12V,24V,48V Victron BMV 700,Battery Monitor,Volt+Amp meter,DC POWER 4WD ,Marine

meetoo · Guru

SOC State of Charge meter

Tony Bev · Guru

I am not a Techi, I can only go from my own experience

Hello John

I just use a ciggy plug type el cheapo volt meter
I use ciggy plugs to charge up the phone, laptop, etc, from the house batteries, so I may well as use it to get the SOG

The secret is to have no load going in, or out, of the battery for a few hours, to get an accurate reading

When I wish to know the SOC (State of Charge), I will disconnect the solar from the battery, when the sun goes down
In the morning before I use any power, or reconnect the roof solar panel, I will look at the volt meter

Not all volt metres are accurate, but most are within 0.1 volt
I look at the volt meter, while checking the battery volts, with a multimeter
I then write the difference such as -1 or +1 on the ciggy type voltmeter
This seems to work for me

I find that when the solar panels are charging the battery, I am actually looking at the voltage going in, such as 13.8 volts
If I disconnect the solar panel, this will come down to the SOC of about 12.8 volts, but will take some time to do so
With the solar panel disconnected, and using power from the battery, it will drop to perhaps 12.6 volts, but jump back up with the power off, but once again it takes time to do so

I am led to believe, so could be wrong, that the expensive SOG metres, calculate the volts/amps/watts used, and the volts/amps/watts going in, to give the SOG

Hope that this info is useful to someone
And also hope that if I am wrong, then someone will come along, and put me right

Perhaps the Techies can explain this, in a better manner than me

Below is a picture of the el cheapo volt meters I use

Ciggy voltmeter.jpg

meetoo · Guru

HI Tony. Thanks for that. I do similar to you currently, but it is a pia to do all that. I have 2 batteries connected together with some outputs coming off one battery and other outputs coming off the other battery, - just for convenience of wiring. For a SOC monitor to work properly would all outgoings have to come off the one battery so everything goes through the shunt? I understand my solar/battery system well, but am lost when it comes to these SOC monitors and shunts etc, and how that all works. Hoping someone can explain it all to me, (hmm simply smile ) and even suggest a type or two that is worth considering.

Cheers, John.

Tony Bev · Guru

I also would like to find out how to wire up an el cheapo shunt, John

I followed the instructions and had it between the negative wire, and the negative battery terminal, but it did not work for me
The amps were showing but they were way out of whack, with what my amp clamp meter was showing

Below is a sketch on how I wired up my house batteries
The original Jayco wire is very light, but I would have to rip a bit of wall and furniture out, to change them

I call them house batteries, so as not to get them confused with the engine starting battery

Battery wiring PNG.png

Warren-Pat_01 · Guru

John,
Have a look at an earlier post called "Doing the Maths" on the same page as this.

Jaahn has posted the voltages that shows the volts vs battery capacity. And like Tony, I've relied on an el-cheapo meter from Jaycar Electronics (around $20) numerous times - again it plugs into a 12v (ciggy) socket. Look up the web site that he listed (Energy Matters) - there is some good info there.

Now this info is for batteries in good(ish) condition. You can get some bogus readings if you rely on volts & the internal "bits" are corroding through.

Warren
PS - you can pay some very big biccies for some SOC meters - eg those handled by Bainbridge Technologies

mr glassies · Guru

I recon every van should have a victron gauge . Shows state of charge in volts , amps in or out , wats in or out , and percentage left in battery .

Dibs

Cruising Cruze · Guru

Hi Dibs

Hi mate feel free to send me one
we would greatly appreciated if you could

Cheers John

mr glassies · Guru

What you want a victron gauge in the mail m888888888888888
How's the new holiday cottage
Dibs

Cruising Cruze · Guru

Yes Please

Lovely now we only need another truck total Gross Combination Mass is to small 4563 kg
Caravan is loaded max 2343 so only 2220 left for the ute
We still have to take the caravan empty over the scales and than with water and see how much that is
I can't recall what it was when we picked up the van, it had some water in the tanks more than half full tanks
Have to sort it out this week coming

Cheers John

PeterD · Guru

Let us get one thing straight. A volt meter will not give you a SOC reading. A batteries terminal voltage at any given state of charge varies considerably depending on whether you are charging or discharging (using) the battery. A volt meter will only give you a rubbery indication of whether the battery is nearly full, nearly empty or somewhere in the middle. In addition if a battery is under charge you need t know both the input current in addition to the terminal voltage to get a rough idea of where the battery is in its cycle.

