Go Power Solar Controller not perfect (sucks)

[dosby]

So I have gotten this new lithium option for my 2021 17B, just for 100Ah. It comes with:
- GoPower battery LiPh 100Ah
- 120V Converter with lithium charging option, WFCO - https://wfcoelectronics.com/product/wf-8955lis/
- Victron Orion Smart DC to DC charger, works with smart alternators, senses when vehicle runs/not runs, can charge battery - https://www.victronenergy.com/upload...60-400W-EN.pdf

Which all work pretty well (I don't know how to test DC-2-DC except drive on a really cloudy day or with someone sitting inside the trailer while driving and manually checking the voltages), but the Solar Charging controller (600W, 30A): https://gpelectric.com/products/30-a...ler-bluetooth/
.. is not perfect.

It does work meaning it charges the battery, it's just not showing correct SOC. Besides, the bluetooth app lives a life of its own and rarely connects to my iPhone. I have not figured out yet why it sometimes connects but most of the time it does not - I tried soft reset, "forget the device", reinstalled the app, etc.
With the button-based LED lights battery monitor being completely useless - it always shows 4 red dots, the only way to know SOC is to bend down and look under the bench. Even then, the % is always 100% and the only correct reading seems to be current Battery Voltage and accumulated charge in AH. Which (AH) you can reset but only from the app
So basically, what I now need is some sort of a conversion table from battery voltage to SOC %. I think it would be relatively accurate unless the battery is under load.
I used an electric kettle and kill-a-watt via inverter to measure discharge, and then I guess I could use cumulative AH reading on the Solar Controller to measure charge.

I wonder what other folks' experience is, especially those who opted to install their own lithium battery/solar/controller/etc.

[MVA]

I wish I had ETI install the prewire option. That being said, when I upgraded to our solar & LiFePO4 system, I selected the following components based on numerous queries to others on this forum and web searches:

Victron SmartSolar MPPT: https://www.victronenergy.com/solar-...-100-15-100-20
Victron DC-DC: https://www.victronenergy.com/dc-dc-...rters-isolated
Battery monitor: https://www.amazon.com/AiLi-Voltmete...80&sr=8-4&th=1

My design basis (everyone's is different) was no inverter, 200W single rigid panel (did not want portable panel, did not want second panel on front of trailer due to others experiences, did not want flexible panel due to living in hot SW), 100 Ahr battery. From an engineering design basis, this design will be plenty for my needs. The DC-DC converter power output can be monitored by the battery monitor. I did not spend the $$$ for the Victron battery monitor; the AiLi has been shown to accurate enough and I did not need BT. I opted for the Victron SmartSolar based on wanting BT (did not want to mount a display on cabinet), MPPT (squeeze out max power on 200W panel), and comments online with GoPower BT dropouts (like you are experiencing).

Based on your current situation, you could add a simple AiLi battery monitor (or the Victron smart shunt https://www.victronenergy.com/batter...-battery-shunt). That would allow you to monitor the battery more accurately.

YMMV

2 cents

[IanC]

Full disclaimer: I don't have an Escape Trailer and I'm still deciding on build options. I do have quite a bit of experience with LiFe batteries in radio controlled gliders. Those batteries seem to hold their voltage with a very steep drop-off when they get to the end of a cycle. With that in mind, it may not be easy to determine the state of charge on a LifeBattery, unlike lead acid batteries that continuously drop in voltage.

[MVA]

Agreed. The LiFePO4 electrochemistry is significantly different from Pb acid. One clear aspect is when one reviews the charge/discharge curves for BB LiFePO4 battery, the internal resistance is negligible. Hence this allows for rapid charging/discharging for a BB LiFePO4 battery (i.e., up to C/1 rate), as opposed to flooded Pb acid. That is why an integrating coulometer (i.e., battery monitor) is needed as opposed to estimating SOC (state of charge) from open circuit voltage on Pb acid.

2 cents

[Brian B-P]

Originally Posted by dosby

- Victron Orion Smart DC to DC charger, works with smart alternators, senses when vehicle runs/not runs, can charge battery - https://www.victronenergy.com/upload...60-400W-EN.pdf

Which all work pretty well (I don't know how to test DC-2-DC except drive on a really cloudy day or with someone sitting inside the trailer while driving and manually checking the voltages)...

You don't need to drive anywhere. With the tow vehicle running but parked, and the solar panels or charger disconnected, check the voltage on each side of the converter (from the tow vehicle and to the trailer. If you have the instrumentation, look at the current too for the full picture, but the voltage alone will tell you if the converter works. The tow vehicle voltage might be low at idle, but that's exactly the issue that the DC-to-DC converter fixes.

[Brian B-P]

Originally Posted by IanC

... I do have quite a bit of experience with LiFe batteries in radio controlled gliders. Those batteries seem to hold their voltage with a very steep drop-off when they get to the end of a cycle. With that in mind, it may not be easy to determine the state of charge on a LifeBattery, unlike lead acid batteries that continuously drop in voltage.

