Opel Ampera battery extender

Discussion about components from Ampera/Bolt and the PSA group which owns Opel these days
arber333
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Opel Ampera battery extender

Post by arber333 »

Last couple of days i worked furiously. I even forgot to take photos. Later on i made some so enjoy...

I got idea couple of years back when we bought a family car Opel Ampera an EV with 1.4l genset.
I later got quite intimate with its inverter, DCDC, charger and battery. That battery configuration got me thinking... How could i fool the car and add more battery in the back. Because lets be honest, 50km range hybrid is not enough, not for to AND from work.

So i now decided on next items:
1x VW passat 9kW battery
1x Ampera contactor
1x Simp BMS
10m length 25mm2 welding cable, cable ends, ties, shrink wrap etc...

What i did was take Ampera to a friend with a car lift. From there it is only a mile to Opel service point.
We followed the procedure from Volt/Ampera manual
1. Disconnect 12V battery GND cable
2. Pull out service disconnect fuse. By that HV is disabled and so inherently safe.
3. Then we took down the covers and shields under the car.
4. We disconnected control cables and coolant hoses for the battery, Here i needed to be carefull. My plan was to bleed as little as possible of the coolant from the battery. I made plugs and hose ends so that we plugged up the coolant hoses before much coolant could leave. Funny thing is i only had to plug the first two hose - socket pair. Inside other one vacuum held the fluid back for me to plugged them up.
5. Next we stacked a bunch of pallets under the car with some heavy timber to take the load of the battery
6. We lowered the whole car to that carrier and preloaded it.
7. We untorqued the carrier M10 bolts and then unbolted them.
8. When we raised the car i also slowly unlatched the HV cables and took them out. They have more play and i could pull battery halfh way out of the channel.
9. Then we lifted the car up and took out the remaining M6 bolts on top. We took the cover off and inspected the battery.
10. I decided on how to rout my additional 25mm2 cables. I connected one cable from the first positive contact all the way back to the right side of the T section. There was enough space to fit grommets there and still move the battery cover around. I decided 25mm2 cable would be ideal, because it would be small enough and it can carry up to 250A current from my add on battery. I routed the cable under the original orange conduit.
11. I connected the negative cable on the left side of T section and routed cable from the back. There is plenty of space there.
12. I left the cable some slack under cover so moving the cover wouldnt cause any load on the cable. Then i drilled the holes in cover on the right side and put two metal grommets there. Yes metal because they can be thinnest and have low profile.
13. We put the cover on and put the remaining cables inside orange tubes so they are marked as HV cablec to first responders!
14. I routed both cables inside just on the side of DCDC converter cables. There is enough space there under the plastic air channel. Finally i put Anderson 175A pins on both cables and put them in one grey connector. I am confident 175A continuous will be enough in paralell.
15. We put everything back in reverse order with minimal loss of coolant. After everything i returned fuse back to its place and put GND back to battery. As a precaution i took out the WOT sensor and taped it to the side of the coolant container. This way the dreaded "service HV charging system" couldnt happen since car wouldnt know if the tank is empty. Then i needed to fill up the tank and hope everything would deair through normal process.
Official procedure is to connect to the car and run some service procedure, but i dont yet have equipment to command the car and deair the system. I saw they command the 4 way valve to swing througl some service procedure and that takes care of every eventuality... Well see.

Now that i have live 360Vdc in the trunk i can play with it. First i will connect my Mazda charger and command some 10kW charging while car will be ON! This will confirm i can use connector normally and car will think it is in regen at the time.
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arber333
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Re: Opel Ampera battery extender

Post by arber333 »

Well finally i have more to report.

Last week i went on testing with my direct connection to Ampera battery.
1. i connected an extension cable from my Mazda directly to Ampera battery connector. Then i turned on charger and commanded slow increments of 5A untill i stopped at 25A which is 10kW and what my household can sustain.
2. I observed what is happening with SOC calculation in Ampera. DOH! Here i found my first obstacle. Obviously Ampera doesnt calculate SOC from the current sensor inside the battery. Rather it uses charger reports to integrate SOC. Now that i fed current into the battery and charger wouldnt report anything SOC wouldnt raise.
3. I also connected original charger and here i immediately got the dreaded "service HV system" error. I managed to erase the error with my Torque pro.
4. Then i continued to charger with car OFF. When i decided that battery is full at 392Vdc i started the car....!!!! Car wouldnt throw a definite error at me, but it did set the SOC at 0% and limit engine throttle so i could drive only up to 50km/h. I tried to erase errors, but i couldnt since there was not any to be found!!! Well in the end i just connected the charging cable and let the car sit on the EVSE for some minutes. In the end car returned 100% SOC and when i tried to drive off it offered up to 80km range from the start.

