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[Poppe]

Yesterday I was driving my Think to work. This was the first time after the holidays I had the opportunity to do so.
I wasted myself with the heater before starting and also while driving, starting at a charge of 100%.
Arriving at work I had roughly 60% charge left which is a little less than usual but probably depending on the heating i used. The trip is 24 km.
On the way home I hade to go a detour to pick up some stuff for the wife but I figured I had enough energy to manage all the way home if I did not use the heating. After the stop I had some 35% energy left and some 13 km to go. Enough to make it home. I drove off and entered the highway when i noticed after maybe 2 km of driving that the car felt very slow and hesitating. I looked at the energy meter and it said 0% ! The Nicometer confirmed this reading.
Where did the energy go ?
I managed to get some 5 km closer to home before calling for assistance and the car was going slower and slower until it almost stopped and I had to pull in to a parking lot.
Can anyone give me a clue of what happened ?

Another thing that puzzles me is that the cooling fan is active when the Nicometer says the batteries are around 11-12 C° and the outside temperature is around 0 °. Is there a connection ?

This morning the car was fully charged again but I drove to work without heat (more clothes) and arrived with 65-70% charge (normal).

[cra]

Sounds like you might have a faulty 12V battery. This will cause the DC/DC converter to charge the 12V battery often, using the capacity from the main battery. The energy meter might not register this, and show more % than you actually have on the battery. Also, if left for long, the main battery will slowly discharge.

I had the same problem when I first got my Think Classic; the energy meter suddenly dropped from ~25% to 0% in an instant. However, using the car for a while got the meter to "learn" the status of the battery again, and it has worked fine ever since.

You should check (and possibly replace) the 12V battery. If the fans/cooling pump runs "all the time", that might be a strong indication that the 12V battery is at fault.

[Poppe]

Thanks for the quick answer.

The 12V is less than 9 months old, this is not a guarantee in it self....

How can a faulty battery make the fans run "all the time" ?

What, exactly, is the energymeter basing its reading on ? Voltage, current in/out or something else ?

[cra]

How can a faulty battery make the fans run "all the time" ?

A faulty 12V battery that doesn't hold the charge will trigger the DC/DC converter (the car will try to charge the 12V battery when it drops below a certain voltage). This will (and should) cause the cooling to run so the DC/DC converter doesn't overheat.

What, exactly, is the energymeter basing its reading on ? Voltage, current in/out or something else ?

I think I'll leave the answering of this to someone that knows. I just know that power may "disappear" from the main battery in ways that the meter doesn't detect, causing the displayed reading to differ from the actual charge state of the battery. But like I said, it will realign after a few charges and some driving.

Another thing to consider is of course how long it has been since the last maintenance charge and water filling? This is the number one concern on these cars. It should be done before the indicator in the dashboard tells you to. Typically every 3.500-4.000km, not every 5.000km / 1060Ahr overcharge like the car is set up to suggest.

[BauDemo]

I would try to get some readings with the nikometer.

There are couple of parameters that can help you out. See how many Ah are reported as charged, before charging, and how many are reported when the car is fully charged. This would give you something to go on.

Also what was the pack voltage before you got the drop? I would bet it the background was yellow, or maybe even red?

I think the fans are triggered not only with battery temp - I get them to run if I drive hard - I think it is based on the temperature of the motor.

[hkaspenberg]

Yesterday I was driving my Think to work. This was the first time after the holidays I had the opportunity to do so.
I wasted myself with the heater before starting and also while driving, starting at a charge of 100%.

You do not write if the car was charged before use, or if it has been stored for a while @ 100%. If the latter, the self-uncharge of the batteries themselves and maintenance charge of the 12V service battery will have drained the main battery significantly. The drop from 35% or so to 0% is due to the BMS detects less than 85V. The temperatures are quite normal. Just charge the car to 100%, drive down to about 40% for a few charging cycles and see if the problem goes away.

;-D Hans

[Poppe]

Hans:
The car was charged during the night before. 100% charge as I mentioned was actually 100%. I am fully aware that the Think can not sit for many minutes before the charge is starting to drop.
During Christmas/new year it was sitting for some 2 weeks and the charge dropped to about 40% by it self.

Nikolay:
I will try to get those readings tomorrow. I dont know the voltage before the drop. I wasnt expecting any wierd behavior fro the car so I did not monitor the meters untill the charge sank to 0%.

Today I drove home and nothing special happened. I managed to drive som 50+ km before the charge was down to around 10%. No heating on the way to work, but plenty on the way home.

cra wrote:

This will (and should) cause the cooling to run so the DC/DC converter doesn't overheat.

OK, understod and accepted.
The last maintenance charge was made roughly 350Ah ago according to the Nicometer.

