Gen 1 hybrid grid charger erratic voltage reading

[defacto7]

Greetings.

This is my first post here. I have found enough info on the site to make my grid charger a reality without to much bother. Thanks for all those who contributed.

I finished installing a home made grid charger last evening built according to the specifications on this site. It seems to work very well. I put it on for the first time and after it's been charging for a couple of minutes, the voltage reading become erratic fluctuating between 170VDC and 195VDC. Now it could be any number of things that are not battery related like the fact that it's 9 degrees F. outside. Also the voltage meter I'm using is really cheep. I checked the specs on the Mean Well power supplies and the adjustable supplies are good for -4F. and the continuous supply is good for -22F. The problem is I can't just keep charging if it's a serious issue, so here I am.

I'm charging 350mA. The voltage is set to 177VDC off load. I have a 2003 Civic Hybrid. Outside of the fact that the IMA light is on, the meters are up and down when driving and I am grid charging in hopes of balancing the cells, the car runs great including the assist.

Any ideas why there would be erratic voltage readings while charging?

Thanks!

[defacto7]

I think I figured out my own problem. ??? The battery was close to full the first time I put the charger on it and because the cells were out of balance coupled with the fact that the off load voltage was too conservative, I was getting this large fluctuation. I increased the charger off load voltage to 195VDC and now it is much more stable. When it reaches the top of the battery charge there are some smaller fluctuations but continuing the balance charge it stabilizes and I think I'm getting the right results.

[Formula413]

Hi I just found your thread and I'm wondering if you've had good results with your grid charger. I also have an '03 HCH and I'm planning to build a charger in the near future. I'm also curious if your charger includes a way to power the fan. Apparently running the battery fan on a Civic hybrid requires modifying or customizing the fan harness, can you co firm this?

[defacto7]

Hello Formula413,

Yes, the grid charger has given me my hybrid car back. It's been a great asset. As far as the fan, I simply added a 12V supply that runs a computer fan that I mounted right over the car fan outlet pulling outward. It runs when it's charging and does the job well. I decided since it does all the cooling necessary I don't need to mess with the cars fan. Anyway, I understand the fan is coded (smart) and not just a simple wire job.

I charge it every couple of days for a couple of hours at 375ma at 195 to 200V. I charge it once every couple of weeks over night for up to 24 hours to balance it a bit. I am ending up with a full 174V still, which is a full battery. I havn't gone through a discharge cycle yet; it just doesn't seem necessary... yet. My IMA light has stopped comming on period. Part of that has to do with resetting the computer every time I do a full charge because the computer doesn't know what to do if the voltage keeps going out of it's range; that's my guess. Our model has a fuse in the "motor" compartment that has to be pulled to reset it. If you pull it for 5 seconds, it resets the computer only. If you pull it for 30 or more seconds, it resets everything (radio etc) which is of no value. I put a switch that I built with a fuse in it that connects to the fuse plug. That way, I just open the hood, flip the switch for 5 sec. and flip it back. Easy.

The whole process has been working like a charm for over a year and if I had not built this charger, the battery would be long gone by now. I think the new computer update from Honda has changed the top charge from the correct charge of 174V down to 162V so you never get a full charge with the car system and this is detrimental to NiMH batteries. It lessens their life span and lowers their overall performance. Punching them up at low amps and higher voltage seems to make them more at home.

I have never regreted the grid charger.

[Formula413]

Sounds great, that's definitely encouraging. I'm hoping to see similar results. I'm going to do more research into the battery fan and see if I can figure out a simple way to run it from a 12V power supply. Fortunately my computer has not had the IMA software update, nor will it as long as I own the car. Also can you tell me which fuse is pulled to reset the SOC? And any thoughts on why your grid charger needs to be run at ~200V rather than the recommended 177V?

[defacto7]

Originally Posted by Formula413

Sounds great, that's definitely encouraging. I'm hoping to see similar results. I'm going to do more research into the battery fan and see if I can figure out a simple way to run it from a 12V power supply. Fortunately my computer has not had the IMA software update, nor will it as long as I own the car. Also can you tell me which fuse is pulled to reset the SOC? And any thoughts on why your grid charger needs to be run at ~200V rather than the recommended 177V?

I hope your fan research works out. I did some. There are ways to use the fan but you need to know how to control the control panel that is connected to the fan. It may be a stat motor, I don't know. You may rebuild it to your own specs but then it won't work when the computer needs it. I'm no expert on it because I decided not to go that direction so if you find out some answers, let me know!

Glad you didn't get the upgrade. Beware the dealer. My dealer has tried to pull off nefarious things with me concerniong the battery and computer so stay clear if you can.

The fuse is #9 labled Backup (10A). It's in the under hood relay box and is right in the middle right to left. You'll see it. Again, by my experience 5 seconds should reset the IMA, 10 may not be too much. If you go too long, it resets the radio/clock/and other settings on the dash. If you have a motor warning light with the IMA you will have to pull it the full 60 seconds then reset the radio etc. Have your code ready. The IMA fuse under the dash does absolutely nothing, at least concerning resetting the IMA settings.

Why 200V? It's helps balance the NiMH batteries as long as it's low amps. 177V will not charge these NiMH batteries to their best advantage. My original post concerning a fluctuating charge at 177V was fixed by raising the voltage to a more reasonable rate for NiMH. The pack was out of sync and the weaker cells were reacting to the stronger ones making the voltage rickoche. Not a good thing to do. Raising the voltage pushed up all the cells and evened them out. The key is -> low amps! They can take the voltage and need it. Once your pack is more evenly balanced, you can do faster charges at higher ampage but it will create more heat and you have to be careful. At 350mA you can charge for a long time without heat issues.

If they were Lithium, that's another story all together, they need to be charged at a voltage no higher than their top end adjusting the amps during charge. NiMH and NiCads are usually charged at higher voltages than they are rated with set amp rates. If I were to charge my battery pack every night, I would not choose a voltage as high as 200V. I would set it at 185V at the least then bump the pack once a month at 200 or 205V. My charger is set right now at 198V and I charge pretty regularly for a few hours now and then and over night once in a while.

Hope this is useful.