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Joined: Fri Apr 28, 2017 4:12 am

80% charge limiter (automated)

Fri Apr 28, 2017 5:22 am

Hi Everyone,

We know that for the sake of extending the traction battery life, it is better not to charge it to 100%. ... _batteries

Mitsubishi is probably limiting the maximum charge level somehow, so the battery would not degrade so quickly.
But many of us don't need the 100% range everyday and would like to have some convenient way to limit the maximum charge to, say 80%.
So far I have found on this forum only solutions with manual timers - which is cumbersome and impractical to use.

Unfortunately, Mitsubishi iMiev does not have an option to charge it to 80% only as Nissan Leaf has.

Has anybody tried to create some automated switch based on current state of charge (SOC) and/or current battery voltage that would disconnect the power to the charger when some preset charge level is reached ? Some device that you would have in (or outside) your car that will do the job without the user ever bothering about it ? If the device could be also used by non-tech users, without any cabling and drilling that would be great.

My personal idea would be a (remotely?) controlled switch (to cut off the power), and the information about SOC taken from the CAN bus ?
How about easier solution, like taping to main battery cables to measure voltage (sending signal to cut-off switch at some voltage level) ?

I know from me it's just ideas without really putting something together, but maybe somebody has got further and can share some experience.

Thanks to everybody for sharing ideas/solutions

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Re: 80% charge limiter (automated)

Fri Apr 28, 2017 9:11 am

There's been speculation but no advanced design or implementation by list members beyond simple charging timers, AFAIK.

I've been waiting over a year now for my JuicePlug to arrive and get this done. Being able to say "Charge to 40% now and 100% by 07:30" would be the best regimen for me, but the JuicePlug specs are still loose on exactly whether that can be accommodated. With Washington State's plentiful hydropower, we don't have Time Of Use metering or hardly any smart grid features on residential accounts, so no prospect for utility incentives as in California.
2012 i-SE "MR BEAN" 98,600 miles
2000 Mazda Miata EV, 78 kW, 17 kWh
1983 Grumman Kurbwatt EV,170 kW, 32 kWh
1983 Mazda RX-7 EV 43 kW 10 kWh
1971 "Karmann Eclectric" EV 240 kW 19 kWh
1965 Karmann Ghia Cabriolet

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Re: 80% charge limiter (automated)

Fri Apr 28, 2017 10:41 am

jozefsvk, as jray3 pointed out, this has been discussed in the past. The two manual options we presently have are the mechanical timer (which I favor) and the Remote (in North America).

The J1772 interface has no SoC measuring capability; however, here's an example of what could be done: CaniOn outputs SoC and thus an output triggered by SoC>80% going to a power disconnect circuit, is certainly feasible. Problem is that there is no commercial incentive to do this and, unless someone is really dedicated to this labor of love, is it really worth someone's time and effort to undertake this? Life is too short...

As it is, Mitsubishi built this car using the KISS principle (Keep It Simple, Stupid) and speculation is that they belatedly added the Remote to North American cars in response to Nissan's Leaf connectivity capability (for which I am thankful).

For me, knowing that the car's fuel gauge goes up by three bars/hour on L2 allows me to simply set the mechanical timer (in one second) to have the car normally stop charging at 12 bars whenever I plug it in.
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