IOTA Engineering IQ4 LiFePO4 Module Discussion

[HRTKD]

There have been concerns posted on the forum about the charge profile used by the IOTA Engineering IQ4 LiFePO4 module. This is a plug-in module used in their DLS series converters that come in different amp ratings as well as different volt ratings. I sent questions to their Tech Support group last week and received a response today. Their responses are in indented quote formatting after my question. Some of the questions highlight my lack of familiarity with their charge profile and charging in general. Their responses have been pasted into this post verbatim.

Link to the main product page for the module: IQ4 Module
Link to the IQ4 LiFePO4 manual (PDF)

1. Why can’t I get to this document (the manual in the second link above) from within your website? Shouldn’t it be available from this web page? I used the search feature on your website and could not find this document.

The spec. sheet is not currently availble on our website. There have been many changes to our website since we were acuired by Acuity, I will bring it up.

2. Why is the bulk charge spec’d out to be 14.7v? Most LiFePO4 batteries want no more than 14.6 volts. In fact, my BMS will throw an exception if charging exceeds 14.6v.

The IQ modules will not fit every battery out there. I beleive the IQ-LifePo was designed around Battleborn batteries.

2a. I have used my converter for a few hours, and I have yet to see in the log of my BMS that the charge voltage has been cut off due to exceeding 14.6v. Is it the case here that the charger is operating at constant current, not constant voltage? I have yet to see my LiFePO4 battery bank go below 70%, so I would assume that my charger has not gone into constant current operation.

The unit will output 14.7V, but since the battery is at a lower voltage you will read a voltage in between. As the battery charges, the voltage you read will increase.

2b. If the trigger is 14.6v, how can it charge at 14.7v?

If the voltage reaches 14.6VDC before the 4 hour mark, the unit will trigger out.

3. The paragraph below (in italics) from the manual is confusing. The criticism on the forum primarily focuses on the 120-minute timeout, saying that if a battery needs more charging in bulk mode than the timeout allows, then the battery may not get charged to 100%.
3a. Can you provide guidance on when constant current operation and constant voltage operation are used?
3b. What are the criteria for determining that a battery is discharged, forcing the charger into constant current?
3c. If the module knows that the 14.6v trigger has been reached, why would it stay in bulk mode for another 15 minutes? Wouldn’t this overcharge the battery?

1. For simplicity, the following explanation will ignore resistances of the cells and cables. A discharged LiFePO4 cell is 3.3V; a 4 cell discharged battery will be 13.2V. When a the charger is energized, it will operate in constant current (CC) mode because the terminal voltage is 1.4 volts below its voltage regulation point (14.6V). As the cell voltages increase the charger will continue to provide the constant charge current until the battery voltage reaches the regulation point of the charger (14.6V or 3.65V/cell). In this example (0Ω), once the charger reaches its constant voltage mode the battery will be fully charged (~95%). Realistically, when resistances are added to the system, the constant voltage mode will provide tapering of the charge current until the cell voltage eventually reaches its end voltage of 3.65V/cell. Briefly stated:
a. During constant current mode the charger controls the charge current and the battery controls the bus voltage
b. During constant voltage mode the charger controls the bus voltage and the battery controls the charge current

2. On initial startup, while limiting its output current to a specific value, the charger attempts to raise its output voltage to 14.6V. If the attached load (cell voltages and the IR losses from cell & cable resistances) results in a voltage at charger terminals of less than 14.6V, then the charger is in constant current mode. It remains in constant current mode until the cell voltages increase to a point that the voltage at the charger terminals is equal to 14.6V, this is the transition point from constant current (CC) to constant voltage (CV) operation.

3. Unlike the 0Ω example above, there are resistances in the cells and in the distribution cables. Ideally, during these 15 minutes, the current tapers down to a minimal value to achieve a finished cell voltage of 2.65V. In addition, during these 15 minutes the Battery Maintenance System (BMS) can balance unequal cells as required.

