Poor man's battery monitor

[jonathanhsm]

Just spotted this cut price Chinese special on Amazon for 26 quid !
CAMWAY Battery Monitor 8-100V 0-350A Voltmeter Ammeter
I've got the same thing branded Ampnogy and it works a treat. Possibly worth a punt - the Victron version is around 5 times more expensive.

 

[superheat6k]

I once had a Nasa BM, it packed up after 18 months, when I realised it is just a fancy voltmeter. So a 2 decimal point VM, with decent accuracy and ideally adjustability for calibration, properly read works just as well - indeed what do you think the internal electronics and fancy display actually observe ?

 

[James_Calvert]

My low tech boat has no voltmeter.

Or permanent USB sockets. Instead I plug a car adapter into my switchboard outlet.

This year I needed a USB-C charger for my new phone, so got an adapter which also lights up a voltage reading.

So much handier to just plug in rather than getting out the multimeter and going under bunk to access the battery box.

Twiddle the 1-2-both switch to check the other battery.

Available for £6.46. From China of course.

12/24V LED Screen Car Cigarette Lighter 2.4A USB USB-C Type PD Charger Voltmeter | eBay

 

[emmalina]

Got one of these มิเตอร์ วัดไฟ Watt Meter / Volt Meter DC 0-200V / 0-200A Power Meter ร้านไทย มีประกัน | Lazada.co.th

 

[arcot]

Great except for lithium ....
Almost flat voltage to discharge.....

 

[Plum]

Just spotted this cut price Chinese special on Amazon for 26 quid !
CAMWAY Battery Monitor 8-100V 0-350A Voltmeter Ammeter
I've got the same thing branded Ampnogy and it works a treat. Possibly worth a punt - the Victron version is around 5 times more expensive.

Thanks, interesting, much better than just a voltmeter. How long have you had your Ampnogy branded one?

Www.solocoastalsailing.co.uk

 

[roaringgirl]

My low tech boat has no voltmeter.

Or permanent USB sockets. Instead I plug a car adapter into my switchboard outlet.

This year I needed a USB-C charger for my new phone, so got an adapter which also lights up a voltage reading.

So much handier to just plug in rather than getting out the multimeter and going under bunk to access the battery box.

Twiddle the 1-2-both switch to check the other battery.

Available for £6.46. From China of course.

12/24V LED Screen Car Cigarette Lighter 2.4A USB USB-C Type PD Charger Voltmeter | eBay

I have one of these too. The volt reading at the USB meter is significantly lower than the reading at the BMS

 

[Daydream believer]

I have one of these too. The volt reading at the USB meter is significantly lower than the reading at the BMS

So if it is inaccurate, what is the point of it?

 

[roaringgirl]

It's not innacurate, it gives an accurate reading of the potential difference between the positive and negative supplied to that 12v socket. This will be affected by (amongst other things):
The voltage of the battery
The length of the cable
The quality of each of the connections is the circuit
The cross sectional area of the cables
The temperature

 

[James_Calvert]

I have one of these too. The volt reading at the USB meter is significantly lower than the reading at the BMS

True for mine too, against a multimeter at the batteries.

Still useful.

 

[Daydream believer]

It's not innacurate, it gives an accurate reading of the potential difference between the positive and negative supplied to that 12v socket. This will be affected by (amongst other things):
The voltage of the battery
The length of the cable
The quality of each of the connections is the circuit
The cross sectional area of the cables
The temperature

But you said that it gave different readings to the BMS. Are you saying that the BMS is wrong. As for connections (!!!!) & temp surely the BMS would have identical issues. Re cableing are you saying that one cannot adjust for that? As for battery voltage, you cannot blame that either. It is supposed to be reading that ( accurately) After all it is battery voltage that one wants- Or is that not the purpose?
It suddenly reminded me of my mother. She used to have 4 clocks in the lounge. They all showed different times so no one knew the correct time.

 

[Refueler]

Great except for lithium ....
Almost flat voltage to discharge.....

?????
Lithium of all types do not have flat voltage discharge. In fact they have a gradient that is distinct and is used by Cell Testers to obtain reasonable reading of charge level.

Here attached is a table of LiPo and LiFe values against charge level. Its significant that the charge level is not linear ... but that's another story.

Near level discharge voltage is a characteristic of NiXX cells (NiCd and NiMh) .... until near discharged where the voltage drop off is sharp.