That was good news for my next planned experiment. To add a 9kW battery direct in paralell to first one and see what happens.
1. I conditioned both batteries to the same voltage of 390Vdc.
2. I made a wooden cradle for individual VW cell modules. Those are wedged between wooden supports such that battery cant fly off in case of sudden stop.
3. I installed the 9kW battery in the trunk and connected it via 300A fuse to HV connector in the trunk. Everything is still for testing...
4. Since batteries were full we went for a drive. We managed to drive for a 78km of mixed driving untill genset turned on. Driving included like 75% of highway driving at 110km/h. I observed increased SOC in the beginning of drive since car thought it was still at 55km.
5. I let both batteries charge through original 3kW charger which even now looks like it would last for 6H. Tomorrow we will again test range if the car can work out more range... I am sure easier driving would show even more range.

Later on i intend to make a box from Alu sheet metal and make a new trunk bottom where i will fit the new cells in the back. I will leave an option to fit a 10Kw 3 phase charger if i will be successful with simulating charger CAN bus reports.
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Re: Opel Ampera battery extender

Post by PatrykS »

Damn, I have ~16kWh installed in the trunk and waiting to play with the car - looks like someone was faster than me :-) Did you install that additional Ampera contactor inside battery yet?

Good luck with experiments, I'm waiting for next news! :-)
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Re: Opel Ampera battery extender

Post by arber333 »

Can you show some photos of your build?
I actually only fitted two cables inside the battery just behind the contactors. That makes the additional battery an organic part. VW cells are more than a match for Volt cells in the upper part of the curve, but in the middle and lower part they lag behind a bit. This is why I see a phase shifted behaviour when in regen after 50%soc.
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Re: Opel Ampera battery extender

Post by PatrykS »

Outlander LEV46 battery in its original steel bed (cut at both ends to fit Ampera's trunk) plus one additional module not fastened yet. Orange wires go to the box with CHAdeMO socket and contactors, both from Outlander. Outlander packet is not the best option in terms of weight and space, but it's a quite cheap option to test how it works. If it will work well then the target is 8 modules from TMS 85 - so 50kWh, CHAdeMO and combustion in emergency would make such Ampera quite a beast :-)

>> I actually only fitted two cables inside the battery just behind the contactors. That makes the additional battery an organic part.
Good for tests, but your HV wires should be isolated at both ends when ignition is off. My idea is to connect my wires directly to the battery-inverter wires, and contactors in the trunk between extra battery and my wires will be controlled in parallel with contactors in battery (coils of contactors will be connected together), this way isolation test done by car will test my wires too in a safe manner (separately positive wire and negative wire), and I won't need to remove battery for making it. Worked fine in Nissan, nos sure how it will work here.
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Re: Opel Ampera battery extender

Post by arber333 »

PatrykS wrote: Mon Jul 13, 2020 7:56 am Good for tests, but your HV wires should be isolated at both ends when ignition is off. My idea is to connect my wires directly to the battery-inverter wires, and contactors in the trunk between extra battery and my wires will be controlled in parallel with contactors in battery (coils of contactors will be connected together), this way isolation test done by car will test my wires too in a safe manner (separately positive wire and negative wire), and I won't need to remove battery for making it. Worked fine in Nissan, nos sure how it will work here.
Really nice! I suggest you strip the plastic and bottom mat so you can access primary structure. Maybe you will get an idea how to fasten the remaining brick in place.
Yeah, we consider Outlander cells too, but they were too large a form. VW are best for testin yes. But later i will probably make a bed for one complete Ampera basttery in the back. But that will probably force me to strengthen the rear springs.

My first idea was also to split the power cable and make a Y connection. I averted from this because i wasnt so sure in that power cable. I needed to make a direct battery connection to experiment and for that 25mm2 cable is good enough.
True, for now i have a direct connection to the battery. But later on i intend to use a contactor, a fuse and probably a reverse diode. This will enable me to charge both batteries with original 3kW charger. I think someone have done this with Outlander vehicle.

I am not so enthusiastic about large battery packs. I see now that there is a lot of SOC that Ampera does not use at all. Large means you also carry uneccessary weigh with you...
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Re: Opel Ampera battery extender

Post by PatrykS »

>> I suggest you strip the plastic and bottom mat so you can access primary structure. Maybe you will get an idea how to fasten the remaining brick in place.
I know that structure and when you strip the metal plates there is just tiny plastic box with cells, so it's best to keep the metal plates which are strengthening the module (brick). I think I'll cut one segment from original steel bed and will fasten it to the full bed below.

