MPP PIP-1012LV-MS Voltage Reading Problem

[JAS]

Hey all,

I've been playing around testing a new PIP-1012LV-MS...

It is having a problem reading an accurate voltage from the battery. I have it connected to a 100AH Zooms battery and AC input (No solar at this time). I'm using all of Will's settings (except I changed the voltage switchover to/from AC range from Will's recommended 11.5v and 12.25v to 12.3 and 13.5).

If just sitting charging and not providing a load the voltage reading on the unit is "close" to the voltage reading on my Ali Meter.(within 2-3 tenths). I also read the same voltage with my multimeter at both the battery terminals and at the connection to the PIP. (again within 1-2 tenths)

However, the problem is when the unit is providing a load. (In my case about 80 watts). The voltage reading on the PIP is about 8-9 tenths lower. For example, last night I let the PIP charge the battery fully to 100%. This evening, I turned everything on and started powering the same 80 watt load. The voltage on my Ali meter is reading 13.3v. My multimeter reads about the same at both the battery terminals and the PIP terminals. But, the PIP is showing only 12.4v. This in turn is flashing a low battery warning on the display and then eventually switches over to AC Bypass when in fact my battery is still about 99% charged?!?!?! I guess the switchover to AC makes sense based on my settings since it thinks the voltage dropped to 12.3. But, why is the voltage reading so low?

After a few minutes, now the PIP voltage is showing 13.8v, the charger is in float mode (according to the solid green charging light), load is still being supplied by Bypass AC power, and the actual voltage at the terminals is only 13.3???

Can anyone shed some light on what is going on?

Thanks,

Jeff

 

[JAS]

Update:

So I just pulled the AC and let it sit for 15 minutes. It continued to read 12.8v when the actual voltage was 13.1. And it continued flashing low battery on the display. (This is with my custom settings for AC switchover set at 12.3v - 13.5v)

So... not really understanding why Will's AC switchover range was 11.5v to 12.25v (Isn't 11.5 too low for LifePo4?). And won't the low battery cutoff of 12v override the low setting anyway? At any rate, I changed the settings to match Will's recommendations and plugged the AC back in. At this point, it stayed on battery powering the load and continued to flash low battery for about another 5 minutes.

And then all of a sudden, the voltage reading on the PIP went to 13.1 (now completely matching the actual voltage) and the low battery alarm stopped flashing. The battery percentage is still reading only 45% (compared to 85% on the Ali), but I understand the battery gauge on the PIPs are not accurate when it comes to Lithium...

So the question is... is this random, or did changing the AC cutover settings somehow change how the unit is reading the battery voltage???

I guess I'll keep monitoring and testing with these new settings...

 

[JAS]

Well...

Either nobody else has experienced this OR... my topic just isn't interesting enough

So I've been letting this thing run as a test powering a laptop and desktop computer for about the last week. It appears after being connected for about a day, voltage readings get "better". It is pretty accurate when sitting idle and discharging. However, when charging it is still reading anywhere from 4 -8 tenths higher than what the battery really is??? Especially when the charge first starts. The voltage reading will jump from 12.7 all the way to 13.7 initially (even though the battery is still reading 12.8). It gets "closer" after charging for a while.

Anyway, I think I found settings that put the charging cycle where I want it (IE: I don't want to run the battery down lower than 20% remaining).

So the low switchover setting (#12) is at 12.8v (which according to my Ali monitor is around 20% remaining) and the high switchover setting (#13) is at 14.3v. (I didn't get a chance to see if this is fully 100% or not so I may end up lowering this setting)

So in summary, Will's recommended settings (11.5v - 12.5v (unit won't accept 12.25 as an option)) would have me running the battery from completely dead (maybe even having the BMS cutoff) to only around 15-20% charged.

 

[ken_am]

I also have a PIP-1012LV-MS but haven't experienced what you are since I am not using Li batteries yet and may never with this device after reading your post. As for the battery power %, the algorithm required for each chemistry is undoubtedly different. But a volt is a volt no matter what the battery chemistry so why the difference, I can only guess that there is a design weakness, perhaps a circuit trace on an internal board is too small, causing an excessive voltage drop while powering a load. I have noticed a lag in response to a change in load/battery voltage/battery power % and that displayed but it should catch up, eventually.

