Ok, so work on total capacity of 1256Ah. << This should be used in all settings for capacity.
2% of 1256 is 25A Your BMV “Charged” parameter for reset to 100% should be 30A for 3 min.
Transition to float should be 25A for the pair.
Correction on the total capacity number for thread continuity, it is 628Ah. Halfling the numbers does it. Thanks again.
When the Charge MOSFETS disconnect the battery is no longer connected to the charger, so at that point it doesn’t matter what charger you are using . The only thing you can do is lower the float voltage (on all of your charging sources) to be low enough to not trigger the OVP which causes the Charging to disconnect. The WattCycle batteries use a very weak passive balancer, approximately 50ma (too small for 314Ah battery).
The weak balancing certainly has added, and continues to add, to the frustrating experience over the five months of working with them. I’m very much on the lower end of the learning curve too, but I’m gaining on it thanks to the help of this community.
After isolating one of the two batteries, I discharged it to 10% SoC, 13.0V, which yielded 298Ah. I reset some charging parameters on both the MultiPlus and the 702 BMV, both networked via the Victron Connect app. Most notably, the charge voltage settings were not identical, so all were set to 13.9V.
The WattCycle did go into OVP before Buk finished at an average cell voltage of 3.419V and a delta of 0.029V. These values were observed several hours after the charge MOSFETs switched off. Absorption parameters should be tuned after some trial data is accumulated (suggestions?). The charge cycle completed without the MultiPlus voltage oscillation I’ve seen on previous cycles. That alone is a small step success. Further charging both batteries in parallel without oscillation is the ultimate goal with this pair.
- The MultiPlus / Fixed charge curve settings at:
- 58A charge.
- 14.11V absorption @ 4 hr.
- 13.35V float.
- The 702 BMV settings:
- Tail current 3.9%
I’m a little late to the party, but there are some reports about these batteries that suggest they don’t play well together when wired in parallel. Reportedly, one battery will disconnect from a 2 battery bank, allowing the other battery to supply the full load until it becomes significantly depleted. When the second battery hits some level of discharge, the first battery reconnects and starts charging the second and supplying the load. The 2 linked videos describe the issue.
Thanks for the post. I became aware of these issues by experiencing them even before the published videos appeared. The parallel behavior was fixed by the September 28 2025 app version. Even before the 28.9.2025 app release, I used them hard several times. They supplied all the power I needed even though the pair weren’t evenly discharged at the end of the test (56% vs 35% SoC). Below is a test run of a roughly 30A load using the RV’s 15k BTU air conditioner and occasional microwave use,.
The WattCycle 314 battery is nicely assembled for RV use, however the BMS needs improvement. The current BMS is workable but the inherent weakness make charging problematic until the cells slowly balance over months. I’m new to the tech side of BMS controls but I’m sure from the marketing/sales aspects, the fix will be forthcoming.
Best of luck with your battery bank. I don’t have any experience with the WattCycle batteries and I’m pretty ignorant regarding how different BMS work, although I have had one disconnect for no apparent reason. In my case, it was one of three LiFeBlue 12V 100Ah batteries daisy chained together. Eventually I was able to reset the BMS, and reinstall that battery into the bank.
It’s clear to me that everyone else has provided advice beyond the level of my technical expertise.
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