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Discussion Starter #1
I found a Gen1 with it's whole battery-pack in a junk yard recently and removed the battery-pack sensors (BCM Connector B). There were four temp sensors plus two additional wires, a red and a black which were both enclosed in red flexible rubber/plastic covering, that were attached to the perimeter of the battery back by very small screws. The schematic indicates these are PTC + and PTC -. My current battery-pack does not have the PTC wires attached (who knows why). My question is when I convert my system to LTO I want to monitor the temperatures but am unsure where / what to connect the PTC wires. Can someone please clue me in. Thanks
 

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^ Some people bypass the cell temp PTC system. Your red-clad wires should still be there, in some form (like perhaps cut), only the ends will connect to each other with a resistor in between, rather than to the pack orange end board...

When you move to LTO, you'll likely just use the 4 thermistors for temp monitoring and bypass the cell temp PTC circuit (if there isn't already a resistor in that circuit as I desribed above, you'd need an ~20Ω one). I think one of the LTO-modders mentioned something about using the PTC circuit, in one of the recent LTO threads. Can't recall what that was about.

Personally, I think it'd be kind of a hassle with dubious benefits to mess with the strips in an LTO pack... I mean, you can probably string them along in some fashion, attach to the cells, maybe supplement with an appropriate resistor to make the trigger temp range appropriate to your pack (say, if you don't use all 20 PTC strips)... I think the DTC is temporary - the PTC strip resistance goes up into the trigger range, it disables the pack, but as soon as the temp falls, it re-enables. Might be interesting to work out a system with a lower trigger threshold, say, 125F degrees instead of the something like 170F+. That's probably the only way I'd even consider using it, because otherwise the temp range is too high to be useful...
 

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Discussion Starter #3
I'm not familiar with the cell temp PTC system. I disconnected the + and - PTCs from a battery pack and it appears one was connected by screws to a positive voltage and the other to a negative. I'm not clear about this system and the strips that are mentioned, i.e. attach to the cells, maybe supplement with an appropriate resistor to make the trigger temp range appropriate to your pack (say, if you don't use all 20 PTC strips). Please explain how 20 PTC strips are connected by two wires. What am I missing?
 

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There's 20 strips, one for each stick, and 6 PTC sensor things per strip, 1 sensor thing per cell.* The strips are all in series, attached to small busbars enmeshed in the orange end boards, and the ends of that series are connected to the red-clad wires. If one cell overheats, it increases the resistance of the whole circuit and throws a code, disables the IMA system.

The resistance profile is exponential - it's flat across a wide resistance/temperature range and then shoots up high and fast once the threshold resistance/temp is reached. This is more of catastrophic cell failure system, because the temps that trigger a disable likely can only be reached if a single cell or more has some serious problem that heats it up a ton... Some people remove the strips on the sticks and instead simulate their combined resistance with an appx. ~20Ω resistor.

There's a graph somewhere around IC that shows the temp/resistance curve.** In my previous post I was saying that the system might be more useful for LTO usage if the temp/resistance that triggers a fault were lower. For instance, if the trigger is at 170 degrees F, and that corresponds to a resistance of say 200Ω in OEM form, you might be able to add a resistor to the circuit that lowered the actual temperature at 200Ω. You'd have to do some research and hone-in on exactly what temp/resistance might work. But really, I don't think it'd work very well because of that exponential behavior. It'd be hard to get the right resistance for the right temperature, and in the end the whole system probably isn't necessary for the LTO, particularly since they are very robust, not prone to burn or explode.

*Here's a link to a webpage that has a couple pics and a brief explanation of the temp PTC strips; scroll down to "PTC strips exposed." http://99mpg.com/blog/batteries/
Don't confuse this, though, with the voltage tap PTCs, the orange thingys attached to the orange end board. Those protect the voltage taps, the strips protect the battery.

** I think this is it, I think IC member Iamian made this...
83026

Take a look at the DTC troubleshooting guide for P1449-73, which explains the system and the fault. Looking at the graph in that guide, the "surge resistance" and fault trigger is somewhere around 176 degrees F...
 

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^ fyi, DTC P1568-70 also has to do with the PTC circuit, it has additional info. This is basically it:

"A PTC (positive temperature coefficient) element shows the characteristics as shown above (i.e. drastically increases the resistance at a temperature between 158 - 212ºF (70 - 100ºC), and it is used to determine if a monitored object temperature exceeds a set value. The PTC is installed in each of the 120 battery cells to detect overheating, an open, or a short individually. If the PTC input voltage is more than the upper threshold or less than lower threshold, a malfunction is detected and a DTC is stored."

