Help - Balance Charger Never Finishes

[Buck Rogers]

I seem to have a problem with my charger - I have one of these:

http://www.jperkinsdistribution.co.u...nd%20Balancers


The trouble is, whenever I use the balance charge program it never finishes. Last night it was on for over 2 hours and still didn't finish.

The charger was reporting the cell voltages as 4.19:4.19:4.2 but the charge rate went down to almost nothing. This happens with all my battery packs too.

This charger used to work ok - what could be causing this?

[flydiver]

That's one of the myriad or re=branded Bantam clones (Imax B6, Accucel AC6, Dynam, etc).

1. If it's that close, don't worry about it. I don't think most of those clones have 0.01 level of accuracy anyway.
I yank mine off about anytime they are over 95% full and the balance is almost right on. A little less charge is better for the lipo anyway.

2. Though they are clones the internals are NOT all the same. Some have a known history of lower grade parts that screw up the balancing like the Imax.
IMAX B6 -- Read this before you buy..
Maybe you have one, but if it worked before that argues against this.

3. If it USED to work and now doesn't maybe your lipos are starting to show their age. Not holding balance well, or having trouble balancing, along with a drop in power output are characteristics I've noticed about my aging lipos.

[Buck Rogers]

Yeah, it could be the batteries I suppose. I did charge a newer pack yesterday and it finished OK.

[flydiver]

There you go. It's not unusual to thrash your first half dozen lipos before you figure out how to take care of them.
Try not to:
Over draw
Over discharge -Flying to LVC is often over discharging. With some ESC it is actually destructive.
Leave charged for long periods of time - that's why there's a storage function on the charger. That time period is debatable (and hotly debated) but I won't go home with charged lipos or if I do I discharge at home.

[Buck Rogers]

Yeah, I do look after my lipos - some of them are a few years old but they still seem to have good capacity and enough punch. Voltage drop under load is within reasonable limits and the cells stay reasonably balanced even after they have been discharged. They don't seem to be in bad condition although clearly they aren't as good as a new pack.

What can't work out is why some of my lipos don't seem to balance - they get to within 0.01v but cant seem to get the rest of the way. Its not like I have cell that are significantly lower voltage than the others.

[MustangMan]

I have an Accucel 6 and have experienced this same problem. My belief is that this is a bug in the charging/balancing algorithm. As I understand the algorithm (based on observation), as soon as any cell reaches 4.2 v the charger will begin shunting current around the high voltage cell to keep it from going higher. If it starts going higher anyway then the charger begins reducing the charge current. It appears that the charger will reduce the charge current to near zero and will remain in that mode for HOURS while imparting very little charge to the low cells in the lipo. As you have noted, the cells are very nearly balanced, according to the charger's measurements. I just terminate the charging and use the battery as is.

[Buck Rogers]

Originally Posted by MustangMan

I have an Accucel 6 and have experienced this same problem. My belief is that this is a bug in the charging/balancing algorithm. As I understand the algorithm (based on observation), as soon as any cell reaches 4.2 v the charger will begin shunting current around the high voltage cell to keep it from going higher. If it starts going higher anyway then the charger begins reducing the charge current. It appears that the charger will reduce the charge current to near zero and will remain in that mode for HOURS while imparting very little charge to the low cells in the lipo. As you have noted, the cells are very nearly balanced, according to the charger's measurements. I just terminate the charging and use the battery as is.

I think you might be right here. I observed something similar myself - when the problem happens one of the cells occasionally shows 4.21V and maybe this is forcing the charge current too low to to finish charging the other cells.

Looks like I'll just have to terminate the charge manually.

[flashburn]

Just set your charge time limit to 60 min.