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Balancing troubles...
#11
(05-23-2019, 01:12 PM)Sean Wrote: Do they not do voltage based charge reduction anymore ? WM4 can trigger limited charge signalling, which is designed for when the mons go into bypass.

Your only problem is management of the mons temperature and an overly short absorb period - you don't want to be dumping energy that could usefully be stored in a cell.

I meant I have no way of telling the FM60 that the WM4 is starting to bypass and it should start reducing charge current. There is no can support on the outback Mate. I think you can do monitoring over the sunspec protocol with an ASX port that converts from outback's specific network to modbus, but it won't allow parameter changes.

Mon cooling is a must, I will look at adding this. The short absorb time is set specifically because I am cooking my mons and they are reducing their bypass current to stop themselves burning up. As they reduce their bypass current the high cells drift higher and we hit HV cutoff at 3.75 and we end up critical cycling. Not that this happens often, but it does happen probably a few times per summer.

The MPPT controller will only reduce it's charge current naturally once it hits it's absorption setpoint. Set that too low, and at low charge rates (winter time), it drops into absorb too soon, requiring a longer absorb time. Ideally the FM/MX60 would be responding to the 'remote' commands from the WM4, but sadly it isn't possible.

I've done a year and haven't killed my batteries or burnt my house down, yet. Think I'll stick with the current settings.
Current system: 9.6kWh wet Nicad batteries, 16S1P Calb LiFePo4, 210aH, Batrium WM4, Outback vfx3048 inverter, mx60 mppt controller, flexware 500 mounting hardware, 2.4kW solar array, 6kW lister diesel genset.

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#12
Can your MPPT cease charge based on a tail current, the next Victron update will feature this apparently.

You can also use the charge complete signal from WM4 to cease PV input, but that's bypass complete conditional.

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#13
(05-23-2019, 01:38 PM)Sean Wrote: Can your MPPT cease charge based on a tail current, the next Victron update will feature this apparently.

You can also use the charge complete signal from WM4 to cease PV input, but that's bypass complete conditional.


It can, set to 10A presently, left over from the days when I was charging wet nicads (urghhh)

It's called Absorb end amps. it will drop to float based on either the absorb timer expiring, or the current dropping below that value.
Current system: 9.6kWh wet Nicad batteries, 16S1P Calb LiFePo4, 210aH, Batrium WM4, Outback vfx3048 inverter, mx60 mppt controller, flexware 500 mounting hardware, 2.4kW solar array, 6kW lister diesel genset.

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#14
You can have the batrium to engage a load when soc or voltage is above threshold. Easiest to dump energy you have. Im y case i export all excess like for instance now. SOC 100% and exporting almost 8kW right now.
emerca likes this post
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#15
You can use that to curtail charge on Li cells as well, based on charge isn't complete at x volts, it's when current has tapered down to y amps.

(05-23-2019, 01:49 PM)daromer Wrote: You can have the batrium to engage a load when soc or voltage is above threshold. Easiest to dump energy you have. Im y case i export all excess like for instance now. SOC 100% and exporting almost 8kW right now.

When my soc = 100% I export to a couple of Leafs, and then resistive storage heaters - nothing escapes.
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#16
(05-23-2019, 01:50 PM)Sean Wrote: You can use that to curtail charge on Li cells as well, based on charge isn't complete at x volts, it's when current has tapered down to y amps.

I might have a play with this setting then...

(05-23-2019, 01:49 PM)daromer Wrote: You can have the batrium to engage a load when soc or voltage is above threshold. Easiest to dump energy you have. Im y case i export all excess like for instance now. SOC 100% and exporting almost 8kW right now.

This would be preferable to using the float relay in my FM60 diverting into water heating via a PWM'd SSR? It can do PWM float relay control to match the solar input

Actually, not entirely sure what I would do with a tank of hot water that was 100m away from the house, in a shed. And the house doesn't even have wet central heating to couple into. Really not sure what the best diversion load would be for us given we heat/cook/heat hot water with a rayburn and have no radiators. And I'm the only driver, and I charge my EV at work.
Current system: 9.6kWh wet Nicad batteries, 16S1P Calb LiFePo4, 210aH, Batrium WM4, Outback vfx3048 inverter, mx60 mppt controller, flexware 500 mounting hardware, 2.4kW solar array, 6kW lister diesel genset.

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#17
You can divert the load remotely. I have so i engage an ssr 100s meters away. yes i convert the solar energy to AC for that but still better than nothing.
The Ultimate DIY Solar and build place
YouTube / Forum system setup / My webpage  Diy Tech & Repairs

Current: 10kW Mpp Hybrid | 4kW PIP4048 | 2x PCM60x | 83kWh LiFePo4 | 10kWh 14s 18650 |  66*260W Poly
Upcoming: 14S 18650~30kWh | Automatic trip breakers, and alot more
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#18
(05-23-2019, 01:53 PM)HughF Wrote: Actually, not entirely sure what I would do with a tank of hot water that was 100m away from the house, in a shed. And the house doesn't even have wet central heating to couple into. 

Perhaps this rather retro use of hot water .....

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#19
(05-23-2019, 02:13 PM)Sean Wrote:
(05-23-2019, 01:53 PM)HughF Wrote: Actually, not entirely sure what I would do with a tank of hot water that was 100m away from the house, in a shed. And the house doesn't even have wet central heating to couple into. 

Perhaps this rather retro use of hot water .....

Genius....

Just looked in the expansion outputs - what's the best one to use to switch on mon-cooling-fans? I don't see a '1 or more mons are bypassing' option?

would 'cooling required' do the same thing, or does that just work on cell temperature?
Current system: 9.6kWh wet Nicad batteries, 16S1P Calb LiFePo4, 210aH, Batrium WM4, Outback vfx3048 inverter, mx60 mppt controller, flexware 500 mounting hardware, 2.4kW solar array, 6kW lister diesel genset.

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#20
I cool my 'mons with a 12V fan triggered by the "cooling enabled" state with the default output relay.
My WM1 doesn't seem to be able to switch the MOSFET outputs based on temp (would prefer this but it didn't seem to work).

With the last pics you're showing this shows a mis-match between the voltages the Outback MPPT & the blockmons are set to.
The pack is in balance & you're still pushing the blockmons quite hard.
You need to back down the charge voltage a bit.

It's a bit of a pain, you need the balance current but don't want to cook the blockmons too hard/too often/too long.

You really, really need to stop the cells getting to 3.75V thing, those cells will die soon.
Running off solar, DIY & electronics fan :-)
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