Lynx Shunt

DIY
, ,
1

Good evening,

Could someone please advise why there is a big discrepancy between the Lynx Shunt and Battery.

Many thanks in advance.

A

Screenshot_20250528_005832_VRM
Screenshot_20250528_005832_VRM1080Ă—2400 158 KB

2

Hard to tell from limited data. What type of batteries and capacity in Ah, screenshot of shunt settings. Is the system new, have the batteries had a full charge to synchronise both SOC readings. Some BMS boards have poor SOC for the first few cycles.

1 Like
3

Thank for the response. Details of batteries below.

Screenshot_20250117_212301_AliExpress
Screenshot_20250117_212301_AliExpress1069Ă—1334 118 KB

4

Hello,
The system has been installed on the 5th April. Please find further information as requested. The screenshot were all done today.

Many thanks in advance

Alan

Screenshot_20250528_095723_VRM
Screenshot_20250528_095723_VRM1080Ă—2400 147 KB

Screenshot_20250528_095649
Screenshot_20250528_0956491080Ă—2400 148 KB

Screenshot_20250528_095633
Screenshot_20250528_0956331080Ă—2400 202 KB

5

Just to confirm you have 18 cells in series and 4 in parallel. What absorption voltage do you charge to and do you ever get to that voltage. Only item that stands out is the tail current in the shunt 4% is normally better for lithium. If you have never got a full charge the SOC will be inaccurate.

1 Like
6

Depending on the type of BMS in the battery and on the operating conditions, Ah counters may drift considerably and thus show different SOC. The only way to tell who’s right is to fully charge and then fully discharge the battery and see which counter is closer.
I’d like to see technical data on the Lynx Shunt (resolution and accuracy of the current measurement, trueRMS or not, sample rate, expected SOC drift per day…), but the data sheet doesn’t tell anything about these.

1 Like
7

18S is not recommended.

Do you have 2x 18S or 4x 18S?

What are the settings of the chargers?
When was the last full charge to more than 64V?
(you need to get above 64V to get the shunt to synchronize)

1 Like
8

Hello

I have two sets of 18 batteries on two shelves, all the batteries in the top shelf are connected together and go to the invertor. The same with the bottom shelf they are also connected together and go to inverter. I hope the photo below helps.

A

20250509_140253(1)
20250509_140253(1)1920Ă—2588 402 KB

9

Hello,

The batteries get charged to 64v quite often. Especially when we have sunny days.
A

10

Todays information below.

A

Screenshot_20250528_125206_VRM
Screenshot_20250528_125206_VRM1080Ă—2400 148 KB

11

Battery and shunt values are not identical, but close enough together to not be the root cause for the large discrepancy in SOC. 95% at 60V doesn’t look right, though. 60V/18=3,33V, which equals roughly 80%.

The value in the Lynx Shunt doesn’t match either.

1 Like
12

The normal reasons for the shunt not working are wrong charged voltage setting, wrong wiring or doing lots of charge / discharge cycles without getting to 100% occasionally. We can help but need information.

  1. Wrong charged voltage. What absorption voltage do you use. What current is flowing when charging switches to float. See Charged voltage setting.

  2. Wrong wiring. You said you had solar, if the solar is DC where is it connected, the cables from the MPPT go to the Lynx distributor on the right. See Shunt wiring

  3. You say you get to 64.0V, how often and does the Lynx shunt reset to 100% when this happens.