Cranking battery State of Charge test feedback

[drivesafe]

Just as a point of interest, if you folks have the time, and a digital multi meter, can you measure the voltage of your cranking battery, at the battery terminals, to see what they are being charged to.

Please allow at least 12 hours from the last time the motor was on, as this allows the battery to settle to close to it’s actual SoC voltage level.

Note, this is a request for both those who have my dual battery systems fitted and those who do not.

If you are interested in participating in this data gathering, please post up how often you use your vehicle and how long you drive for when you do drive.

It would be interesting to get some independent feedback, to see what the real SoC of cranking batteries are.

Thanks in advance, Tim.


EDIT, this chart will help with SoC readings.

https://www.aulro.com/afvb/images/imported/2016/06/640.jpg

[winaje]

2009 D3, Varta 950A battery, 13 hours since last run, 45mins/16km daily,each way to work, some weekend running around.
12.07v (~50%SOC?)
Hope there's no issue with the battery... Interestingly, the Optima D34 that has never been used or connected to a charger is sitting at 12.61v. Will be installing Traxide kit with USI-160 very soon, so will check again on SOC of main battery after that's done, and the car has sat overnight.

[Geedublya]

2010 D4 V8 driven 13 hours ago for 40 min/25km, this is my normal daily commute. Traxide SC80 connecting the second battery.

Varta G14 - 12.13V

Otima D34 - 12.03V - has an engel 40l on it

[p38arover]

Tim, do you want the second battery disconnected? I ask because won't both batteries show the same voltage if connected?

With my dual battery system (I have yours, BTW), the batteries are significantly different in age. Also, my starting battery has flattened a few times from the car not being used.

When I get out of bed, I'll go and measure mine.

[loanrangie]

Ron, they should be electrically isolated when not on ignition so i would'nt think it would matter ?

[p38arover]

Tim,

My Rangie gets little use so the battery mainly gets charged by an external automatic charger. I just returned from 7 weeks away to find the starting battery dead flat and neither of my multi-stage chargers would even attempt to charge. While I was away I had an auto charger attached but there was a black-out a week after I left and the charger won't restart charging, it has to be manually selected. A dumb charger got enough into the battery for the multi-stage to accept the battery wasn't shorted.

Anyway, today's measurements, the car hadn't been driven for over 16 hours.

Initial voltages after unlocking car and opening doors to get out a multimeter

Dual batteries connected:
Starting battery 12.33 volts
Second battery (in rear loadspace but measured at the front of the car at the SC40 dual battery controller plug) 12.38 volts

Batteries disconnected:
Starting battery 12.39 volts
Second battery 12.45 volts

However, both terminal voltages drifted slowly higher. after a couple of minutes:
Starting battery 12.42 volts
Second battery 12.50 volts

I didn't wait around to see if they went higher. The second battery is just a normal N70 car battery.

[p38arover]

Ron, they should be electrically isolated when not on ignition so i would'nt think it would matter ?

Not with the Traxide SC40 dual battery controller. The batteries disconnect when the main battery voltage drops below a certain point. The description here http://www.traxide.com.au/isolators/sc80---90-amps-standard.html for the SC80 applies to the SC40.

[drivesafe]

Initial voltages after unlocking car and opening doors to get out a multimeter

Dual batteries connected:
Starting battery 12.33 volts
Second battery (in rear loadspace but measured at the front of the car at the SC40 dual battery controller plug) 12.38 volts

Batteries disconnected:
Starting battery 12.39 volts
Second battery 12.45 volts

However, both terminal voltages drifted slowly higher. after a couple of minutes:
Starting battery 12.42 volts
Second battery 12.50 volts

I didn't wait around to see if they went higher. The second battery is just a normal N70 car battery.

Hi Ron and it always looks a bit strange when you measure a battery that has been sitting for a while and when you put a small load on it, the battery voltage slowly rises slightly.

This is actually quite normal and as you opened your doors, the interior light would be a small enough load to start the chemical reaction in the battery, and this is why there is a slight rise in voltage.

