Overcharging?

[Iliade]

My house batteries had a hydrogen sulphide generating episode recently and I suspected overcharging as they were both low on electrolyte. They are of a sealed type and I destroyed one figuring out the best way to refill them. The battery suppliers said that it was likely to be a dead cell triggering the issue. So I bought another house battery, left it disconnected, and have run on just one of the original house batteries for the last month. As yet I haven't topped it up, but it was only just below the refractometer eye, and it has been running the fridge and an average of about two hour's autopilot, plotter, etc per day.

So, in the best part of 30kt, yesterday I noticed this on the aerogen (Marlec) display:



It was sunny and I also have 150W of solar connected to just the house battery using its own regulator. There was nothing wrong with my engine battery last month and I know of no reason for it to have been particularly flat yesterday. #1 is house, #2 engine.

Is this normal behaviour for a Marlec controller in strong wind conditions? (It did drop back to 14V when the fridge cycled.)
Is it being confused by the less than perfect house battery?

 

[rotrax]

IMHO and long experience over 14.7v is asking for trouble.

You will need to check your regulation.

 

[VicS]

ITYWF the Marlec regulator ( HRDi ??) is unsuitable suitable for an Aerogen generator .

An Aerogen has to have a regulator which diverts the output to a shunt type dump resistor . See https://www.absak.com/pdf/manuals/LVM/aero6gen_man.pdf
The HRDi is only suitable for use with Marlec ( Rutland) wind generators

The Aerogen regulators are NLA.

 

[Mistroma]

Is the Marlec regulator ( HRDi ??) suitable for an Aerogen generator . I thought they had to have a regulator with shunt type dump resistor

They do sell it for use with their wind gens. such as 913 and it has input connections for wind and solar. It would be worth checking the settings. The default charge level ( maximum voltage per cell ) is 2.400 V / cell, voltage you are seeing is way too high.

I see that you have 150W solar on another charger, it would be worth checking settings on that controller as well. You could also cover the panels and use some nav. lights for a short time to drop the voltage. Watch the voltage on HRDi after turning off the nav. lights to see where it levels out.

I used to have a much higher setting when I only had 145W of solar with 450Ah Trojan T-105s. The default setting caused the HRDi to waste available Wind and Solar well before the batteries were charged. I think I used 2.55V which worked well because the HRDi always made use of all available wind or solar. I rarely had shorepower and always reset to default when using mains charging.

The default setting is pretty safe for most battery types. I only tweaked it because I was living on the boat for 6-7 months with insufficient solar and batteries happy with 14.7V to reach 100%.

I would guess OP might have something bigger than a 913 because 490Ah in 746 hours seems too high (average output around 0.66A and 16Ah/day). My 913 averaged about 10-12Ah per 24 hours during the sailing season.

 

[ryanroberts]

Is it automatically equalising? That's a hell of a voltage for normal charging

 

[Mistroma]

Is it automatically equalising? That's a hell of a voltage for normal charging

Not on the HRDi, that's why I suggested checking the other regulator and also covering the panels to check the effect. The HRDi is at PWM unit that pretty much just tapers off the current as it reaches the max. voltage setpoint (default is about 14.4V). No functions for boost, equalise etc.

 

[Iliade]

Thanks all, I will investigate the cut-off voltage tomorrow.

 

[Mistroma]

Just another thought about your HRDi. The picture shows batt 1 "Chg/Reg" at 15.6V and batt 2 "Bulk" at 15.8V. The maximum voltage per cell setting would have to be set pretty high to still be on Bulk at 15.8V.

You mentioned battery problems and a dead cell. I wonder if the HRDi decided to auto-detect a 24V battery and that means it would be trying to reach 28.8V with the default 2.4V per cell setting.

The HRDi should detect the battery when it is first connected and decide if it is 12V or 24V. I vaguely remember someone having a problem because his mains charger was a bit haywire and he disconnected the HRDi and re-connected it before working on the mains charger later. It saw a higher than usual Voltage and decided it must be a 24V system.

Unfortunately, I don't think there's any way to confirm this as the HRDi only shows a "System Voltage nnV" message when first connected to a battery. You would need to follow the installation instructions to get the System Voltage message and would need to get details from the manual. I'm pretty certain that the only way to confirm 12V or 24V is to start have the HRDi powered down completely first.

The cell level setting would need to be very high to get the readings shown, probably at least 2.66V. I can't see it getting there by accident and wouldn't be surprised if it is still 2.4V.

I would check the other charging sources and then power down the HRDi if nothing is found and look for the "System Voltage nnV" when it powers up again.

 

[Iliade]

I checked today and the set voltage is 2.4V/cell. Without the gales and with an overcast the voltages were more sensible. The solar system doesn't overcharge in nil wind/bright sunlight.

I read in the manual that the 913 (Sorry, I used aerogen generically, as in 'hoover.') should slow down when being regulated (and the regulator indicate that it is doing so.) Maybe the strong winds overcame the capability of the regulator to limit the voltage?

It has been very windy of late, hence the high Amps/hour achieved, I suspect...

 

[Mistroma]

I checked today and the set voltage is 2.4V/cell. Without the gales and with an overcast the voltages were more sensible. The solar system doesn't overcharge in nil wind/bright sunlight.

I read in the manual that the 913 (Sorry, I used aerogen generically, as in 'hoover.') should slow down when being regulated (and the regulator indicate that it is doing so.) Maybe the strong winds overcame the capability of the regulator to limit the voltage?

It has been very windy of late, hence the high Amps/hour achieved, I suspect...

I'm not surprised to hear that it is still set to the default, I doubt many people adjust it. The strong winds should not have resulted it the voltage you saw. I've been on board in high sustained winds and never had the regulator fail in that way. I have had damage which made it stop working completely and I had to replace a chip. I remember sitting in strong wind for a couple of days and wind provided more than 140Ah in 24 hours (averaging about 6A every hour. Solar provided another 60Ah during the day and the voltage never went above the set value.

Did you try powering down and up again in case it had somehow reset to think you had a 24V battery? Not very likely to be honest but it would give high voltage with limit set to 2.4V / cell maximum. I don't think you can determine the setting but a reset will give the 12V message.

I had a quick look at the manual regarding the power down.

Note : With the shutdown switch still in the stop position wires may be disconnected in order to start again should the settings not be as required.​

You should have been generating a lot more than 3A with 30kts wind. It is probably the maximum the fully charged batteries will accept whilst gassing furiously.

I would try to check the solar regulator and the HRDi individually as either could be at fault. I do think that you are very likely to have a fault, especially as you mention a recent issue with your batteries needing a lot of water.

My gut feeling is that a fault in the solar regulator would show up sooner because you are getting sunshine fairly regularly. The HRDi will often be putting in almost nothing or 3-4Ah per day and you might not notice an issue.