2002 E825 GE Sentry Regenerative Braking question

Hey, I’ve got an '02 (01/2002 mfg date) long bed, with a T1 controller. It seems most '02’s have the T2 controller from what I can tell? Maybe mine is a T1 because it was made so early in '02?

I don’t have any desire to adjust top speed, or anything else, but I’d like to be able to adjust my regen braking. I’m used to a Diesel truck with an exhaust brake, so I’d be thrilled to have something similar. Bonus points if I could turn it off and on with a switch, or even better a paddle! (I know, I’m dreaming…)

From what I can gather, I need the GE Sentry software so I can reprogram my controller, along with a collection of cables. I found this: http://www.forklift-electronics.com/GemT1home.html but it says they’re out of stock.

Two questions:
1 - Anyone know where I can find the collection of cables I need?
2 - Assuming I find the hardware, can anyone tell me exactly what settings I need to adjust so I get regen braking when I let off the “throttle” pedal? I have a lot of hills, and the 2 foot fred flintstone braking is getting old.

Dave @Inwo can sell you the cables and software. I think its $150.
Your car should have come with regen turned on unless someone disabled it. You can change how suddenly it comes on and how much regen it applies with the controller but not on the fly. I too would like to be able to turn it on and off as desired but there’s no direct way to do it. I’ve considered building a circuit that goes in the path of the motor speed sensor that would allow me to switch it in and out as needed. It would mess up the speedometer when turned off, but would still allow me to jake only when needed. That will be a Fall project for me at the soonest though.
If you happen to be in NorCal, I’d be willing to meet up and let you use my programmer if we could work out a schedule.

T1 and T2 don’t have an input for a regen switch. T4 uses pin 12. I never researched it, but assume it goes to an early brake switch.
If enough interest I will look into regen or plugging on demand. Might be easier to change controllers. But then why not go all the way with a PMAC motor and controller.
That, I am researching and parts will be here today.

For T1 dongle and sw. $150
Or maybe Vern would rent his. No need for everyone to have them! :slight_smile: A hobby for me, so no problem sharing. :wink:

Thanks for the info Mr Vern. I’m in San Luis Obispo County. I work in Palo Alto/San Jose periodically though. Not sure what you consider norcal. I don’t make it beyond the Bay Area very often.
Oh, and mine doesn’t regen when I release the pedal (at least not to any substantial degree?). I’m looking for a regen similar to when I hit 25mph.

I may have a solution. :slight_smile:
Program the controller to limit speed to a low value. Turf mode may work.
Set “battery level to plug” lower than battery level.
Crank up “plug braking”.
Motor will then plug when over speed.
Switching to 12mph turf mode will put controller in “over-speed” mode and plug.

Risky to actually use the turf switch as it can easily go into reverse.

MM method:
Program controller to 1/2 speed.
Set MM to compensate and regain full speed.
Put a switch on MM to return all pulses. Simulating over-speed.

If that doesn’t work I have an untested doubler. Built for another application.
Switch it online for instant overspeed condition.
Say you’re 20 mph, a switch will tell controller you’re going 40mph. etc.

Wheels are turning now. :slight_smile:
No need for a complex doubler circuit. I only need to build a speed spoof set to 1 mph over speed limit.
Switch it on line for instant jake brake. I bet a jake brake audio chip is out there already.
I can build it in.

Jake brake audio chip! ha!

At least half of what you’re saying is greek to me, I have no idea what plug braking, or “battery level plug” is. But I dig the direction you’re going on this.

A switch that will turn on motor brake. (plug brake)
Sound effects, better yet?
The only jake brake horn I can find is $100.


For programming T1 and T2 controllers I prefer an LX Handset. Usually available from ebay or inwo. If you want a spread sheet with factory settings for T! and T2 (they are different.) Email me…

You are different from most flat land owners. This is the first feature most of us disable. I guess if your in the hills you might be comfortable with it.

It can be adjusted from mild to throw you thru the windshield.

@TJelecD I’m near Grass Valley. A bit of a drive, especially with your car in tow. I wouldn’t mind loaning mine out if I had an assurance of getting it back. I still play with it a lot and would not want to lose it.

