I also found that sometimes you will send the command to switch between line and battery mode or other way around. The inverters will respond with a ACK stating it got the command. But will only do it up to 5 min later.

That sounds like there is a missing call to send an event to the multitasking software. There are 8 tasks running in parallel, with a complex system of flags to tell the DSP when to dispatch the right task.

 

What command were you using?

I will have to check but it is the one to switch between line and battery mode or the other way around.

I get the impression that the DSP wants to set what mode it's in. Perhaps you are setting only the priorities. In that case, it may take 5 minutes for the conditions to be right to switch modes. It will be interesting to check when you're back from the bush.

 

I have a trace file to show you I issue the correct commands and will get random NAKs back when calling the parralel and fault codes. Can you help with that?

I can certainly try.

 

I also found the inverters will go into a mode were it keeps on giving the same values. The only way to fix it is close and open the port.

That sounds pretty weird; I can't see how the DSP cares or knows whether your comms software considers that the port is open or not.

Question for Coulomb

 

Given your experience with the firmware - is there a chance you can change the firmware to increase the upper limit of Menu item 26 (Bulk/CV) so we can Equalise our batteries at a higher voltage (currently 58.4).

 

I was thinking of 62V (or more) as Trojans for example need it to be 61.92 from my calculations and the data sheet.

 

Will the charging circuit allow this...  It would make a huge difference to alot of us.

 

Thanks

Mark

Hi Mark,

 

Great question!

 

As most of us here in Spain have been using this inverter with tubular flooded lead acid that need a 64V equalization charge and a daily absorption charge of at least 60V.

 

But according to Coulomb above:  BTA2 commands must not be over 60.0 V, so I do not have high hopes, but at least 60V is 1.6V over 58.4V that we are limited to now.

 

Gustavo

 

 

 

Question for Coulomb

 

Given your experience with the firmware - is there a chance you can change the firmware to increase the upper limit of Menu item 26 (Bulk/CV) so we can Equalise our batteries at a higher voltage (currently 58.4).

 

I was thinking of 62V (or more) as Trojans for example need it to be 61.92 from my calculations and the data sheet.

 

Will the charging circuit allow this...  It would make a huge difference to alot of us.

 

Thanks

Mark

Given your experience with the firmware - is there a chance you can change the firmware to increase the upper limit of Menu item 26 (Bulk/CV) so we can Equalise our batteries at a higher voltage (currently 58.4).

It would not be hard with the firmware. The question is, will the hardware handle it? My feeling is that they had a figure of 59 or 60 V maximum in their minds, and that's why they chose 63 V rated capacitors and 75 V rated MOSFETs, for example. Remember that the MOSFETs have to deal with spikes over and above the instantaneous battery voltage, so their margins seem thin to me as it is.

 

I was thinking of 62V (or more) as Trojans for example need it to be 61.92 from my calculations and the data sheet.

Will the charging circuit allow this...  It would make a huge difference to alot of us.

 

 

I suspect that 62 V would be asking for trouble. 64 V would exceed the rating of the capacitors. It's a shame that Trojans require such non-standard voltages. I think to do a 64 V equalise, you'll need to use a separate charger. and disconnect the PIP while it's happening.

 

I don't even know about 60.0 V. It might work just fine, or most likely it will appear to work fine for a while,but will accelerate the ageing of the capacitors and cause the MOSFETs to eventually blow up (the capacitors protect the MOSFETs from the worst of the voltage spikes). How long this would take is hard to say without knowing more details about the design, and/or making tricky measurements.

 

So while I could technically do it, I'm reluctant to. Even if I cautioned people about the potential problems, if and when their inverters blew up, they may suddenly fell different about it.

 

There is also how the manufacturer, Voltronics, would feel about this. If I release a patch that ends up making their product look bad, they may not be so generous about ignoring my activities.

 

It may be that with higher voltage capacitors and MOSFETs, this could be done safely. But it's a lot of work, and not everyone has the skills to do this, or knows anyone nearby that can. So some people will likely just take the chance without modifying the hardware, and that could still lead to ill feeling.

 

So for now, that's a no. Sorry.

 

 

Hi Mark,

 

Great question!

 

As most of us here in Spain have been using this inverter with tubular flooded lead acid that need a 64V equalization charge and a daily absorption charge of at least 60V.

 

 

I think you need to ask the manufacturer for a high voltage model, or for a design change that will handle these higher voltage batteries officially. If these are becoming popular, the manufacturer will see the market demand for them, and may choose to respond with a new or redesigned model.

 

Or perhaps they are available in 6 V modules, or 2 V modules, and you could adjust the string voltage to be within range?

For example, instead of 8 nominal 6 V modules in series for a nominal 48 V string, perhaps you could use 7 6 V modules, for 42 V nominal. Then the 64 V equalisation (8 V per 6 V module) would come to 56 V, within range. But I don't know what voltage they will sag to under load at low SOC; the PIP might not work well with this.

 

If two volt modules were possible, then a 22 cell string (instead of the usual 24 cell string) would come to 58.67 V for the equalise; 58.4 V might be close enough for that. But that's a 2 x 22 = 44 V nominal battery; there might still be problems at the bottom end.

The real problem is that the PIP isn't designed for the extreme 1.33:1 equalise to nominal voltage ratio of these new batteries. Or even the 61.92:48 = 1.29:1 ratio of the Trojans.