 

[JAS]

IDK... After letting it cycle for about a week, it seemed to at least become consistent... While at rest or discharging, the voltage was accurate. And while charging, it read several tenths of a volt higher than at the battery. (But, I suppose that is better than reading too low and risk having the BMS cutoff)

I've just decided to set it up as a UPS for now until I get my solar panels hooked up. Once that is done, I'll see how it behaves...

 

[jw77]

Hi, I'm running two Zoom 12.8 x 100Ah batteries with the 2024 unit. Seeing the same strange voltages as you which is what had me searching. I found another thread talking about reading V at the battery terminals and the inverter terminals to check the wires and they were exactly equal (27.6V) to rule out my wiring breakers and fuses. I just bought all this in December so I just finished hooking up everything last week. Out back I have two 260W panels in series. I saw 385W peak during the day here in NJ.

Some observations tonight:
No load, AC input off, inverter on, LCD reads 26.3V, Battery terminals 27.6V.
No load, AC input on, inverter off, LCD reads 26.1V. Battery terminals start climbing to 27.9 before I stopped. In this state, the inverter is in bypass and it tries to charge the batteries while the inverter is off.
No load, AC input on, inverter on, LCD reads 26.3V

Without load and charging with either solar or AC, the unit got up to about ~26.9V~27.1V displayed on the screen but the charging icon and watchpower still showed charging. My back to discharge voltage is set for 26.5V and back to charge at 25.5.

My concern was that the unit seemed to never finish charging, holding mostly around 26.6V, and I'm using Zoom's recommendations on charging voltages multiplied by 2. So 14.2V on mine I have set for 28.4V and float at 27, having also tried 27.2 and 27.4. Zooms manual states 13.8 float setting so 27.6v on a 24v system. I'm glad I didn't push to any higher charge settings on the battery as it seems it's already higher than actual battery levels at displaying 26.3~26.6 on the LCD.

For reference, I noticed the SOK table on the forum but didn't see Zoom's. Here's an extract from their manual. I set my cut off disconnect at 22.4V and now at 23V because it did shut down one night leaving the inverter running after the laundry finished.

Capacity	Voltage
100	13.5
99	13.4
90	13.3
70	13.2
40	13.1
30	13.0
20	12.9
10	12.8
1	10.8 - recommended low disconnect
0	9.5

I can say overall I'm happy but want to figure this out for safety's sake. I ran toaster oven 1300w, 2 loads of laundry by doing 1 with sun up and 1 in the evening from what charged. I'll be glad to help where I can. It would be best if MPP would open this source up and let us run our own rules on the system as people have requested on when to set charge from utility among other things.

I also use Emporia power monitoring and use 2 of the smart switches to shut utility off when I want it to use only battery and monitor the power being used by the inverter from AC. It likes to just start pulling from AC whenever it likes, and I think it's from inrush surges pulling voltages below the back to charge setting where solar wasn't enough to fulfill the current demand.

 

[JAS]

@jw77,

While I don't have any answers for you... I'm glad I'm not the only one experiencing this. I still have yet to get my solar hooked up. So I haven't done anymore testing/monitoring with my unit. Odd that yours is reading low and mine is reading high though.... In my case, I just assumed there are some additional voltage losses going on inside the unit. (EDIT: That doesn't make any sense in my case, but, it would in yours) But, maybe the volt meter inside the MPP units are just not reliable/accurate?

I get the feeling that most people using these units are either only using them as emergency backup or dedicated to solar with only occasional AC Inputs (ie: Generator). That's why I'm hopeful the unit will behave better once I have solar going to it. But, in your case, I would also be concerned about the low voltage readings and thereby overcharging your batteries

 

[jw77]

@jw77,

While I don't have any answers for you... I'm glad I'm not the only one experiencing this. I still have yet to get my solar hooked up. So I haven't done anymore testing/monitoring with my unit. Odd that yours is reading low and mine is reading high though.... In my case, I just assumed there are some additional voltage losses going on inside the unit. (EDIT: That doesn't make any sense in my case, but, it would in yours) But, maybe the volt meter inside the MPP units are just not reliable/accurate?