If you want a fairly reliable indication of SOC then you need something like one of these and they will cost you big bickies.

LCD Battery Computer S with Smart-Shunt

The DrifterBM

NASA battery monitor.

BMV-700 series

One thing that annoys me is people who keep insisting is those who call electrical meters - gauges. One thing you can guarantee is that anyone who uses the term gauge for electrical instruments has little appreciation of the subject. I hope others recognise that others recognise their lack of expertise and ignore their ramblings.

Depending on usage, a gauge can be described as "a device for measuring a physical quantity", for example "to determine thickness, gap in space, diameter of materials, or pressure of flow", or "a device that displays the measurement of a monitored system by the use of a needle are pointer that moves along a calibrated scale".

-- Edited by PeterD on Thursday 5th of October 2017 04:59:37 PM

Tony Bev · Guru

Your first link is not working, Peter

As I am not an Electrician, or even a techi, I am sure that what you are saying is absolutely correct

Below is my layman way of explaining why I use an el-cheapo volt meter

For my (and I assume for many others) situation

I do not have the expertise/equipment to place wires through a wall, and set up a battery monitor

My motorhome came with a cigar lighter type 12 volt socket
The el-cheapo volt meter, at least gives me a rubbery ball park number to crunch

I find that if the number is 12.8 or higher then I have something in the batteries
If the number is 12.2 or less, then I would have to stop using the batteries, to protect them

Prior to using an el-cheapo volt meter, I destroyed a 100 AH GEL leisure battery, by relying on the original Jayco charging stuff
I have no idea of the use or abuse, of this original battery

When the TV went off, I would go for a drive to charge the leisure battery, to keep the boss happy
Over a few weeks, the time limit for the boss to use the TV, got less and less, until the battery died

If at that time I was using an el-cheapo volt meter, I would have realised that the charging system, was not capable of replacing, what I was taking from the battery

I now have (gaining the information from this forum)
Better batteries, better charging systems, and happy to use my el-cheapo volt meter

macka17 · Guru

Tony.

There is a little unit you put into Truck battery line
to cut off output from battery when it reaches a set Voltage.??
REDARC have one built into their solenoid dual battery units.

Anybody??.

If you get one of them and stick it in line.
'Surely that would cover your battery overdrawing.
Tripping out battery\s at certain Voltage.

I just stick a multi into one of the tray H\D Dual Cig lighter sockets
to check battery's in rear.
Though the 80w panel on roof usually sorts them.

Tell you what.
This NO welding anymore. (Spinal Chord implant)
REALLY stuffs the "doing little jobs all the time"
Everything gotta be, hacksaw. Fold, then rivet or bolt.
Plus gasket for Waterproofing.
SUPER Annoying.

I feel like turning it off.
Welding.then turn back on again.
He says Ins' won't cover that. Bummer.

Apart from loading panels till you hold above 12.5v by daylight. ?????
Sorry.

I just bought 2 more 130w. Good Chinese and Jap cell panels at $1 per w. Del.
Vic Offroad. ($260 for 260w)

Del today. Good quality. One with a coupla goodies in there.
STD plugs. Anderson Plugs. and 18in Rigid Framed LED light with sw.
Bonus hey. Unexpected.

3 x. At those prices. and a little patience. Hire Trestles\plank .
days work.
Efficiency forever. (As long as you stay up here in QLD hey... ) Chuckle.

I never sed d'at.

Tony Bev · Guru

Tony.

There is a little unit you put into Truck battery line
to cut off output from battery when it reaches a set Voltage.??

