After thinking about doing this for a long time I finally put a system together. Its extremely simple, actually overly simple. There are still a ton of things to work out but. . . it works. The basic set up is this, 3 x 48V DC power supplies plus 2 x 12V battery float chargers hooked up in series to get about 168V. There is a diode to prevent current from flowing out of the car battery too and that drops it to about 167V. Is this safe? Well, I took several readings of the battery charge and saw it up to 170V( and as low as 145V.) If it normall goes to 170 then 167 should be safe (I think.) The MAJOR problem is that I'm bypassing the battery control module and it doesn't know that the battery is being charged. After starting the car and driving a few minutes the battery control module realizes that the battery is full and resets the state of charge (SOC) to full. To take advantage of the charge I have been driving in higher gear, lower RPMs more battery assist and coasting in neutral the last few miles before home instead of allowing parasitic hidden charging/ normal cruising charging. The power supplies are only 0.3 amps so I'm charging the battery very slowly (hopefully safer.) Also, you can't just hook the positive connection to the top of the battery pack unless you always leave the car on. I have it hooked up to some resistor thing down below (I have no idea what it is but it reads 160ish V when the car is off.) I'm sure I'm going to get a ton of comments about this especially admonishing my bypassing the BCM. The BCM and SOC are not so good in the first place. I always got low voltage SOC resets in the past so I wouldn't be surprised if the SOC is more accurate after a little plug in charging. I will add more info later, just excited about this and wanted to post. I have had it on for only 2 days and driven about 200 miles. The mpg increase is slight so far.
Umm, nicely done??? Don't really understand what real benefit you will get from this, the battery still discharges under boost and recharges while braking and coast. Sure, you might be able to start off with a full battery every morning, but you are still paying for it with house hold A.C. and risking your battery, your life, and personal injury. If you want a plug in car, get one.
slower is safer your right about that much... 0.3 amps is about ~1 / 20 the rated capacity of the stock batteries so this part should be ok...
The biggest problem I see is that since you are bypassing the normal SOC control and battery level indication... You don't know what the SOC of the batteries is... Since NiMH does not track the Voltage directly to the SOC you are being a bit risky by charing to a voltage point instead of by amp counting as the SOC stock system does.... At first this won't be an issue... over time it might cause you a big problem... as the SOC that the car thinks it should have gets more and more off from what it is.... only time will tell...
The only other concern I would voice is that NiMH Batteries if charged above 80% capacity on a regular basis tend to have a serivce life around 300 to 500 charge cycles..... If you keep the battery in a sweet spot.. including not charging above 80% or bellow 20% ... then NiMH can have a service life more like 10,000 charge cycles.... that is why honda keeps such tight control of the SOC.... Since you are bypassing that SOC control... be careful you don't charge the battery pack over 80% or you may end up wearing it out much faster than it ever normally would. . . . and remember SOC on NiMH is not linearly conected to the Voltage like a Lead Acid battery is.
But only time will tell....
make sure to let us know how it ends up working for you.
and congradulations.
Eventually my plans for something like this is a bit different.... Eventually I plan to setup a second battery that I can charge up and then use that second battery to extend the use of assist in the car while driving ... by giving the car an extra 20 amps or so from the second battery when it does assist... so if I am doing like 40 amps of assist I should be able to do it for twice as long... kind of like the way Mike does his but I am planning for a high voltage booster battery instead of a lower voltage that needs to be steped up... if you have any questions about trying this you may want to check out Mike's plug in Insight mod at.... http://www.99mpg.com some nice stuff . . . .
I don't understand the point of doing this either. If the Insight had an electric only mode then it might be worth doing but it's not the Insight has a history of a low battery state that needs additional charging. When I had my CVT it always had more than enough juice in the batteries from regenernative charging.
The only other concern I would voice is that NiMH Batteries if charged above 80% capacity on a regular basis tend to have a serivce life around 300 to 500 charge cycles.....
I'm with Ian on this one, charging up to full SOC and back down again will dramatically shorten the life of the battery.
You can do 100% discharges 10,000 times with the new LiIon types, but with the old NiMH tech in the Insight battery deep cycling could kill it far more quickly than you expect.
Having said that, I'm TOTALLY pro-plug-in for dozens of reasons. It would just be safer for your wallet to take a booster battery approach - at least when a lead-acid pops you won't be shelling out for a new IMA battery.
Tell me more about your booster battery idea. I don't want to rig up a fifth wheel or anything crazy but I do have 144V + worth of small 7 Ah lead acid batteries. That would basically double the battery capacity and only add about 100 Lbs to the car. I already have a way to charge the system, how would you inject the charge? I want to keep this as simple as possible.
First of all, the 5th wheel is not crazy, it works quite well, and I am considering making a high power version for non hybrid pickup trucks and vans.
The safest way to charge is through the SOC current sensor as I have, and only do it when the car is on. The charge voltage under normal conditions can go as high as 180V, the highest I have seen the pack when not charging is 169V. You are probably ok if limiting to 168V, but as Clett and Ian warn, you could be shortning the pack life. Armin is doing something similar to what you are doing, and has many months of data reguarding this type of charging.
Good luck, and be careful that you do not let that expensive smoke out of the batteries, the will not work well once that happens.
I appreciate that Honda limit charge range to 20-80% of capacity and that using full 0-100% range will shorten battery life, however we cannot discharge below 20% (can we?) as BCM willl not allow it, if the author perhaps limits charge to 90-95% of max he might get a useful increase in available IMA power with only minimal impact on life. Who knows. I like the idea of starting with a fairly full IMA pack each day especially if charged from some renewable source at low rate <500ma.
Perhaps we can safely charge with the vehicle off, if it recognises the change in SOC after a few minutes use, which the author reports it seems to do. The cold/low ima pack, cold engine morning starts are an mpg killer as we know. Please keep us updated. Peter
I connect right to the battery pack output terminals, and it takes care of passing through the SOC sensor. If I remember correctly, The charge can be applied while stopped, but certain conditions can set a code, so be prepared to reset the IMA if you set one.
Connection: http://www.99mpg.com/TheBestHybridmix/b ... tteryprog/
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Plug in Charging (I did it)
