Sector e1 Regenerative braking after Lithium upgrade

[Tommy2bits]

Hello, new member. I am about to buy a new old stock 2023 e1 with only 8 miles on the unit and a nice new 13.5kw Lithium upgrade. When going downhill, the regenerative braking stops the buggy completely. Tried it on a moderate slope and also on a significant slope. Did not see any error appear but didn't really know what to look at either at the time. A gentle nudge of the throttle and it goes just fine and there are zero other issues with the machine and this appears to be a minor inconvenience and just weird to hut the gas going downhill. From my research, I read that if the battery is fully charged, the regenerative braking may act erratic because the BMS on the battery stops the charging which may disable the motor and it is possible that it will engage the brakes. It did not feel like the brakes were doing anything, it felt more like the motor was braking, Another interesting fact is that I tried three units and they all acted the same way, so that let's me know there is not something "broken".

How does the braking react with other e1 owners? With or without a battery upgrade?

I am excited to bring it home tomorrow as I have 5 ac of property with lots of trails and gullys that I currently ride with my Rhino and I also have a house at a lake community with crappy roads that I get bounced around in my golf cart so this should bridge the gap and I can sell the other two. 

[mark walkom]

there's another thread on something similar to this but it sounds like you are overloading the batteries and they're cutting out to save themselves

 

I am not an engineer by any means, I do wonder if you could charge to 90% and leave it space for the regen to feed into the batteries?

[Tommy2bits]

8 hours ago, mark walkom said:

there's another thread on something similar to this but it sounds like you are overloading the batteries and they're cutting out to save themselve

I am not an engineer by any means, I do wonder if you could charge to 90% and leave it space for the regen to feed into the batteries?

Yes that is what I read too as I noted it just seemed like the machine would freewheel if the battery went onto stand by mode but who knows I am going to do some testing at a lower charge once I get it home. I guess I will be in the hunt on how to disable the regen braking if I can't find a solution, just too weird pressing the throttle to go down hill.. I saw one post that instructed to unplug a connector on the brake pedal but if I remember correctly it turned out to be the brake light connection 

[GNFO]

Mine is a 2020 model and both before and after the lithium conversion the regen has never been enough to completely stop the UTV on any slope, let alone a moderate to high slope. Also, unless Hisun has significantly changed something it doesn't have the ability to engage the friction brakes. That would require the addition of an actuator and better total system control.  Since you saw the same thing on multiple units, maybe they did some change.  Thing is, regen on its own can't hold the wheels still on a slope.  It requires rotational movement to generate electricity which of course also slows down the UTV.  Regardless of whether or not the batteries have cut themselves off, physics will dictate that on a slope the UTV will still roll forward.  So in EV cars that can come to a complete stop that means they're either automatically applying the brakes at the very end when the speed is too slow to generate electricity (and stopping force) or actually applying electricity to the motor to stop the rest of the way to zero.  

I did see in a different thread that Hisun changed the motor controller from Sevcon to some other brand.  If the ones you tested all have this new equipment, maybe they really did implement some added functionality.  Only other explanation I have is if the parking brake isn't adjusted properly and is causing some friction that is being overcome when pushing the accelerator.  The parking brake mechanism isn't exactly the best in the world.

[Tommy2bits]

I had my first long drive and spend the weekend at the lake community and the regenerative braking happens at any battery level so that is not the overcharging problem. It will pull hard and come to a complete stop if I am not on the gas even on a flat road. I can tell it has definitely nothing to do with the brakes, there is zero drag when I am on the throttle. The amp meter goes straight to the green charging zone when it is slowing. Problem is that you have to be on the throttle twice as much to fight against the engine breaking so it kind of cancels out the whole recharge feature. It's definitely not performing as intended. I'm just gonna deal with the minor inconvenience and see if I can disable that feature altogether 

[GNFO]

4 hours ago, Tommy2bits said:

