Global LF Series Pure Sine Wave Inverter Charger 48v - Low battery alarm voltage

[MaikaiLife]

I'm posting here to share some insights I recently gained while helping a client. I had to reach out to AIMS Technical Support, who confirmed that their manual is lacking in detail and could be improved significantly.

Unit installed

Link to manual

I have a client who had another solar installer sell and install an AIMS 10K Inverter/Charger for residential use. Although this device is primarily intended for marine applications, such as on boats, it functions quite well as a standard inverter.

The client wanted the generator start feature to work, but the previous installer was unable to configure it and seemed not to have made a genuine effort.

To add complexity, the client uses six EG4 LifePower4 batteries, which the inverter/charger does not natively support. The closest supported chemistry is Gel, which bulk charges to 56V and floats at 54.8V—slightly high for float which actually won't float on generator input anyway, but acceptable for bulk charging.

According to the manual, the generator is activated when the "low battery alarm" is triggered, but the manual does not specify the voltage for this alarm. After consulting with AIMS, I learned that the "low battery alarm" is set 1V higher than the low battery trip point. With the Gel setting and dip switch 1 in position 1, the low battery alarm triggers at 47V, and the low battery trip point triggers at 46V.

Unfortunately, with this inverter, the LifePower4 batteries must drain to 47V, approximately 5% state of charge (SOC), before the inverter triggers the low battery alarm and starts the generator. The generator then charges the batteries to 56V before shutting off. According to EG4 documentation (page 5) the battery will shut off between 47-44V depending on load, hopefully, it doesn't shut off before the inverter detects and activates the low battery alarm.

While this configuration is not ideal, and certainly nothing I would install, it should function adequately, especially during summer months when the air conditioning runs all night and the battery bank might be completely drained and need the generator to activate and recharge the batteries.

I’m open to other ideas or perspectives on the configuration that don't involve additional equipment purchases, as the client has already spent enough. I'm posting this here to help anyone else who might encounter this situation, in hopes that this information will be indexed by Google or appear in DIY Solar search results for others to benefit from.

Cheers!

 

[sunshine_eggo]

The AIMS/Sigineer units are not well suited for LFP, but IIRC, GEL and one of the AGM programs usually gets you there.

I'd say it's as good as it's going to get.

 

[MaikaiLife]

The AIMS/Sigineer units are not well suited for LFP, but IIRC, GEL and one of the AGM programs usually gets you there.

I'd say it's as good as it's going to get.

Much appreciated for taking a look, unfortunately, when you're brought in afterward to clean up someone else's job and the client has spent their budget, you do your best to make it work. Question though, is the low voltage shutoff in the EG4 batteries configurable in the advanced/edit mode of the BMS test tool? I'm wondering if the manual page 5 is suggesting that the 47-44V is default, but that it can also be configured via the BSM tool?

 

[sunshine_eggo]

Since it's directions for setting the equipment using the battery, one would expect the actual cut off to be LESS than those listed, but it's implied current level influences it, so it's hard to say for certain.

I would hope that you could change the cut-off levels in the ParameterSetting tab.

 

[marionw]

If the batteries do not have the latest firmware (v3.37) then you can use the BMS_Test tool and the latest firmware which can be downloaded from the EG4 website.

Unfortunately the BMS_Test software will not allow you to change/modify the Protection or Alarm parameters, but hey were changed with each version update.

You can also get the firmware update tool from Signature Solar for free which will load v3.37 without the need for a computer or cable.

The updated parameters might work better for you.

These are the parameters in my six LifePower4 batteries by version (I reloaded each version bin file just to get the ParameterSettings)
The version is displayed at the bottom of each picture.

See the "PACK_Vol_Protection" and "PACK_Vol_Alarm"

 

[MaikaiLife]

So it looks like pack_uv_start protection is 40 and alarm is 43.2… which should mean just getting the latest software would allow me to get below 47V and trigger the inverter gen start without any adjustment to the batteries.

 

[MaikaiLife]

Unfortunately the BMS_Test software will not allow you to change/modify the Protection or Alarm parameters, but hey were changed with each version update.

I don’t want to get anyone in trouble so I’ll leave out the password, but if you see the password field on the right, it’s been a while but I’m pretty sure once you put that password in, you can edit any of those parameters.

 

[marionw]

They did not change

I don’t want to get anyone in trouble so I’ll leave out the password, but if you see the password field on the right, it’s been a while but I’m pretty sure once you put that password in, you can edit any of those parameters.

You can, and the password is available from somewhere (its the same six digits used on the Config tab) and that password is available on this forum as provided by EG4.

Keep in mind you might get a Protection Cell_UV_Start (2.5 volts) on one cell before reaching the PACK_UV_Start which will also cause the BMS to turn off the discharge MOSFETs

 

[marionw]

An additional thought. Research research.

The new EG4 Charge-Inverter has a communications port for communicating with the batteries (much like an inverter) and also has dry contacts for controlling a generator. Not sure if the EG4 Charge-Inverters AC power can come from a generator that is not running with the EG4 Charge-Inverters internal logic being powered by the batteries. There are setpoints for starting and stopping the generator.

The manual can be downloaded from Signature Solar or the EG4 website.

6.5 WORKING WITH A GENERATOR
The Chargeverter-GC dry contacts are specifically designed to interface with a generator. The charger
AC input is simply plugged into the generator 240 VAC output and the dry contacts are used to
start/stop the generator based on user defined thresholds of battery SOC or voltage. During this mode
of operation, the charger is powered from the battery’s DC voltage.

I don't own one (yet) so I can't comment as to would this work but others on this forum may be able to provide more input

 

[MaikaiLife]

An additional thought. Research research.

The new EG4 Charge-Inverter has a communications port for communicating with the batteries (much like an inverter) and also has dry contacts for controlling a generator. Not sure if the EG4 Charge-Inverters AC power can come from a generator that is not running with the EG4 Charge-Inverters internal logic being powered by the batteries. There are setpoints for starting and stopping the generator.

The manual can be downloaded from Signature Solar or the EG4 website.

6.5 WORKING WITH A GENERATOR
The Chargeverter-GC dry contacts are specifically designed to interface with a generator. The charger
AC input is simply plugged into the generator 240 VAC output and the dry contacts are used to
start/stop the generator based on user defined thresholds of battery SOC or voltage. During this mode
of operation, the charger is powered from the battery’s DC voltage.

I don't own one (yet) so I can't comment as to would this work but others on this forum may be able to provide more input

That is pretty cool, a little pricey for nearly $500 but it certainly would solve the problem if I can’t get the AIMS inverter to work with the 47V low voltage requirement.

Question, it says RS485 and compatibility with EG4 batteries, but I don’t see a matrix or a mention of anything other than the EG4_LL. I’m assuming this works with ALL EG4 batteries including the LifePower4 and possibly the older gen GILL batteries?