HCH II BCM Cable Balance
 

Greetings guys,

My father has a 2006 Civic Hybird with over 250k miles on the car. The battery has been replaced several times by the dealer, but it is now beyond warranty and beyond overdue for some TLC.

I started digging through the battery area and noticed that the BCM cable looked rather similar to some other connector that I had seen before.

https://dl.dropboxusercontent.com/s/...or%20Check.png

After some hours on Google Image search I was able to successfully match it to a Subaru headunit wire harness.


Lucky enough for me my local Bestbuy had the cable harness and priced matched Amazon. Took the cable home and it is a match.

So I started measuring voltages of the cells and preparing a rig to individually balance the cells. However, once I put a load (10 mA) on the cells I found that the voltage dropped down to nearly 2V. I do not believe that the cells are that bad and have a feeling that it has to do with the orange bugger inline with the cell. Does anyone know what that component is actually called? I was thinking about discharging and charging the cells at 1A if I could get this setup to work.

Re: HCH II BCM Cable Balance
 

Nice find on the connector.

Yes, those prohibit you from doing what you want. They are there as a safety in the event of a harness short. They massively increase resistance as current increases. I don't know what they're called.

You need to understand there is a 99.9% change that every penny and second you expend on this effort are going to be in vain. As you've experienced with "several" replacement batteries, these things are garbage. I currently have 11 in my house, and I can't build a single good one from that pool.

The harness wires are very thin gauge. Even if those weren't there to prohibit current, I wouldn't run any significant current through them.

Better to buy 2X APC-15-350 with AC input wired in parallel and DC output wired in series (56-200VDC). Remove and charge the pack as a whole for 24 hours with a box fan blowing through it. If voltage holds constant for 8 hours, or if the air trickling through the pack is warm to the touch, terminate charge before 24 hours. Charging should be indoors in controlled temps.

Let the pack sit. Measure and record the tap voltages to two decimal places at:
1 hr after charge termination
24 hrs after charge termination
48 hrs after charge termination
72 hrs after charge termination

See what's happening.

Re: HCH II BCM Cable Balance
 

Just the person I was hoping to have reply to my thread. I was going to PM you directly, but this worked.

I was surprised to that in all these years no one had found that connector. Anywayss, I guess I am going to have to do some searching to find out what those are orange things are.

As for the "grid charger"... I am using a LPC-100-500. This thing actually works great as a power supply, but just topping the thing off does not do it enough. I did try to use the light bulbs and discharge the pack then charge and repeat, but that is a rather tedious solution. I have built a secondary pack in parallel with the original pack... And I have to say that it works wonders. IMA light is gone and does not come back on. Also car starts from battery in the back and not from the starter.

http://www.mouser.com/ProductDetail/MEAN-WELL/LPC-100-500?qs=5CXH7KqCnSgVR7BOf5khXg%3D%3D

Re: HCH II BCM Cable Balance
 

No one found it because there hasn't been a need for it.

The orange things aren't relevant. They must be bypassed. But here you go anyway:

http://99mpg.com/blog/batteries/theptcthermistors/

There's no meaningful way to use the harness to charge/discharge the subpacks, nor is there a way to use the harness to charge multiple sticks unless you're skipping a pin - and even then, the thermistors will thwart you. Keep in mind that the pins are effectively voltage taps, not isolated circuits. On subpack 1, the (-) terminal is also the (+) terminal of subpack 2.

I'm very familiar with that power supply. For 5.5Ah cells, it's marginal in that you will almost certainly overcharge an old battery due to its deteriorated capacity. It will need more effective cooling.

If you've already conducted charges and discharges at the pack level, you've already proven that any further efforts on that pack will not bear fruit.

I don't know why you find that tedious. Have you considered the time it will take to charge or discharge each of the 11 subpacks at 1A? Have you also considered how meaningless a 1A discharge capacity value is?

Impressive that you've managed to put packs in parallel; however, you are likely unaware that NiMH should NEVER be put in parallel. You are at risk of thermal runaway particularly if either pack is isolated from the MCM and not being monitored at the tap level.

You commonly have 1 or more cells in a subpack fail due to excessive SD. What happens is that the other cells in the subpack attain higher SoC due to current shunting from the other parallel subpack/pack. At some point, you run the risk of having multiple cells at or near 100% SoC. When they hit that the -dV phenomenon occurs, and you have all parallel cells dumping their current into the cells that are lower voltage EVEN WHEN NO CHARGE IS OCCURRING.

If the two batteries are in excellent condition, the risk is very low. If either of the two packs has thrown an IMA light at any time in its life, the risk is high.

There's a reason NiMH battery packs are always in series - even the big ones like the Rav4 EV and EV1 with the Ovonics pack.

Good luck,

Steve

Re: HCH II BCM Cable Balance
 

Thank you for the link. Positive Temperature Coefficient thermistors do make sense and what I was afraid of. Even though they are only voltage taps you could still charge/discharge the individual subpacks as long as all of your charger had an isolated ground.

Why I find it tedious? Well discharging a bad pack as a whole doesn't allow me to isolate the bad cells and try to correct them without putting extra cycles on good cells. Also, there really isn't a good cheap way of discharging the pack without having to monitor the light bulbs and change them out for lower values as the pack dies. Had the BMS wires been more like balance leads Honda could have extended the life of these batteries much longer and you could attach multiple chargers to the packs and only cycle the down cells without ever removing the pack from the vehicle. What the RAV-4 EV's had.

The booster pack is not NiMH and is monitored by it's own circuit. Unfortunately the booster pack does need to be charged outside of the vehicle, but does allow for the IMA system to work well enough to not throw the CIL to pass smog and run the AC. It would be cool to make a LiPO that was a drop in replacement for the IMA battery, however, I am not sure if I want to take on that project just yet.

Re: HCH II BCM Cable Balance
 

11 isolated grounds sounds like a bit of a pain.

Extra cycles on good cells is a non-concern. I've put 30 cycles on subpacks. Capacity and IR were unchanged. SD improved slightly. Overall, sticks were garbage. 5000mAh of capacity, but they'd lose 4000mAh in a week.

Cycling cells at 1A is pretty worthless. These things see 100A discharge and 50A charge - 1A isn't going to tell you much, and it can be misleading.

Here's how you can isolate the bad subpacks:
Grid charge pack for 16 hours WITH EFFECTIVE COOLING (500mA PSU).
Disassemble pack
Let it sit 7 days.
Measure the 12 cells in each of the 11 subpacks.
Subpacks should be > 7.90V and within 0.1V
Cells within a subpack should be within .03V (these will be marginal. Truly healthy ones will be within 0.01V).

Anything outside of that is bad.

You're likely going to find that you have only 11 bad subpacks due to 1-4 failed cells in each. You'll likely find 3-6 individual sticks that are good, but since their welded to the adjacent turd, they're turds too.

Good luck,

Steve