Jump to content
Do Not Sell My Personal Information


12v battery maintenance


 Share

Recommended Posts

Mooly, quite.

Regarding bluetooth monitors, the percentage might be related to its capacity at the time, but I think it also shows the voltage which is actually more important.  

Percentage might suggest the Battery will have sufficient voltage to get the car into Ready mode in a number of days that, as you say, can be a variable, but experience will tell.

Voltage OTOH is likely to warn you that it won't or that it might. 🙂

  • Like 1
Link to comment
Share on other sites

54 minutes ago, Roy124 said:

the percentage might be related to its capacity at the time,

The percentage is based only on the terminal voltage. The monitor has no knowledge of what the actual capacity really is.

It is like you having a car with an unknown size of fuel tank. Unless you know for sure the actual capacity when full then the gauge percentage reading might not be quite what you expect. If two similar cars are made with one having a 5 litre fuel tank and the other a 50 litre the fuel gauges will always read the same when full.

The Battery capacity reduce like this shown below. The percentage meter always reads the same when based on voltage.

1 hour ago, Roy124 said:

but I think it also shows the voltage which is actually more important.  

That's right, the voltage is the important factor when it comes to 'will it work' or not.

You have no way of knowing whether that Battery is (an analogy again) a 100 litre fuel tank that is full or a 1 litre tank that is full. Back to batteries and the last one would be drained with a few flashes of the headlights. Both however correctly show 13.7 volts (or whatever it is) and 100% based on how the monitors work. 

 

 Capacity.thumb.jpg.f42793a37a6b3a54de8a0e4cf0ac4008.jpg

  • Like 1
Link to comment
Share on other sites

19 hours ago, Roy124 said:

Molly, basically that's what I meant.  

OK, that's good.

10 hours ago, dannyboy413 said:

So, basically, if I am understanding you gentlemen correctly,  the percentage shown can be useful, but the voltage reading is more useful - or am I still on Sunday night setting?

They are two separate things. 

The voltage is an absolute in that if the voltage is good the car is going to start but it tells you nothing on the capacity of the Battery. The capacity is an unknown and determines how long it will run various items before running flat.

For example you could not differentiate a common AAA 1.5 volt Battery from a AA or a C or a D type by a simple voltage check. All read the same voltage when new and healthy but they all have vastly different capacities. That is the problem, you have no way of knowing from a simple voltage check what the actual capacity is of the Battery in the car.

 

 

  • Like 2
Link to comment
Share on other sites


21 minutes ago, Kental said:

One minor point, what is the power draw of the bluetooth on the battery monitor?

The following is pretty close to my thought of 'no idea' 

A typical BLE SoC (i.e. a all-in-one Application + Radio chip) typically consumes: A few hundreds nA while in deep sleep, 2 to 10 µA while a RTC tracks time (needed between radio events while advertising or connected), 10 to 30 mA while CPU or Radio runs (computing data, TX, RX)

 

  • Like 1
Link to comment
Share on other sites

A problem with the BT monitors is a potential lack of range.  Now if I could sit in my kitchen, check the condition, and then decide whether it was good to go or I needed to charge/jump it would be ideal. 

I am undecided at the moment and think probably relying on my jumper pack. 

Link to comment
Share on other sites

I use this to find out the capacity:

https://www.amazon.com/KONNWEI-100-2000-Automotive-Alternator-Analyzer/dp/B09FFBNG66

for long-term car parking, I recommend a 20W solar panel with a controller
in bad weather - clouds, rain - the next morning the voltage is not less than 12.4V
in good weather - sun - the next morning the voltage is 12.6V-12.7V
after seven days of standing, when I opened the car in the morning, I measured a voltage of 12.7V

  • Like 1
Link to comment
Share on other sites

Hi.

I own a 2019 Corolla Hybrid. I noticed my 12 volt Battery dropped from 12.6 to 12.1 in a couple of days. I've discovered that this only happens when I set the parking brake to come on automatically when the gear selector is in Park. I now apply the parking brake independently.