BULK STAGE - During this state, the charger will operate either at Full Current output or Constant Voltage output depending on the discharged state of the battery. A discharged battery will dictate the voltage and force the charger into constant-current operation. As the battery charges, the charger transitions to a constant-voltage operation. This BULK STAGE will continue for either 120 minutes or until the battery voltage reaches the “High Trigger” value (whichever occurs first). At this point, the BULK STAGE will operate for another 15 minutes before switching to the FLOAT STAGE.

 

[cinergi]

Interesting. That's effectively the charge profile of the Victron equipment, but at different voltages and they don't differentiate between CV and CA by saying that CA is bulk and CV is absorb (like Victron). Victron LFP profile CA's until 3.55vpc and then goes into CV and 3.55 for 1 hour and then goes to float at 3.375vpc. If they indeed CV at 14.6, you're almost guaranteed to trigger a BMS shutdown because that's an average of 3.650 vpc and your cells would have to be absolutely perfectly in balance for that not to trigger -- and that's physically impossible. They'll be off by at least a few mv so one of them will drive higher than 3.650. A 14.6 CV profile is too high for LFP.
The voltages they're using "A discharged LiFePO4 cell is 3.3V" are just wrong. Battleborn is no different.

 

[Samsonite801]

Informative conversation, thanks for providing this...

I did just buy one of the IQ4 LiFePO4 modules to toy around with (to get new life out of my old IOTA 55w charger)...

As soon as I finally get the 8x cells from China I could put together the two 12v banks and OverKill BMS's which they have the bluetooth management so could provide some good cell monitoring, where I can observe the charging behavior of the IOTA on it...

I wonder if the IQ4 module has any pots inside it or anything which could allow for any tweaking... I'd almost be curious to dissect it and see what the board looks like in it

 

[HRTKD]

For what it's worth, I have evidence that the converter does indeed go constant current but not a high voltage. A few days ago I fired up the generator on my trailer and once the AC power was available (slow automatic transfer switch) I freaked out because my multimeter showed a voltage that wasn't much different than before I started the generator. The other observation I made is that I don't seem to be getting the rated 55 amps out of my converter, but the converter had been on for only about 5 minutes.

 

[cinergi]

If you're in constant current mode, voltage means nothing because LFP's resistance is so low. At that SoC, you're not going to see voltages in the 14's no matter how many amps the charger is throwing at it (ok, well, it could, but it would have to either be hundreds of amps or a bad connection somewhere).
That said, you're only getting 29 amps with a voltage of 13.39 ... I don't understand what the converter is doing for you in that screenshot. If it was trying to float at 13.6, I'm not sure you'd have 29 amps (maybe ... depends on the size of your battery) ... and I don't know why it would be in float mode - the voltage is too low. So color me confused.

 

[snoobler]

How close is your converter to your batteries? Most normal trailer wiring is going to have a noteworthy drop when pushing current. If the converter is seeing 13.8V when you're BMV reports 13.4, it may be in the reduced voltage "absorption" phase.

 

[cinergi]

Yeah that's a clearer and possible explanation; check the voltage at the converter when driving high amperage and compare with the BMV.

 

[HRTKD]

If you're in constant current mode, voltage means nothing because LFP's resistance is so low. At that SoC, you're not going to see voltages in the 14's no matter how many amps the charger is throwing at it (ok, well, it could, but it would have to either be hundreds of amps or a bad connection somewhere).
That said, you're only getting 29 amps with a voltage of 13.39 ... I don't understand what the converter is doing for you in that screenshot. If it was trying to float at 13.6, I'm not sure you'd have 29 amps (maybe ... depends on the size of your battery) ... and I don't know why it would be in float mode - the voltage is too low. So color me confused.

I'm confused too. The only explanation I can come up with is that the converter had not been charging long enough to be "fully" charging. I dunno.

How close is your converter to your batteries? Most normal trailer wiring is going to have a noteworthy drop when pushing current. If the converter is seeing 13.8V when you're BMV reports 13.4, it may be in the reduced voltage "absorption" phase.

The converter is about ~15" from the bus bar. Bus bar is ~18" from battery. 6 awg from converter to bus bar. 2/0 from bus bar + to battery +. 2/0 from bus bar - to shunt then triple 8 awg from shunt to battery -. I read the same voltage at the converter terminals as the BMV was seeing at the shunt.