>> But later i will probably make a bed for one complete Ampera basttery in the back.
Do you plan to strip the cooling from it? Because it's also quite big battery. Weight of 8 TMS modules (40kWh) is the same as my 6 Outlander bricks and similar to Ampera battery - about 200kg.

>> But that will probably force me to strengthen the rear springs.
For sure it will be needed.

>> I averted from this because i wasnt so sure in that power cable.
Why?

>> But later on i intend to use a contactor, a fuse and probably a reverse diode.
Hmm, you want to just charge the trunk and not use it for driving or what? :-)

>> Large means you also carry uneccessary weigh with you...
But it's a very sweet weight :-) Especially in long route :-)

BTW: I will drive through your country 2 weeks from now - on way to Croatia.
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Re: Opel Ampera battery extender

Post by arber333 »

Hm... in 2 weeks i think i will be on my way to TUV sud in Munich to make my TUV there. Maybe on your way back?

I didnt mean to strip plastic from the cells. I meant to strip the car trunk and use the chassis to make custom cell holders.

I actually have split Ampera cable right here. I use it for my tests with Volt inverter. But when i observed the battery and the simple structure i decided to just install cables to battery.
Dont forget you ned to get to the power cable first and that is quite a task if you dont release the battery from the car underside.
Dont be afraid using thin cables. I decided on 25mm2 because they just fit. I could use 16mm2 and it would still be good.

Today we made 78km range driving on the highway for the most part. So 16kWh Ampera pack + 9kWh VW Passat pack = 25kWh and to get the usable value 25kWh * 0.70 = 18kWh. I use 70% SOC since 10% in the upper range is not used and 20% in the lower renge is off limits as well.
This makes consumption at 230W/km which is quite higher than my Mazda at 185W/km on highway!

This is what i meant by carrying dead weight.
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Re: Opel Ampera battery extender

Post by PatrykS »

>> Hm... in 2 weeks i think i will be on my way to TUV sud in Munich to make my TUV there. Maybe on your way back?
Hard to say if we will stop there - 2 day journey to Croatia for family vacation and 2 day back usually make us a little hurry, we're from north of Poland :-)

>> I didnt mean to strip plastic from the cells. I meant to strip the car trunk and use the chassis to make custom cell holders.
I see. I just lied steel bed on the flat floor of the trunk, and I intend to fasten it to the chassis using some belt (wrapping).

>> Dont be afraid using thin cables. I decided on 25mm2 because they just fit. I could use 16mm2 and it would still be good.
But thicker cable means less losses, with a little more weight. So far I used 50mm2 for Nissans.

>> I use 70% SOC since 10% in the upper range is not used and 20% in the lower renge is off limits as well.
Correct. I'm curious if charging it up to 4,2V/cell (before longer trip for example) would not make Ampera unhappy - now you can check quite easily :-) At the bottom you can get to 16% with MyVoltHold, or near 0% if you kill the engine somehow (like removing spark cables).

>> This makes consumption at 230W/km which is quite higher than my Mazda at 185W/km on highway! This is what i meant by carrying dead weight.
What Mazda is that? Maybe a lot lighter? Other tires?
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Re: Opel Ampera battery extender

Post by arber333 »

82km with one charge and driving in traffic on highway.
Notice 8.8kW consumed! This shows that car actually uses internal current sensor for driving. But for charging something else is used. Maybe simple CAN string of values....
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Re: Opel Ampera battery extender

Post by PatrykS »

Any other news?
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Re: Opel Ampera battery extender

Post by arber333 »

PatrykS wrote: Fri Aug 21, 2020 7:20 pmAny other news?
Yes well I took battery apart since we needed to go for our vacation in Genoa.
When I return I will make a permanent metal bed for the battery with compartment to access emergency equipment and charging cable. With my first makeshift arrangement I couldn't get to tools and equipment under the trunk. I will also use a contactor and a diode because when you switch the car off there are strange currents going about which disturb BMS and HPCM2.
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Re: Opel Ampera battery extender

Post by PatrykS »

On Monday I got connected 16kWh in the trunk to main battery, so far so good, occasionally I'm seeing P1E00 with P1EBC, something with controlling relay coil. MyGreenVolt reports power/current of main battery, power divides more or less in half between batteries, depending on SOC. AC charging works. I've been using CHAdeMO for the last two months (with ignition on), limited cautiously to 20kW/50A, now I need to connect it back and try full 40-50kW/125A. Great car made even greater :-) :-) :-)
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Re: Opel Ampera battery extender

