Hi all,
I have an older model, 1999 e4 GEM that I’m converting to lithium. Currently I have the 910-7200 DeltaQ charger and will be upgrading with a 912-7200 DeltaQ charger to have lithium charging profiles. From what I gather, the new charger has a 72 V interlock but I believe the car was designed for a grounding interlock. Does anyone know an appropriate relay and wiring I could use to covert the interlock use for new Delta Q charger?
Thanks,
Martin
72vdc relays are scarce. I believe that I’ve used 120vac relays on 72vdc. I can check if you want.
A ssr may work, or I could come up with a transistor to ground interlock, if I know the current required.
I’m not entirely sure how the interlock works. Specs indicate that the new DeltaQ put out line voltage (72vdc) through the green wire, assuming it triggers a grounded (ssr) relay somewhere, perhaps in the controller. My old Gem has a grounding wire and I’m not sure if it’s grounded when plugged in or not. NC vs NO. Solid State would be fine but costlier, perhaps a transistor but I really don’t know how much current. I think it would be minimal current since it’s only an open/closed signal. I hoped someone has done this before.
This is one I sent to Grant
Where do I get one?
Downside to adding relay. It is always on. Small current drain.
This should convert any model charger to 72v out DQ.
The key section may not follow all models, but modification should work.
I would like some input before you try this.
Ugh. That diagram doesn’t make much sense to me just yet. I’m having a hard time reading some of the details due to image resolution. Let me study it a bit. I don’t have the new charger yet. I was trying to get it all together since it’s at my vacation house. I was hoping a simple relay with 72v DeltaQ green/B- on one side of the relay and car interconnect wire with something else (12v, 72v or ground on the other). Seems like nothing is so easy.
Will the small current drain from the relay stay active with the ignition switch off?
Yes, relay will always be on unless charging.
Rodney suggests a 120vac relay connected to charging cord.
Your idea of a relay will work fine. Connect NO contacts across original interlock circuit. Pull a 72v relay coil in, from green and black wire from charger.
A dc ssr will work the same way. Use standard 5-32 volt in with a resistor. I can show you how.
Email me for higher res.
All it involves is a jumper across interlock and connecting green wire to the relay that you already have.
Rodney’s idea is very clever, putting a relay on the 120vac charging cord would work for any future charger upgrades as well. Plus, there’s no parasitic power draw when unplugged.
The only thing I’m not certain about is how the Ground interconnect works on the older gem cars. Is the GEM car interconnect wire live voltage 12v, 72v, or ground? What does it “ground” to? If the car interconnect circuit is closed, is the car enabled or disabled?
Sorry. I’m missing that piece of the puzzle. If I had my car at home I could just measure it.
The easy thing about it is that it doesn’t matter how it works.
Just jumper the interlock. Either with a jumper wire or NC contact of relay.
I thought interlock is just one wire, what do you jump it to? B-? Sorry for all the questions.
It depends on what charger you have. I guess I should have asked.
Delta Q. The deltaQ just has the green 72v wire for the interconnect. The Gem has one wire connected to the deltaQ that is supposed to be a “ground” interconnect. What does that get grounded to 12v+, 12v-, B+, B-…?
Ok, so you are removing a DQ and putting in another model DQ?
This is the only one I found. 2 wire interlock.
Do you have the old one to test. Check cont. from green to ??
Thanks David, Thats the schematic, showing a single wire disconnect!
Both delta Q charger models 910-7200(old) 912-7200(new) have 4 wires with black/White wired together. See schematic regarding wiring of the new DeltaQ charger.
The new DeltaQ Green wire interconnect outputs battery voltage (72v) when the charger is not plugged into AC to provide an interlock function.
The older model DeltaQ/Gem also has a 1 wire interlock that is simply a “ground loop” but I can’t find any documentation of what that wire grounds to (chassis, B-, or +12v). I suspect it just grounds to the chassis and I’m overthinking it.
I know several people on the forums have done a similar upgrades and was hoping to get some advice since I need to bring everything with me to finish the conversion.
I may have to have to measure the voltage across the wires while the cart is plugged in and unplugged. Hopefully that will give me the answer unfortunately I’ll have to make it to my vacation house to do that. 
The white and black looks connected but is the temp. sensor.
The green outputs 72v as you know.
The schematic posted shows 2 wire interlock. Y/w and Blk.
5 wires total.
You do not have to power original charger to determine how the interlock is connected.
The interlock wire will be connected internally to one of the other wires. Use an ohmmeter to see which one.
Do you know what the colors were?
Heres the Easy cheapest way out
Connect the coil to the power cord and the existing interlock wires to the NC contact
$5 and your done in a half an hour.You guys sure get tangled up complicating something simple.
110V AC Coil Power Relay DPDT LY2NJ HH62P L JQX 13F 10A with PTF08A Socket Base | eBay
Rodney
[quote=OLD HOUSEBOATER;32629]Heres the Easy cheapest way out
Connect the coil to the power cord and the existing interlock wires to the NC contact
$5 and your done in a half an hour.You guys sure get tangled up complicating something simple.
Rodney[/quote]
Thanks Rodney!!! 
Hello,
How do I see the schematics or diagrams mentioned here? I have the same problem with the interlock on my Gem and a new DeltaQ Charger. The new DeltaQ Charger doesn’t have the interlock wires that the old one has.
Would appreciate a detailed diagram and instructions.
Thanks!