12v battery maintenance

[tfc]

Just done another reading, car has not moved or switched on since last Thursday lunchtime ( been using the mgb with the top down.)

Two photo's with everything switched off

[tfc]

Two photo's switched on and the engine fired up. The voltage was higher when first fired up about 14.89 in that region but after about 15 secs it dropped down as the Battery didnt need all that voltage.

 

[tfc]

It will always draw mA when the vehicle is parked up it has to keep the electronics in the background working, even my mgb is drawing mA and that as only a electric clock and a live going to the radio to keep it from loosing it's memory.

3 mA is nothing, converting it to watts it's only 0.036 watts.

 

[Dala]

25 minutes ago, tfc said:

...3 mA is nothing, converting it to watts it's only 0.036 watts....

3 mA = 0,003A

the value on the device is 0,26A = 260mA

3,12W x 24 x 7 = 524,16W / week

0,26A x 24 x 7 = 43,68A / week

 

[tfc]

18 minutes ago, Dala said:

3 mA = 0,003A

the value on the device is 0,26A = 260mA

3,12W x 24 x 7 = 524,16W / week

0,26A x 24 x 7 = 43,68A / week

 

I was always crap at maths

It's still  below normal paracitic draw for a modern vehicle.

[Dala]

260 mA is below the limit for parasitic drain from the car Battery?
Interesting opinion.
What do you think the limit for parasitic drain ?

[tfc]

50 to 80 on modern cars

Haha I done it wrong again 

Hang on , Isn't 00.26 reading not 26 mA not 260mA 

[Roy124]

2 hours ago, tfc said:

The voltage was higher when first fired up about 14.89 in that region but after about 15 secs it dropped down as the battery didnt need all that voltage.

The initial 14.89 is clearly while the startup drain is replenished.  What did it drop to after that? 

When you switched off it will probably drop further and then drop gracefully over the next 24 hours or so. 

If it was initially under 12v I think the Battery might have a problem. 

[tfc]

My yellow multimeter maybe under reading. I've never have a issue with the 12v Battery with the vehicle parked up maybe 5 to 6 days a week and when its used it might do about 9 miles per week.

The Battery tester showing 100% soc soh and voltage 12.03v and cca is higher than what the Battery states

 

The initial 14.89 is clearly while the startup drain is replenished.  What did it drop to after that?  Roy it stabilized at 14.1 which is roundabout normal .

Edited May 29, 2023 by tfc
mistake... soh not soc

[Roy124]

1 hour ago, tfc said:

My yellow multimeter maybe under reading.

That was one of my questions earlier.  In my case I found a discrepancy between my meter and a BM6 attached to the Battery. The multi was over reading.  When I put the Battery on charge with the CTEK the BM6 readouts were spot on with the CTEK program. 

Although both BM6 and the Multimeter were both first class pieces of electronics from China 🤣 it was reassuring that the German bit agreed with the BM6. 

[Dala]

8 hours ago, tfc said:

50 to 80 on modern cars

Haha I done it wrong again 

Hang on , Isn't 00.26 reading not 26 mA not 260mA 

but yes
it is correct as I wrote

  

https://www.tme.eu/Document/fb7d6a8180ca867bed7cbc86a77cbf92/UT213ABC.pdf

if the parasitic drain 45 to 55 mA, the display would show 00.05

better is clamp meter with 0.001A indicator

for example :  https://www.amazon.com/UNI-T-UT210E-Capacitance-Multimeter-Resolution/dp/B075ZHDQFP

 

[tfc]

Dala, in your previous post you wrote

0,26A x 24 x 7 = 43,68A / week..

so if I have  a 43ah Battery it will go flat in a week or is there another formula for this ??

[Dala]

12 hours ago, tfc said:

so if I have  a 43ah battery it will go flat in a week ..... ??

Yes 😞

you wrote

On 5/29/2023 at 11:36 AM, tfc said:

Just done another reading, car has not moved or switched on since last Thursday lunchtime ( been using the mgb with the top down.)

Two photo's with everything switched off

we will rely on the measurements and car Battery is ok

Thursday to Monday = 4 days

parasitic drain 260 mA for 4 days = - 24,96 Ah

43Ah - 25Ah = 18Ah = 42 %  ( from value 43Ah )

smart charging does not charge the car Battery by driving to 100%
so a value of 11.76 V corresponds to a discharge about of 70%

this value of 11.76 V confirms a parasitic drain of 260 mA

[tfc]

2 minutes ago, Dala said:

Yes 😞

you wrote

we will rely on the measurements and car battery is ok

Thursday to Monday = 4 days

parasitic drain 260 mA for 4 days = - 24,96 Ah

43Ah - 25Ah = 18Ah = 42 %  ( from value 43Ah )

smart charging does not charge the car battery by driving to 100%
so a value of 11.76 V corresponds to a discharge about of 70%

this value of 11.76 V confirms a parasitic drain of 260 mA

Thanks Dala, now I'm starting to understand 👍

[camellia30]

I've logged the sleep current draw peridocally over the last few days.

