VGate Battery Assistant battery monitor

Something no one seems to understand is that the lithium battery is isolated from the lead acid battery and the 12V system. The isolator controls the the charging of the lithium battery as needed. It's not possible for the lithium battery to adversely affect the system.

The reason I am switching isolators to an adjustable one, is because in the summer, the 12V system voltage level does not reach the threshold needed to trigger the isolator (13.3V) to charge the lithium battery. The maximum voltage in warm conditions does not exceed 12.6V. This is controlled by a temperature sensor in the battery, and is designed to extend the battery's longevity.

This new adjustable isolator will allow me to reduce the cut-in threshold level to below the 12.6V level, so that the lithium battery can be charged while driving.

 

I hate repeating myself, because it makes others look stupid, but my lithium auxiliary battery is disconnected from the main system most of the time. Think of it as a big lithium power bank that you are charging in your car. You'd never worry about it being incompatible with your system.

Yesterday, I had a trip of a few hours, and the lithium battery had gone down to 10.2 volts, running the cooler. The reason it never received any charge from the system is because the isolator has a fixed kick-in threshold of 13.3 volts, which was never reached because the voltage regulator operates differently in summer than it does in winter. In the winter, I was seeing 14.1V quite often, but after a long drive, where the car interior had warmed up the battery, it went down to between 12.2 and 12.6V. The Prius 12V battery has a temperature sensor incorporated into it.

I plan to install my new isolator soon, which has adjustable kick-in and kick-out values.

 

Sorry, but I'm sure you don't know what you're talking about.

 

You are the one not getting it.

The adjustment will simply allow the isolator to open at the lower voltages, so that the auxiliary lithium battery can be charged when the system is at 12.6V or below Currently, when the ambient temperature is warm, the BMS limits the voltage to the 12.5 range, to protect the lead-acid battery. The voltage cut-in of the isolator was 13.3V, which never happened on a warm day on my 15 hour road trip, because the cut-in voltage was never reached. The auxiliary lithium battery had gone dead from running the cooler all day.

If the system voltage (14.2V in cooler temps) exceeds the rated level of the Lithium battery, which is 13.8V, it will cut off, never exceeding its rated voltage.

It no different from charging your phone or a data bank in your car, except by degree. There is a 20A self-resetting breaker in the circuit to the isolator to prevent excessive current drain on the car system. I may add a current limiter if I find that the breaker and the line resistance is not limiting current sufficiently, but so far, it's just fine. In the winter, when I started out with a dead lithium battery, it charged up fully with no high current issues at all. The 20A fuse didn't blow at all.

You couldn't possibly understand that and tell me I'm wrong.

 

What are you on about? For about a week, I was trying to find out what type of battery my car had. I had called the dealer and they told me it was an AGM battery. It turned out they were wrong, and I admitted my mistake.
I think it's very petty and childish of you to try to get back at me this way. What's the shame in being wrong about something? Just correct the mistake and move on.
Like an adult.

 

I just finished installing the new adjustable battery isolator. It identifies the standard battery as "Battery 1" and the secondary (auxiliary) as "Battery 2." I adjusted the cut-in voltage at 12.1V, and the cutout voltage at 12.8 V. I'm taking a long road trip tomorrow, and I'll be able to monitor both voltages, and see if any tweaking will be required. If I did it right, the auxiliary battery should charge with any voltage over 12.1V and will not over charge past 12.8V.

 

Thanks for the tip. I didn't know the car could be locked when it's running.

 

I didn't buy the 100Ah lithium battery for the cooler, but it came into use for that purpose after I realized I couldn't replace my 12V lead acid battery for it. I devised the system to extend the time I could leave the car parked without running the risk of a dead battery. The battery still goes dead occasionally in an unreasonably short time. This is meant as a way to start the car without boosting or a service call, when it goes dead unexpectedly while parked.

 

I was inspired to find a solution after I had parked the car for about 2 hours to take a hike. I returned to a dead battery, where the battery voltage was too low to start the car. I had ordered the large lithium battery thinking I could replace the original. This was not the case due to some extra leads coming out of the battery, which I assume are temperature sensors. I have since found several solutions to the battery drain, which I won't elaborate on here.

 

While the dealers never disclosed that they had found a cause, I believe the high parasitic drain happens when the car is doing system updates while parked in a dead spot, where it keeps trying to connect by increasing radio power.