Daox's Enginer PHEV 4kWh install

Comparing one quick trip with a previous one doesn't really tell you anything. There are too many factors that can change from one drive to the next (temp/headwinds/warm-up, etc.). You need to be comparing on a tank by tank basis.

 

Hi Doax,
What is the no load voltage coming from your converter? I am getting 245v.
You can turn everything off.
Unplug the two wires where the converter is connected to the pigtail that goes to the Prius HV battery.
Insulate the Prius wires.
Connect your volt meter to the coverter wires. Be sure it is set on a reng to read 240v.
Make sure you have no shorts.
Then Power up the Prius.
Turn on the Enginer Kit.
Look at your voltage on the Voltmeter.
Then turn everything off and reconnect the Kit to the Prius HV Battery.

When your car is on with your Enginer kit turned on and with the car setting still you should see a rise of about 1 bar in 6 minutes.

By the way I saw somewhere that 65% is about 7 bars.

Thanks,
Dan

 

From looking at the scangauge today, 65% is definitely 7 bars. It was all the way up to 67% at one point with the same bars. I've seen it up to 70%, but that was pretty much a one time deal with an extended higher speed highway run.

 

Daox,

I have a plan, please let me know your thoughts:

1. Since the DB8 is already monitoring each cell (to 3.75v) and it turn off the MOSFET driving the charger current; my plan is to connect a simple 12vdc relay coil thru the DB8 charger circuit to turn off the 115vac into the charger. The DB8 MOSFET can only drive DC, thus the relay. This will also insure top balancing ! One potential problem is the whole system can get into a metastable state, turn off and on too quickly. One solution is to use a delay relay, so that the relay state off for a set duration. But then it is not a "simple relay". And then there is that question about the initial high in rush current when the charger is switched on.

2. Bottom balancing is achieved by hacking the DB8 buzzer signal to turn off the DC/DC converter; since the buzzer goes off when any cell drops to 2.8 vdc. Since the Enginer control switch is really just a 5v switch. I understand that buzzer is AC powered though, but we really just need a trigger. Again, there is a potential for flip flopping so we would need some sort of delay.

what daya think ? am I full of it ?

By the way, I'm a newbie, been lurking and studying. Got myself the 4kw system for Xmas but haven't the time/chance to put it in. I also think there is a heat problem with the current integration design. Just feel the heat coming up through the bottom pan from the muffler, even with the external heat shield. I think a lot more batteries are going to get fried when summer comes around.

Cheers, Paul

 

I don't know much about batteries or BMS but I can tell you what I think I understand.

The main reason you need a BMS is because each cell is a different capacity. So in order to protect the battery pack you want to make sure you don't over charge or over discharge a cell.

Its like the the saying goes your chain is as strong as the weakest link. Same goes for these LiFeP04 batteries. If you have nine cells that are 50Ah and one cell that's 40 Ah then you really only have 40Ah to play with because once that one 40Ah cell is discharged the other nine cells have 10Ah remaining. If you try to use that extra 10Ah then you run the risk of making that one now dead cell even more dead to the point you will have to replace it.

I think you should be able to protect the cells in a few different ways.

1. Bottom balance your cells. Discharge all cells to the maximum discharge voltage. During charging when your weak cell reaches its maximum capacity just stop charging. For an example if you had nine cells of 50Ah and one at 40Ah when the 40Ah cell reaches 3.xx volts it should have excepted about 40Ah of energy. The 50Ah cells should also have 40Ah of energy. This is all you need to work with. Now when you discharge the battery all batteries should reach the 2.xx volts maximum discharge at the same time. When you reach your maximum discharge voltage just turn off the battery so you don't over discharge.

2. Top balance your pack. This is pretty much the reverse of the bottom charge. Charge every cell so they are all the same maximum voltage. Now when you discharge you will want to turn off the battery when your first cell reaches the maximum discharge voltage.

If this can be done the ony way you should see a failed cell is because of its age.

Again this is from what I understand so far from my reading.

 

Hi Paul,
The charger shut off needs to turn it off and keep it off. If the charger turns back on it goes to constant current mode and trys to pump 15a into full bateries. This would be a killer. So set up your relay to stay off and do a manual reset to turn it on the next time you want to charge. Also be sure to run your 12 volts though both balancers in series so the either balancer doing a triger will turn of the charger.

I do not understand your coment about the 2.8v lower limit? I would not hack the lower limit. You are in the car if that warning alarm sounds. You should be able to hear it and turn the switch. The normal operation is for the converter to turn itself of at 46v. 2.8*16=44.8v so you have 1.2v of margin. You should never have a lower limit alarm if you are anywhere close to balancing at the top and you are doing buddy cells.

Thanks,
Dan

 

Just a reminder that the power bars overlap somewhat:

65% can be either the 6th or 7th bar.

I've always wondered if it was lets say in the 5th bar when energy was
being put into the battery, but in the 7th when energy was taken out.

Or would it be the other way 'round? :noidea:

 

Dan

agree with your 1st paragraph. Once the one cell reach the upper 3.75v, the pack is pretty full anyway.

You can't rely on the auto shutdown as the pack can be above 46v but one cell can be below 2.8v. I was trying to use the alarm to turn the converter off, in case I can't hear. My wife and kid drives the Prius, it has to be handoff (as opposed to idiot proof when I drive).

-Paul

 

all this talk about chargers, balancers, and changing this and that makes an enginer system seem more and more remote or am I reading the unusual not the customary?

 

Hi Don,
Yes,
What we tell on Priuschat is "Warts and all"

Enginer has a good design concept but they still have bugs. We are working those out.

Today, you need to be an engineer or technical person or have one closely available to you in order to make the Enginer system work.

I expect it will be about 3 months before Enginer gets these bugs resolved. In the mean time we are testing and evaluating for Enginer.

The good part is that Jack at Enginer is very responcive. He has quickly replaced defective and damaged components.

Thanks,
Dan

 

One other thing that has been nagging me:

The way the balancers are connected, because each DB8 is balancing its own 8-cell pack. One pack can settle to a different voltage than the other pack. The cells are balanced within a pack, but not all balanced ensemble.

I am thinking of wiring the balancers in serial like this attachment:

View attachment 20942

does any body see a problem ?

thanks

 

Hi Paul,
The problem is that I can not see your attachment.

Yes, I can forsee problems between the top 1/2 and the botom1/2. I have not seen any of this in my system so far. I do look for it by noting the total voltage reported after cell #8 on each balancer.

I have thought of solutions but not tested any.

Thanks,
Dan Lander