[Spel1]

Tim:

Two batteries, one of your USI 160's
Constant driving for work, about 120km yesterday on Fwy.
New alternator. All recently cleaned and/or replace earth cabling.
Not much to draw, but I did have the doors open a few times last night. Might check again tomorrow to see if its different by leaving the bonnet unlatched etc.

12+ hours (overnight)

Cranking battery. Near new Optima Blue 12.33V
Second Battery. Year old deep cylcle AGM 12.33V

The digital voltmeter inside (connected to cranking batt) read 12.5 after I opened the doors and turned ign to the first postion. When I have compared the inside meter to a multimeter previously they were very close.

[TonyC]

Hi Tim,
95 Defender 130 300Tdi.

Has been sitting for approx. 2 weeks, but yesterday, started and stopped 8-10 times with run times between 1 and 10 minutes between idle and fast idle.

Cranking battery Supper Charge N70 something 12.55V 90+% :)
Second battery N70 case deep cycle 12.79V 100+% :):D

The isolator is an ignition triggered solenoid.

Well be doing some decent runs next week, I'll get some more numbers for you.

Tony

[Graeme]

2010 3.0 D4 30 mins after a 500km run today with quite a few stops, the final stint about 45 mins.

Cranking battery 9 month old Varta G14 (AGM) 12.30V then recovered to 12.40V once door/bonnet open timed out. Other modules are still drawing power.

Aux battery 80AH Remco AGM 6+ years old via Matson rebranded VSR, 12.63V, fridge connected but switched "off" soon after end of trip.

My observations have been that the D4 cranking battery's voltage progressively drops over time since last drive, presumably due to several modules continually drawing power. Maybe another time I'll measure the voltages sooner after a trip as I suspect the starting battery had already been depleted, but possibly the Varta AGM doesn't charge as high as the Remco AGM.

Edit: 15 hours after stopping the main is 12.12V and the aux is 12.48V, with some opening of the tailgate and a door having occurred, interior lights permanently set off and vehicle not locked.

[keithand]

Hi Tim

I have a new D4 MY2014 TDV6 (4 weeks old) 50 Km per day commute, no long trip yet. Has not been on a battery charger. Battery is Exide AGM 90Ah

Opened car/battery box and reading was 12.35V. After 10 minutes reading was 12.53V

About to buy a traxide dual battery system, so I can start the setup for touring. I will then monitor changes after system installed.

Cheers

Keith

[scarry]

Checked mine this morning,i have the SC80 kit.
Yesterday did 500k's,before that the battery was on float as had been on the smart charger overnight.

This mornings voltage was 12.57v,read on my Fluke digital meter.

This is the highest i can remember i ever seeing.

Short drive to shops today,6k,will see what it is at in the morning.

[Rick1970]

'86 Rangie. Usually driven to work each day, 45+45km. Dual batteries with simple HD solenoid. 2 x Supercharge NS70's. Driven to work Friday, sat all Saturday, moved it Sunday, sat all Monday. Main 12.68 aux 12.64.


93 Disco. Drove it to work today. Can sit for a week without use sometimes, Narva VSR Supercharge NS70 and Delco 82AH start/deep cycle. Engel in and running ATM. Been sitting for approx. 4hrs. Main 12.65 aux 12.4

[d2dave]

Tim. Do you just want results from Landrover vehicles or are you interested in other vehicles that I have?

[drivesafe]

Hi Dave and the more types of vehicles the better.

Makes it interesting comparing different charging systems.

[d2dave]

D2 Td5 12.6v 42 hours *
D1 Tdi Starting 12.1 23 hours *
Aux 12.57
Ford LTD V8 12.3 24 hours *
P38 12.51 7 Days
Husqvarna mower 12.72 15 hours **
John Deere mower 12.73 24 hours
Ski Boat 12.68 7 to 8 months.

* These batteries are all under six months old

** This battery would be about four years old and came out of my D1
when it would no longer start it in winter. Works fine in the mower.

My aux battery in the D1 is a second hand N70z which was one of two
taken from a Kenworth truck(starting battery) which had a bank of four. They mistakenly changed the wrong two. I got this about 5 years ago.