EDIT: Slight correction. My multimeter was reading 13.4v at the converter. It reads only one decimal place, FYI.

 

[snoobler]

I'm confused too. The only explanation I can come up with is that the converter had not been charging long enough to be "fully" charging. I dunno.

The converter is about ~15" from the bus bar. Bus bar is ~18" from battery. 6 awg from converter to bus bar. 2/0 from bus bar + to battery +. 2/0 from bus bar - to shunt then triple 8 awg from shunt to battery -. I read the same voltage at the converter terminals as the BMV was seeing at the shunt.

EDIT: Slight correction. My multimeter was reading 13.4v at the converter. It reads only one decimal place, FYI.

At this point, I'm not a fan of the IQ4 LFP module.

Hence, my push to use Powermax PM3 units with user-adjustable absorption voltage.

 

[chrisski]

At this point, I'm not a fan of the IQ4 LFP module.

Hence, my push to use Powermax PM3 units with user-adjustable absorption voltage.

I did not know about Powermax inverters. I’ll keep those in mind. Does not have all the different options that Iota does though.

 

[snoobler]

Hm... "all the different options" =

1) if you don't buy an additional component, you get a "dumb" charger either with 13.4V constant voltage supply or a 14.2V constant voltage, which can cook a battery if left unattended.
2) Purchase a multitude of IQ4 options that provide minor tweaks to charging profiles with an arguably worthless LFP unit.

Powermax = constant voltage supply (user adjustable) or user adjustable 3 stage smart charging in one unit. No add-ons needed.

I'd say the Powermax gives far greater flexibility given that you need multiple add-ons to get the same function from an Iota. I went down the Iota path initially. Now I have 3 Powermax.

 

[chrisski]

Powermax = constant voltage supply (user adjustable) or user adjustable 3 stage smart charging in one unit. No add-ons needed.

I'd say the Powermax gives far greater flexibility given that you need multiple add-ons to get the same function from an Iota. I went down the Iota path initially. Now I have 3 Powermax.

How do you equalize your batteries? After looking at Powermax, eqaulaization is not an option. Those add on chips for Ioata seem to be the only way I have found that allow four stage charging.

 

[grizzzman]

How do you equalize your batteries? After looking at Powermax, eqaulaization is not an option. Those add on chips for Ioata seem to be the only way I have found that allow four stage charging.

On converters like that, an "equalize" is nothing more than a short "rebulk" that gives the uninformed person the incorrect belief that the battery has been equalized. What a crock of "banthar po do"!

 

[grizzzman]

Hm... "all the different options" =

1) if you don't buy an additional component, you get a "dumb" charger either with 13.4V constant voltage supply or a 14.2V constant voltage, which can cook a battery if left unattended.
2) Purchase a multitude of IQ4 options that provide minor tweaks to charging profiles with an arguably worthless LFP unit.

Powermax = constant voltage supply (user adjustable) or user adjustable 3 stage smart charging in one unit. No add-ons needed.

I'd say the Powermax gives far greater flexibility given that you need multiple add-ons to get the same function from an Iota. I went down the Iota path initially. Now I have 3 Powermax.

I agree they work well. Make sure that they have "LK" in the description.

 

[snoobler]

Equalization is not understood by many. It's part of why FLA often die before their time, particularly with first-time users.

Equalization should be a manual operation. A decision to equalize should follow:

1. Topping off cells with water 24 hours prior to check.
2. Battery fully charged and in float for 2+ hours.
3. Specific gravity check of all individual cells with documentation. Apply temperature correction factors.
4. If specific gravity is below minimum or if variations are greater than allowed, THAT is when you equalize. The criteria are established by the manufacturer.

An equalization follows a normal charge to full. It entails:

1. Opening all caps/vents unless they're designed to work closed with equalization.
2. Apply sufficient current to raise battery voltage to 16.2V unless otherwise specified by manufacturer. Voltage temperature compensation applies.
3. Continue equalization until SG stops increasing or battery temperature exceeds 100-120°F (manuf. recommendations vary).

Automatic equalization should only be implemented after long term evaluation of the battery and establishing the frequency of need. My neighbor's 24kWh 24V (12 2V forklift-style cells) hasn't needed an equalization for 4 months because the SG is above minimum and within a .005 range across all cells.