@Inwo I like where you’re going. I hadn’t thought of using Turf mode because I’ve programmed it for my family to use with limited speed. Might be able to add the Jake and get both. I am planning to build a custom display module using Arduino this fall that will track all the key data I want. I had envisioned adding a switch on there and doing something like you have done with MM as a basis for the regen selection. I like the more simple approach you are moving towards.
For the sound, my future includes the installation of a Bluetooth amp for my stereo. I don’t see any use for a head unit and having to find a place to mount it. Perhaps I could add a Jake brake audio clip to play every time I hit the button. LOL

Doug is going ahead with the 24s Volt upgrade.
Someone needs to start a thread to share experiences, and keep smoke to a minimum.
The part that always gets damaged is bms. There is only one safe way to connect it, and I don’t seem to do a good job explaining it. :frowning:

The T1 and T2 don’t seem to run over 95v, even with spoof.
Older carts need suspension work.
Even a prewired harness needs to be tested before plugging into bms. (each pin)
Have bms off.
Plug in B- section first.
Isolate bms chassis from “floating” frame.
Extending lcd cable needs shielded wire and away from power cables.
First and last pins of bms plugs are duplicates.
Batteries are in series. One “low side” B-, and one “high side”. B+ (or two of each)
Harness plugs are not keyed.

Anything to add?
Most users don’t wish to share their smoke stories.
C’mon jump in, the waters fine. :slight_smile:

I’ll start a thread for my 24s Volt battery upgrade.

Hopefully I won’t have any smoke stories, but if I do, I won’t have any problem sharing them. No shame here.

I plan on trying to reprogram my T1 for more aggressive regenerative braking after I finish the lithium upgrade… Don’t want to mess with too many things at once.

Here’s my Lithium upgrade thread: Another Chevy Volt Lithium thread

Low side vs high side wasn’t clear when I was doing my project and I’m a EE. It just didn’t register. I had to really stare at the batteries and then the schematic before I hooked it up. Now, it is totally obvious but not when you first look at it.
What it means is there are 2 battery packs that are ~48V each. If you start at the first cell of the battery pack connected to car B-, the cell voltages increment by ~4V with each cell as you work toward the B+ connection. The first pack will have cells relative to ground from 4V to 48V. The second pack goes 52V to 96V relative to ground or B- on the car (remember that the car does not use a chassis ground like a normal car). The Pack that reads the lower 48V is the low side. See if the pic helps.

If using 4 packs for ~100AH, it should be wired similar to below:24S2P%20Battery

For what it’s worth, I like to see the neutrals tied together. It helps take the load from the small balance leads. IMO

I’ve also heard from those advocating “inverse parallel” connection. @grantwest, I think it’s a plumbing term.
What I mean, is connecting B+ to the top battery.
I can’t see it making much difference, but it seems correct intuitively.

In practice, my car looks more like this under the seat but I thought that would be more confusing than helpful. LOL

Regen . I run regen all the way up , love it . From the factory it is set pretty low . i set mine to max and have it come on faster when i let of the accelerator pedal . Max regen is what a Tesla does , its sometimes refereed to one foot driving . This is really nice when : your cart goes much faster then stock , you live in a hilly area , you have front drum brakes .

so your racing along and need to slow down , let off the pedal and the cart immediately starts slowing fairly hard . If you dont want to slow that fast you feather the accel pedal. so there isn’t really a need to turn it off or on . And you are putting all that motion energy back in your pack instead of wasting it as heat (braking).

I like that approach and will try it. I don’t like how when I lift off the pedal going downhill the regen slows me more than I want to slow. From what your saying, I should be able to give it just a bit of throttle and get my target speed. I’ve always assumed that any pedal at all and I’m applying power which on my hills will have me speeding.
I’m going to play with those settings and see if I going the opposite direction of what I’ve done works better.
I love having the lithium because it can accept most of the current from regen. With lead, they can’t take the charge that fast so its mostly lost anyway.

i think there is a miss conception that is you apply a little throttle during regen that you are now using power . what it is actually doing is adjusting regen . i would run some tests and post results but the highest elevation in my city is … wait for it … wait for it … 3 feet ! seriously 3 feet . Not a whole lot of time to do down hill regen testing . Also you can reduce your plug braking with high regen . Plug braking is BAD .

What two settings are you changing to increase regen? I am trying to get mine to 1 pedal driving Tesla/Power Wheel style