[pawl]

D1 300Tdi, both batteries AC Delco HCM24SMF and car has now been idle for 20hrs.
Driven 15kms each way to work each day, although 3 days ago car had a 3 1/2 hr drive that would've given batts. a good charge.
Cranking Batt. 12.78V
Aux Batt. 12.94V

[Mick Young]

Hello Tim,
Sorry to intrude but I'm very interested in your Traxide Kit. What is it. I'm putting a dual system on my D2 very soon, cheers.

[scarry]

Checked mine this morning,i have the SC80 kit.
Yesterday did 500k's,before that the battery was on float as had been on the smart charger overnight.

This mornings voltage was 12.57v,read on my Fluke digital meter.

This is the highest i can remember i ever seeing.

Short drive to shops today,6k,will see what it is at in the morning.

The next day it was on 12.56.Then after 30 minutes was on 12.67v.
What happens is when i unlock it,it wakes up and drags the voltage down,then it comes up slightly as it goes back to sleep.Mine is usually locked up as under a carport.

[Petetheprinta]

D1 300tdi, 24 hrs after 200k run. Traxide-160. Optima red starter, 12.22v optima yellow au, 12.22v both batteries are new (2months old)

[d2dave]

D1 300tdi, 24 hrs after 200k run. Traxide-160. Optima red starter, 12.22v optima yellow au, 12.22v both batteries are new (2months old)

Something not right here. A fully charged battery should have 12.7 volts

I had two out of the eight I posted with 12.1 and 12.3, both less than 6 months old.

And now you have two that are low.

[Petetheprinta]

Something not right here. A fully charged battery should have 12.7 volts

I had two out of the eight I posted with 12.1 and 12.3, both less than 6 months old.

And now you have two that are low.

I wondered about that, just after a run they are about 12.5v, but go down very rapidly. If I don't use for a few days they go down even lower. My starter battery goes lower than aux, which I sort of assume can't be right. I talked to Tim and he said to flick the traxide switch but that made no difference. My aftermarket voltmeter shows charging at about 14.2 volts so I assume alternators working alright. Any suggestions what I should look at??

[Eevo]

i have 3 batteries here that are not in a car. (not sure if this is useful to you)
all 3 of them charged about 5 days ago

2 d34's: both at 12.36 volts
1 x-pack: 12.65 volts

[Petetheprinta]

I have just tried to do a amp draw test. I disconnected aux battery and removed neg cable from starter battery. I attached multimeter and it showed .54 for 2 secs then steady on .04 (amps I assume) I removed fuses and redid tests. The only fuse to make a difference was no 6 fuse in satellite 2, which seems to be AUX with a diagram of trailer there. I had a constant read of .06 when it was removed. Should this mean anything to me or should I keep looking??. Interestingly since disconnecting battery the volts have INCREASED slightly. Is that significant??

[drivesafe]

Interestingly since disconnecting battery the volts have INCREASED slightly. Is that significant??

That can be a bit of a concern.

For the voltage to rise after you disconnected the batteries usually means you had a more than minimal load on the batteries while they were connected.

Tell us a bit more about how much the voltage rose and some more details about your setup!

[Petetheprinta]

As best as I can, I have a red top starter and a yellow top aux. Both new. They are connected via a USI-160 as per your supplied instructions. The starter does all the normal things and the Aux runs power to the back, spotlights, etc. Vehicle? Has no electronics. So only thing drawing power is radio, red alarm led and your traxide thingy with its yellow led. Both batteries charge well at about 14.2v. When I switch off volts drop continuously on both batteries. Down to 12.2 within 24 hours. I removed aux battery by disconnecting earth wire and fuse to it (removing it from system) and starter battery increased volts to 12.35v I then used Ctek charger on main and got 12.7 volts. 24 hrs later 12.65 v. I then did the same with aux battery and it holds voltage It appears that traxide or aux battery is running the system down. I am not knowledgable in electrics but that is what's happening. Batteries by themselves ok. Introduce traxide, they run down??

[drivesafe]

Hi Again Peter and I’ll take a guess here and say you have a 75Ah cranking battery and a 55Ah auxiliary battery.

If this is the case then you have other factors to be taken into consideration.