I had my first long drive and spend the weekend at the lake community and the regenerative braking happens at any battery level so that is not the overcharging problem. It will pull hard and come to a complete stop if I am not on the gas even on a flat road. I can tell it has definitely nothing to do with the brakes, there is zero drag when I am on the throttle. The amp meter goes straight to the green charging zone when it is slowing. Problem is that you have to be on the throttle twice as much to fight against the engine breaking so it kind of cancels out the whole recharge feature. It's definitely not performing as intended. I'm just gonna deal with the minor inconvenience and see if I can disable that feature altogether 

Well, if Hisun really has implemented a strong regen then that's actually good. If you don't have any experience with full battery electric vehicles it may seem strange at first. If they did it right, you're not really "fighting" against the engine. There's a point where the accelerator position is not applying electricity to move forward, nor regenerating electricity back into the battery and you are coasting at a constant speed. That point changes based on slope and vehicle speed and is controlled by computer. The idea is that you're controlling speed with the accelerator, not absolute power output like with a gas pedal. In EVs it's called "one pedal driving" because you have control over both the acceleration and deceleration with just the accelerator pedal without having to keep moving your foot from brake to accelerator. It's one of the things I really like about driving an electric car (especially in traffic) and I wish my E1 really did have a strong regen. The brakes can be "grabby" on a steep hill and makes it jerky trying to control speed coasting down a hill.

[Tommy2bits]

41 minutes ago, GNFO said:

Well, if Hisun really has implemented a strong regen then that's actually good. If you don't have any experience with full battery electric vehicles it may seem strange at first. If they did it right, you're not really "fighting" against the engine. There's a point where the accelerator position is not applying electricity to move forward, nor regenerating electricity back into the battery and you are coasting at a constant speed. That point changes based on slope and vehicle speed and is controlled by computer. The idea is that you're controlling speed with the accelerator, not absolute power output like with a gas pedal. In EVs it's called "one pedal driving" because you have control over both the acceleration and deceleration with just the accelerator pedal without having to keep moving your foot from brake to accelerator. It's one of the things I really like about driving an electric car (especially in traffic) and I wish my E1 really did have a strong regen. The brakes can be "grabby" on a steep hill and makes it jerky trying to control speed coasting down a hill.

It does have that point but it is a tiny sliver and as you said, that sliver changes with the speed and angle of the road. I spend the majority of my time hyper focused on trying to find that sweet spot where it's not feeling like its slamming on the brakes but not accelerating and I am not a leadfoot. It grabs so hard that it pushes your body forward when it slows you and that is just barely letting off. It might be wonderful for those people who like micromanaging the throttle pedal but for me it is a pain and going to go away of I can get it to. Sometimes I do feel it working correctly but then it falls back into super slow down mode easily coming to a full stop if I don't give it "gas" 😢👉🍻

[GNFO]

23 minutes ago, Tommy2bits said:

It does have that point but it is a tiny sliver and as you said, that sliver changes with the speed and angle of the road. I spend the majority of my time hyper focused on trying to find that sweet spot where it's not feeling like its slamming on the brakes but not accelerating and I am not a leadfoot. It grabs so hard that it pushes your body forward when it slows you and that is just barely letting off. It might be wonderful for those people who like micromanaging the throttle pedal but for me it is a pain and going to go away of I can get it to. Sometimes I do feel it working correctly but then it falls back into super slow down mode easily coming to a full stop if I don't give it "gas" 😢👉🍻

Got it.  I guess Hisun implemented a stronger regen, but did not do it well.  In a car it allows fine speed control without being difficult or abrupt.  Sounds like Hisun didn't factor enough pedal travel into its system to keep it from being jerky.  That's a shame.  I'm guessing the regen is built into the motor controller, so I'm not sure you can turn it off without reprogramming the motor controller. You could try getting a technical response out of Hisun to see if what you are experiencing is now their normal, but I don't know how responsive they are.

[GNFO]

@EVSupport What has been your experience with the 2023 or newer E1s and regen braking?  Is what Tommy2bits describing now normal?  If so, if someone has the appropriate Sevcon reprogramming equipment and software can they alter the parameters to smooth out the regen?