 

Charging batteries isn't trivial.

It would not be hard with the firmware. The question is, will the hardware handle it? My feeling is that they had a figure of 59 or 60 V maximum in their minds, and that's why they chose 63 V rated capacitors and 75 V rated MOSFETs, for example. Remember that the MOSFETs have to deal with spikes over and above the instantaneous battery voltage, so their margins seem thin to me as it is.

I suspect that 62 V would be asking for trouble. 64 V would exceed the rating of the capacitors. It's a shame that Trojans require such non-standard voltages. I think to do a 64 V equalise, you'll need to use a separate charger. and disconnect the PIP while it's happening.

I don't even know about 60.0 V. It might work just fine, or most likely it will appear to work fine for a while,but will accelerate the ageing of the capacitors and cause the MOSFETs to eventually blow up (the capacitors protect the MOSFETs from the worst of the voltage spikes). How long this would take is hard to say without knowing more details about the design, and/or making tricky measurements.

So while I could technically do it, I'm reluctant to. Even if I cautioned people about the potential problems, if and when their inverters blew up, they may suddenly fell different about it.

There is also how the manufacturer, Voltronics, would feel about this. If I release a patch that ends up making their product look bad, they may not be so generous about ignoring my activities.

It may be that with higher voltage capacitors and MOSFETs, this could be done safely. But it's a lot of work, and not everyone has the skills to do this, or knows anyone nearby that can. So some people will likely just take the chance without modifying the hardware, and that could still lead to ill feeling.

So for now, that's a no. Sorry.

Thanks for reply. I agree and appreciate the VERY sound argument.

M

Sent from my SM-P605 using Tapatalk

It's a shame that Trojans require such non-standard voltages.

 

I am sorry, but i HAVE TO ... NO, I shall NOT ... I HAVE TO ... !!!

 

Trojans, tried and tested by many many users over many many years, have never had a days problem operating in golf carts, forklifts nor solar applications. 

 

So, I think, it is more a shame that Voltronix did not cater for Trojans. 

 

Case sample: I see batteries, i.e. Trojans, I want them, check the voltages and adjust my charge controller to set voltages. Done.

None of this tampering with firmware, hampered by hardware, trying to make Voltronix match off the shelf, stock standard batteries like Trojans. 

From what I've read, this is a typical problem with Chinese-made inverters, that their voltages are sometimes a bit conservative. One of my favourite youtubers (knurlgnar24) has a video where he modifies a 12V inverter not to cut out at 11 point something volts, and in many of his reviews he complains about inverters that cannot handle over 15 volts, while vehicle batteries easily see that on very cold mornings...

Thank you for the reply Coulomb!

 

Yes, very much along those lines is one of the latest treads in the Spanish forum, translated as: Equalizing with the 48V Inverter, Using only 23 2V cells.

 

So the idea is basically, you built the system from start with 23 2V cells, and the brings all the values about 2.5V down. You may set all parameters within the acceptable parameters:

 

- Absortion: 23 * 2.44V = 56.1V
- Float: 23 * 2.32 = 53.4V
- Equalization: 23 * 2.55 = 58.5V

 

And the inverter will start up as the cold start voltage is 46V.

 

What I do in my case, I use a little midnight solar KID for equalization charges. Since the 48V inverter can work in bypass mode without batteries connected, I shut down the DC side of the inverter and apply the equalization at 64V once a month.

 

 

 

 

 

 

 

 

 

 

 

 

 

I think you need to ask the manufacturer for a high voltage model, or for a design change that will handle these higher voltage batteries officially. If these are becoming popular, the manufacturer will see the market demand for them, and may choose to respond with a new or redesigned model.

 

Or perhaps they are available in 6 V modules, or 2 V modules, and you could adjust the string voltage to be within range?

For example, instead of 8 nominal 6 V modules in series for a nominal 48 V string, perhaps you could use 7 6 V modules, for 42 V nominal. Then the 64 V equalisation (8 V per 6 V module) would come to 56 V, within range. But I don't know what voltage they will sag to under load at low SOC; the PIP might not work well with this.

 

If two volt modules were possible, then a 22 cell string (instead of the usual 24 cell string) would come to 58.67 V for the equalise; 58.4 V might be close enough for that. But that's a 2 x 22 = 44 V nominal battery; there might still be problems at the bottom end.

The real problem is that the PIP isn't designed for the extreme 1.33:1 equalise to nominal voltage ratio of these new batteries. Or even the 61.92:48 = 1.29:1 ratio of the Trojans.

 

Charging batteries isn't trivial.

 

 Since the 48V inverter can work in bypass mode without batteries connected, I shut down the DC side of the inverter and apply the equalization at 64V once a month.

It can? I thought it always needed a battery connected.

On page 24 of the manual, under operating Mode description:

 

3rd Fault mode: Utility can power the loads when the unit starts up without battery. (Only available in the 4K/5K model with single operation).

 

I tried it one day and it bypasses so I have been using it since then, otherwise the house would not have AC while equalizing.

 

 

 

 

 

It can? I thought it always needed a battery connected.

3rd Fault mode: Utility can power the loads when the unit starts up without battery. (Only available in the 4K/5K model with single operation).

 

I tried it one day and it bypasses so I have been using it since then, otherwise the house would not have AC while equalizing.

Thanks! Good to know.