For those batteries to loose 40% of their capacity in 24 hours, they would need to have a constant load of at least 4 amps.

This is because “if” the batteries were in a good state of charge, meaning at their maximum capacity, not just fully charged, you would need to use more than 50 amperes of capacity to get them down to 12.2v ( 60% SoC ).

My USI-160 isolator draws less than 0.15A or less than 150 milliamps and at that current draw, it should take around 14 days to discharge your batteries down to 12.2v and this is normally the case, not 24 hours.

Lets see if we can sort this out for you.

What sort of driving are you doing?

Also, have you measured the voltage after 48 hours. I suspect you will still have 12.2v in the batteries.

This then would be their settled voltage and would indicate they need the charge cycling I posted about earlier.

[d2dave]

My USI-160 isolator draws less than 0.15A or less than 150 milliamps and at that current draw, it should take around 14 days to discharge your batteries down to 12.2v

Tim. I have just crunched some number in the calculator and at 150 milliamps I equated this to about 4 amps per day.

Have I got this correct?

[drivesafe]

Tim. I have just crunched some number in the calculator and at 150 milliamps I equated this to about 4 amps per day.

Have I got this correct?

Close enough, 3.75 amps and this would be on the high side because the USI-160, in SHEARED mode draws about 0.13 amps but I like to be on the caution side when calculating energy consumption.

[d2dave]

Isn't that a fairly large parastatic drain?

[drivesafe]

Hi Dave and for a vehicle in daily use, no, it make no difference.

But with more and more people leaving their vehicles unused for weeks at a time, yes it can be.

There is a simple fix. If you have an SC80 and if you do not use your vehicle for long periods of time, there is a thin earth wire coming from the SC80, this wire is either Green with a Yellow trace, or Brown.

You can cut this wire and fit a small switch in the wire.

The switch can be turned off when you know you are not going to be using your vehicle for a while and then turn it back on when you are going to be doing some driving.

NOTE, this is only for the SC80.

The USI-160 ( post 2012 ) and the DT90 have the TIME-OUT feature incorporated into their programs and they shut down automatically if the vehicle’s motor is off for more than 3 days.

[d2dave]

I have the SC80 yet to install it. Why can't this have the "go to sleep" function like the others?

[drivesafe]

Hi again Dave and the next generation of the SC80 will have the TIME-OUT feature but because of the huge number of orders I have been receiving for the last 7 months, all R&D is now shelved.

The next generation of SC80 isolators was to go into production some time next year but this too is now shelved.

[Petetheprinta]

Hi Again Peter and I’ll take a guess here and say you have a 75Ah cranking battery and a 55Ah auxiliary battery.

If this is the case then you have other factors to be taken into consideration.

For those batteries to loose 40% of their capacity in 24 hours, they would need to have a constant load of at least 4 amps.

This is because “if” the batteries were in a good state of charge, meaning at their maximum capacity, not just fully charged, you would need to use more than 50 amperes of capacity to get them down to 12.2v ( 60% SoC ).

My USI-160 isolator draws less than 0.15A or less than 150 milliamps and at that current draw, it should take around 14 days to discharge your batteries down to 12.2v and this is normally the case, not 24 hours.

Lets see if we can sort this out for you.

What sort of driving are you doing?

Also, have you measured the voltage after 48 hours. I suspect you will still have 12.2v in the batteries.

This then would be their settled voltage and would indicate they need the charge cycling I posted about earlier.


Hi Tim, referring back to my post no.27 I can tell you the following. The red top (cranking battery) is only a 50amp hour, the yellow 55amp hour, so red is on the low side but it was recommended to fit ok. I have left the aux disconnected and the main connected. On Sunday I charged both to approx 12.8v with Ctek as stated. 3 days later red top (connected) is reading12.56v yellow top (earth lead disconnected) still 12.72v.

Now (deep breath) previously after a long run and with everything connected both batteries down to 12.2v within 24 hours.

My driving is usually a couple of long runs per week. I do not do stop start driving in vehicle.

The draw from red top is according to my measurements approx .04amp the yellow 0. As there is nothing connected that draws power when not in use.