[hens]

This is a typical monday issue.
The battery was probably fully charged at friday, and with a good temperature the self discharge in the battery steel about 30% of the charge during the weekend. This self discharge is a process inside the battery, and will not be registered by the capasity meter.

So when you start driving on monday, you have a capasity of 70%, despite the meter say 100%.

To avoid this,  do not leave a nicad battery fully charged for a while.
The self discharge increase with the temperature, and the charge level in battery.

Use a timer to step up the charge during the weekend, 30 % (2hours) at friday night, 30% saturday night and top up 30% at sunday night if the battery is close to empty, 20-30%, at friday afternoon.
At sunday night the battery have probably cooled down, and eliminated the self discharge.

[El rayo]

Where did the energy go ?

Agree with Hens, this is called a monday issue. The battery is lazy from not being used during the holydays. 3 - 5 charge cycles will bring the battery back to normal. One cycle each consecutive day is OK.

Another thing that puzzles me is that the cooling fan is active when the Nicometer says the batteries are around 11-12 C° and the outside temperature is around 0 °. Is there a connection ?

Actually there are 4 things that have temperature sensors that will start the cooling fan. Agree with Nikolay that it was probably the motor temp in your case. The DC/DC converter temp, the motor controller temp and the battery temp can also cause the cooling fans to start. All of these things are water cooled.

[Poppe]

El rayo wrote

Agree with Hens, this is called a monday issue. The battery is lazy from not being used during the holydays. 3 - 5 charge cycles will bring the battery back to normal. One cycle each consecutive day is OK.

What you are saying is that only on fridays I have a fully charged battery !?

I have never heard of "monday issue" before even with 70.000 km in electric cars, most of it in Renault Express. The Express batteries are disconnected by a relay circuit when the ignition is off and the self discharge of these batteries (same as in Think) are very limited. Having the car sitting for a couple of months is no problem. Off course the charge is not 100% after such a time but my experience is that a weekend as far to short to be noticed in SOC reduction.

Has anyone tried to have a circuit breaker installed so the batteries are disconnected when ignition is off ? What lessons can be learned from such an experiment ?

[elektrolux]

The problem with Think classic is that the 12V battery may initiate charging of itself at 4 hrs intervals.

This prosess draws about 1 hr for every time, meaning you loose up to 6 Ahr every 24 hrs. If you leave such a car for more than 15 days, it will have drained even a fully charged traction battery.

A circuit breaker for the battery needs only be connected to the 12V battery, but if anybody switches it during driving ore charging, it will break the DC-DC converter.

[Poppe]

A circuit breaker for the battery needs only be connected to the 12V battery, but if anybody switches it during driving ore charging, it will break the DC-DC converter.

That is why it needs to be on the traction battery side.  Or maybee one on each side.
Has anyone tried that ?

[El rayo]

El rayo wrote

Agree with Hens, this is called a monday issue. The battery is lazy from not being used during the holydays. 3 - 5 charge cycles will bring the battery back to normal. One cycle each consecutive day is OK.

What you are saying is that only on fridays I have a fully charged battery !?

Sorry I was not more clear on that point. The monday issue is most likely noticed when the Th!nk classic is parked with a full charge for one week or more. You mentiononed that the problem occoured after the holidays, so I assumed that the car had been sitting for one week or so.

Self discharge in a good NiCd battery is biggest for the first 24 hours after a full charge, about 10%. Battery temperature also plays a role in self discharge. Self discharge is probably more for the most worn cells in our now 10 year old battery. Therefore the calls can be so much out of balance after sitting for one week that the weakest cells will not be fully charged during the first 3 - 5 charges.

Has anyone tried to have a circuit breaker installed so the batteries are disconnected when ignition is off ? What lessons can be learned from such an experiment ?

Actually the drive battery is disconnected by the main relay in the HV-box. But as Elektrolux says the BMS "wakes up" now and then and checks the state of the 12V service battery and then starts the DC/DC converter and water pump to recharge the service battery if necessary.

In my opinion the Th!nk classic works OK as is. Introducing extra cirquit brakers or other things may have an unwanted effect that we can not foresee.

[El rayo]

The expression "Monday issue" is from the electric fork lift business. Weak batteries are first noticed on Mondays because the battery have been sitting since Saturday morning fully charged.

[Poppe]

Yesterday I managed to drive 57 km (without heat at all) and the SOC went down to around 10%.
After one nights charge the Nicometer says "The latest charge is:" 79Ah

El rayo wrote:

Sorry I was not more clear on that point. The monday issue is most likely noticed when the Th!nk classic is parked with a full charge for one week or more. You mentiononed that the problem occoured after the holidays, so I assumed that the car had been sitting for one week or so.

The Think did sit for some 2 weeks, and was down to 40% SOC according to the meter, but was charged the night before I had the misshap.