Battery monitor

Many Other Versions 50/100 amp.

hairydog said:
It depends what you want to monitor. Monitoring the voltage is easy, but pretty useless on its own.

The voltage of a battery is only an indication of its remaining charge if no current has flowed in or out of the battery for the last hour or two. Which makes it an impractical measure, even though many people on WC seem to think it tells them something.

In theory you can calculate the state of charge by measuring both the voltage and the current, but the reality is that this is never accurate either, even with fancy calculations involving Peukert's formula.

The only worthwhile way is to monitor the current going in and out and try to keep track. This is fairly reliable as long as the battery is charged right up to the top fairly often, or run right down flat (not recommended!) However accurate they are, small errors can build up, so getting up to 100% from time to time helps keep them accurate.

As far as I can see, the Victror 712 is one of these, with the addition of a bluetooth bit to provide connectivity to an app.

The one I use (which works brilliantly, and has done for many years) looks exactly like DC Battery Monitor Positive Negative Current +/- 30A Voltage 120V Car Volt Meter 754610748905 | eBay which costs less than £15. But if you would rather pay more than ten times as much to be able to open an app instead of looking at a display, that's fine by me!

[Later] Mine must be a bit different because it measures charge currents way over 30A. Perhaps mine is a 50 or 60 amp one. I don't remember, to be honest. It was installed many years ago.
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Good explanation:D Many different sizes of that meter on ebay, (once you find them), the 30amp version look like you would need to run your main input and outputs through the monitor, ok if your are fitting meter by battery or somewhere near those main cables, perhaps you had a shunt with your gauge. Another option I found there, following your link was:-

Battery Monitor Meter Wireless DC 120V 100A VOLT AMP AH SOC Remaining Capacity%% | eBay

Wireless and £25
 
chas142 said:
Good explanation:D Many different sizes of that meter on ebay, (once you find them), the 30amp version look like you would need to run your main input and outputs through the monitor, ok if your are fitting meter by battery or somewhere near those main cables, perhaps you had a shunt with your gauge. Another option I found there, following your link was:-

Battery Monitor Meter Wireless DC 120V 100A VOLT AMP AH SOC Remaining Capacity%% | eBay

Wireless and £25
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If you got to post #19 in this thread you will see a photo of that one in use that I posted (https://www.wildcamping.co.uk/forum...base-/73267-battery-monitor-2.html#post984540)
 
hairydog said:
I suspect that there is a hall sensor that the cable goes through, a box of cleverness on a short wire that can't be extended, and also a longer (extendable) wire to the dsplay. So the box of cleverness will need to be near the sensor.

The one I have that uses a shunt is fine with a few metres of flex between the display and the shunt, though it was far from happy when I tried it with multicore telephone cable. It just happened to be what was to hand, but it was no good.
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That is right - and the longer cable on my unit is the USB Cable.

The one you just ordered looks like the cable from the sensor goes into the meter (3 wires from hall sensor, 3 pin port into meter) so you might be stuck with display positioning?

On the units with the shunts that don't come with specialist wiring, I typically use 3-core 1mm flex as the neatest option. The meters usually need Vin, GND and the two sense wires - so I bring in the 2 senses, plus power from battery bank and then just pick up a local ground.
 
hairydog said:
Yes, any meter can only monitor one point where all the current passes through. The one you linked to can only monitor current in the wire passing through its hole. My experience of these hall effect sensors is that they are not reliably accurate, but I have ordered one of these: Battery Monitor 6in1 300V 100A State of Charge SOC AH VOLT AMP Charge Discharge 732140263808 | eBay, so when the Slow Boat arrives, I'll be able to compare.

The shunt or sensor doesn't have to be anywhere near the meter's display. Mine is installed in the earth cable to the battery bank, with a very long wire to the meter in the dash.
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I know what you mean about hall effect ammeters, I was a Auto Electrician 25 years ago, then it seemed the more you paid and the age of the meter made a big difference. Not been involved much for some time and always used my old meters mostly. Updated a few bits recently, everything is much cheaper now, even if on a paddle steamer from the other side of the world.