[EVSupport]

We dont see it as an issue. Heaviest regen comes in when the brake pedal is used, otherwise the initial regen can be controlled by use of the right foot. This is a common issue with all EVs many drivers expect them to work like an automatic vehicle where you mostly coast with no power, and it shows up that drivers spend a lot of time on and off the power. Here in the UK fewer drivers have autos so we are more used to driving an manual vehicle, if you are up and down on the throttle all the while, it just doesnt work. So I guess we find it more natural to drive an EV (Hisun / Polaris included) in a more appropriate fashion not expecting them to drive like an auto.

The Degree of regen and the brake pedal regen can be adjusted. I have only done this once for a customer.

The latest E1s dont use a Sevcon, and the software to do anything, just isnt accessible. Even the importers version is limited and the software is entirely in Chinese.

[GNFO]

Thanks.  I don't know if he has any experience with a real car EV regen, which is why I brought it up. We have two Teslas that we love (and we're old enough to have learned to drive on stick - for the US anyway), so I know what a good regen feels like, but at least what he's describing seems to have too narrow of a transition band from accelerating to full regen braking.  I just wasn't sure if that had been noted in other 2023 or newer models.  Also, what you're describing probably wouldn't account for being able to come to a complete stop on a hill from regen alone with no brake pedal application, unless his description isn't quite accurate.

The regen in my 2020 could honestly be stronger in my opinion, but it would certainly be a problem if not implemented properly.

[EVSupport]

Or the brakes are binding, especially the parking brake if the cable to the parking foot pedal has been caught, not obvious but again something which we see a lot of. If the cable gets damaged the parking brake caliper doesnt return, so brake always on.

 

[Tommy2bits]

As I have been riding more I can definitely tell it's not the brakes. When the needle goes to the green, regen mode, is when the motor starts drag. Sometimes it operates normally but sometimes it's just heavy-handed. A big problem is when I'm going down a steep hill on a trail at my property, it literally will lock up the rear wheels, and I'll end up sliding down the hill. No brakes are being applied. That's a dangerous way to go four wheeling.

That brings up another issue that is just normal design... the machine won't let you hit the "gas" and the brake at the same time, normally that's just fine until you're on the side of a hill with 2 inches from the edge and you really need to give it a little bit of gas to hold it in place while you let off the brake because when you just switch from brake to gas, it's going roll forward a little before the motor kicks in and you'll fall off the hill. 

Back to regen... I thought I hit on something when I looked on the BMS controller screen, I realized it was a touchscreen and there was a discharge mode on and off and a charge mode on and off. I turned the charge mode off, thinking it would freewheel and I would just turn it back on when I needed to charge the batteries... it worked for about 30 seconds then I got an error code when it wanted to regen and it couldn't. 

Sure wish I could adjust it. I don't know what controller it has or if it was adjustable. would love more info on that. When I feel it working properly it is great, I see what it wants to do so I understand how to use the pedal

[GNFO]

16 minutes ago, Tommy2bits said:

As I have been riding more I can definitely tell it's not the brakes. When the needle goes to the green, regen mode, is when the motor starts drag. Sometimes it operates normally but sometimes it's just heavy-handed. A big problem is when I'm going down a steep hill on a trail at my property, it literally will lock up the rear wheels, and I'll end up sliding down the hill. No brakes are being applied. That's a dangerous way to go four wheeling.

That brings up another issue that is just normal design... the machine won't let you hit the "gas" and the brake at the same time, normally that's just fine until you're on the side of a hill with 2 inches from the edge and you really need to give it a little bit of gas to hold it in place while you let off the brake because when you just switch from brake to gas, it's going roll forward a little before the motor kicks in and you'll fall off the hill. 

Back to regen... I thought I hit on something when I looked on the BMS controller screen, I realized it was a touchscreen and there was a discharge mode on and off and a charge mode on and off. I turned the charge mode off, thinking it would freewheel and I would just turn it back on when I needed to charge the batteries... it worked for about 30 seconds then I got an error code when it wanted to regen and it couldn't. 

Sure wish I could adjust it. I don't know what controller it has or if it was adjustable. would love more info on that. When I feel it working properly it is great, I see what it wants to do so I understand how to use the pedal

Might want to have a conversation with whoever did the conversion.  The screen you're talking about is not OEM equipment.  Also, I can hit both the brake and accelerator at the same time for the exact scenario you're talking about. If the conversion was done by a 3rd party business like EVSupport has in the UK, they might have had the capability to alter the Sevcon programming (if the 2023 models still had that motor controller) and that could explain why it is reacting differently than my experience.

