Re: Solar Upgrade Reply #25 – March 05, 2025, 03:31:20 pm I had a question regarding whether the batteries I had installed by Discount Solar were heated or not. The installer invoice stated they were, but the manufacturer literature doesn't mention heaters. After talking to Craig, the owner of Discount Solar, he confirmed that they are indeed the heated variety. Then I received this message from the manufacturer, which gave me a 'warm" feeling. Thank you for purchasing our lithium 12V battery. I am sorry there was no indication of heater on your packaging or battery. We will be looking at adding this to all the labels going forward. Based on the information shared with us, your serial number contains the letters "EV" which indicates there is a heater. We stopped offering non-heated versions about a year ago but they contain "DX" in the serial number. Please let me know if you have any questions.Zack CoxU.S. Battery Mfg. Co.US 12V G24 Lithium-Ion Battery | Essential Li® | U.S. Battery Mfg.
Re: Solar Upgrade Reply #26 – March 30, 2025, 03:50:31 pm No big deal but just curious; the Blue Sky solar controller states that the battery voltage is 13.6V but both the Victron monitor and the battery BMS’s are at 13.3V. Why would it be different?
Re: Solar Upgrade Reply #27 – March 30, 2025, 05:46:06 pm Off the top of my head: unless the Blue Sky controller has a separate voltage sense wire, it's telling you the voltage at the controller's output, whereas the Victron monitor and the battery's BMS are telling you the actual voltage at the battery.Why the difference? My first guess would be voltage drop between the controller and the battery, due to undersized wiring. Measure the length of that cable run, check the wire gauge, and plug those numbers into a voltage drop calculator to see what comes up.What charging voltage does the battery want to see? If you're losing three tenths of a volt in the wiring, then the battery isn't getting a full charge... and that is indeed a big deal.
Re: Solar Upgrade Reply #28 – March 31, 2025, 09:05:56 pm I think the battery may still get a full charge, but slower than it could be. As the battery approaches full charge, the charging current decreases, the voltage drop (which is proportional to current) decreases, and the Blue Sky voltage will increase to approach the battery monitor voltage. 1 Likes
Re: Solar Upgrade Reply #29 – April 02, 2025, 10:25:39 am "the Blue Sky voltage will increase to approach the battery monitor voltage."If the Blue Sky controller doesn't know the actual battery voltage (the voltage shown on the battery monitor), I'm not sure that will be the case. The controller needs to know the true battery voltage if it's to do its job. While three tenths of a volt difference doesn't sound like much, when charging a battery it can be significant.Again, I'd take a look at the wiring gauge and length, and calculate the resulting voltage drop to see whether that's the problem. If it's possible to add a separate voltage sense wire to the controller, that would be a good thing to do.
Re: Solar Upgrade Reply #30 – April 02, 2025, 12:08:43 pm Thanks, Andy. I'll take a look at that. Does anyone know how the wiring is run from the roof to the solar controller in a MidBath?
Re: Solar Upgrade Reply #31 – April 02, 2025, 12:22:21 pm Quote from: Andy Baird - April 02, 2025, 10:25:39 amAgain, I'd take a look at the wiring gauge and length, and calculate the resulting voltage drop to see whether that's the problem. If it's possible to add a separate voltage sense wire to the controller, that would be a good thing to do.Greg, I think I asked before, did the solar installer increase the size of the wires coming down from the solar panels when you upgraded the panels and batteries at Quartzsite?When adding more solar panels to the roof, the wires bringing the power down to the solar controller need to be increased in size to reduce voltage drop.If the wires were not upsized, you are losing charging power, which may explain the voltage differences. Installers probably do not want to do this, as it is a PIA to perform. It is worth doing if you are looking for maximum charging efficiency.Remote electrical troubleshooting is one of the more difficult things to do. Problems that can be found in a few minutes with the use of a voltameter may never be mentioned during discussions on the Forum, there are dozens of potential trouble spots. Your issue may simply be a poor connection....who knows?Larry
Re: Solar Upgrade Reply #32 – April 02, 2025, 01:26:30 pm Hi Greg; Rest easy, there are too many other things more important to worry about. If you boondock for weeks at a time and have to rely on your roof kilowatts of solar, charging your twelve batteries, then highest efficiency is a concern, but just leave your system alone for now. Trust me. RonB
Re: Solar Upgrade Reply #33 – April 02, 2025, 01:42:15 pm Ron, we are not heavy boondockers at this point in our lives so will take a wait and see approach so long as there is no danger of overheating wires.Larry, yes I remember we talked a little about the controller wiring size at Morro Bay the day you and Steve came over to the rig. I pulled the controller out after that conversation to take a peek at the wiring. It appears to be 14 AWG, which is probably factory. The batteries are tracking closely now that we swapped the hook-up cables. Batteries are consistently charging to 99.5% SOC, according to the battery BMS's.