Specs per single cell:
158 degrees F (70C) or below - 2Ω or less
212 degrees F (100C) or above - 600Ω or more
"Set value": 440Ω, activated at 194 degrees F (90C) or above
 

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Discussion Starter #6
I've been reading that if the PTC circuit is removed a 20 ohm resistor must be placed across the + and - wires so no lights will come on. I noticed when I last removed my battery that those PTC wires were not connected to the connector. I have never had a light. Can someone please explain if I need the 20 ohm resistor or not. Thanks
 

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Look at page 32-6 and particularly photo 109 of your Electrical Troubleshooting Guide. Plug B red wire(B11) and black wire(B22) are the ends of the PTC circuit through the battery. Are you saying that there is no red and black wires on your B plug?

edited-correction
 

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I've been reading that if the PTC circuit is removed a 20 ohm resistor must be placed across the + and - wires so no lights will come on. I noticed when I last removed my battery that those PTC wires were not connected to the connector. I have never had a light. Can someone please explain if I need the 20 ohm resistor or not. Thanks
Isn't this the same question you originally asked (minus the LTO part)? Not sure what part of my answer you're not understanding...

It sounds like you're saying that you have no red-clad wires (they're black and red under the cladding) coming out of the BCM connector, is that so? If so, I'm not sure what that's all about. As I recall, HCH1s could have the PTC system disabled, such as by dealer service, the BCM would be swapped and in this case the PTC wires would be cut and NOT reattached.* But I don't recall that procedure being available for the Insight, I could be wrong. But even so, there was never anything about pulling the wires out of the BCM connector itself, just cutting the wires...

Seems like you should have a DTC if the wires aren't there; if they're not there then the PTC circuit is open - I'd guess you should be seeing the code I mention above - the P1568-70. Does your IMA light actually work - does it light at key ON?

*Here's a snip from a Honda service bulletin on junction board replacement that mentions in passing the PTC wire cut. The bulletin covers the Insight as well, but it does not mention this PTC wire cut thing in that context, only in the context of the HCH1 2003-2005:
83065
 

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Discussion Starter #9
thanks for all your responses eq1. I'm sorry if I wasn't clear; let me try again. The NiMH pack that's currently in my Gen1 has only 4 wires to the BCM, no red-clad ones to connect the PTCs, and no resistors to simulate the PTCs, therefore I believe this circuit is open. My IMA light works, but not on, yet I get no codes as a result of the PTC circuit not connected/open. 1) this doesn't make sense and 2) once I get the LTO packs installed I guess I have a choice of connecting the 20 ohm resistor or not since I'll be using the same BCM.
 

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@minor4326

John, you didn't answer my question in #7 above. That is a critical check. I know you have the Electrical Troubleshooting Guide because you showed it to me. I suspect that you do have the wires at the B plug, because otherwise you would have P1449 battery code. Yes, the red sheaths may be missing and the black and red also missing at the battery, but B11 and B22 wires must be present otherwise you would have P1449. (Only highly unlikely exception, someone modified the internals of the BCM.) The most likely explanation is that someone installed the resistor somewhere within that cable between the battery and BCM and then taped over it. That was done on my HybridRevolt battery.
 

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^ Yeah, what Jime says... If you don't have those wires/terminals at BCM connector B, then what's going on is anyone's guess.

Here's a couple pics of what it should look like. Temp PTC connections at far left. The second pic shows my PTC bypass, underneath the black heatshrink. Normally, the two ends of the red-clad wires that are connected here by a resistor, snake down to the orange end board and connect at opposite ends of that board...
83085

83086
 

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Discussion Starter #14
@minor4326

John, you didn't answer my question in #7 above. That is a critical check. I suspect that you do have the wires at the B plug, because otherwise you would have P1449 battery code. I only have 4 wires at the plug. There is no red or black wires. I don't have any codes. (Only highly unlikely exception, someone modified the internals of the BCM.) The most likely explanation is that someone installed the resistor somewhere within that cable between the battery and BCM and then taped over it. That was done on my HybridRevolt battery. AH! My battery is a HybridRevolt battery that's now 3 years old. That must be the answer. Still can't explain why only 4 wires are at the plug though. I guess I don't use a 20 ohm resistor since there are only 4 wires at B plug??
@ eq1: Thanks for the pics. TI think we're on the same page now with regard to having no PTC wires.
 

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^OK. I trust now that you only have 4 wires on the B connector. Why you do will have to be chocked-up to being one of the great IC mysteries... Maybe you should open-up your BCM and see if there's anything unusual that pops out, like a resistor that looks like it was added in.

(moments later...) Not being good with having lingering mysteries, I opened up a BCM I have sitting here and I see that it would be a trivial job adding a resistor between the pins where the PTC connections should go. So, my guess is that that might be something a battery vendor would do, to make the bypass 'cleaner'... Here's a pic of the BCM internals in that area, pretty sure the pins are the two on the end, by the "26" and "13"...

83092
 
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