I will connect all back up go for a long drive, check voltage after 24 and 48 hours and see what happens again.

Hopefully this makes sense to you

Thank you. Pete

[drivesafe]

Hi Pete and first off, with no load, you do not get a real idea of the actual SoC of the batteries, but that is a simple fix, just turn your headlights switch to PARK and leave them on for about ten minutes and you will get a fairly accurate of the SoC.

Next, I am not quite sure what you mean by you charged the batteries to 12.8v?

When charging batteries with a battery charger, the charge terminating voltage should be no less that 14.4v.

If your charger is not getting the batteries up to that voltage level, there is something very wrong somewhere!

Even if you leave the charger on and in fully charges the batteries and then goes into FLOAT mode, the minimum FLOAT voltage should be at least 13.5v.

[JamesH]

I went away camping last weekend and gove my batteries a hammering. What is not known is the state of charge before I left but I know the crank dropped below 12 at the camp site as the SC80 kicked in. After the drive back the batteries were at 12.34 after sitting twelve hours. I decided to plug in the ctek 5amp charge and give them a topup.

I only managed to give them 4 hours on the charger as I had a couple of errands to run (short trips). The charger did cycle all the way to stage 7. I used AGM mode.

Measured this morning and I am 12.3. Not real good. I think I need to do the 8 hours on 8 hours off and 8 hours on trick that Tim came up with (need to find that thread though).

[Petetheprinta]

Hi Pete and first off, with no load, you do not get a real idea of the actual SoC of the batteries, but that is a simple fix, just turn your headlights switch to PARK and leave them on for about ten minutes and you will get a fairly accurate of the SoC.

Next, I am not quite sure what you mean by you charged the batteries to 12.8v?

When charging batteries with a battery charger, the charge terminating voltage should be no less that 14.4v.

If your charger is not getting the batteries up to that voltage level, there is something very wrong somewhere!

Even if you leave the charger on and in fully charges the batteries and then goes into FLOAT mode, the minimum FLOAT voltage should be at least 13.5v.

Hi Tim, my fault, my lack of terminology is showing. When attached to batteries voltage reads 14.8v on Aux and 14.75v on starter. 13.8v was my reading some time after removal of Ctek charger.

[Lionel]

After a 15 Km trip, with the car left for 12 hours, the voltage read 12.61

It's a Defender Xtreme 2004 (TD5), & the battery is the one which was in the car when it was purchased as a demonstrator with 1200Ks on it.

It is a Supercharge MF31-931. 10 years & still counting! ;)

Cheers,

Lionel

[PhilipA]

I am not sure how helpful this is as I keep a 4 amp charge and maintain charger on my batteries last boosted up until 11AM yesterday.

Car is D2 TD5 batteries 750CCA Optima blue with 130AH AGM house battery connected through Traxide with cutoff at 12.4 v.
Driven approx 15Km yeaterday at 3PM checked this morning at 9PM so 18 hours and voltage 12.8.

Regards Philip A

[Eevo]

D34 in 200sx with a parasitic drain, left 14 days, 12.01 volts.
and started fine.

[Gerokent]

Hi Ron and it always looks a bit strange when you measure a battery that has been sitting for a while and when you put a small load on it, the battery voltage slowly rises slightly.

This is actually quite normal and as you opened your doors, the interior light would be a small enough load to start the chemical reaction in the battery, and this is why there is a slight rise in voltage.



A long time ago I was told if trying to start with a flat battery, sounding the horn may up the voltage enough to start the engine. Is this along the same lines as your above post?

[PAT303]

I've done three batteries in three years,all failed internally and would drop to 9V overnight,CAT batteries are the only choice if you regularly drive on corrigations. Pat

[Keithy P38]

Tim, here's something for you that may surprise!

My P38 sat for 24 days without being started. It has an SC80 (with a switch on the earth wire which was left on for this 24 day period).

Both batteries are Supercharge All-Rounders at 105ah and 760cca.

24 days without starting or even opening a door:
Main - 12.23v
Aux - 12.27v

The SC80 was still in active mode. The engine cranked first spin.

Cheers
Keithy