Yes, that charge/discharge profile (relatively flat in the middle, steep on the ends) is typical of any lithium-ion battery (not just LiFePO4)

Originally Posted by MVA

Agreed. The LiFePO4 electrochemistry is significantly different from Pb acid. One clear aspect is when one reviews the charge/discharge curves for BB LiFePO4 battery, the internal resistance is negligible. Hence this allows for rapid charging/discharging for a BB LiFePO4 battery (i.e., up to C/1 rate), as opposed to flooded Pb acid. That is why an integrating coulometer (i.e., battery monitor) is needed as opposed to estimating SOC (state of charge) from open circuit voltage on Pb acid.

The low internal resistance isn't really the reason for the voltage versus state of charge profile, but I agree that the shape of that profile means that a proper battery monitor is required for accurate SoC indication.

The solar charge controller does not have a battery current measurement, so it can't use anything other than voltage to guess the state of charge. Regardless of brand, it won't be accurate.

[alanmalk]

Originally Posted by dosby

...
It does work meaning it charges the battery, it's just not showing correct SOC.
...

Obtaining the State Of Charge - SOC - on a LiFePo battery is tricky. Ordinary methods that use voltage are bound to be confused thanks to the flat discharge voltage curve of Lithium chemistry. Or in other words, the battery will hold a nearly full voltage until it is almost dead. Great for camping and trolling motors, but essentially useless for monitoring how much power is remaining in the battery.

As previous posters have mentioned, the best way is a shunt-based monitor. It is looking at current going in and out of the battery and when calibrated to the battery in question, it will give a good indication of how many Amp-Hours remain of your original 100AH.

Now I am going to hijack your thread a bit...

I am going to upgrade to LiFePo4 soon, probably 2 batteries for 200AH. In my previous 7 years of ownership I have not worried about SOC. I just draw power from my 200AH AMG batteries (2) rather conservatively - no big inverters - and deploy an extra portable 150 Watt solar panel when in shade or camping in the shoulder seasons of low sun. I will upgrade my Go Power solar controller to a newer version with a Lithium profile but that's about it. The WFCO converter will stay the same, and will power the trailer when at a full-hookup site. Yes, during that time the Lithium battery may not be fully charged, however, Lithium batteries don't mind being at less than full for a long period, per the manufacture's instructions.

[bborzell]

Our soon to be built 21C has the same Power Center and Victron DC-DC charger on the build sheet.

I have yet to understand the charging roles of the lithium battery charging element of the 8955 LiS and the fact that the Victron is designed to do just that.

Is the battery charging unit in the 8955 LiS left unused?

[alanmalk]

Originally Posted by bborzell

Our soon to be built 21C has the same Power Center and Victron DC-DC charger on the build sheet.

I have yet to understand the charging roles of the lithium battery charging element of the 8955 LiS and the fact that the Victron is designed to do just that.

Is the battery charging unit in the 8955 LiS left unused?

The WFCO 8955 is charging your battery when plugged into 110 VAC. (And it also powered all the DC devices in your trailer at the same time.) Far from unused.

The Victron DC-DC charges your battery when driving and powered from the tow vehicle.

[bborzell]

Originally Posted by alanmalk

The WFCO 8955 is charging your battery when plugged into 110 VAC. (And it also powered all the DC devices in your trailer at the same time.) Far from unused.

The Victron DC-DC charges your battery when driving and powered from the tow vehicle.

Interesting. I spoke to tech support at Wyco and got 5he impression that they don't see a need to have an additional charger, even for Lithium batteries. Maybe TV alternator charging falls short of the voltage level needed to keep Lithium batteries happy.

[alanmalk]

Originally Posted by bborzell

Interesting. I spoke to tech support at Wyco and got 5he impression that they don't see a need to have an additional charger, even for Lithium batteries. Maybe TV alternator charging falls short of the voltage level needed to keep Lithium batteries happy.

My tow vehicle fails to deliver enough voltage to charge my AGM batteries if anything of significance is running in the trailer. Typically that means if the 'fridge is running on 12V (instead of propane), the trailer batteries will discharge due to the voltage drop between the alternator and the load. The DC-DC converter boosts the alternator voltage to overcome that voltage drop. (Note, there are about 80 feet of wire between the alternator and 'fridge - and returning. And it is cheap, undersized wire in many places. Thus the loss of voltage.) Don't count on charging anything from the tow vehicle unless you do a complete rewire, and that still won't help with Lithium. DC-DC converter is a must if you absolutely have to charge Lithiums while under way.

On the other hand, the tech support is essentially correct. If you have solar, and drive un-shaded highways, and don't run a high load while on the move, then the solar will provide a reasonable charge. The DC-DC converter is just another charging option that may, or may not, be of use to you in your particular circumstance.

[bborzell]

Makes sense. Thanks.

[Semievolved]

Just stumbled across this thread and hope I am not too late. To evaluate where you are in SOC on LFP batteries in mid range is virtually impossible based on voltage becauwe the V vs SOC is so flat from around 15% up to 90% or so SOC. I saw the meter you were planning to install to measure SOC and wanted to let you know that I have that same meter on a Bestgo LFP battery and it is not accurate for current at all which means it also is not reliable for SOC. To replace it, I am using a Victron BMV-712 which I have been using on my home solar and have verified its accuracy. OTOH, if you still want to use that meter from Amazon, I will sell you an almost new one for cheap!

