Minor4326 LTO Conversion
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Msv or Esv parameter IIRC.
Current Draw leads to dead 12V battery daily
really need help and it's current draw.
I've had a dead 12V the past two days and I had to be towed home both times.
Backstory is : got my car running using the basic LTO setup with only and Fooler and the LTO BMS boards (6) (CAN bus to monitor all cells). So today with a charged battery, I monitored the CAN bus current since I connected them directly to the white lead and the black ground lead at the DC-DC. The current draw appears to be either 4 mA or 2 mA. It seems to cycle although I haven't held the meter on long enough to see it cycle. One time it's 2.0 mA and the next time it's 4.0 mA. So the LTO BMS's are directly connect to the 12-volt. So I disconnected the positive lead of the CAN bus, and measured directly at the battery post. There seems to be the same 2 or 4 mA draw even with the CAN bus disconnected. So I connect the CAN bus and there's still the same 2 or 4 mA draw at the battery. I pulled all the fuses under the hood including the big 80 amp fuse, and I still got the same draw. That baffles me. The car has no interior lights on, the keys were not in the ignition and no external lights on.
My question is what is the typical current draw, and how can you explain the measurements I'm getting at the battery post with and without the BMS connected. Also how do I go about troubleshooting the current draw to get it down to zero if possible. Do I start pulling fuses on the inside of the car? I'm afraid to drive the car to work with the CAN bus disconnected because that might not be the problem and the car insurance probably wouldn't like 3 tows in a week with the same issue. Sure appreciate your thoughts.
really need help and it's current draw.
I've had a dead 12V the past two days and I had to be towed home both times.
Backstory is : got my car running using the basic LTO setup with only and Fooler and the LTO BMS boards (6) (CAN bus to monitor all cells). So today with a charged battery, I monitored the CAN bus current since I connected them directly to the white lead and the black ground lead at the DC-DC. The current draw appears to be either 4 mA or 2 mA. It seems to cycle although I haven't held the meter on long enough to see it cycle. One time it's 2.0 mA and the next time it's 4.0 mA. So the LTO BMS's are directly connect to the 12-volt. So I disconnected the positive lead of the CAN bus, and measured directly at the battery post. There seems to be the same 2 or 4 mA draw even with the CAN bus disconnected. So I connect the CAN bus and there's still the same 2 or 4 mA draw at the battery. I pulled all the fuses under the hood including the big 80 amp fuse, and I still got the same draw. That baffles me. The car has no interior lights on, the keys were not in the ignition and no external lights on.
My question is what is the typical current draw, and how can you explain the measurements I'm getting at the battery post with and without the BMS connected. Also how do I go about troubleshooting the current draw to get it down to zero if possible. Do I start pulling fuses on the inside of the car? I'm afraid to drive the car to work with the CAN bus disconnected because that might not be the problem and the car insurance probably wouldn't like 3 tows in a week with the same issue. Sure appreciate your thoughts.
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1) Do what Bulldog said.
2) Cut the green/white wire at the dc-dc plug so the (new) 12v battery gets charged properly by the car in future.
3) Cut the green/black wire at the dc-dc plug so the MCM doesn't turn off the dc-dc when it feels like it.
4) Charge your old 12v battery up and take it with you and a 10mm spanner so you can change out if necessary.
5) Use two old IMA sticks in series and some crocodile clips to make an emergency jump starter battery. Charge it up off a power supply at home to around 16-17V or so at 300ma.
6) How are you measuring the parasitic load?
7) A good (charged) 12V battery say 35Ah can supply a 250ma load for 140hrs~
With a 4ma load it should last for weeks/months.
8) Get some jumper leads.
2) Cut the green/white wire at the dc-dc plug so the (new) 12v battery gets charged properly by the car in future.
3) Cut the green/black wire at the dc-dc plug so the MCM doesn't turn off the dc-dc when it feels like it.
4) Charge your old 12v battery up and take it with you and a 10mm spanner so you can change out if necessary.
5) Use two old IMA sticks in series and some crocodile clips to make an emergency jump starter battery. Charge it up off a power supply at home to around 16-17V or so at 300ma.
6) How are you measuring the parasitic load?
7) A good (charged) 12V battery say 35Ah can supply a 250ma load for 140hrs~
With a 4ma load it should last for weeks/months.
8) Get some jumper leads.
I measured the load as I described. As far as I know there is only one way to measure current draw, with an amp meter.
I had my battery charged and checked a month or so ago.
After work today the CAN bus will have been disconnected for two days and the car has been sitting in the garage that long. I'll try starting the car after work.
What's the difference in results of cutting the two different wires above, grn/WH and grn/blk?
I had my battery charged and checked a month or so ago.
After work today the CAN bus will have been disconnected for two days and the car has been sitting in the garage that long. I'll try starting the car after work.
What's the difference in results of cutting the two different wires above, grn/WH and grn/blk?
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Honestly, if you have an LTO pack you should cut both wires. It seems not many people want to cut the Green/Blk wire but that will allow you to sit in the car, turn the key to the ON position, and be able to run your radio and lights without the car battery draining.
As the car is setup now if you try and listen to the radio in the car with the key in the ON position, but the engine not started, the 12 volt battery does not charge. Which is such a stupid thing and I was surprised it was setup like this, I always expected it to always charge the 12 volt in the ON position.
