Green New Energy Active Balancers-do they do anything?

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Re: Green New Energy Active Balancers-do they do anything?

Postby NealinPerth » Wed Apr 26, 2017 11:41 am

I was thinking along the same lines myself.
The manufacturer supplies no specific info relating to the charge balance method employed.
I had assumed it was probably some sort of inductive charge shuttle arrangement which supposedly avoids the problem of small cell voltage differences and is apparently much faster than the capacitive charge shuttle method. With no info I'm only guessing.
Hopefully I'll get a detailed response to my email from the supplier.
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Re: Green New Energy Active Balancers-do they do anything?

Postby NealinPerth » Fri May 05, 2017 4:05 pm

OK, I’ve been in touch with the supplier who arranged for the manufacturer to contact me. They were both very helpful and keen to resolve the issue. GNE requested further information so I performed another charging cycle with much better results.
There were two problems with my previous tests.
Firstly, I suspect that my bench power supply I was using to test to Vabsorb of 14.4v is faulty. Planning to scrounge a scope to confirm this.
Secondly, and more importantly, I was terminating charge too early (charge current tapered to 8 amps) and at a Vabsorb of 14.0 volts which is too low.

The following table shows the measurements I recorded:
Capture.GIF
Capture.GIF (6.9 KiB) Viewed 1957 times

Although the manufacturer maintains that balancing occurs all the time during the charging process, as can be seen from the table, the cell volts continue to diverge up to >3.50v. After this balancing can be seen to be occurring. The charger terminated Vabsorb a little early with cell delta volts at 14mV but I am confident that, with a longer time, cell delta volts would have reduced to the 10mV specified by the manufacturer.
Gordon, you mentioned that your Vabsorb is 55volts (3.43v/cell?) Possible that our conservative charge voltages may be the cause.

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Re: Green New Energy Active Balancers-do they do anything?

Postby Gordon-Loomberah » Fri May 05, 2017 4:56 pm

I'm more concerned with keeping the cells alive as long as possible, so don't generally take them over 55V these days. Initially with the EVPower balancers I had to go to 58V (3.65V av) to achieve balancing action.

However, occasionally I do take them to 56V, or a bit more, in order to speed up charging, as it is a bit slow at 54.8V, and that certainly does bring them closer together for a while, especially if I terminate the absorb stage at a net charging rate <4A. Once I've done that, I find the 2 battery halves are much closer together for months, but there is still a bit of variation between individual cells.

With my cells almost 4.5years old now, I'm finding they will not accept as high a charging rate as when they were younger, so I may be forced to go to a bit higher Vabsorb a bit more often, in order to get fully charged on short winter days when I am using a large amount of their capacity.
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Re: Green New Energy Active Balancers-do they do anything?

Postby Warpspeed » Fri May 05, 2017 5:05 pm

Gordon,
What exactly is your charge regime ?
Do you charge up to a fixed voltage, and terminate when current falls below a certain threshold, or what ?
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Re: Green New Energy Active Balancers-do they do anything?

Postby Gordon-Loomberah » Fri May 05, 2017 5:58 pm

It's variable! It significantly depends on the weather and how much energy I use for the day, and I am not concerned with reaching full charge every single day. For example, yesterday I was about 3kWh short of full charge just before the sun went behind the hill. 1-3kWh short of fully charged for the day is not uncommon.

The FM80 does not have provision to terminate charge at a set net amount, only gross, and with an extremely variable load profile, that is useless. So I currently have the large PV 4.2kW array FM80 set to 2.5 hours, and the small 2.8kW array FM80 set to 3 hours, and I often re-start Absorb towards the end of the day if the net charging rate had still been >20A at the end of absorb time.
Vabsorb is currently about 54.8V, but I'll sometimes increase that to 55.xV to speed up charging by reducing the time required at Vabsorb if I'm not looking like getting to anywhere near fully charged in the time remaining.
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