Hoping someone can help me! On my 5th wheel RV I installed a MultiPlus ll 2x120, 1 Enduro 300 ah Lithium Battery, and 800 watt solar a couple years ago. The solar works great and the system has served me well but I do need to charge my battery occasionally with my generator. I have tried every setting I can think of but I cant keep my Generator from surging up and down. The best I can do is about 1000 watts then it will fall off to almost nothing then cycle back and forth. I have a Westinghouse 4400 watt Inverter generator. I was hoping the larger gen would allow me to charge fast to not be a nuisance to other campers but bouncing from 1000 to 0 watts will take forever and the sound is very annoying! I have discharged my battery to about 25% to do the testing and adjustments. It seems the voltage is spiking above the 14.4 absorption voltage, sometimes up to 16 volts, shutting the charging down to a low rate, then back up again. I can get it to smooth out if I turn the charge current down to around 30 amps and getting about 250 watts charging. Im starting to think my Battery may just not take enough charge at a fast rate but I seem to remember the max charge rate on the Battery was like 120 amps! Unfortunately, Enduro has gone out of business, so I cant get any help from them but the Battery holds a lot of charge and will last us all day and still be at about 70% doing normal things while dry camping. I have tried Turning on the Dynamic current limiter but changes nothing. I’ve tried hundreds of combinations of different AC input current limits and charge currents and nothing works. I did notice when I plugged into my 50 amp shore power the charging watts was bouncing up and down just like on the generator. I will include my current VE Config settings and appreciate any help anyone can give me. Thank You in advance! [1000010987 (002)] [1000010984 (002)] [1000010985 (002)] [1000010986 (002)]

Does the LiFepo battery have its own BMS where you can check the cell voltages? Check all cable connections from the Multi to the battery. Maybe you have a Single Cell with a Overvoltage and the BMS shut down the Charging

If you have 2 units in split phase, the charge current should be double what you have in Veconfig. The 60A you have in there will be 120A. You should try and lower the voltage. If you have a BMS disconnect at 14.4V, try 13.8V and then raise it to 13.9V, 14V and see if it keeps disconnecting. If you can do absorption at 13.8V, the battery will 99% charged.

It is a “Splitphase Multi”- “MultiPlus ll 2x120” The Charger only work on the L1 Leg of the Splitphase

Hi, My thoughts on this would be: Your 4400w generator could produce 37Aac @ 120v. When this is converted to DC (120v(ac)/14.4(dc) = 8.3 * 37Aac) for battery charging this could become a potential 307Adc. Solely limited by your MP DC charging output. You mentioned you have a single Enduro 300Ah Lithium battery. Almost without exception the maximum charge rate for lithium cells e.g EVE is 1C (300A). I would investigate the battery BMS settings and it’s Alarm logs. I suspect you are experiencing the BMS shutting down charging based on Over Current Charging Protection, it’s also possible there may be an issue with Cell Over Voltage Protection too as pointed out by @Netrange . My first ‘test’ would be to limit the input current to 13Aac (reducing your battery input Current to about 108Adc). This would be a more comfortable 0.33C charge for your battery BMS, and would also help increase you battery cell cycle life too. Most lithium cell data sheets spec 0.25 - 0.5C for the nominal charge rate (for your battery this would equate to 75-150Adc ()). You mention that when the input current is set at 30A (30Aac * 8.33 (120/14.4) = 249Adc) things seem to resolve the issue, and I suspect that is somewhere close to the Charging Over-Current protection threshold on your BMS (if this was set at 85% of 1C, that would be 255A) Do you have the original battery and BMS manual?? If this was your battery supplier, you can see the list of BMS protections, but there are no thresholds specified: Lithium Battery FAQs - Life and More | Enduro Power The BMS app on the the Play store looks like a fairly typical end user, limited interaction BMS app. That is to say they design for safety and life, and don’t enable end users to make changes to BMS settings, meaning you may well just have to live with what you have. This is one of the reasons I build my own LiFePO4 12V batteries utilising the JKBMS 200A. I’d also say this: Fast charging degrades battery cell cycle life more than any other action. LiFePO4 likes to cycle between 60-90% SoC for maximum cell life. Maybe you could post a screenshot of your battery BMS settings and Alarm logs, if they might be of any use?

I have some node red code that dynamically reduces the charge current as the voltage rises i posted an example for another poster. I do this for one of my systems, so the solar finishes off the charging. You might be able to see how I do it and use some of the code. Just change the values to a 12v for example, start reducing at 13.6V and have the min current at 14V. This works really well because as you reduce the current, the voltage also drops. [image] Adaptive charge curve with Multiplus 12v 3000 and LFP DIY Hey folks, This has been an ongoing saga for me, where the multiplus causes voltages spikes in the absorption cycle. I’ve boiled it down to: My batteries are damn full and and bit of extra current causes the voltage to spike. Unfortunately I have integrated BMS with no comms. With my mppt I can set the tail current to something like 1amp (365 amp/h bank) and I never experience voltage spikes. Multiplus can’t do that. Nor can I reduce the absorption time less than 1h. Here’s my question: Can…

It has a BMS but I have no idea how to communicate with it. Pretty sure there’s no Bluetooth connection to it. Harrison Smiddy, Enduro Owner, was very helpfull when I bought the battery but his number has been disconnected. Enduro says max voltage is 14.6 so I’m sure it’s shutting me down and causing the oscillation. All connections are secure. Thanks for your reply!

I did try lowering the voltage to 14 but will try it lower. Thanks

[image] anon39974850: BMS settings and it’s Alarm logs Do not know how to do that. [quote=“NeptuneUK, post:5, topic:34175”] I suspect you are experiencing the BMS shutting down charging based on Over Current Charging Protection, it’s also possible there may be an issue with Cell Over Voltage Protection too as pointed out by @Netrange . [/quote] I am sure of this! Sadly, I do not. This is on their website [image]

I really appreciate you guys spending time to help me. I will do some more experimenting today and let you know how it turns out. I do have a 2000 watt Champion generator and may just use it and be satisfied with a slow charge rate.

Have you installed their BMS app? They have an Android and Apple version on the respective app stores and it’s free to use. If you installed that app, enable BT on your phone, you should see the battery and it’s info.

Generator Charging Surge

DIY

owenb79 (Owen) 31 May 2025 08:38 6

I have some node red code that dynamically reduces the charge current as the voltage rises i posted an example for another poster. I do this for one of my systems, so the solar finishes off the charging. You might be able to see how I do it and use some of the code. Just change the values to a 12v for example, start reducing at 13.6V and have the min current at 14V. This works really well because as you reduce the current, the voltage also drops.

Topic		Replies	Views
Charging Two Paralleled 314 Smart Batteries Q&A and troubleshooting diy , multiplus , rv , parallel	26	1807	20 November 2025
SmartSolar Charger MPPT 100/30 over voltage spikes DIY parallel , overvoltage , mppt_controllers , agm_battery	18	377	27 May 2026
Help to resolve High Cell Voltage warnings DIY beginner , parallel , lithium_battery , cerbo-gx	22	568	20 August 2026
New Multiplus Goes Crazy in Absorption With New LiFePO4 Battery DIY marine , victronconnect , diy , multiplus	12	1089	4 November 2025
How does the Multiplus trickle charger work DIY marine , rv , trickle-charger , starter	27	8270	12 April 2026

Generator Charging Surge

Related topics