[Tommy2bits]

10 minutes ago, GNFO said:

Might want to have a conversation with whoever did the conversion.  The screen you're talking about is not OEM equipment.  Also, I can hit both the brake and accelerator at the same time for the exact scenario you're talking about. If the conversion was done by a 3rd party business like EVSupport has in the UK, they might have had the capability to alter the Sevcon programming (if the 2023 models still had that motor controller) and that could explain why it is reacting differently than my experience.

Yeah the screen is the battery monitor that came with the battery, I talked to the seller and he said he did not have the equipment to program the motor. He is a dealer but just barely, really just some guy with a warehouse flipping bikes. 

That is nice that you can hit the throttle to hold the unit while the brake is still on

[GNFO]

11 minutes ago, Tommy2bits said:

Yeah the screen is the battery monitor that came with the battery, I talked to the seller and he said he did not have the equipment to program the motor. He is a dealer but just barely, really just some guy with a warehouse flipping bikes. 

That is nice that you can hit the throttle to hold the unit while the brake is still on

But he's the one who did the conversion? Anyway, could you confirm if we're even talking about a Sevcon motor controller or the newer Chinese motor controllers?  I still don't know when Hisun did the transition. The motor controller is mounted along the center between the batteries. Based on what I've seen, the new ones are branded "Tercel".  If it is the old Sevcon and they didn't change the programming, I'd still check the parking brake mechanism. If it's a new one, I don't know what those are like.

[Tommy2bits]

Been raining so I haven't checked the controller but yeah, he just gets new old stock machines, slaps in the LiPo04 and the display and charger that comes with it and moves on to the next one, I did see this in the manual today. (see attachment) Regen increases in Low. Unfortunately I see the increased Regen across the board and mostly in "M" but I am just going to run it in High all the time after reading this unless I am climbing a hill. VERY happy with the machine overall. 

As a side note, on my first steep hill climb at my property, I was accidentally in 2WD and High gear and it did great  

[GNFO]

Almost all of my driving is done on 4WD Low because of the terrain on my property and of course as I mentioned I don't have the same amount of regen you do, although I do have that same table in my manual. I will switch out when I'm on pavement to reduce wear on the tires, but that isn't much.

Please see my response to your other comment in a different thread about the 12V battery. I'm confused (and a little concerned) about how your seller treated charging. What brand and model of LiFePO4 batteries did he use and how many? Can you see how they are connected to each other (i.e. are there CANbus cables running between each of the batteries in addition to the power cables)?

How is the "charger that came with the battery" wired/used, and is that Delta Q really still also installed? Are there wires running from the 12V battery to the small DC/DC converter mounted high up along the centerline on the same side as the 12V under the driver's seat?

[Tommy2bits]

9 hours ago, GNFO said:

Almost all of my driving is done on 4WD Low because of the terrain on my property and of course as I mentioned I don't have the same amount of regen you do, although I do have that same table in my manual. I will switch out when I'm on pavement to reduce wear on the tires, but that isn't much.

Please see my response to your other comment in a different thread about the 12V battery. I'm confused (and a little concerned) about how your seller treated charging. What brand and model of LiFePO4 batteries did he use and how many? Can you see how they are connected to each other (i.e. are there CANbus cables running between each of the batteries in addition to the power cables)?

How is the "charger that came with the battery" wired/used, and is that Delta Q really still also installed? Are there wires running from the 12V battery to the small DC/DC converter mounted high up along the centerline on the same side as the 12V under the driver's seat?