Post by PatrykS »

Today test - 75km/h, 155km and 19km left was estimated by car. Veeeeery nice for me :-)
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Re: Opel Ampera battery extender

Post by PatrykS »

Next test - 110km/h, range about 120km. I drowned the battery beyond limit (using MyVoltHold) and got 10,8kWh from the main battery and 13,2kWh from additional one. Before the test charged slowly from AC to about 4,07V/cell, during the test disccharged to 3,53V/cell. Then 125A from CHAdeMO to 80% raised temperature of additional battery by 9 degrees (from 22 to 31 degrees C), power started from 43kW end ended with 48kW. Niiiiiice car! :-)
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Re: Opel Ampera battery extender

Post by PatrykS »

About P1E00 with P1EBC - seem to be gone since I corrected relay signal connections. For now zero errors from the car, that was the biggest unknown for that battery extension.
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Re: Opel Ampera battery extender

Post by arber333 »

PatrykS wrote: Mon May 24, 2021 5:33 am About P1E00 with P1EBC - seem to be gone since I corrected relay signal connections. For now zero errors from the car, that was the biggest unknown for that battery extension.
Thanks for sharing.
You mention you corrected relay signal conditions. What do you mean by that, main battery relay or the additional battery relay? And what is your protocol for correction please.

I also get those two messages when i stop and turn off the car if both batteries are full or nearly full. It doesnt appear if i drain cells below 50%.
We simply reloaded firmware to HPCM2 module and everything worked.

tnx
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Re: Opel Ampera battery extender

Post by PatrykS »

arber333 wrote: Mon May 24, 2021 6:36 amYou mention you corrected relay signal conditions. What do you mean by that, main battery relay or the additional battery relay? And what is your protocol for correction please.
I have basically copied Ampera's HV relay module in the trunk - for additional battery, and I did a mistake in wiring of one of the relay control signals (for AC charger), that relay was not needed at that time, but probably caused some glitches.
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Re: Opel Ampera battery extender

Post by arber333 »

PatrykS wrote: Wed May 26, 2021 5:31 pm I have basically copied Ampera's HV relay module in the trunk - for additional battery, and I did a mistake in wiring of one of the relay control signals (for AC charger), that relay was not needed at that time, but probably caused some glitches.
Hi

Where do you tap into start signal for aux battery relay then? Did you draw a schematic? Maybe drawn on original Ampera wiring. Maybe you can share it?
I am thinking of using APM modules Enable signal. It comes online when you press Start button and it goes away when you stop.
Do you use any time delay from start of main battery to start of aux battery?

tnx

Arber
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Re: Opel Ampera battery extender

Post by arber333 »

Yesterday i found some spare time and i set our Ampera up to replace plastic trunk bottom with alu plate. Idea was to make a flat surface for mounting any kind of aux battery mount, whitin reason of course.
I decided to setup my VW Golf GTE hybrid battery first. It has some good features for aux battery use. It is low profile, compact rectangular shape and it is just big enough to still keep a usefull boot after the mod.

First i cleared the trunk and put come C profiles on the bottom of the car. They will allign to accept the main floor where i will eventually fasten the battery mounts. I had to carefully clear away the plastic and wiring. Then i used existing M6 bolts in the trunk to fasten the profiles to the bottom. In front of the APU module i used its mounts empty mounting slots to fasten additional profile. This makes the complete flat plate really stiff.
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Despite the supports i decided to have the edges of the plate bent down so that they provide additional stiffness and support on the sides. And i can use that to seal the sides against dust and moisture. Because C profiles are aluminum i cant effectively fix the M6 nuts from the underside, so i had to go and put “rivnuts” in the top of the profiles. Those are M6 nuts encased in aluminum rivet that can be expanded inside a hole by a special lever. This allows the nut to be firmly fixed for me to bolt the flat sheet down on the profiles.
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Then i bolted the actual floor to the supporting structure. I made sure it clears the underside devices and especially the APU converter. Alu sheet was impossible to make fit the rear of the trunk where plastic takes a rounded shape. There is about 20mm gap at the widest spot and i decided i will deal with it next time with a specialised sheet metal cover which will seal the opening.
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There is also a 12V aux battery to consider. At any time i get DTC from the HPCM2 i can delete it and reset it using my Torque pro tester – if i can. But in case that is not effective i will need to resort to taking the minus pole from the battery and this will clear the HPCM2 memory. But this requires access to the 12V batery. This is why i put a hole in the floor of 78mm diameter that i can plug with plastic cover for domestic drain pipes. It works really effectively. of course i will install the one without the hole.
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Next i thought up a simple mount that will allow my battery to be suspended to in case of a braking and/or accident. I thought up a two inox profiles. One is Z profile and will caprure battery module from the front and fix it from one side. The other will be C profile and i will use it to bolt the batteries down.
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Some more photos of battery from front and rear.
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Re: Opel Ampera battery extender

