No takers so far

but a little humility goes a long way

 

If it drains it in two hours a high school kid with a meter could find out what device was sucking up amps.

Something is seriously wrong with the story we are hearing.

By the way why are we hearing this months long rant? Toyota Corporate has a team of customer support people to step in when a legitimate issue is presented to them.

On top of that, there are lemon laws that would refund the purchase if even half of this story actually happened.

One has to wonder how important "drinks" are to the situation.

 

The answer you are looking for is not on this forum...at this time. We all understand your frustration, but playing the soldier and/or victim "here" will solve nothing at this point.

So I'll take one more stab at this. Did your Dealership/s Service Department/s duplicate the standard use where you stated the battery depletes to the level of needing a jump?

 

He has messed up the cut-in and cut-out voltages of his battery isolator, and his cooler is constantly draining his primary battery now.

VGate Battery Assistant battery monitor | Page 2 | PriusChat

 

One of two things is true:
1) You installed a device in your car which is causing a parasitic draw
2) You need a new 12V battery

 

In fifteen years of Gen III Prius ownership, my battery has never worn down. I replaced [email protected] battery once only, after ten years, just as preventative maintenance.

So, yeah, your car has a bad battery or a parasitic drain and it’s probably because you messed something up, because that’s the cause of 99% of parasitic drains.

 

it was probably the drinks cooler in your gen 3. we went south for 3 months every winter, leaving our gen 3 in the garage, and it always started when we got back, until it didn't

 

you brought up your gen 3, i'm just replying. i'll give you some thoughts about why it was draining, if you want to ask in the pip forum.

 

maybe, but where's the fun in that?

 

That is exactly what it is:

• The cooler is continuously connected to the primary battery at all times because he lowered the cut-in voltage from 13.3 V to 12.1 V, resulting in a tens of amperes of parasitic drain.
• The current primary battery is highly sulfated and no good anymore because of the resulting repeated full drain.

Only he knows what he exactly did and what kind of problems he has been experiencing and at what times in the history of his car, but he had posted earlier that his battery problems had been solved and he was no longer having parasitic drains after the dealer had replaced the original battery and fixed the problem with the Toyota connected services or something like that. He then installed an auxiliary 12-V LFP battery and a cooler attached to it through a battery isolator, but the auxiliary battery would drain. However, he repeated that he was no longer having problems with his primary battery. He then said that he figured out the problem with the auxiliary battery and got an adjustable battery isolator, and he lowered the cut-in voltage to the point that now, the primary battery is connected to the cooler and drained by it at all times.

The following is the typical battery-insulator setup with typical cut-in/cut-out voltages. The auxiliary battery is isolated from the car and only connected to the load, which is the cooler in his case, unless the charging voltage reaches 13.3 V. It is isolated again when the charging voltage falls below 12.8 V. In this way, the primary battery is not drained by the load (cooler in his case) when the car is not charging the primary battery.



What he then did was to lower the cut-in voltage to 12.1 V, which resulted in the auxiliary battery and the load (cooler) being connected to the primary battery at all times. Now, a cooler is a huge parasitic drain.

It also makes no sense to lower the cut-in voltage below the cut-out voltage. Chances are that when you do that, the battery isolator always connects the primary battery to the load.

Another issue is the use of a 12-V LFP battery. A 12-V LFP battery’s voltage is about 1 V higher than that of a flooded-cell lead–acid battery for a given state of charge (SOC). Therefore, it is unlikely that an LFP battery would be compatible with the Gen 4/Gen 5 Prius HEV/PHEV 12-V battery-management system (BMS), which likes to keep the DC–DC converter voltage as low as possible. It would be even more challenging to use it as an auxiliary battery through a battery isolator because of the additional complexity of the cut-in/cut-out behavior. That explains why his original battery-isolator setup resulted in the drain of the LFP battery. Then, he went ahead and entirely messed up the cut-in voltage, and now the auxiliary battery and load (cooler) are continuously connected to the car and severely draining its battery.