My el-cheapo volt meter will probably do the same job manually, Macca
At a much cheaper price

If I ever see the leisure batteries volts drop too much, I shall manually disconnect the batteries from the 12 volt system, via the isolation switch

This is only my theory of course, as I have yet to see the volts drop low enough to worry me

Terryt · Veteran Member

Tony Bev. I have no doubt that PeterD is an expert and anyone who refers to a meter as a gauge should be flogged to within an inch of their life and totally ignored but I strongly agree with you re the 12.8 got lots. 12.2 take care. As good as any other method and would only possibly get iffy if your battery was on the way out anyway. ie show 12.8 but as soon as you put a load on it drops like a stone. Lots cheaper than the fancy stuff too. When my fridge kicks in it drops the voltage by .1. When it cycles off back up it goes.

mr glassies · Guru

www.ebay.com.au/i/391874674194%253A%252F%252Frover.ebay.com%252Frover%252F1%252F705-139619-5960-0%252F2%253Fmpre%253Dhttps%25253A%25252F%25252Fwww.ebay.com.au%25252Fi%25252F391874674194%25253Fchn%25253Dps%252526dispItem%25253D1%2526itemid%253D391874674194%2526targetid%253D345717126183%2526device%253Dt%2526adtype%253Dpla%2526googleloc%253D9070524%2526poi%253D%2526campaignid%253D903935190%2526adgroupid%253D45410936819%2526rlsatarget%253Dpla-345717126183%2526abcId%253D1129316%2526merchantid%253D7647642%2526gclid%253DEAIaIQobChMIutrwybjl1gIVCR9oCh1yYAuREAQYBCABEgKE0PD_BwE%2526srcrot%253D705-139619-5960-0%2526rvr_id%253D1331948327295

It's what I put up before

PeterD · Guru

The link still does not work. Try using the link insertion facility to insert the link. Switch to "Advanced Editor." Type a heading, underline it and then click on the chain link symbol.

aussie_paul · Guru

Is it this?

Mouse over image to zoom

Have one to sell? Sell it yourself

12V,24V,48V Victron BMV 700,Battery Monitor,Volt+Amp meter,DC POWER 4WD ,Marine

meetoo · Guru

mr glassies wrote:
www.ebay.com.au/i/391874674194%253A%252F%252Frover.ebay.com%252Frover%252F1%252F705-139619-5960-0%252F2%253Fmpre%253Dhttps%25253A%25252F%25252Fwww.ebay.com.au%25252Fi%25252F391874674194%25253Fchn%25253Dps%252526dispItem%25253D1%2526itemid%253D391874674194%2526targetid%253D345717126183%2526device%253Dt%2526adtype%253Dpla%2526googleloc%253D9070524%2526poi%253D%2526campaignid%253D903935190%2526adgroupid%253D45410936819%2526rlsatarget%253Dpla-345717126183%2526abcId%253D1129316%2526merchantid%253D7647642%2526gclid%253DEAIaIQobChMIutrwybjl1gIVCR9oCh1yYAuREAQYBCABEgKE0PD_BwE%2526srcrot%253D705-139619-5960-0%2526rvr_id%253D1331948327295

It's what I put up before

Thanks for the link Graeme. I guess that is one answer to the OP. Anyone know if this unit works just the same if it is hooked up to a bank of two 12volt batteries that are joined in parallel? Does it equalize between the 2 batteries and give a proper average read?

Another question.... I'll get around to it. I have plenty of things hooked up to the 2 batteries, half to one battery and half to the other battery, mainly because all the connections won't fit on to one terminal. With the above unit, everything should go through the shunt. Hmm, too many connections to fit. Now to get around to the question, is there some item that all the connections will connect on to one side, with just one wire coming out the other side that would then connect to the shunt? It would tidy everything up nicely.

There's gotto be some experts out there; even armchair ones will do. smile smile

Cheers, John.

-- Edited by meetoo on Wednesday 11th of October 2017 01:01:28 AM

mr glassies · Guru

John mine is connected to 2 200 amp batteries set up as 12 volt consists of 8 cells works a treat tell me state of charge in % amps in or out depending on wether it's going into the batteries or out watts used from full batteries and voltage of batteries .

Dibs

mr glassies · Guru

Thanks Paul . I did check when I put it up and it worked musta just hit the rite spot lol .

In my opinion for what it's worth every van should have 1 of these no mater what sort of solar controller they have .