I would assume the reasoning for Honda not allowing this is with the crappy NIMH packs these cars came with, there was no way to really be sure what the state of charge of the pack was, and I guess it was too risky to power the DC/DC converter without the engine running to keep the NiMH pack charged. However, with a high capacity LTO pack, there is no reason why you shouldn't have your DC/DC converter always on when the key is in the ON position.
I wonder what would happen if you left the key in the ON position with the lights and radio on. Would that drain your LTO pack down below 1.5 volts per cell?
I seriously can't be the only person who sometimes needs to sit in the car and wait, and wants to listen to the radio without the engine running?
As the car is setup now if you try and listen to the radio in the car with the key in the ON position, but the engine not started, the 12 volt battery does not charge. Which is such a stupid thing and I was surprised it was setup like this, I always expected it to always charge the 12 volt in the ON position.
I would assume the reasoning for Honda not allowing this is with the crappy NIMH packs these cars came with, there was no way to really be sure what the state of charge of the pack was, and I guess it was too risky to power the DC/DC converter without the engine running to keep the NiMH pack charged. However, with a high capacity LTO pack, there is no reason why you shouldn't have your DC/DC converter always on when the key is in the ON position.
I wonder what would happen if you left the key in the ON position with the lights and radio on. Would that drain your LTO pack down below 1.5 volts per cell?
I seriously can't be the only person who sometimes needs to sit in the car and wait, and wants to listen to the radio without the engine running?
CONFIRMED: 6 LTO BMS boards connected directly to a 12V unswitched source will drain a good battery in 24 hours.
In the last three days I've done a back-back test with the ONLY variable being the LTO BMS boards connected / disconnected. Say what you want but this is confirmed. I tried earlier to measure the current and what I measured didn't amount to what would normally drain a battery. I did remark that it appeared the drain was cyclic.
In the last three days I've done a back-back test with the ONLY variable being the LTO BMS boards connected / disconnected. Say what you want but this is confirmed. I tried earlier to measure the current and what I measured didn't amount to what would normally drain a battery. I did remark that it appeared the drain was cyclic.
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If I recall correctly, cutting the black and green wire at the back of the DC/DC will give you a CEL.
Minor's 12V battery problems should not be this bad. He almost certainly has a dead 12V and needs a new one.
Powering the LTO BMS
I had issues with LTO BMS 12V wiring, but I ended on what I think is a good solution:
Minor's 12V battery problems should not be this bad. He almost certainly has a dead 12V and needs a new one.
Powering the LTO BMS
I had issues with LTO BMS 12V wiring, but I ended on what I think is a good solution:
- Install a relay under the cupholder
- Relay gets activated by one of the +5V lines over there when the car is on
- Cut the white/red wire that goes to the OBDII port
- Put the relay in series with the ends of the cut wire (you may need to extend them)
- Now the power goes to OBDII port ONLY if the car is on
- Splice in a new line from there to the back to the IPU compartment to power the LTO BMS
- I also run a ground back there from the front, but you can probably ground them back there instead
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It doesn't..
Different issue:
Seeing as how I have not yet added-back my BMSI or the VPin and Fooler input inline resistor, what is the purpose of adding these two resistors? I understand both have to be added at the same time. Seems as if these are not needed? What benefit do these add? Thanks
Seeing as how I have not yet added-back my BMSI or the VPin and Fooler input inline resistor, what is the purpose of adding these two resistors? I understand both have to be added at the same time. Seems as if these are not needed? What benefit do these add? Thanks
The Vpin and fooler pre-resistors essentially lower the battery voltage threshold at which average regenerative charging takes place. The two inline resistors "fool" the BCM into thinking the battery voltage is lower than it actually is, so the average charging from regen and background is higher than it would be without the preresistors..
For example, before I installed the pre-resistors my battery would gradually discharge in around-town driving until it reached 144V(2V/cell), which is my operational minimum. After I install 10k pre-resistors, my battery now stabilizes in such driving at around 155-156V, well above my minimum.
Are they needed? It kinda depends on how you want to use your system. If you wanted to operate the car as a PHEV, then you would probably charge every night and would not want the car doing a lot of regeneration, therefore you would maybe not use pre-resistors. If you wanted a more maintenance free system, as I do, then yes they are necessary.
That's my take anyway
Later: I may have muddied the waters a little. I'm still running the original Interceptor S/W. Since my system is now working well, I haven't bothered to update the S/W. The answer to your questions may differ somewhat with the new S/W.
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System inaccuracies.
Over the weekend I set the tiny switches on the small current hack board in the MCM (already installed but set to zero) to the 20% mode and installed a 510 ohm resistor into the BCM to match the 20%. I'm amazed at the power this 20% provides. I'm going to keep that level and not increase to 40% which adds, IMHO, additional stress to the system. My system continues to run well.
Next weekend as my next step I'm going to install my 'hacked' harness which includes the VPin resistor and I'll install the Fooler in-line resistor. The 'hacked" harness has a B+ connection for my LTO BMS boards which turn power off with the ignition. That leaves the BCMI board which, if all goes well, will be inserted the following week.
Next weekend as my next step I'm going to install my 'hacked' harness which includes the VPin resistor and I'll install the Fooler in-line resistor. The 'hacked" harness has a B+ connection for my LTO BMS boards which turn power off with the ignition. That leaves the BCMI board which, if all goes well, will be inserted the following week.
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