Energy Matters Forums

[FarmerJohn]

The car would keep accelerating hard to much faster speed but as you can see as soon as you reach 135kph the computer reduces the power to keep the max speed limited to 135kph.

"Captain, she canna take it much more. Another 15 sectors and the engines'll burn up fer sure"

(excuse me, I'll get my coat)

[offgridQLD]

In Japan they often put silly speed limiting functions on there cars. A lot of the high performance Jap import cars are limited to 180kph.

I often hit the 135kph limit when i merge into the 110kph zone on the motor way. The first time it happened I thought it was a limit on how long you can hold full power . Its funny though as even at 135kph your only using just over 1/2 the available power when it backs off to hold that speed.

The car in all has been limited to strike a balance between performance and economy/range. The battery cells are capable of 500A bursts - 10c but they have limited them to 150A 3C max in the Imiev.

The great thing about electric cars is if you want performance its a lot easyer to extract than using a internal combustion engine. You just tweek of the controller and you have it . The battery's will deliver the power and its there to be taken. At the expense of range though. Even the Mitsubishi Imiev evo electric pikes peek race car is just using four x stock Imiev electric AC motors. They just feed them double the power each (100kw) for a total of 400kw!

Just to give you some idea of how fast these electric pikes peak cars are.
http://www.youtube.com/watch?feature=player_detailpage&v=D0bygKFvnSI

This weekend when I drive the 104km home from the coast I will run the Air conditioning all the way home and see if there is any noticeable reduction in the SOC gauge compared to last weeks trip.

I'm finding we are doing lots of driving around just for the hell of it in the Imiev. In the gas car you would get a reminder if you did this in the form of a $75 reduction in your wallet contents. At under $2 - 100km its like winding the clock back 20 years on fuel prices

Kurt

[offgridQLD]

I have been using end amps to determine when to switch to float. I have a 3hr absorb time out set though my end amp setting of 16.5A is usually kicks in way before 3hrs and we switch to float. The 16.5A takes into account the typical base load on the system through out the day.

Today we had to go out from around 9:30AM untill around 1:00pm. I wanted to return around 6kwh into my Imiev's battery so I put it on charge around 9:30AM. The house bank was on bulk at the time at around 57v . We had enough power to keep the house bank slowly charging at a few hundred watts and cover the Imievs charger. When I returned home just before 1:00pm the Imievs battery was just balancing at a few hundred watts and the house battery was in absorb 60v and the amps slowly dropping down towards (end amp setting)

This just had me thinking if I should be using end amps when charging the imiev or if its fine now to just count on the absorb timer. Most days I tend to just put the Imiev on charge after the house bank is on float so its not a issue.

Anyhow after spending the week driving our diesel 4wd. (I had to do a bit of heavy towing) getting back into the imiev today felt so smooth and quiet. Having just pumped $95 for 60lt of diesel into the ute on Friday Its was a depressing experience handing over two $50 notes and getting back just enough change for a ice cream.All just for a few hundred km of driving. It all made charging the Imiev for free today even more pleasing.

Kurt

[jimbo]

I have my end amps around 12.5 which takes into account the background load once the fridge compressor switches off. Now that the worst part of the year is over I have reduced the max absorb time from 4 hrs to 3 just in case an appliance like a fan is left on and the end amps aren't triggered.

Hopefully midnite release their shunt that will allow the classic to measure amps leaving the battery bank.

[offgridQLD]

Yes the external shunt monitor will be great I had forgotten about that. I'm a little out of touch with the classic side of things. I still need to update my classic to the latest firmware and have a good read of the forums to catch up on the latest improvements.Some times when things just work its nice to leave it that way for a while

As soon as the car charger stopped it didn't take long for the amps to drop off and trigger end amps.

I am holding back a little on installing the additional 4200w of PV as I am so indecisive about where to put the actual PV . Some times having to many choices is a bad thing. I'm also procrastinating on whether or not its time to move all my components out of the large tall steel vented cabinet they were installed in originally .

There is some room there but when I add one extra classic charge controller and a combiner boxes along with a large external shunt for my inverters logger to handle the two classics along with a few other things it will start to get i little tight and I hate bending down to shin height to access things. I like everything to be at eye level with good space in and around each component. I was trying to hold off on this job untill I upgraded to lithium as the cabinet provides a little bit of a barrier from corrosive gasses. Not a issue with the lithium's.

Shame all the analog kwh meters and hr meters for the generator are all in there so its a lot of reconfiguring and rewiring More than I can handle in one weekends work so it might be a job for next holiday time.

Kurt

[Gordon-Loomberah]

How much under 3 hours do you normally reach an end amps triggered end of Absorb?
How constant is the current in the i-miev charging routine?

I'd be inclined to leave end amps set as they are for now, and make sure Absorb time is sufficient to cover deeper than usual DOD days. Staying at Vabsorb a bit longer than the minimum required is no problem for flooded cells, and can actually reduce the need for Equalise charges, as the electrolyte has a regular small stir each day.
Once you are living there full time, the loads will probably be all over the place, but you can be more hands on and adjust settings as required.

[offgridQLD]

The imiev charger consumes 2200w and is a constant current charger. It ramps up from 0w - 2200 over about 20 seconds (kind of like a soft start) . Then it will hold the constant current (works out to 2200w on my inverters 240v) For 90% of the charge. Then it will reduce the charge down slowly as is balances. Usually from 2200w down to around 300w over 30min - 1hr depending on how much balancing it dose.I think the balancing stage has a timer and it just times out and sits at 2.2w standby after that.

I don't often do a full charge most times I keep the pack between 40 - 80% charged so I am always seeing 2200w in this zone. I could adjust the end amps on the fly for when I am charging to cover the car changers load I guess.

I we usually only see absorb for 30 - 1hr before we drop to end amp trigger point due to my shallow cycling . Though my wife has a habit of hand rinsing dishes turning the tap on and off 30000 times over 1hr just as the 20 second end amp trigger point it about to kick in .(STOP RINSING AT LET IT GO TO FLOAT ) The absorb voltage is reasonably high on my cells (factory recommended 60v)

Kurt

[Gordon-Loomberah]

The absorb voltage is reasonably high on my cells (factory recommended 60v)
Kurt

Interesting, I wonder if that is related to your post corrosion issue - more vigorous electrolyte bubbling, with a less than perfect sealing around the posts, leading to greater level of corrosion?
Still, anything that brings on the Lithium sooner is good eh!

[davidg]

Though my wife has a habit of hand rinsing dishes turning the tap on and off 30000 times over 1hr just as the 20 second end amp trigger point it about to kick in .(STOP RINSING AT LET IT GO TO FLOAT ) The absorb voltage is reasonably high on my cells (factory recommended 60v)

Sounds like you need a decent pressure bottle on the water line (I use a 100litre one) stops a lot of start stop on the water pump.

[offgridQLD]

I just took a 2nd look at the spec sheet for my cells . Picture below


Yes it was 60v for absorption.

I also noticed that max charge rate is 10% of C10. C10 on my cells is 800AH so only 80A This could be a issue with my additional classic charge controller and PV as I would have the potential for 160A or more! My thinking is I could just set a Amp limit of 40A On each controllers setting until I upgrade to lithium. Now that may sound silly but often the times I need the extra 4000w of PV total 8000w is when its overcast and both controllers would be under 40A. Then take the restraints off once I go lithium





Good idea on the pressure bottle for the water pump. I will look into one I think.

Kurt