question

jtcook avatar image
jtcook asked

SmartShunt 500A SOC issue going from 54% to 98% while charging from a vehicle

I was camping over the weekend and I have 3 LiFePO4 100 Ah batteries in my trailer. I discharged the batteries from 100% to 54% during my camping trip. I started home and connected my truck to the trailer and charged the batteries with a few amps over a 4 hour period. During this time, the SmartShunt app showed the SOC go from 54% to 98% with very little energy going into the batteries.

IMG_7899.PNGIMG_7900.PNG

I have included screenshots from the Victron app showing the current and voltage when SOC increased dramatically.


Has anyone else seen the issue described above?

Is there an issue with the Smartshunt firmware?

SmartShunt
img-7899.png (244.4 KiB)
img-7900.png (212.5 KiB)
1 comment
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

kevgermany avatar image kevgermany ♦♦ commented ·
More likely the shunt settings. Jumps like that can be expected with a charged voltage that's too low and a low charge current.

It would be worth checking the charger settings to see why the charge current is so low. Also for high resistance between charger and batteries.


2 Likes 2 ·
1 Answer
snoobler avatar image
snoobler answered ·

Two approaches to sync:

1) strong, consistent charger (AC charging, DC-DC, where you can count on a significant and consistent charge current) - you sync when float criteria are met.

2) weak, inconsistent charger (solar) - you sync when absorption and tail current criteria are met.


#1 = 0.2 or 0.3V below float voltage, tail current set to something very low.

#2 = 0.2 or 0.3V below absorption voltage, tail current set to a suitable termination value (2-4% for lead acid, 4-6% for LFP)


IMHO, it sounds like your charged voltage and tail current criteria were met due to the very low charge current, i.e., the charging was so weak, it was OVER the charged voltage and under the tail current - ON THE WAY to a full charge instead of after a full charge is achieved.


IMHO, you should be able to avoid false syncs using the #2 method.

2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.