#142955  by Mark
 Sat Jul 21, 2018 8:51 pm
"#4 is also wireless AND Hall - so no wiring needed at all!!"
Interested? It would be really good if anyone buying any of these units could then post a review of their findings.
I will do one for #11, so that's a star
As soon as I have a new motorhome, I'll buy #4 and review it. (Should be in about a month, I would guess.)
 #142957  by vansvilla
 Sat Jul 21, 2018 10:27 pm
Neddy. I have been doing a bit of research on the cheaper battery monitors and Puekerts Law or equation raises it's head.
It is maintained that they are little more than amp counters and unless reset at 100% often, very quickly fall out of synch with the batteries actual condition.

The likely effect being that the condition you are trying to avoid, ie discharging too far is likely to occur.
So my query to you- do you know if any of the monitors you portrayed have some sort of Puekerts compensation in them or do the typically low current draws not incur the wrath of Mr Puekert?
 #142967  by Neddy
 Sun Jul 22, 2018 2:10 pm
Peukert's exponent is used to estimate the battery run-time remaining for a given battery State Of Charge at a specific discharge rate. (The higher the discharge current, the lower the run-time).
Since none of the 11 battery monitors listed incorporate a "Run-Time" readout, they have no use for Peukert's equation.

The most sophisticated Battery Monitors I have seen are built by Bogart Engineering, as exemplified by their Pentametric models.
These are very expensive "top of the market" units, but as with the majority of cheaper brands and models, they make NO use of Peukert's equation.
Here's why :- http://www.bogartengineering.com/wp-con ... mments.pdf

Neville.
 #143288  by Neddy
 Thu Aug 02, 2018 5:17 pm
Review of TF03 Battery Monitor (#11)
TF03.JPG
This monitor cost NZ$78 and took 12 days to arrive from China. It was tested by connecting its shunt in series with my existing Votronic shunt, enabling the two different monitors to be directly compared.

Install. This was quick and easy. The Shunt bolted directly to the Battery negative terminal and a single wire needed to be run from the Shunt unit to the battery Positive. A five-way plug-in cable (supplied) then connected the Shunt to the Meter readout unit.

Calibration. As with most battery monitors, the battery capacity (in AmpHours) needed to be entered.
After fully charging the battery, the capacity% readout was set to 100%. This was accomplished by a single key depression. Again, quick and easy.
There is an audible "Low Battery" alarm that can be set to any desired Ah level.

Don't know your battery capacity? Plug a couple of 230v lightbulbs into your inverter and turn it on. This will discharge the battery until the Inverter hits its "low voltage cutout" point and switches itself off. Then set the meter to 0% (a single key depression) and charge the battery. When the battery is fully charged, read its Ah capacity off the meter, set the battery capacity to this figure and set the Capacity% to 100%.

Performance. This meter gave the same Volts, Amps, AmpHours and Battery% readings as the Votronic unit. I don't mean about the same, roughly the same or approximately the same. I mean exactly the same. Meter response was fast and stable with no hint of fluctuating current readings - despite their being updated twice a second. Where the Votronic takes 5 seconds or even more to climb to the correct current reading, the TF03 was pretty much instantaneous. Similarly, when a heavy load is suddenly cut, the Votronic current reading slowly falls step by step to zero while the TF03 reacts straight away. Fluctuating current readings can be an issue with battery monitors but in my opinion the Votronic unit is severely over-damped, to the extent that it is incapable of recording transient peak currents such as you get when the engine first starts.
I particularly liked the TF03s "one button" 100% charge setpoint, and the "one button" 0% charge setpoint made it very easy to measure the battery capacity for accurate calibration of the unit. I particularly liked being able to see all relevant parameters simultaneously, rather than having to page up and down through the 7 Votronic options to find those of particular interest - one at a time.

Cons. The meter comes with a 1.5 meter connection cable and this is too short for my install. It will be relatively easy to lengthen, but still. It would be good if the screen had a bit more contrast. There was no manual (!) but this doesn't really matter because all the info you need can be found here :- https://www.aliexpress.com/item/100V-10 ... autifyAB=0
I would have preferred that the display showed only the 5 parameters that are of interest to me, but I guess that is a minor quibble. The ammeter reads to 0.01A which seems like needless accuracy for a battery monitor. The screen backlight flashes constantly if the battery is under charge. Needless and a bit annoying, but at least it can be turned off if you prefer.

The bottom line. A 100Amp TF03 is $78. A 100Amp Votronic is $270.
A 500Amp TF03 is $96. A 400Amp Votronic is $329.
Ignoring the large price differential, the TF03 meets my requirements better than the Votronic.

Neville.
 #143291  by Nut17
 Thu Aug 02, 2018 6:47 pm
That is a very positive result Neville. That unit would appear to be really good low cost alternative to the Votronic. Thank you for spending the time and effort to bring us this report. :TU
 #144544  by Mark
 Sat Sep 15, 2018 11:42 am
Not a full report, but my experience, so far with #4 monitor in this thread.
Image

It arrived in about 2 weeks (in fact the day I got home with the Kea).

There are 3 parts:
A Coil through which the main DC feed cable goes - either positive or negative
A Sender unit, into which the coil is plugged via a (maybe) 125mm cable and which has a USB port that can power the screen.
A Monitor screen that reads the data wirelessly but has to be powered through a USB port.
Plus an instruction sheet and some plugged cables to be used for handling voltage sensitive switching and an external power supply.

In my situation, the hardest part about installation (with batteries under the passenger seat) was physically mounting the coil and sender units - particularly with the rather short interconnecting cable. I have ended up sticking the coil to the seat base using double sided tape.
The Sender unit is powered from the batteries being monitored (although it can be powered externally). There is a jumper that determines where it gets its power from - the default is external and it is much easier to shift the jumper before installation than after (tell me about it!).

At this stage the monitor screen is "stuck" to a convenient surface, handy to a USB outlet.

As Neddy has said, it is a very crowded screen but gives you all the parameters you could possibly want without having to scroll through several screens (Votronic).

The screen lights up and all the numbers seem to change, indicating that it is measuring something. Until I do a proper capacity set, I have set the capacity to (a not completely arbitrary) 132 amphours (140 * .97^2 - the batteries are 2 years old).

I thought I would see what sort of draw-down the fridge used overnight and was dumbfounded this morning to find the batteries still full at 132 amphours. B*****r!

Then I noticed that the current seemed to working in reverse: positive amps while the fridge was cycling and negative amps when it switched off.

Now I had thought that the arrow on the body of the coil should align with a current travelling from the battery positive towards any load.
Either I don't understand these things (entirely possible) or the arrow has been affixed pointing the wrong way.

I have now turned the coil 180deg and things seem to be making more sense. I will now allow the sun to charge the batteries until there is negligible current flowing - at which point I'm happy they are fully charged.
 #144580  by Skiwi
 Mon Sep 17, 2018 9:20 am
Neddy wrote:
Thu Aug 02, 2018 5:17 pm
Review of TF03 Battery Monitor (#11)
TF03.JPG
This monitor cost NZ$78 and took 12 days to arrive from China. It was tested by connecting its shunt in series with my existing Votronic shunt, enabling the two different monitors to be directly compared.

<snip>

The bottom line. A 100Amp TF03 is $78. A 100Amp Votronic is $270.
A 500Amp TF03 is $96. A 400Amp Votronic is $329.
Ignoring the large price differential, the TF03 meets my requirements better than the Votronic.

Neville.
Hi Neville, does the monitor show amps in as well as amp out? ie does the 100amp model range from -100 to +100 or from 0 to +100?

Cheers
Skiwi
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