Wired very simple, Only a single battery and both chargers are attached. Going to correct the Delta Q soon so not looking to beat this set up to death. It had zero miles on it so it hasn't been like this for any length of time 

[BuggyBoy]

On 8/19/2025 at 1:42 PM, Tommy2bits said:

Hello, new member. I am about to buy a new old stock 2023 e1 with only 8 miles on the unit and a nice new 13.5kw Lithium upgrade. When going downhill, the regenerative braking stops the buggy completely. Tried it on a moderate slope and also on a significant slope. Did not see any error appear but didn't really know what to look at either at the time. A gentle nudge of the throttle and it goes just fine and there are zero other issues with the machine and this appears to be a minor inconvenience and just weird to hut the gas going downhill. From my research, I read that if the battery is fully charged, the regenerative braking may act erratic because the BMS on the battery stops the charging which may disable the motor and it is possible that it will engage the brakes. It did not feel like the brakes were doing anything, it felt more like the motor was braking, Another interesting fact is that I tried three units and they all acted the same way, so that let's me know there is not something "broken".

How does the braking react with other e1 owners? With or without a battery upgrade?

I am excited to bring it home tomorrow as I have 5 ac of property with lots of trails and gullys that I currently ride with my Rhino and I also have a house at a lake community with crappy roads that I get bounced around in my golf cart so this should bridge the gap and I can sell the other two. 

I had a problem with regen braking tripping the battery BMS's at max regen down a step hill - the whole system would shut off and would only reset with ignition on/off.
Would also somehow throw the batteries out of sync and they then wouldn't charge properly with the onboard DeltaQ charger, had to buy a cheap $100 48v separate charger that didn't care about voltage differences and would bring them all back up to 52v. The DeltaQ would then charge as normal.

Fixed the issue by removing the regen brake pedal switch - still have regen if i go over 10kmh, but means i can now control when i want regen (i.e. batteries are very low). Had no issues since, but do miss the extra braking power down the very steep hill. One thing i miss about the old AGM's - no sensitive BMU to shut off batteries if current/heat exceeds limits, but better to extend battery lifr in the long run of course...

[Tommy2bits]

9 hours ago, BuggyBoy said:

Fixed the issue by removing the regen brake pedal switch 

I mainly just cruise around my lake community with crappy roads since the golf cart was too harsh and the regen is more annoying than helpful, can you point me to the regen switch to disconnect? I've only seen one other post about this and the wire on the pedal they thought it was affected something different

[BuggyBoy]

9 hours ago, Tommy2bits said:

I mainly just cruise around my lake community with crappy roads since the golf cart was too harsh and the regen is more annoying than helpful, can you point me to the regen switch to disconnect? I've only seen one other post about this and the wire on the pedal they thought it was affected something different

Just to be clear, removing the brake pedal switch doesn't fully remove regen, it just stops it activating alongside the brakes - if you fo down a hill over 10 kmh in low, regen will still activate.
You don't actually have to physically remove the switch either. If you get down and look at the break pedal closely you will see a very small reed switch and two wires coming out of it and going through the bulkhead. If you then trace/identify those two wires coming out of the other side of the bulkhead, from memory all you have to do is cut them and join them together with a connector block. This permanently completes the circuit (the reed switch works by breaking the circuit when you brake). This worked for me, but i'm not an electrician or expert so cant gaurantee it will work for you...!
if it doesn't work, you can simply connect the wires back up using the connector block as you haven't removed the switch.

[Tommy2bits]

29 minutes ago, BuggyBoy said:

Just to be clear, removing the brake pedal switch doesn't fully remove regen, it just stops it activating alongside the brakes - if you fo down a hill over 10 kmh in low, regen will still activate.
You don't actually have to physically remove the switch either. If you get down and look at the break pedal closely you will see a very small reed switch and two wires coming out of it and going through the bulkhead. If you then trace/identify those two wires coming out of the other side of the bulkhead, from memory all you have to do is cut them and join them together with a connector block. This permanently completes the circuit (the reed switch works by breaking the circuit when you brake). This worked for me, but i'm not an electrician or expert so cant gaurantee it will work for you...!
if it doesn't work, you can simply connect the wires back up using the connector block as you haven't removed the switch.

thanks, I appreciate the info. It really just bothers me when I let off the throttle, not when I hit the brakes. Now I know just in case though! 

