Leisure battery monitor

UFO

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Currently we only have the control panel lights, (13.0V, 12.5V. 12.0V, 11.5V, <11.5V) to show the leisure battery condition. I don’t want anything fancy, it would be good to know how much energy is going in, from vehicle alternator and solar panel, and how much is coming out. Considering two of these, one to measure charge, one to measure discharge.

https://www.amazon.co.uk/dp/B01JOUZ...uPWNsaWNrUmVkaXJlY3QmZG9Ob3RMb2dDbGljaz10cnVl

Simple and inexpensive, you can get 2 for £23 on ebay. At the start of a trip I would ensure batteries are fully charged on EHU, reset the ‘energy’ reading on both meters and then keep an eye on the readings to make sure they are balanced, ideally more going in than coming out. Can convert the Wh reading to Ah, using formulae (Wh)/(V) =(Ah) to calculate battery Ah remaining from original, although there will be some inaccuracy due to voltage change from 12 to 13 volts as battery discharges.

Battery monitor charge discharge.JPG

Even simpler would be a more precise voltmeter to measure the battery voltage to get the state of charge as below. Measured with a small constant load, e.g. a light on.
Battery AGM state of charge.JPG

Thoughts from our resident experts appreciated.

thanks
 
As you don't say that you are !always' running flat, I'd be inclined to just have an accurate indication of the battery voltage.
I have noticed that my Sargent control panel under-reads both Leisure and Starter batteries by 0.2V.
Until I discovered this I thought my charging regime and leisure battery were suspect.
Now I'm happy enough.
Technically for voltage to give a true indication of SOC the battery should have stood a good while after charging.
However with experience you'll get a reasonable indication an hour or so after solar stops working.
As you say some lighting draw of will pull off the 'surface charge' and you can check voltage again in morning before solar picks up again.
I'm not a battery watcher (I prefer paint drying 😀) and just let it get on with it!
 
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We just have a simple digital (Chinese) violt meter.
I appreciate this only shows voltage and not SOC or any other details.
I can easily see it during the evening and even with blown air heation on for some of the time..
The displayed voltage can drop from 12.9 to 12.7
Sometimes as low as 12.6 at 3 am...."Suits us Sir !"
Back up to well over 13.2 in the am after some solar input !
 
UFO said:
Currently we only have the control panel lights, (13.0V, 12.5V. 12.0V, 11.5V, <11.5V) to show the leisure battery condition. I don’t want anything fancy, it would be good to know how much energy is going in, from vehicle alternator and solar panel, and how much is coming out. Considering two of these, one to measure charge, one to measure discharge.

https://www.amazon.co.uk/dp/B01JOUZ...uPWNsaWNrUmVkaXJlY3QmZG9Ob3RMb2dDbGljaz10cnVl

Simple and inexpensive, you can get 2 for £23 on ebay. At the start of a trip I would ensure batteries are fully charged on EHU, reset the ‘energy’ reading on both meters and then keep an eye on the readings to make sure they are balanced, ideally more going in than coming out. Can convert the Wh reading to Ah, using formulae (Wh)/(V) =(Ah) to calculate battery Ah remaining from original, although there will be some inaccuracy due to voltage change from 12 to 13 volts as battery discharges.

View attachment 57295

Even simpler would be a more precise voltmeter to measure the battery voltage to get the state of charge as below. Measured with a small constant load, e.g. a light on.
View attachment 57296

Thoughts from our resident experts appreciated.

thanks
Click to expand...
Those monitors you have identified are very good. Good for tracking things like the energy being harvested from Solar, or the energy being used by an Inverter, but not the best tool for your requirement.
I have used them and wired them up precisely as you have shown in the diagram to see power useage and power input, but as a way to simply check net power and battery level, a proper Battery State of Charge Monitor is a much better way and they start from not much more than a pair of those monitors you have indicated.
 
wildebus said:
a proper Battery State of Charge Monitor is a much better way and they start from not much more than a pair of those monitors you have indicated.
Click to expand...