I equalize mine much more often because they're used Trojans that are 3-4 years old. I have tested all 8 for their actual capacity and use them as though they they are 120Ah instead of 150Ah rated.

The IOTA has no meaningful function in proper equalization with or without an IQ4 module.

Powermax at least has the option of acting as an adjustable CC/CV source to allow manual equalization of 12V systems around 16V.

Per grizzzman, this is NOT an equalization charge:

https://www.donrowe.com/v/vspfiles/pdf/iq4_spec_sheet.pdf

It's garbage marketing.

The Powermax PM4 line has this added re-bulk feature.

 

[HRTKD]

Since the IQ4 LiFePO4 module is for LiFePO4 batteries, let's keep the discussion focused on that.

 

[Samsonite801]

Hm... "all the different options" =

1) if you don't buy an additional component, you get a "dumb" charger either with 13.4V constant voltage supply or a 14.2V constant voltage, which can cook a battery if left unattended.
2) Purchase a multitude of IQ4 options that provide minor tweaks to charging profiles with an arguably worthless LFP unit.

Powermax = constant voltage supply (user adjustable) or user adjustable 3 stage smart charging in one unit. No add-ons needed.

I'd say the Powermax gives far greater flexibility given that you need multiple add-ons to get the same function from an Iota. I went down the Iota path initially. Now I have 3 Powermax.

I don't see the IOTA without the 'additional component' as a dumb charger or even a charger at all. I just view the IOTA as a power supply (it actually says 'Power Converter' right on it) until you add on the device which supposedly brings along the 4-stage charger logic.

So I ordered the LFP unit a couple days ago, to try it out for kicks, I've had one of these IOTA converters with the lead-acid charging module for probably 15 years now, I used it to charge my router closet batteries for many years, and I just thought it was a cool thing to try the LFP module, in attempt to bring new life to the old IOTA (as I've already decomm'd it a long time ago, it's sitting in a box in storage now).

When I had the lead-acid charger module it was parallel cabled into 2 Optimas and one big AGM battery for about 10+ years and those batteries still work today. I just donated that AGM battery to a friend who is using in their RV now (that battery is like 20+ years old now) ... (so their lead-acid charger logic couldn't have been that bad anyway).

I will probably only use this old IOTA with the LFP module for mainly bench work charging anyways, if it will work well enough for charging a 12v LiFePO4 on the bench until I'm able to get my solar panel system up and running, then it should be useful for testing a few things like fan controllers and some lighting experiments in the meantime.

Those Powermax look like pretty good units looking at them, but I already had the IOTA in my inventory so that's the only reason I felt tempted to just get the $21 LFP module to try out...

 

[snoobler]

Since the IQ4 LiFePO4 module is for LiFePO4 batteries, let's keep the discussion focused on that.

Agreed. Tangent is my middle name.

Back to the loathing at hand:

Their claim concerning 14.7V charge voltage:

"The IQ modules will not fit every battery out there. I beleive the IQ-LifePo was designed around Battleborn batteries."

Ah... no.... (from BB FAQ)

 

[Bob142]

I don't see the IOTA without the 'additional component' as a dumb charger or even a charger at all. I just view the IOTA as a power supply

Same. I bought 4 of the $40 30 amp used cheapies from this thread so that I can do attended benchtop charging of LFP banks.

So I ordered the LFP unit a couple days ago, to try it out for kicks

A couple of us also tried that out and abandoned it in favor of using the dual voltage plug to get it up to 14.2V. So I've got an IQ4 LiFePO4 module I'll never use. At least it wasn't too costly.

My plan is to use two of the IOTAs independently, and also in parallel for 12V bank charging, and the other two in series for 24V bank charging. In every case it will be without the IQ4 module.

Bottom line: my opinion is the IQ4 LiFePO4 module is not useful in most situations. Look elsewhere for an unattended LFP converter/charger.

*Finally, I'll add to the tangent and agree with @snoobler on the PowerMax being the much better option for unattended charging. I plan on ordering a 24V one soon.

 

[HRTKD]

I was wondering if the dual voltage option might be a better charge.