[MVA]

Originally Posted by Semievolved

Just stumbled across this thread and hope I am not too late. To evaluate where you are in SOC on LFP batteries in mid range is virtually impossible based on voltage becauwe the V vs SOC is so flat from around 15% up to 90% or so SOC. I saw the meter you were planning to install to measure SOC and wanted to let you know that I have that same meter on a Bestgo LFP battery and it is not accurate for current at all which means it also is not reliable for SOC. To replace it, I am using a Victron BMV-712 which I have been using on my home solar and have verified its accuracy. OTOH, if you still want to use that meter from Amazon, I will sell you an almost new one for cheap!

I assume you are referring to the AiLi shunt/meter not being accurate. How did you measure accuracy for the AiLi and the Victron 712 shunt meters? Did you use both on your home solar system and compare output to the power company metering?

[Semievolved]

Originally Posted by MVA

I assume you are referring to the AiLi shunt/meter not being accurate. How did you measure accuracy for the AiLi and the Victron 712 shunt meters? Did you use both on your home solar system and compare output to the power company metering?

Yes, that is the meter I have as well although I cannot say which current range it is. I assume it is the one with the large current range because the battery it was intended to monitor was intended for EV usage.



I use a clamp meter (several actually) to measure the current through the lines vs what the meter is showing. I also did complete charge/discharge testing on the Bestgo battery using a very accurate instrument that reported the current flowing into or out of the battery. THe AiLi meter was typically off between 15-20% on both charge and discharge although not necessarily the same error magnitude in each direction.

I don't have the same tests on the Victron because it is installed in my system. When I check its readings with clamp meters, they all agree very well. I have other independent semi-quantitative ways of assessing as well too involved to lay out here but FWIW it seems to do an excellent job monitoring the SOC. I didn't want to spring the $200 for another 712 for my trailer but I simply have found no other way to accurately monitor SOC.

[MVA]

Originally Posted by Semievolved

Yes, that is the meter I have as well although I cannot say which current range it is. I assume it is the one with the large current range because the battery it was intended to monitor was intended for EV usage.



I use a clamp meter (several actually) to measure the current through the lines vs what the meter is showing. I also did complete charge/discharge testing on the Bestgo battery using a very accurate instrument that reported the current flowing into or out of the battery. THe AiLi meter was typically off between 15-20% on both charge and discharge although not necessarily the same error magnitude in each direction.

I don't have the same tests on the Victron because it is installed in my system. When I check its readings with clamp meters, they all agree very well. I have other independent semi-quantitative ways of assessing as well too involved to lay out here but FWIW it seems to do an excellent job monitoring the SOC. I didn't want to spring the $200 for another 712 for my trailer but I simply have found no other way to accurately monitor SOC.

Thanks for the assessment - that is helpful.

[John in Santa Cruz]

an engineering friend calls clamp-on ammeters 'amp-guessers'. shunts such as the victron are far more accurate.


btw, LiFePO4 (Lithium-Iron-Phosphate) on a glider? huh, I would expect those to use LiPoly or traditional LiIon, unless you are talking about a full sized sailplane kind of glider, as opposed to a scale RC thing. I have a LiPoly 'USB" battery pack here thats 72 watt hours (20,000 mAH at 3.6V) and weighs 12.6 oz (358 grams), that is about twice the energy density of a LiFePO4. LiFePO4 is used for higher capacity things where the tendancy of overcharged Li-Ion to catch on fire would be hazardous.

[Semievolved]

Originally Posted by John in Santa Cruz

an engineering friend calls clamp-on ammeters 'amp-guessers'. shunts such as the victron are far more accurate.

No doubt shunts can be far more accurate if they are set u and calibrated correctly for their application. However, for checking components in working conditions clamp meters are very useful. I have found that when using several clamp meters, they may differ by a few percent, they typically agree well . A person could average the values to lower uncertainty. At any rate, the reply was to the OP who was considering an AiLi meter which I have demonstrated to be inaccurate in my application. In fact, the battery has an integrated AiLi meter and I have one remote as well. The two meters agree with each other nicely but not with any other measuring device I have used! That to me indicates a lack of calibration at least at the low charge/discharge rates I was using. I also had shunt-based amp meters on a couple battery management systems I tried and some of those were just plain awful. The AiLi is not awful, just not terribly accurate in my experience.

[IanC]

Originally Posted by John in Santa Cruz

btw, LiFePO4 (Lithium-Iron-Phosphate) on a glider? huh, I would expect those to use LiPoly or traditional LiIon, unless you are talking about a full sized sailplane kind of glider, as opposed to a scale RC thing.

Sorry to go off topic, but to clarify re John's question, I'm using 2 cell LiFe batteries (lithium iron phosphate) in RC gliders. No motor. The battery is just used for receiver and control surface servos.