I get the feeling that most people using these units are either only using them as emergency backup or dedicated to solar with only occasional AC Inputs (ie: Generator). That's why I'm hopeful the unit will behave better once I have solar going to it. But, in your case, I would also be concerned about the low voltage readings and thereby overcharging your batteries

Update after a week. That next evening, I powered off the whole unit with the DC breaker for a couple minutes.
I switched volt meters for a newer one and the readings are same between the unit display and the batteries. Make sure you disconnect AC input and loads to see if that gets you more accurate reading. I also set my low voltage cut off to 10.8 as Zooms recommends and it's much more accurate. When I hit 26.8 now, it also matches to where the 99-100% is, even though the other intermediate values can't be trusted with "user" setting of batteries not being same voltage curves. I think that helps the system know its hitting its 100% and not keep pushing too much into the battery after it holds steady. I haven't seen these discrepancies since.
It's been doing very well otherwise. Drain them and give them enough load to finish the day at about just less than nominal 12.8v so it's ready for the morning solar. I switch the inverter off and use the smart switches to disconnect its input AC so it holds overnight.
Also, this week, I bought and esp32 chip, flashed it with esphome and put pipsolar on it. Very nice way to be able to monitor the power and voltages from my PCs and phone while heavy loads are in use, just in case. I'll automate it to trigger my AC smart switch on as a safety and already looking to add a GPIO pin relay switch on the inverter.

So... I'd agree with Zooms, and Will's lower point, that setting low voltage cut off is right to put it in as 10.8. It helps the inverter know the size and avoids the alarms. Just make sure your recharge point is set, mine is 24v, so 12v on yours, and know that you'd want to catch it before it really gets too low, which is why I added very inexpensive external monitoring with the esp32. This way under load it does dip down, but stopping the load you'll see the battery is higher. For example, I see my fully charged 26.8v drop to 25.4v under a 1300 watt load when it cycles on and off.

 

[JAS]

So... I'd agree with Zooms, and Will's lower point, that setting low voltage cut off is right to put it in as 10.8

I'll give that a try and see if/how the behavior changes

 

[12VoltInstalls]

So neither of you are running solar panels?

 

[JAS]

So neither of you are running solar panels?

Not yet

 

[jw77]

So neither of you are running solar panels?

I have the solar hooked up since the start. Two 260 Watt in series. I see 440 W on a good day, usually 360 W with moving clouds.

 

[JAS]

Update:

I've had my solar hooked up now for a while. Still experiencing the same problems... When charging under full sun with a light load, the voltage reads 3-4 tenths higher than reality. In contrast, when under a load, the voltage reads up to 8 tenths lower than reality.

I've been in contact with Ian at Watts247 and he provided me with a utility for calibrating the voltage on the unit. However, he is waiting on instructions from MPP that are specific to this model.

 

[12VoltInstalls]

When charging under full sun with a light load, the voltage reads 3-4 tenths higher than reality. In contrast, when under a load, the voltage reads up to 8 tenths lower than reality.

I think you have resistance in the circuit that shouldn’t be there.

 

[JAS]

Further testing yesterday...

Under a 300+ Watt load and between 150-250 Watt solar input, I see the following:

Shunt Reads 13.40V



1012 Reads 12.06V



And then just a few minutes later with no other changes...

1012 Reads 12.78V. (it bounces around like this over the next 15 minutes)



Then when removing the load, Shunt reads 13.09V (this makes sense)



but, the 1012 then reads 13.63V ! Where the heck did that number come from?!?



Note: Voltmeter reads the same voltage at the 1012 terminals as the shunt does. These whacky voltage readings are internal to the unit...

Ian has asked me to give him a call. I'll follow up with what he says...

 

[JAS]

Update: Ian is sending me a new board. Hopefully, that resolves it ?

 

[realdouglasquaid]

Update: Ian is sending me a new board. Hopefully, that resolves it ?

Any updates on the new board? I seem to have the same problem.

 

[JAS]

Any updates on the new board? I seem to have the same problem.

I have it installed. But, haven't hooked the unit back up yet. Still working out some wonkiness with my Victron Shunt... I'll be sure to follow up once I have it hooked back up. (Should be by this weekend at the latest)

 

[JAS]

Got the unit hooked back up and did some testing. With a full battery, the unit still reads a slightly higher voltage under no/low load and a slightly lower voltage under a high load (500W). But, it is within a tenth of a volt both ways.. so much better than what I was seeing before. However, I'll have to wait until the battery is lower and the unit is charging to see what really happens...

 

[JAS]

Update: Didn't have a chance to see what voltages look like while charging yet. However, it's looking like this board is acting the same:

Checking voltages tonight and the unit is reading a full tenth of a volt higher than reality under a less than 30W load..