Dibs

Jaahn · Guru

meetoo wrote:
mr glassies wrote:
www.ebay.com.au/i/391874674194%253A%252F%252Frover.ebay.com%252Frover%252F1%252F705-139619-5960-0%252F2%253Fmpre%253Dhttps%25253A%25252F%25252Fwww.ebay.com.au%25252Fi%25252F391874674194%25253Fchn%25253Dps%252526dispItem%25253D1%2526itemid%253D391874674194%2526targetid%253D345717126183%2526device%253Dt%2526adtype%253Dpla%2526googleloc%253D9070524%2526poi%253D%2526campaignid%253D903935190%2526adgroupid%253D45410936819%2526rlsatarget%253Dpla-345717126183%2526abcId%253D1129316%2526merchantid%253D7647642%2526gclid%253DEAIaIQobChMIutrwybjl1gIVCR9oCh1yYAuREAQYBCABEgKE0PD_BwE%2526srcrot%253D705-139619-5960-0%2526rvr_id%253D1331948327295

It's what I put up before
Thanks for the link Graeme. I guess that is one answer to the OP. Anyone know if this unit works just the same if it is hooked up to a bank of two 12volt batteries that are joined in parallel? Does it equalize between the 2 batteries and give a proper average read?
Another question.... I'll get around to it. I have plenty of things hooked up to the 2 batteries, half to one battery and half to the other battery, mainly because all the connections won't fit on to one terminal. With the above unit, everything should go through the shunt. Hmm, too many connections to fit. Now to get around to the question, is there some item that all the connections will connect on to one side, with just one wire coming out the other side that would then connect to the shunt? It would tidy everything up nicely.
There's gotto be some experts out there; even armchair ones will do.
Cheers, John.
__________________________________________________________________________________________________________________________________

Hi John
I clicked on that link and it worked OK. Had to find the sweet spot for the cursor to show ! But to move on to your questions. If you want your batteries to work well and share the load well then you should set them up well. The cables connecting them should be large and even so the loads are shared properly. There are some sites which give some guides. It has been discussed here.
There are brass blocks available with multiple sockets to attach wires into. Get one of these for the + & - wires and properly connect them into the wiring along with the shunt. I have done that with my setup for one big battery. Mounted on a wooden board to hold them securely near the batteries. An electrical supply company will have them available to see and cheap. The caravan and 4WD shops will have a restricted range at many times the price.
The Victron unit will work OK with two batteries properly connected together and the capacity programed in correctly. But it cannot compensate for a bad setup or cannot show an in-ballance of the batteries in parallel. Two units would !
Cheers Jaahn
PS Here is a link to an online store just for some ideas of what you can get. There are more types as they are used in the electrical trade all the time.
http://stores.ebay.com.au/industrial-electrical-warehouse?submit.x=0&submit.y=0&_nkw=links
Got a lot of wires and things then get the 60 hole unit
OR get 2 of these type and get one black and one red cover for the - & + wires.
http://www.ebay.com.au/itm/10-Hole-Black-Neutral-Link-Red-Active-Link-You-Choose-Electrical-NEW-/190395006072?hash=item2c546d3c78:g:G3kAAOxy4dNSz0Iv

-- Edited by Jaahn on Wednesday 11th of October 2017 09:03:28 AM

-- Edited by Jaahn on Wednesday 11th of October 2017 09:12:15 AM

8Baker · Member

to answer your question re- shunts.

ALL connections to the negative terminals should go through the shunt, including the solar coming in and any alternator charging you want to do. Will involve re-wiring your batteries in this case. Also have a look at how your batteries are hooked up in parallel, as one or the other will probably be healthier as you have them now, re-wiring like this:

the-correct-way-to-connect-two-batteries

and I too can recommend the victron meter

meetoo · Guru

meetoo wrote:
mr glassies wrote:
www.ebay.com.au/i/391874674194%253A%252F%252Frover.ebay.com%252Frover%252F1%252F705-139619-5960-0%252F2%253Fmpre%253Dhttps%25253A%25252F%25252Fwww.ebay.com.au%25252Fi%25252F391874674194%25253Fchn%25253Dps%252526dispItem%25253D1%2526itemid%253D391874674194%2526targetid%253D345717126183%2526device%253Dt%2526adtype%253Dpla%2526googleloc%253D9070524%2526poi%253D%2526campaignid%253D903935190%2526adgroupid%253D45410936819%2526rlsatarget%253Dpla-345717126183%2526abcId%253D1129316%2526merchantid%253D7647642%2526gclid%253DEAIaIQobChMIutrwybjl1gIVCR9oCh1yYAuREAQYBCABEgKE0PD_BwE%2526srcrot%253D705-139619-5960-0%2526rvr_id%253D1331948327295

