Thread: Defender flattening battery when left sitting

Originally Posted by EchiDna

what's essential?
the clock? the radio presets? is there anything essential to keep powered up in a defender over time?

when my county is sitting around waiting for the next trip, the battery isolator key is removed and there is no current going anywhere - it can last months (it has!) without the key being turned over and without lost charge.

Same with a TDi

In a TD5 would the main ECU under the seat need to remain powered ? I don't know what you'd lose if you powered it off for any length of time. Maybe Tombie or someone could answer that.

Bad earth may be?

How you've measured the parasitic load: from "-" of the battery and load or "body" as a ground and load? If it is bad earth contact, it can heat up and cause more parasitic usage of a battery.

I’m sorry folks, but I’m flat out trying to keep up with incoming orders ( and not succeeding ) so I’ll keep this to the basics.

Hi Captain, how long do you drive for when you actually take your rig out.

If you are not driving long enough, when you get home, your battery is still going to be anything but fully charged and this will easily allow the battery to self discharge to a low voltage in quick time.



Hi Scallops, when you measure a battery’s voltage just after you have turned the motor off you are actually measuring what is know as the SURFACE voltage and this is usually much higher than the battery’s actual State of Charge.

A fully charged battery will have a maximum voltage of 12.7 to 12.8, so your 12.4 reading shows your battery is holding it’s charge well.

Cheers

I have a clamp meter that reads dc as well as ac current.
Checked the d2 td5,and it draws .4 of an amp when turned off,& still warm.It may draw less when it completely cools down & goes to "sleep",will check it in morning.
The battery is 950 cca,& 200 minutes,whatever that means.
Hope this helps

Capt,dont know where you live,but if you want to test the fender with the meter,PM me.

As said by drivesafe,happens to my sons clubby,he doesnt drive it often,only on small trips,& the battery never gets to be fully charged,so it eventually wont start.

I bought a "CTEK" battery charger yesterday to try and keep proper charge in the 130's battery as it doesn't get driven much.

It has some special 8-stage charging cycle and you can leave it connected to the battery indefinitely. It does desulphation and reconditioning and pulse charging at different stages, so am hoping it will keep the battery in good nick between drives.

There are small ones for under $100 but I got a mid sized one (can't remember the Amps) but they are around $250/$260. Got it from Battery World. If I got ripped off - please don't anyone tell me, because I just walked in and bought it without shopping around!

Originally Posted by Ruslan

Bad earth may be?

How you've measured the parasitic load: from "-" of the battery and load or "body" as a ground and load? If it is bad earth contact, it can heat up and cause more parasitic usage of a battery.

Without wanting to be a nark, I don't see how a bad earth could increase current draw from the battery. A bad earth could only offer a higher resistance, which would decrease current ( as simple Ohm's law would dictate ). (Unless you also had some sort of direct short between + and ground but then it's the short that's the problem and not the earth.) A bad earth can cause numerous problems but it won't flatten the battery any quicker. Or am I missing something ?

All - Thanks for your help!

Tim - The car usually gets 20-40 minutes drive when it does get out.

To the people suspicious of the earth - I did have that problem in the past when the dealer didn't do up the earth strap to the gearbox. That crippled the charging - all it would do was mid 12's. At the moment it's doing 14.4 volts on charge so I don't think that's the problem. I will check though.

My method when testing was to disconnect the negative to the cranking battery and put the ammeter between this. When I get the car back tonight or tomorrow I will re-run the tests with more time on my hands!

Thanks!

PS I agree I should just drive it more. I've been busy since we got back but we're ok now so I'll try and fix that problem.

Hi Captain, I would say a good long drive would probably solve your problem, say at least 4 hours total and you should then have a well charged battery.

Alternatively, as suggested above, hook up a battery charger if you know your not going to be driving the rig for a while.

You don’t need anything fancy or large, just make sure it is a multi stage charger so you can fit and forget. Jaycar have some 3.5 amp multi stage chargers for a reasonable price, they would do the job perfectly.