Re: Solar Upgrade Reply #34 – April 02, 2025, 05:54:53 pm Quote from: HiLola - March 30, 2025, 03:50:31 pmNo big deal but just curious; the Blue Sky solar controller states that the battery voltage is 13.6V but both the Victron monitor and the battery BMS’s are at 13.3V. Why would it be different?The Blue Sky controller does not really know what the battery voltage is - it simply is reading out the voltage at ITS output terminals. And, at that voltage, the batteries are likely fully charged. If in the daytime, is there a significant charge current from the Blue Sky? If not, the battery BMS has shut off charging. With no or little charge current, there will be no voltage drop, so likely either the BMS or the Blue Sky calibration is off. A good voltmeter will tell you which.Steve
Re: Solar Upgrade Reply #35 – April 02, 2025, 07:34:09 pm Quote from: Steve - April 02, 2025, 05:54:53 pm With no or little charge current, there will be no voltage drop, so likely either the BMS or the Blue Sky calibration is off. A good voltmeter will tell you which.Learning to use a voltmeter is a necessary skill that owners who work on their own RVs' electrical systems should develop.It can help answer a lot of questions,Larry
Re: Solar Upgrade Reply #36 – April 07, 2025, 12:41:05 pm Quote from: Andy Baird - January 27, 2025, 12:27:25 amIt'll be interesting to see how the SoC indicated by the batteries matches up with that of the SmartShunt. Ideally they should match pretty closely. But several of us have observed that they don't necessarily. If you find that the readings diverge as the battery discharges... trust the SmartShunt. :-) Let us know what you find out.Just perusing this thread, a little late to the party. Some info I just received from the manufacturer of my lithiums (Lifeblue) touches on this. In short - there is no SoC you can trust all the time, at least with heated/bluetooth enabled batteries. Not Victron, not Lifeblue BMS. This is why SoC synchronization is routinely necessary between battery BMS and external shunts like the Victron.There were a couple reasons relayed to me, again specific to Lifeblue but likely similar across other brands. First up - shunts have difficulty detecting very small amounts of current. Here's a snippet provided from an email exchange with Larry and Lifeblue.All SoC meters have an issue with counting very low current. Below a certain threshold, they don’t see current. This is why all SoC meters need regular calibration. Calibration happens each time you fully charge the battery. The SoC resets to 100%. With the LiFeBlue BMS, if you continue charging after the battery is full, you may reach the High Voltage event (HV in the App). This resets the BMS to read 99% until charged again.All batteries have a self discharge rate and if the bluetooth is active this adds to the total current use.Example: Consider a constant current is just 10ma. If that is below the measurement threshold, in 24 hours you have lost 0.24AH that is not registered by the SoC circuit. In the 180 days you could loose 43AH. The BMS SoC still reads 100% because it has not counted that usage. This accounts for having to charge them after 6 months and is why we recommend checking the battery voltage periodically and recharging if it is below 13.0V while in storage.On our newer batteries we have added a 15 day hibernate counter to the firmware that turns off the BMS. We also have installed a power switch on our ULTIMUS models." I encountered the above with my Lifeblues. They sat on a shelf in the garage for over 6 months and the internal BMS showed a SoC of 99%. This was false, as I found out when I first hooked them up to the MultiPlus and checked the charging function. I don't know how far down they actually were, but the MultiPlus charged at bulk for several hours before going into absorption and finally float mode.Continuing on, and specific to heated batteries - the current used for heating may or may not be picked up by an internal BMS on a battery, but definitely won't be picked up by an external shunt, Victron or otherwise. Further - the power for heating may or may not even come from the batteries themselves, so you can't trust the SoC shown by Victron SmartShunts when some batteries are in heating mode. The SmartShunt will apply all current going into the battery to SoC calculations, but as mentioned in the documentation from Lifeblue below - a portion of the current goes to heating the battery, not recharging them.There are likely many approaches to heating batteries, but again specific to Lifeblue - here's how they design their process.LiFeBlue low temperature model batteries will warm the batteries when necessary prior to charging. Our BMS is automatic so the user does not need to monitor temperature or take any action. It is important to know that the battery does not use any of its stored energy to heat the battery. Heating turns on only when the cell temperature is below a threshold, about 32°F, and you are charging with sufficient current. BMS Logic The charge source can be any combination of chargers that make nominal 12 Volts; shore power, alternator, generator or PV solar. When you begin charging and the cell temperature is below the threshold, one of three things will happen:1) If sufficient current is available, about 7 Amps per 100AH, the heater controller will activate to warm the battery cells. Heaters will remain on until the release temperature is reached, about 40°F. During this time the Event Page will display “Battery Warming”. After release temperature is met, the BMS switches the charge current to the cells.2) If charge current is less than 0.07C (7% of battery rated capacity), the heater will not turn on and charge current will be sent to the cells. This low current mode will not harm the cells and is very useful for PV solar power charging.3) When charger current rises above 0.05C but is less than the minimum required for the heater, the battery will not charge and a 5 minute delay timer will start. After 5 minutes, the BMS will sample the temperature and current and begin heat when criteria is met. Otherwise it starts the 5 minute timer again. Important Notes LiFeBlue Batteries must be installed in an upright position so the internal temperature sensor is at the top of the battery. All Low Temperature models are for 12 Volt, parallel installation only. You may not connect them in series. There has been 3 revisions in the BMS low temperature operation programming. Your version may be different than described above. 3 Likes
Re: Solar Upgrade Reply #37 – April 07, 2025, 03:23:52 pm That's very useful information, Will--thanks for posting it!My new Epoch 460 Ah battery has the same issue as far as the internally calculated SoC is concerned. When close to fully charged, the value it reports is within a few percent of what my Victron BMV-712 battery monitor tells me. But as the charge level goes down, the disparity widens. Soon after installing the Epoch battery, I deliberately ran it down to 20% as a test. When the BMV-712 read 22%, the Epoch battery's app read 52%! I don't even look at its SoC any more; I rely on the Victron battery monitor. 3 Likes
Topic: Solar Upgrade (Read 2437 times)
previous topic - next topic
Topic: Solar Upgrade (Read 2437 times)
previous topic - next topic