Results are:
Battery volts prior to test: 12.58v
Then, Ign on but no start.
Turn on headlights. Volts=11.98. NOTE: dont close the door or lights will turn off.
Wait 5 minutes. Volts=11.95
Turn off headlights and ign. volts=12.07
After 3 minutes volts=12.39
After further 3 minutes volts=12.44.

I believe the battery is 3 odd years old.

Also Drivesafe has posted this thread in 2017
On-Line auto electrical info

It contains lots of info.
Thanks for sharing your expertise.
Regards
GIL

Hi GIL and excellent info.

The results are not looking good for your battery, BUT.

Your battery may note be on it's way out, it may have lost a fair bit of it's capacity but it may just need some reconditioning.

The easiest way to try to recover lost capacity is to try the suggestions in this link.

On-Line auto electrical info

GIL, as you have already documented your voltage readings so far, if you have the time and patience, it would be interesting to see if the reconditioning cycles work for your cranking battery.

Thanks again for the great info.

Hi Tim,

Thank you for the response.
I had an inkling after the voltage drop seemed outside your info above.

I will try the reconditioning process documented in your
On-Line auto electrical info thread and advise results.
I have a smart 7 stage battery charger.
Regards
GIL

GIL, just a word of caution.

If your battery charger has a RECONDITIONING MODE, do not use it on any AGM battery.

The RECONDITIONING MODE of any battery charger is specifically meant for WET CELL batteries and can damage AGMs.

Originally Posted by drivesafe

If your battery charger has a RECONDITIONING MODE, do not use it on any AGM battery.

Hi Tim,

My charger DOES have a recondition feature. It has settings for four battery types GEL,AGM,WET,Calcium. This is the only selection mode it has, although the later updated model also has a charge current setting.
The manual suggests the recondition stage provides constant current of 0.3 to 2.25 A for 4 hours and the difference between the different battery types is the voltage at which it supplies these amps - AGM being 14.4v.
So now I am a bit confused. I thought my charger was a reasonable one.
Am I doing the wrong thing by my battery by using it?
I have used it for the last couple of days overnight as suggested above in the thread.
Regards
GIL