It is true that the cells can give an early or false neg delta, In the case of the Robitronics Overloader 2, you can bypass the problem, the user can set a time limit before the charger begins monitoring for negative delta V.
It is true that the cells can give an early or false neg delta, In the case of the Robitronics Overloader 2, you can bypass the problem, the user can set a time limit before the charger begins monitoring for negative delta V.
You can also set a maximum over-capacity (eg 150% of rated capacity) which is probably more useful than time. I often use this on 10% to give a quick charge to sticks so that a discharge cycle won't hurt the sticks. That will pump in about 650 Mah (in about a minute or two) before it stops due to the 10% rule.
FYI, the Robitronics Overloader 2 is the new version of the Overloader. They have added a USB port to it.
The old one is a rebadged Supernova Competition, as are the Duratrax ICE and the Team Checkpoint TC1030. In the US, the Duratrax and Team Checkpoint are more available. I like the Tc1030 because it can charge at 10 amps instead of 8 and it has a backlit screen that is easy to read at 2am when I go down to put the next set of batteries on charge.
I'll investigate the OL2 for its' USB port, but it may not be practical for me. I'm currently running seven chargers at once.
Reliability: The Supernova clones can discharge at up to 30 amps (pulsed), but the fine print is that these rates are for sub-C packs. Honda sticks are "D". 7.5amps is a practical limit on discharging. I have blown 3 TC-1030s and one Duratrax ICE. My less sophisticated chargers, SuperBrain 989 models, are more durable, being able to discharge at 10 amps, but I kept taking them back to the factory until they rewired the power lines for me. I kept melting the banana plugs to the power supplies. They don't mind fixing them, because I'm probably their heaviest user and they're getting plenty of real world reliability data from me. i run my chargers 24/7 with rarely more than a couple hours break between cycle runs.
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2000 MT #4227 175K miles - Citrus Yellow, BetterBattery
The voltage is adjusted with a small single turn pot just below the terminal strip you can see them in the side view of this collage: http://www.99mpg.com/Projectcars/mim...dcharger.jpg,0
700MA would work with a smart charge terminator, but when you are looking at 120 cells, the delta V is useless, as some cells are going to be rising when others are falling. Delta V is good for single cells and becomes less useful and reliable as more cells are charged at the same time.
The idea of the simple charger was to have an inexpensive way to grid charge and top off the pack to do some rebalancing.
The 350MA is right at the top edge of what I feel comfortable with for current in a dumb charger, but the price is right, and it should be able to bring back packs that are doing recalibrations or having other issues.
The 12V fan supply can be adjusted down to 10.8, and that is how I used it. The fan will have no problems running overnight or for weeks continuously for that matter. That's what they are designed for, and cooler is better as far as the cells are concerned.
As you know, I use a four contact trailer light plug (indexed) for my charging input. That leaves two contacts un used. I am planing, soon, to add two more wires to bypass the 12 switch for the fan and on the plug from the power supply I will short those two pins together. Then whenever the power supply is plugged it it will also activate the fan full time. I decided I needed to do this since summers nights here can be over 85F.
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Jim Isbell
2000, 5 speed, 250,000 miles
"If you are not living on the edge, well then,
you are just taking up too much space."
We need to get someone with a pack that is having recals on a regular basis to try rebalancing their pack with this prototype charging system, before we consider a group buy of the supplies.
I charged my spare pack, but don't have time to swap it for testing with my old 146K pack that is buried under my boost supply and air compressor in the batmobile.
Anyone in this area want to give it a try, so we can take this to the next level?
Has anyone ordered the supplies and built another prototype?
The discharge cycle can be simply and safely accomplished by MIMA owners with the current software.
MIMA active (mode 1) which has Automatic Background Charge, can completely disable regen if the ABC is adjusted for zero background charge. Then you manually assist as much as you like to drain the battery until it no longer provides assist, and you have safely completed a discharge with all subpack monitoring for cell drop off in place.
The Calpod IMA disable will do the same for the non MIMA insights.
I put up the schematic and bought and tested the charger, as a service to the Insight community.
We have needed a tool like this that can keep packs balanced and allow limited PHEV for people with short commutes.
I do not intend to sell these supplies, so consider this an open source project, and feel free to build your own units and finish and improve the design.
As far as the prototype is concerned, I ran a test cycle, and am satisfied that the concept is sound, the supplies work well in this series configuration, and it does meet my design goal.
If people want to do a group buy of the supplies, someone should grab the ball and go for it.
I have several big projects that I am devoting most of my time to.
Yesterday I just powered up and drove the basic chassis of a solar charged electric yard maintenance system.
I have an IMA motor that I will add bearings to so it will run stand alone, and will build a custom driver for the Insight inverter to run it.
The modified Prius synergy drive is mounted to a test stand, with its inverter, and I will be building a custom driver so that will operate stand alone, in preparation for using it in a full EV insight.
I hope to buy some lithium batteries and develop a lithium booster pack, possibily using Peters BCS, or another cell level monitoring system to keep them safe.
I want to make a better user interface and work on improving the MIMA software.
Since I do not own a pack that is having recalibrations, I have no way to further test the concept, but do not want to send my prototype to someone, as I want to have it here for test if someone wants to try it on their pack.
As I suggested, if anyone with a pack that is acting up that is willing to drive up, I will be happy to charge the pack using my prototype, so we have more test information.
I have a labview based data acquisition system that I will write a charger test program for to log the pack voltage during charge, and get a better idea of the end of charge rate of change, and the voltage settling characteristics, with the eventual goal of making the charger smarter and possibily adding a safe fully automatic and monitored discharge of the pack by monitoring the 10 subpack taps.
All of the assumptions and theories will not help if we do not do some real world test to see how a troubled pack responds to the 350MA CC with fan running.
This will not damage the pack, and if connected with the main switch turned off,is relatively safe to connect.
The charger has a long insulated positive probe, and an alligator clip negative lead, is fused, on input and output, and can be connected to the pack without removing the pack from the car.
I will add an output diode to further improve the safety.
My feeling is that even without the discharge cycle, this system will rebalance most recalibrating packs, and for less than $100 in materials, is something that any technically competent Insight owner should build and use.
I put up the schematic and bought and tested the charger, as a service to the Insight community.
Thank you for your efforts.
Good stuff.
Quote:
Originally Posted by Mike Dabrowski 2000
I have several big projects that I am devoting most of my time to.
I'll second that.
I have plenty to do if I somehow had 35 hours every day instead of 24... bored with nothing to do??? change your thinking ... the world is full of projects that need building... theories that need testing .... hmmm projects and testing ...
You know what the worst insult is... "I hope you perfect all your projects." ... if all my projects are 'perfect' how boring would that be... there is always room for improvement... less money$ ... more efficient ... smaller ... greener materials ... etc...etc... there is no end goal ... enjoy the trip.
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Smart Chargers & false neg delta V