Post by PatrykS »

arber333 wrote: Thu May 27, 2021 8:42 am
PatrykS wrote: Wed May 26, 2021 5:31 pm I have basically copied Ampera's HV relay module in the trunk - for additional battery, and I did a mistake in wiring of one of the relay control signals (for AC charger), that relay was not needed at that time, but probably caused some glitches.
Hi

Where do you tap into start signal for aux battery relay then? Did you draw a schematic? Maybe drawn on original Ampera wiring. Maybe you can share it?
I am thinking of using APM modules Enable signal. It comes online when you press Start button and it goes away when you stop.
Do you use any time delay from start of main battery to start of aux battery?

tnx

Arber
Hi!

>> Where do you tap into start signal for aux battery relay then?
In parallel with main the main battery contactors - coils and contacts.

>> Did you draw a schematic?
Well, kind of - it's closer to netlist than to schematic :-)

>> Maybe drawn on original Ampera wiring. Maybe you can share it?
Maybe someday, not yet.

>> I am thinking of using APM modules Enable signal. It comes online when you press Start button and it goes away when you stop.
APM is connected in parallel with main battery output, APM and inverter are connected permanently with each other. Please mind you need to have two contactors - for negative and for positive terminal of the battery as they are connected separately, positive little later than negative because of precharge resistor.

>> Do you use any time delay from start of main battery to start of aux battery?
No, exactly the same moment, contactors of main battery and of auxiliary battery are just paralleled on input (coils) and output (power terminals). Please mind that AC charger has it's own set of contactors.

Regards,
Patryk
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Re: Opel Ampera battery extender

Post by PatrykS »

>> Yesterday i found some spare time and i set our Ampera up to replace plastic trunk bottom with alu plate.
Wow, impressive work!

>> There is also a 12V aux battery to consider.
I needed to disconnect it few times so far, no big problem, except the last time - when I got trunk full of ceramic tiles. I mean FULL :-) After that I took two 25mm2 wires and a massive switch and now I can disconnect it from chassis without emptying the trunk :-) In case 12V dies I have connected third 25mm2 wire to positive connector - so I could connect additional 12V without having to remove the auxiliary battery.
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Re: Opel Ampera battery extender

Post by arber333 »

PatrykS wrote: Sun May 30, 2021 9:55 pm
>> Do you use any time delay from start of main battery to start of aux battery?
No, exactly the same moment, contactors of main battery and of auxiliary battery are just paralleled on input (coils) and output (power terminals). Please mind that AC charger has it's own set of contactors.

Regards,
Patryk
This sounds like you are connected in front of contactors. So you really need to disconnect both lines.
My plan is to connect behind hv contactors and use only one aux contactor with diode across it so i can charge using original charger. Current will flow back but not forwards unless i use contactor. That should eliminate surges after a short drive and calm down hpcm2.
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Re: Opel Ampera battery extender

Post by PatrykS »

arber333 wrote: Sun May 30, 2021 10:54 pmThis sounds like you are connected in front of contactors. So you really need to disconnect both lines.
Correct - I didn't want to touch Ampera's battery.
arber333 wrote: Sun May 30, 2021 10:54 pm My plan is to connect behind hv contactors and use only one aux contactor with diode across it so i can charge using original charger. Current will flow back but not forwards unless i use contactor. That should eliminate surges after a short drive and calm down hpcm2.
For me the contactors are doing that - after disconnection there is no current flowing. It means some current usually will flow right after connecting them again, but it doesn't make car to report any problem, only contactors could get some tear prematurely, we'll see. I'm looking on current flowing after I stop, but before turning ignition off, usually less then 1A, sometimes even 4A. I'm using BMSes built into Outlander modules and current sensor from Outlander, so I have pretty good overlook on what is going on in every moment.
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Re: Opel Ampera battery extender

Post by PatrykS »

If you would move the current sensor in the main battery to the wire between contactors and junction point of the batteries then current flowing between batteries won't be measured and won't cause any problem to the car.
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