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CT2007HCH 04-01-2014 12:59 PM

2007 HCH Battery replacement
I wanted to start a thread on my progress toward replacing my 2007 HCH IMA battery.

Car has 125K miles. IMA battery came on once but went back out. Mileage is OK at ~40Mpg. Power is very low and battery gauge drops almost instantly.

I bought a reconditioned set of batteries off ebay. Remove the existing battery and replaced the cells inside the battery pack.

The behavior is improved but not great. IMA light came back on. Battery indicator sits a 2 bars then goes to full charge quickly. If any assist is used it will go back to 2 bars. The improvement is that there is now some assist.

I'm in the process now of testing the old batteries to see if they can be saved.

If anyone is interested in the details I'll post my procedure and pictures

Daox 04-01-2014 01:43 PM

Welcome to the site CT2007HCH. We would love to hear about your battery replacement progress.

Cobb 04-01-2014 07:04 PM

Do you have the error codes? Maybe something other than batteries. Usually when the capacity falls below .65 amp hours in capacity it trips. Sounds like that has happened.

The IMA system uses taps at every other stick so if it senses an imbalance it stops and switches modes.

Testing the sticks is a passive way to go about it. If you can get a hobby charger to charge/discharge 5 cycles or so you can actually recover some usable capacity and get a better idea of a good vs bad stick and helps you to size them up so you can pair them off with a good/bad stick.

msantimanzano 04-15-2014 11:45 AM


Originally Posted by CT2007HCH (Post 418258)
If anyone is interested in the details I'll post my procedure and pictures

Very interested in what exactly you do here with your batteries. I have a Accord Hybrid and I also just purchased an entire battery pack (the whole thing, not just the battery pack by itself) on ebay and I also want/need to go through and check all batteries, refresh, cycle etc., and then I will pull mine from my car and do it to those as well. I really have next to no idea what I am doing, so I will eagerly watch what you do and go from there.

If you would also post all of the equipment you use, such as what specific charger, etc etc etc, it will be greatly appreciated.

How exactly are you testing the batteries etc.?

CT2007HCH 04-15-2014 12:55 PM

Reconditioning batteries
Well it has been a tough month for my battery replacement. I've had a battery pack that worked better, one that worked great and now battery pack is dead. I'll post what went wrong if I ever figure it out. But how to recondition batteries?

You can look around for details on how to remove the pack. I found a great youtube video for the pack removal in the civic. I don't know what it will look like for the accord but I assume it is similar. Warning the fully charged pack is 170V DC. It will kill you. Turn off the breaker. Then you are only exposed to 18V at a time.

Here is a picture of my charging setup /

You'll need a charger/balancer. I bought 4 cheap ones. Turnigy Accucell 6. The only downside to these is the max discharge is 5W so it takes ~12 hours to discharge a stick of 6 batteries.

So from the picture you can see the batteries come in pairs with the ends welded. Each stick is 6 batteries. I recorded the voltage of every stick when I removed it. Then I waited a day and checked it again. This will give you an idea if you sticks have a self discharge problem. Wait a week would be better

What did I do and what did I learn. I took each stick 22 total and ran it through a discharge/charge/discharge/charge cycle. All of mine were close to dead so the 1st discharge was ~0.

I discharged to 6V or 1V per cell.
I charge to a default setting of delta v 5mv per cell.
The cells are suppose to be 6500mah and you should set your charge max to 120% of that. So I started by setting my charge limit to 7500 mah. I had 1 cell reach a temp of 160F. So I aborted that and change to a max charge of 6500mah after that. I also changed my charge current from 5A to 3A.

So in summary you need to disassemble your pack and run them through the chargers. With 4 chargers I was able to do all mine in about a week.

What makes a bad cells? Discharge is low. All mine were about 4500mah discharge after a 6500mah charge. So pretty good. Self discharge. How much dose the voltage drop in time. A week is a good measurement.

One mistake I made was to put my old batteries back with 2 pairs replaced. Worked great for 1 day. The next day I had an IMA light. I took the pack back apart and the replaced cells measured 16V while the old cells measured 14-15. I think the problem was cells out of balance.

I'll post more if I get some success.

msantimanzano 04-15-2014 10:50 PM

Thanks for that update. Seeing the batteries in the open and such does help. What is your opinion on doing "grid charging" versus taking all of the sticks out and doing the charge/discharge?

I am waiting to get my battery pack delivery, and I will photograph and document my own process and post it online. Hopefully I will do things right, and it may be able to help another HAH owner, who finds him/herself in the same situation I am in.

I have purchased a Bio-Rad 3000Xi Digital Computer Controlled Power Supply, which I plan to use to charge the pack. It is adjustable for 25 to 3,000 volts DC, 0-300 milliamps and 0-400 watts. Being able to set it to run at specific numbers for specified time will help (I hope) me to do this right.

CT2007HCH 04-16-2014 12:12 PM

Grid Charging

The power supply you bought looks like it would work as a grid charger not as a battery conditioner. I like the specs on it, I may get one as a grid charger.