I use a CTEK XS 7000 to keep my Battery healthy if I'm not using the car much.

Hope this might be of some help.

  • Like 2
Link to comment
Share on other sites

David,

how do you connect your charger? I have a touring sport with Battery in the back. With my previous Passat GTE I used to charge the Battery in the boot via the positive terminal in the fuse box under the bonnet.

Link to comment
Share on other sites

19 hours ago, Roy124 said:

My dealer will be wiring the CTEK  cable so I can plug in as required. 

I am going to ask for the CTEK  auxiliary cable to be connected to the Yaris (12v Battery under rear seat) at the service and I can use the crok clips on the Corolla as the Battery is under the bonnet

  • Like 1
Link to comment
Share on other sites


Interestingly, I just found this in the user manual:

To prevent damaging the vehicle (M20A-FXS engine)
The exclusive jump starting terminal is to be used when charging the 12-volt Battery from another vehicle in an emergency. It cannot be used to jump start another vehicle.

Link to comment
Share on other sites

Hi Roy, I am just looking for the easiest place to attach my Ctek charger when we leave the car to go abroad on holiday. Sounds like I can attach it to the jump start terminal under the bonnet rather than remove the side panel in the luggage compartment and have cables coming out of a window.

The car is parked in a carport so a solar charger won't work I think.

Link to comment
Share on other sites

Stuart,  I don't know.   The jump start terminal is what you would use for a Battery pack.   For the CTEK charger I have gone for hard wiring to the Battery

In your case,  with the car in the carport,  using the CTEK and letting it run on a float charge would keep the Battery charged but connecting directly to the battery would need you to run the cable into the locked car.   The cable is thin,  you could probably just run it through the door. 

Someone did suggest fitting a solar panel on the garage/carport roof. You could then used the OBD port. 

Link to comment
Share on other sites

  • 2 weeks later...
On 8/24/2022 at 11:25 AM, Roy124 said:

Stuart,  I don't know.   The jump start terminal is what you would use for a battery pack.   For the CTEK charger I have gone for hard wiring to the battery. 

In your case,  with the car in the carport,  using the CTEK and letting it run on a float charge would keep the battery charged but connecting directly to the battery would need you to run the cable into the locked car.   The cable is thin,  you could probably just run it through the door. 

Someone did suggest fitting a solar panel on the garage/carport roof. You could then used the OBD port. 

CTEK or NOCO charger has a good controller although CTEK can be very hot after a while. They are better than most unknown brand solar panel charger.  You only need charging the Battery if you leave the car for weeks. If it is less than 2 weeks, don't bother.  I never need to connect any charger in the past 6 years until COVID19 came and I did not drive for couple of weeks and start to worry if it may need charger.  Just drive the car regularly, once a week for at least 30 minutes, you never need charger. 

  • Like 1
Link to comment
Share on other sites

  • 2 months later...
10 minutes ago, GrahamJGriffiths said:

But does the hybrid battery continue to charge the 12volt battery even though the engine is not ticking over? So long as it is Ready mode is it charging the 12volt battery?

I always thought it did, but according to others on here it doesn't always; If there's a volt meter plugged into the 12v socket it should show 13-14v+ when the battery's charging, but according to a few people it doesn't, not all the time anyway.

 

Link to comment
Share on other sites

The hybrid Battery will only charge the 12v Battery if it requires charging.  Once a certain voltage is reached charging of the 12v Battery will stop, this then reduces the drain on the hybrid battery.   Frequent trickle charging of the 12v battery is a good idea as it maintains the voltage in the battery thereby reducing the load on the hybrid battery allowing more of the stored energy to be use to propel the vehicle which helps to reduce fuel consumption.

  • Like 1
Link to comment
Share on other sites

  • 1 month later...

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share





×
×
  • Create New...




Forums


News


Membership