Yes, shunt or sensor can be well away from the gauge, with a long wire. I looked at the 30 amp unit like your link, well one of them on ebay, (it was saved earlier as it was the cheapest, ha ha), and that didn't show a shunt, showed it in line with a charger / alternator, without a shunt or sensor, you would obviously have problems if you had to cut into the wires and run them half way around the MH.

Are you finding much of a volts drop across the shunt ? One reason why I never fitted Split charge diode systems, if I found them on the trucks that I maintained they would automatically be removed and replaced with a heavy duty relay system.

Let me know how you get on with the Chinese monitor, there is a post above with a picture of the monitor I linked, (just seen you linked to a different type again, so many options), and their link for I suspect the same unit for about £32, that shows more details than the link I posted. I've got to go back to it at some point but I don't know if it's a bit of over information. I've got to read it all to understand it and decide if I want that much info. Brain slowing down as I get older.:beer:
 
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hairydog said:
I think they are nearly all the same: the meters work on a 75mV difference across the shunt.
Mine is a 50A meter (I think: I've had it longer than the eBay purchase history goes back) so the voltage drop should be 1.5millivolts per amp. Not enough to worry about, I reckon.
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Yes, I agree to that, on some of the trucks that I worked on you could lose 2 or 3 volts in the system, if they had batteries mounted on the trailer for tail lifts etc. No chance of them charging up!!
 
wildebus said:
If you got to post #19 in this thread you will see a photo of that one in use that I posted (https://www.wildcamping.co.uk/forum...base-/73267-battery-monitor-2.html#post984540)
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Re the ebay monitor with the hall sensor it has connections for Vext Power, any idea ? I'm assuming from the diagram that it could show voltage of say the starter battery, could be handy, I wonder if that set up with the relays would also give you the option of cutting off the radio power, on the starter battery side when voltage low. Mind you can buy separate low voltage cut off for that for a few pounds, or wire the radio into the leisure battery side. I keep taking out the fuse when parked up but sometimes forget. The solar controller charges both starter and liesure batteries and can be changed for priority, % wise.

Vext Power.jpg
 
Simple Voltmeter

I use the above Only £5.
Cheap and very cheerful.
The led display is always active.
By monitoring the voltage..with regard to which items are in use I believe it ensures my battery never suffers.
Ok if the truma heating and fan are in use I can see the voltage drop to say 12.7 so turn the fan off and the voltage rises (dependent on solar). Then once the voltage is up to say 12.9 I can use the fan again if needed. I also KNOW that the EB does get topped up.
Finally I sometimes use a 150 watt inverter for a laptop again mabe using the inverter for 10 mins then pausing enables the laptop to be fully charged on most days.
Ps I also use a 12V dc to 19v dc adapter for laptop.
Only 1@ 85AH battery but no issues (6 months Summer only)

PS1 I have used the above to "maintain" my LB for the last 4 summers (2015) having purchased a new LB.

I think LBs (and EBs) can often be neglected over the winter solar will usually solve this
Before I had solar 1 winter (2014-15) when I was not able to "Plug in at home" knackered the LB but it was 8 years old !


PS2 I needed a new EB in 2018 original one from 2006 !

I appreciated some may need a more complicated setup especially those with Electric fridges and more so be it
But in general KISS Keep It Simple (and) Sufficient
 
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wildebus said:
Looking at the size of the studs on them, I reckon you are right.
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Yes the black box is the shunt and wireless connection RF, you can see the shunt wires across the 2 bolts.

The relay connections are shown in both 2w and 3w, so I assume that would let you use the relay function on both battery circuits, but for one of the protection options on each system only. For me the 2 battery system would work well as I could set up low voltage protection on both systems to protect both systems from under voltage.

This would allow me cut off radio memory drain on main battery and to cut off, (none essential), output sockets on leisure battery when using dehumidifier in rear, approx. 2hrs a day, set up on timer. When solar brings batteries back to normal voltage, (set), systems would be reactivated.

This type of monitor would give lots of useful information on both systems. Mmm I am almost sold on it. Less than £40 is a good price and think it can save your batteries as well with the additional relays.

