Wakespeed charging SmartLithium batteries at 13.50v after DVCC update

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bomax182 asked Jul 6, '24

Wakespeed charging SmartLithium batteries at 13.50v after DVCC update

I noticed that my Wakespeed WS500 controlled alternator is only charging the Victron SmartLithium batteries at 13.50-13.52v (@100amps). This seems low to me, and I expected it to rise to 14.2v for absorption and cell balancing. But that doesn't seem to happen (at least within an hour or so of monitoring).

I have the Lynx Smart BMS controlling everything via DVCC after the latest firmware update from Wakespeed. The Wakespeed reports it's correctly in Slave Control operation as before.

Otherwise everything is working as it always has, but it seems now that the DVCC has been introduced in this firmware update, the system is limiting the alternator charging voltage to 13.50. It is as though it's limited to Float. I am almost certain it used to rise to 14.2v as expected prior to updating the Wakespeed firmware.

Is this expected/normal?

Lithium Battery DVCC alternator

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Answer 1 · 2024-07-06T20:57:17Z

pwfarnell answered · Jul 06 at 08:57 PM

When running on the WS500s own charge algorithm every time you started the engine the alternator would go to absorption at 14.2V and then after absorption it would go to float at 13.5V. It would do this even if an absorption charge was not really required, even if the batteries were quite full.

Now the Lynx BMS controls the charge voltage and you need to understand how the Lynx BMS looks after charging and read this in the manual. To explain briefly, once the Lynx has completed absorption, it requests float voltage of 13.5V. It stays on float voltage until either 30 days have passed or the SOC falls below 70%. Therefore, the batteries only get an absorption charge when required, if the SOC is still above 70% when you start the engine it charges at 13.5V and this is high enough to keep the battery around 100% SOC.

You can see this if you go into your Venus device (Cerbo etc) or VRM and look at the CVL (charge voltage limit) value, this is what the BMS is asking the chargers to charge at.

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pwfarnell commented · Jul 06 at 09:00 PM

@bomax182 here are the Ly x settings which control a new charge cycle

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pwfarnell commented · Jul 06 at 09:07 PM

@bomax182 If you go into the Venus device menu and go to the Lynx BMS and click on this you should see the following page to show the limits the BMS is setting.

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bomax182 pwfarnell commented · Jul 06 at 09:42 PM

@pwfarnell Thanks for the quick and detailed replies. Everything you said makes sense. What I forgot to mention in my original post is that the SOC was only about 50% when I fired up the motor, well below the 70% charge threshold (I confirmed this is what mine is set to).

I also checked the Parameters screen per your suggestion and confirmed the CVL is set to 14.20v as I’d expect.

I just tried everything again after verifying correct settings on the Wakespeed. Now the voltage rises up to 13.62 @ 106A but doesn’t seem to want to rise above that.

Is there something that could be making it difficult for the alternator to bring the voltage to the requested 14.2v? I’m running it at a healthy RPM (2000rpm) and it’s not overheating (90°C). Field is at 100%.

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pwfarnell bomax182 commented · Jul 07 at 07:05 AM

If the SOC is down at 50% and the field is at 100% then the alternator is maxed out at 106A and you will have to keep charging to refill the battery and get the voltage back up, the alternator is in bulk phase, i.e. current limited. Keep charging till you get the batteries full, you said you monitored an hour or so, you have not said what size bank you have, if you have say 800Ah then at 50% SOC you need to recharge 400Ah which will take 4 hours.

Now, if the alternator used to deliver more than 106A then something is not right. With DVCC you input the max alternator charging rate, is this correct. Also, have you got the feature in wire OK. Otherwise get the alternator checked over.

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bomax182 pwfarnell commented · Jul 07 at 10:53 AM

@pwfarnell I think you are spot on… the system is working, but still in bulk, current limited. It’s a 600Ah bank. You were also correct about the DVCC max charging rate — I had this initially set to 100 but just adjusted to 115A (a bit optimistic) when reviewing settings per my last post. This is likely why the alternator was able to squeeze out the extra 6A and .10V.

I think me inadvertently limiting it to 100 is what “changed” with the new firmware update. Thanks again.

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