It's what I put up before
Thanks for the link Graeme. I guess that is one answer to the OP. Anyone know if this unit works just the same if it is hooked up to a bank of two 12volt batteries that are joined in parallel? Does it equalize between the 2 batteries and give a proper average read?
Another question.... I'll get around to it. I have plenty of things hooked up to the 2 batteries, half to one battery and half to the other battery, mainly because all the connections won't fit on to one terminal. With the above unit, everything should go through the shunt. Hmm, too many connections to fit. Now to get around to the question, is there some item that all the connections will connect on to one side, with just one wire coming out the other side that would then connect to the shunt? It would tidy everything up nicely.
There's gotto be some experts out there; even armchair ones will do.
Cheers, John.

-- Edited by meetoo on Wednesday 11th of October 2017 01:01:28 AM

In the diagram here, it shows the shunt with 2 connections. Is the top connection with the black line going upwards, (marked, battery negative system ground) where all the negative wires join to the system?

Cheers, John.

-- Edited by meetoo on Wednesday 11th of October 2017 01:49:25 PM

Jaahn · Guru

meetoo wrote:

In the diagram here, it shows the shunt with 2 connections. Is the top connection with the black line going upwards, (marked, battery negative system ground) where all the negative wires join to the system?
Cheers, John.
_________________________________________________________________________________________________________________________________
Hi John
Short answer yes.
Long answer, that is the connection where I suggest you should have a 'link' brass block and connect all the -ve wires into it as well as the vehicle earth if you use a conventional system. So the shunt is measuring all the current returning in the negative wires and then going through the shunt and to the battery. Nothing connected to the battery direct.
You would have your two batteries connected together in parallel not like that diagram shows. Not sure what is happening there ??
Like this diagram 8baker showed.
jaahn

-- Edited by Jaahn on Wednesday 11th of October 2017 03:33:22 PM

-- Edited by Jaahn on Wednesday 11th of October 2017 04:01:14 PM

meetoo · Guru

Righto, I have put it all together now. The attached pic that I drew up is my understanding how it should be. Please can I have some confirmation that I finally have got it right or not. Thanks.

Cheers, John.

meetoo · Guru

Here tis.

Cheers, John.

Jaahn · Guru

John smile

Excellent !! If the wires between the batteries and also to the brass links and shunt are heavy enough it is perfect. Well done. You will know at last what is going on.

I was impressed with that Victron unit and when I get some new batteries and redo my system I might invest in one. It seems the cheapest way to do it and good too. I already have some Victron gear. aww

Jaahn

meetoo · Guru

Thank you very much to all responders. It is a relief to have it all worked out. I am sure there will be times when it will have been worth spending a couple hundred dollars on this. The no going back hold your breath moment will be cutting off the ring terminals off all the wires to the batteries disbelief so they will fit in the brass links. I guess there is no way around this? Thanks all.

Cheers, John.

Jaahn · Guru

Hi John smile

Depending on the size of the wires and the crimped connector you can cut the ring off and remove the plastic cover and then use the crimped end piece direct in the hole and the clamp screw will press on that. May not suit the big wires. But whatever will give a good secure connection. You can get crimp on connections which have a straight parallel 'finger' or a round reduced size 'finger' to use ínto screw connections. They make it a bit tidier and easier to undo and redo connections but are not strictly necessary.

Cheers Jaahn

meetoo · Guru

Thanks Jaahn. Would never have thought of that. Was wondering how to put a small wire into a larger hole securely. Re placement of the Victron BMV700 display unit, does anybody know if you can turn off the display or does it continuously shine away all night?

Cheers, John.