To answer another question on here, not all meters need a shunt or monitor, if the main power cables are run through a coil in the back of a meter that will work an standard analogue swing type meter, or a digital meter if shunt and electronic control fitted in the back of the meter, like I assume what appears here:- DC Battery Monitor Positive Negative Current +/- 30A Voltage 120V Car Volt Meter 754610748905 | eBay
 
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You mention drain from the radio a lot - just how much power is your radio using when it is off? it should be so small to not care UNLESS it has been wired up incorrectly.
 
wildebus said:
You mention drain from the radio a lot - just how much power is your radio using when it is off? it should be so small to not care UNLESS it has been wired up incorrectly.
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I'll get back to you on that one with the details, it is small but it is tied in 24/7, like some other systems, alarm, immobiliser, clock. They all add up to enough to drain the battery if not used for a couple of weeks. The solar and dual controler will have probably solved that issue but not getting much out of that, (140w panel), at the moment.
 
chas142 said:
I'll get back to you on that one with the details, it is small but it is tied in 24/7, like some other systems, alarm, immobiliser, clock. They all add up to enough to drain the battery if not used for a couple of weeks. The solar and dual controler will have probably solved that issue but not getting much out of that, (140w panel), at the moment.
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All radios are connected 24/7 - otherwise all the settings (radio presets, etc) would be lost everytime the power is disconnected. Removing power to that and to the clock would be a PITA as everytime you would need to reset them.
Removing power to the alarm would probably - depending on alarm - set it off as it would see it as a tamper.
I don't think the immobiliser uses much power at all when the ignition is off either. If you did disconnect the immoliser on a low voltage situation, then you would not be able to start the engine and get the charge back up.
 
chas142 said:
Yes the black box is the shunt and wireless connection RF, you can see the shunt wires across the 2 bolts.
The relay connections are shown in both 2w and 3w, so I assume that would let you use the relay function on both battery circuits, but for one of the protection options on each system only. For me the 2 battery system would work well as I could set up low voltage protection on both systems to protect both systems from under voltage.

This would allow me cut off radio memory drain on main battery and to cut off, (none essential), output sockets on leisure battery when using dehumidifier in rear, approx. 2hrs a day, set up on timer. When solar brings batteries back to normal voltage, (set), systems would be reactivated.

This type of monitor would give lots of useful information on both systems. Mmm I am almost sold on it. Less than £40 is a good price and think it can save your batteries as well with the additional relays.

To answer another question on here, not all meters need a shunt or monitor, if the main power cables are run through a coil in the back of a meter that will work an standard analogue swing type meter, or a digital meter if shunt and electronic control fitted in the back of the meter, like I assume what appears here:- DC Battery Monitor Positive Negative Current +/- 30A Voltage 120V Car Volt Meter 754610748905 | eBay
Click to expand...

Hello Charlie
Could the wiring come straight from the already existing Sargent ec480 ? displayed
 
wildebus said:
All radios are connected 24/7 - otherwise all the settings (radio presets, etc) would be lost everytime the power is disconnected. Removing power to that and to the clock would be a PITA as everytime you would need to reset them.
Removing power to the alarm would probably - depending on alarm - set it off as it would see it as a tamper.
I don't think the immobiliser uses much power at all when the ignition is off either. If you did disconnect the immoliser on a low voltage situation, then you would not be able to start the engine and get the charge back up.
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The drain across the fuse in the fuse box is 195ma, I am going to pull out the centre dash section to remove and check the radio memory draw separately. If my maths is correct that is just under 5amps a day.
 
grahammay2 said:
Hello Charlie
Could the wiring come straight from the already existing Sargent ec480 ? displayed
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I doubt it, but I don't know the Sargent EC480, I have had a quick look on ebay and no wiring diagrams for the ones there, no thick connectors, you might be able to link it in to tell you what the draw is when you switch items on. Have a look at the following link, the various pictures, it show in effect how it would be fitted in-line without a shunt for the basic 30amp unit. I think it the same meter as the other link, less info and slight difference in price. It shows a charger but that could also be your alternator. Battery Tester DC LED 90V30A Digital Voltmeter Ammeter Voltage Gauge Panel Meter 754610748905 | eBay
 
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