The charger/conditioner will cycle the batteries (charge/discharge). It will discharge to a voltage and will keep track of how many milli amp hours have been removed from the cell. This is important to determine the capacity.

The charger also has a circuit that will automatically detect full charge when the voltage starts to drop. It also has a temp sensor to abort charge when the temp of the cells gets to high.

Grid chargers. Well in my opinion it depends on what is wrong with your pack. My pack had 2 problems.

1) Fast self discharge. The cells are very old. For example when we left the car at the airport for a week the IMA battery was 100% dead. Grid charger won't help this. I also saw this on the cells after I pulled them out. I may do an experiment where I charge some and let them sit, then measure the voltage every day.

2) 1 or 2 cells in my pack were bad. Since the cells are in series current has to flow through every cell to charge or discharge. Because I had a few bad cells the total charge was limited. Grid charger should help this by forcing charge through the bad cells at a very low current. I ordered some part to build my own grid charger but the one you bought looks much better.

Here is the video that shows how to remove the pack in the civic.

I'm guessing the accord is similar. They didn't sell the accord for long but I think it was a similar system to the 06 civic.

msantimanzano 04-16-2014 12:26 PM

I am glad you think the power supply I bought looks like it will work to grid charge. I think I knew it would not work to do the discharge, but I thought the charging aspect would be more important than anything. I'll tell you that the unit is a high quality precise lab power supply and so, if its working properly, it should hopefully allow very precise settings to charge. I keep reading the manual but I still need to understand and learn. If I read it correctly, it has something called "steps" that allow it to be programmed to charge at a particular set of settings for a specific time, and then to switch to other settings. If I understand it correctly, it could allow for structured timed drops in charging power levels, which I think I have read would be good as the batteries reach specific state of charges?

Beautiful would be to find a device that can be connected to a battery to monitor the voltage, that would automatically shut off at a specified voltage. Then something to drain the battery could be connected to it, and one would know the discharge would cease when the critical voltage level for discharge has been reached. There isn't any such thing for sale out there is there? Could maybe one of those r/c battery balancer units be used to discharge the entire pack to a specified voltage level?

I have the manual on pdf for the BioRad if you would like it.

CT2007HCH 04-16-2014 02:31 PM

Final battery install
OK I finally have a successful battery install. Learn from my mistakes.

Background. A recal or recalibration is when the battery starts at 0 bars. Then the charge comes on at about 1/4 and runs until 2 bars. The it jumps to full 8 bars. If it ever jumping between 2 and 8 bars it is running a recal.

First install. Pulled pack and replaced with batteries bought from ebay. Seller says the packs are min of 5000mah. New cells are 6500mah. I just put them in and reinstalled pack. Initial recal starts and looks good. Driving is so so. Get good assist at full charge but it drops to 2 bars after just a bit.

2nd install. It the week the 1st install was running I went through all my batteries with the conditioner. All of them measured > 4000mah discharge to 6v. There we 2 pairs that I though had issues. So I put in 2 of my ebay pairs. Good initial recal. Car ran great. Good assist good charge. Charge state stayed at 4-5 bars. Thought I was good. Next morning dead. Recal started but errored and IMA light came on.

3rd install. Email from Matt at Hybrid Revolt. I bought cells from him. Told me batteries should be fully charged before install. So I fully charged the ebay cells and re-installed. All bad. Instant IMA light. I finally got my ODB2 reader, my ODB wouldn't work on civic. Code was P1570. Batteries out of balance.

4th install. Email to Matt . Said to check the connections to the sensors. Sure enough one was broken.

Soldered wire to short broken connection. Every thing good so far. Good recal, 4-5 bars good assist.

Moral of story. Charge your batteries before install. I could have avoided 2 weeks of problems if I had done that.

CT2007HCH 04-16-2014 03:07 PM


The power supply looks very nice and highly accurate. I still think a dedicated charger will be better.

A charger can charge at 5A. That means you can charge a set of cell is ~1 hour. 2 hours at 3A. 300mA will take 20 hours.

Knowing discharge is more important than charge.
To know your SOC state of charge you need to measure how many mah come out of the battery. The charger will do this by measuring the current out and multiply it by the time. So 700ma for 1 hour is 700mah. But the current changes as the battery discharges. So the charger will do this in 1 second increments. To know your battery SOC do a full charge, charge until voltage drops 5-7mv per cell. You know it is full. Then discharge it fully to 0.9 -1v per cell. The total discharge will tell you how much capacity your cells can hold. Then to do it right. Fully charge them. Let them sit for a week and discharge them. That will tell you how much self discharge is happening over a week.

You will not find a charger that can do this for the entire set. It would run at 180-200V.

I'm thinking of building a system that will cycle the battery like you said. My plan is to connect a set of wires, cut an extension cord and leave female side out next to headrest. Then do discharge connect a 500W shop light to it. Making a circuit to turn it off at a voltage is much harder. Then you can hook up the power supply at a low current 300ma and charge it over night.

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