There is a pattern, the current drops to 100mA within the first 5 minutes, then drops to 60mA at about the half-hour mark. Then within the first hour there is a spike of current for a few seconds to between 1 to 1.5Amps, then usually it goes back to 60mA. Except for last night, after the ~1A spike, it dropped to 450mA and stayed there all night.

Edited June 20, 2023 by camellia30
Adding a photo

[Gareth Lloyd]

I’m beginning to suspect that the problem is that the car doesn’t charge the 12V Battery properly. I have a bluetooth voltage monitor on mine after it kept going flat. The voltage barely changes even after a 4 hour drive and it hovers at about 50% charge. But putting an external charger on the Battery gets a very different response. It goes to 95% charge and slowly goes back to 50% over a week or so. The difference between the car charging and a external Battery charge is very noticeable.

The top plot is after a 4+ hour drive, the second is the charger.

 

[FROSTYBALLS]

Similar topics merged.

[camellia30]

19 hours ago, Gareth Lloyd said:

I’m beginning to suspect that the problem is that the car doesn’t charge the 12V battery properly. I have a Bluetooth voltage monitor on mine after it kept going flat. The voltage barely changes even after a 4 hour drive and it hovers at about 50% charge. But putting an external charger on the battery gets a very different response. It goes to 95% charge and slowly goes back to 50% over a week or so. The difference between the car charging and a external battery charge is very noticeable.

The top plot is after a 4+ hour drive, the second is the charger.

 

Looks as though it's doing exactly the right thing to me.

The car is maintaining the charge.

The charger is charging the Battery as fast as it can and then maintaining the charge.

I have current plots of the charging cycle too, I'll dig them out.

 

[barriechris@aol.com]

I have owned a 2020 C_HR for about two years. Previously I have owned one hybrid Yaris, several Prius’ and an Auris. Never had a flat 12v Battery and many were left at airports whilst on holiday. Last week the car would not start and following a call to Toyota Roadside Assistance, the AA arrived and tested the Battery. The result was a voltage of 3.8v. The previous seven days amounted to approximately 800 miles, so not due to lack of use. The AA jump started the car, my main dealer had the car and tested the Battery to find it required changing. This battery is three years old on a car that has covered 32,000 miles. The dealer changed the battery under warranty at no charge to myself. Having driven Toyota hybrids for many years because they are so reliable, indeed apart from tyres and servicing never spent any money on them, they have been absolutely faultless. So, what has changed with the 12v battery. I was pleased with the services of both the AA and main dealer, but doesn’t this suggest something has changed with respect to the fitted 12v batteries now used by Toyota?

[DC_Ms]

I have to fit a telematics device as per my insurance contract - will this potentially creat me problems with the Battery ? 

[Don Mac]

4 minutes ago, DC_Ms said:

I have to fit a telematics device as per my insurance contract - will this potentially creat me problems with the battery ? 

It should be wired to ignition power, so no.

I suggest observing whilst the technician fits it;

1- it's interesting to see how they conceal them

2- You'll know where it is so that you can easily disable/remove it if you change insurers or sell the car.

[DC_Ms]

49 minutes ago, Don Mac said:

It should be wired to ignition power, so no.

I suggest observing whilst the technician fits it;

1- it's interesting to see how they conceal them

2- You'll know where it is so that you can easily disable/remove it if you change insurers or sell the car.

It is self install wired directly onto the Battery.

 

 

[Don Mac]

1 hour ago, DC_Ms said:

It is self install wired directly onto the battery.

😮 That's a new one on me.

In this case it presumably will draw power all the time. How long it would take to drain your Battery is impossible to say without knowing how much current it takes.

Is there a power rating marked on the device, or (better) do you have access to a multimeter? (just looked at the manufacturer's website & I can't see anything helpful there)

[DC_Ms]

2 hours ago, Don Mac said:

😮 That's a new one on me.

In this case it presumably will draw power all the time. How long it would take to drain your battery is impossible to say without knowing how much current it takes.

Is there a power rating marked on the device, or (better) do you have access to a multimeter? (just looked at the manufacturer's website & I can't see anything helpful there)

This is how it looks installed on TS 2.0 Time will tell if it will draw too much from the Battery.

Is it a problem if I couldn’t push all the way back that plastic red cover ? The attached red wire is in the way 

 

@TonyHSD what is your take on the cover not going back to it’s place ?

[TonyHSD]

1 hour ago, DC_Ms said:

This is how it looks installed on TS 2.0 Time will tell if it will draw too much from the battery.

Is it a problem if I couldn’t push all the way back that plastic red cover ? The attached red wire is in the way 

 

@TonyHSD what is your take on the cover not going back to it’s place ?

You can try but you may damage the cable. Perhaps just leave it like that or undo the nut and reposition the connector differently to allow the cable bending and cover closing if possible. This device connected directly to the Battery I am not sure how will affect it. Have you measured with multimeter to see if any power drains happen while the car is off?