[LAMA]

On 28. 8. 2025 at 16:53, Tommy2bits said:

Protože jezdím čím dál častěji, můžu rozhodně říct, že to nejsou brzdy. Když se ručička přesune do zelené, do režimu regenerace, motor začne brzdit. Někdy funguje normálně, ale někdy je to jen těžké. Velký problém je, když sjíždím prudký kopec na stezce u svého pozemku, doslova se zablokují zadní kola a já skončím ve smyku z kopce. Nebrzdím. To je nebezpečný způsob jízdy na čtyřkolce.

I am concerned that the problem is related to the battery replacement, which was not done professionally. Probably the BMS protects the battery from a large recuperation and the recuperation is interrupted and the motor is disconnected, which if disconnected can slow down the wheels a lot through the high gear and as you write, the wheels will lock up.

[Tommy2bits]

7 hours ago, LAMA said:

I am concerned that the problem is related to the battery replacement, which was not done professionally. Probably the BMS protects the battery from a large recuperation and the recuperation is interrupted and the motor is disconnected, which if disconnected can slow down the wheels a lot through the high gear and as you write, the wheels will lock up.

The only specific concern that you cited appears to be that the battery was "not done professionally."  Please explain what is concerning you that a "professional" would do differently beyond remove 8 old batteries, install 1 lithium battery, and charger that comers with the battery. There is nothing else to do. This is the setup that many non -professionals have done. Yes you can further reprogram the controller but many have have not done this. Please explain what is the technical concern thanks 

[LAMA]

On 8. 9. 2025 at 4:44, Tommy2bits said:

Jedinou konkrétní obavou, kterou jste uvedl/a, se zdá být, že baterie nebyla „odborně vyměněna“. Vysvětlete prosím, co vás znepokojuje, že by „odborník“ udělal něco jiného než vyjmutí 8 starých baterií, instalaci 1 lithiové baterie a nabíječky, která je součástí dodávky. Nic jiného se dělat nedá. Toto je nastavení, které provedlo mnoho neprofesionálů. Ano, můžete ovladač dále přeprogramovat, ale mnoho z nich to neudělalo. Vysvětlete prosím, v čem spočívá technický problém. Děkuji. 

The second sentence of my post explains my concern "Probably the BMS protects the battery from large recuperation and the recuperation is interrupted and the motor is disconnected, which when disconnected can slow the wheels down a lot despite the high gear and as you write, the wheels lock up."

I have read all your posts and I think that the problem is not in the strong recuperation that almost locks the wheels. I think that the battery is weak and cannot handle a larger recuperation, which is why the BMS protects it and disconnects it, and the motor then brakes strongly through high gears and locks the wheels. I am not in a position to better determine the error. I can only guess at the possible error based on what is written.
If you write that the wheels lock, then it is not normal, it is bad and I recommend contacting the dealer. Here we can only guess.

[GNFO]

4 hours ago, LAMA said:

The second sentence of my post explains my concern "Probably the BMS protects the battery from large recuperation and the recuperation is interrupted and the motor is disconnected, which when disconnected can slow the wheels down a lot despite the high gear and as you write, the wheels lock up."

I have read all your posts and I think that the problem is not in the strong recuperation that almost locks the wheels. I think that the battery is weak and cannot handle a larger recuperation, which is why the BMS protects it and disconnects it, and the motor then brakes strongly through high gears and locks the wheels. I am not in a position to better determine the error. I can only guess at the possible error based on what is written.
If you write that the wheels lock, then it is not normal, it is bad and I recommend contacting the dealer. Here we can only guess.

While I would agree that the installer should have used two of those particular batteries, my opinion is based more on the fact that the output continuous discharge limit of that battery is 200A vs the 400A capability of the motor, not because of the regen input limits.  His Newtipower 48v 135ah battery supposedly has a 200A BMS and a 2C rate.  According to the Hisun dashboard meter the max regen input is 100A, so even his one battery should be capable of handling it.  

The other reason I'm not convinced it's the regen is that when BuggyBoy had issues with his BMS tripping due to reaching max capacity, it caused errors in the system requiring him to turn it off and back on, not locking the wheels, which I don't think a free spinning motor could do.

"Locking the wheels" is definitely not normal, but there's something more to the issue. It would be interesting to know if that installer had ever put in two such batteries and to see how the UTV handles with that.