I just converted to a Volt Lithium setup on my car and I’m testing it out. Unreal difference in performance. However, in checking for any hot spots or problems the only thing other than the motor that is generating a lot of heat is the contactor. I’m curious if anyone knows how hot they should run. I would have assumed that they would pass most current through them and not drop any real voltage nor generate any real heat.
Anybody know?
I’m going to go out and try to measure voltage drop across it while under a load to see if there is anything to learn there but could really use one of the smart guys to enlighten me.
It’s the coil that runs hot.
It may run hot enough to burn out at high voltage.
If it becomes an issue, I can come up with the right sized resistor.
If you would measure the coil ohms, I’ll do the math. I’ve been lucky and hoping for the best. Just a matter of time to lose a coil.
I wondered if it was just the coil but I wouldn’t have expected it to run that hot but then again we upped the voltage by quite a bit and may be pushing it too hard. I’ll measure it later this evening and order a 1/4W resistor for it once I know the value needed. I have it charging right now. I did a major dumb-dumb. When I was wiring everything up I needed a long cable to tie my second pack in parallel with the first pack(I’m running 1 outside and 1 center pack tied in series, then tied in parallel to the twin setup on the other side). I went about fabricating one and my kids interrupted me. When I got back to the project, I connected all my cables and went for my test ride. She ran beautiful but didn’t get the range I was expecting.
I came back and decided to hook up the BMS so I could start recharging and when I connected to the second connector we had a fireworks show. I quickly removed it and went to figuring out what I did wrong. Turns out, I never finished fabbing the cable and so I was only running on one pack and not the 2 in parallel. When I connected the BMS cable there was about a .5V difference of potential and the connector did double duty as a fuse 
The one battery has no output at the BMS terminal so something inside must have blown. The cells themselves all test fine but unless I figure out how to open the top of the battery and fix the internals, I won’t be hooking my BMS to that group of 24 cells. At least I know why my range was less than expected. Right now I’m trying to bring the voltage in the one pack back up to match the other one so I can finish connecting them in parallel. Everything had gone so well right up until then too.
It’s time consuming but not difficult to connect balance leads direct.
Cut the plug of and solder one at a time to the copper part otf tabs. You could also solder quick connect terminals to each battery tab, and mating ends to yellow wires.
Then measure voltages and connect one at a time to matched terminals. ie. 4v to 4v, 8v to 8v.
A 1/4w won’t cut it. Most likely 5 or 10 watt.
I’m googling to find coil specs. No luck yet.
This is a Generic coil.
FEATURES for your SW200 Style Single Pole Single Throw (SPST) 400A 80VDC 250VAC 12V, 24V, 48V, 60V, 72V, 96V or 120V DC Coil EV Contactor Set
o 400A Contact Switching
o SPST-NO Contact
o Maximum Coil Energy Waste: 18W
o 1.5A Power Draw
That’s a lot more power draw than I would have guessed! I’m at an in-pass right now. It seems as though my R4F charger tops out at 87V. Can’t get any current draw past that point. Do you know if they can be tweaked up or do I need a different charger? I have a newer Delta Q in my other GEM but I’d rather buy another charger than tear into that car and swap them. Any brilliant ideas?
That coil need 60 ohms and dissipates 3.75 watts.
5 watts in a cool area or mounted to al.
I suggest a 30-60 ohm 10w to start. Then measure volts at coil.
Let me see what I have.
Have these 50 ohm 10w if you can’t find locally.
Is the contactor the original GEM contactor. If not you probably have the wrong contactor installed.
Yeah, its the stock contactor. After seeing the specs Dave posted I’m sure he’s right that the extra voltage I’m running is pushing the envelope. I’ll add the resistor he recommended as soon as I get all the other challenges solved.
How high have you charged?
Grants t2 will not run at 98 volts.
My t4 runs ok.
I haven’t been able to get above 91V so far. I’m hoping to run 94-95 most of the time to prolong battery life. Maybe bump up to the upper limits if I know I’m going to be needing to run a long distance.
My daughter and I ran 20 miles in the hills mostly wide open the other day and dropped from 91V to 75V. That’s more than we will typically need for range. I was trying to test the range plus it was just fun to be able to go places we were never able to go with lead acid.
I’m loving this setup so far. The extra power gets us up the hills at 25 which is the speed limit in our community. Can’t ask for more than that.
So your car will start and run at 91volts but nothing higher. Dave’s right I just installed some Chevy sparks in a 2002 with T-2 controller and Dave’s voltage spoof and my car gives a code -77 (this is at 98 volts)
I think he is saying that the charger he has only charges to 91v.
I think you need a heater in your Gem, Grant. 
This will discharge same rate as your DQ charger, and heat a bucket of water.
Dave has it correct. My R4F charger is peaking out at 91V. Waiting for a call back from their tech before I open it up and start frobbing randomly.
Still have not found anything around here to draw down the battery 8 volts
How about some of your grow lamps from the basement?
Can’t Dave just build you a 23V spoof or whatever you need?
He ran into another issue with T2 controller.
The spoof only allows the car to start. It will still give error if voltage goes over 96v while motoring.
Experience has shown this to be a non-issue on cars with T4.
Whether it’s the T1/T2 controllers that are more sensitive to high voltage, or it is just his controller, I don’t know.
There will always be issues that come up when hot rodding beyond standard performance.
Should be no problem up to 96v or 95v for sure with some tolerance.
Grant wants to run 98.5 volts hvc. at times.
Most feel 4v is a good limit for long battery life. Which happens to be 96v for 24s.