iSpindel battery voltage readings

[JockyBrewer]

I've used my iSpindel for a few batches, but weirdly on the last couple of brews I've noticed that the battery voltage readings are starting off a bit higher each time.

Here's the starting voltage being reported to Brewfather for my last 8 batches.

4.1v
4.1v
4.1v
4v
4.1v
4.3v
4.4v
4.6v

After usage I clean the iSpindel and then charge it just before the next fermentation.

Have I got a battery fault or is something else not right?

 

[Rwilts]

Just a guess , but does the temp of the wort effect the voltage reading?

 

[Agentgonzo]

I get similar readings. Normally between 3.9 and 4.2V on a full charge.

I just ignore it and chalk it up to differences in charging/voltage reporting stuff. It's probably had less effort putting in to it compared to mobile phone charge levels by the developers

 

[JockyBrewer]

I'm just a bit concerned at over volting a lithium battery.

I think that after this batch I'll take the cell out of the ispindel and test the voltage with a multimeter to see whether the iSpindel is reading correctly or not.

 

[Rwilts]

In support of @Agentgonzo post , whilst I have never noticed a difference with my iSpindele in 30 + brews , neither have I ever been concerned about it.

 

[RoomWithABrew]

I'd ask how long is your ferment?

What is the battery voltage at the end of your ferment?

It's very likely that you can do more than one ferment with a single charge on your ispindel.

One of my ispindels in an imperial stout was in there for 186 days, battery voltage was 4.08 at start and 3.31 at end.

Not charging a lithium ion to full and not running it flat prolongs its' life, plus a gentle slow charge rather than a 3 amp race.

 

[Agentgonzo]

Interesting...
My iSpindel is generally not in the fermenter for more than 3 weeks. It sends its data every 30 minutes. It's in a stainless fermenter, so that possibly requires more power, so flattens the battery. It's normally ~4.10V at the start and ~3.6V at the end, though this varies. To charge, I just plug it into whatever USB3 charger I have

I dont' think I would be able run my iSpindel for 186 days

 

[RoomWithABrew]

Mine was sitting in a dessert wine, in a spare fermenter near a wifi relay and sending every half an hour.
TBH the 10litre dessert wine kit is going to last me a very long time.
I don't really mind if the ispindel konks out after the ferment, most of my beers are moved on within 10 days.

 

[JockyBrewer]

I'd ask how long is your ferment?

2-3 weeks usually

What is the battery voltage at the end of your ferment?

Previous ferment was 3 weeks, voltage started at 4.4v and finished at 3.9.

Previously it would start around 4.1 and finish at 3.9 over the course of 2 weeks.

Not charging a lithium ion to full and not running it flat prolongs its' life, plus a gentle slow charge rather than a 3 amp race.

Sure, although the charging circuitry is built in to the iSpindel (and decides where to cut off) so it's difficult to under charge it deliberately. I replaced a previous iSpindel because one day it didn't stop charging so I didn't trust it any more to not cause a battery fire.

I'm now wondering if the charging circuits are failure prone and whether I should use a stand alone 18650 charger.