Thanks - could you point me in the direction of suitable Battery State of Charge Monitors?

thanks
 
UFO said:
Thanks - could you point me in the direction of suitable Battery State of Charge Monitors?

thanks
Click to expand...
There are quite a few options around which work well and others which claim to be SOC Monitors but are rubbish.
On the GOOD side, Victron and NASA Marine are the main contenders but in the upper price bracket.
Going cheaper, the only one I would recommend is this "AiLi" version. Works very nicely and is not too expensive as all

AiLi Battery Monitor Voltage Tester Voltmeter Ammeter Voltage Current Meter 80V 100A Caravan RV Motorhome UPS Lithium Iron Lead-Acid 999 AH: Amazon.co.uk: DIY & Tools

Free delivery and returns on all eligible orders. Shop AiLi Battery Monitor Voltage Tester Voltmeter Ammeter Voltage Current Meter 80V 100A Caravan RV Motorhome UPS Lithium Iron Lead-Acid 999 AH.
amzn.to

I'll say the 100A model would be find for most setups, but the 350A version might be needed if you have a biggish Inverter.
You would need to get a cable to fit from Battery -ve to Shunt, same as with the pair of Monitors you originally linked to.
 
wildebus said:
Going cheaper, the only one I would recommend is this "AiLi" version. Works very nicely and is not too expensive as all

AiLi Battery Monitor Voltage Tester Voltmeter Ammeter Voltage Current Meter 80V 100A Caravan RV Motorhome UPS Lithium Iron Lead-Acid 999 AH: Amazon.co.uk: DIY & Tools

Free delivery and returns on all eligible orders. Shop AiLi Battery Monitor Voltage Tester Voltmeter Ammeter Voltage Current Meter 80V 100A Caravan RV Motorhome UPS Lithium Iron Lead-Acid 999 AH.
amzn.to

I'll say the 100A model would be find for most setups, but the 350A version might be needed if you have a biggish Inverter.
You would need to get a cable to fit from Battery -ve to Shunt, same as with the pair of Monitors you originally linked to.
Click to expand...
Thank you, I spotted this one on Amazon and read the reviews, which are predominantly positive. The main negative comments were the bright back lighting and flashing to indicate charging - keeping people awake at night! A comment on the youtube video below says it can be turned off and on, by pressing the V and % buttons simultaneously and holding for a second or two.

Some useful youtube videos, including this one from an enthusiastic American

My inverter is only 150W, which draws 6.3A when charging the laptop battery. The inverter won't charge the battery when the laptop is on and running so I may need to upgrade the inverter, but probably to no more than 500W.
 
I have tried one of those ones that Will Prowse uses but I was not keen. IGNORE THAT COMMENT. I thought it was Will Prowse talking about the rectangular Monitor he also uses. The Aili monitor he talks about in THAT video is very good :D

The one I linked to I just found worked well and when I ran one at the same time as a Victron BMV I found the results were within 1% of each other, so I tend to stick with that when asked for lower cost solutions.

(When mounting, it is also a lot easier to drill a round 54mm hole than make a neat rectangular one ;) )
 
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We just have a simple digital volt meter connected to our leisure batteries, it gives a good enough indication of their state of charge. We don't need to know what's going in or out, but guess seeing numbers might be a bit interesting initially? Probably more useful to know what amps your alternator is supplying?
 
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[QUOTE="Phantom, ? Probably more useful to know what amps your alternator is supplying?
[/QUOTE] it tells what amps is going into your battery. From solar , engine ,and on board charger,
 
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Phantom said:
Sounds like the laptop battery is weak. Just remove it and run directly off inverter if only for van use!
Click to expand...
If the laptop baattery is low
Then charge it up when not in use !
Asuming it (laptop) then gets to say 95%
Then either use it plugged in so it stays at 95%
Or let it run down unplugged and as above re-charge it when not in use preferably the next morning when solar is good !
OR get a 12v to 19v unit from power4laptops again using it in the morning !
I have used several laptops and we rarely use EHU and have not had a problem..and i use the laptop a lot
maybe get a 300w inverter use it at appropriate times including whilst travelling so your alternator is providing power !
 
wildebus said:
I have tried one of those ones that Will Prowse uses but I was not keen. The one I linked to I just found worked well and when I ran one at the same time as a Victron BMV I found the results were within 1% of each other, so I tend to stick with that when asked for lower cost solutions
Click to expand...
Wildebus – appreciate your comments, very useful. Just to clarify the BM in the Will Prowse youtube video ‘$200 Victron Solar Battery Monitor? Try this $30 Chinese one instead! Great for off-grid Solar’ is the same as the one you provided the Amazon link for.

AiLi Battery Monitor Voltage Tester Voltmeter Ammeter Voltage Current Meter 80V 100A Caravan RV Motorhome UPS Lithium Iron Lead-Acid 999 AH: Amazon.co.uk: DIY & Tools

Free delivery and returns on all eligible orders. Shop AiLi Battery Monitor Voltage Tester Voltmeter Ammeter Voltage Current Meter 80V 100A Caravan RV Motorhome UPS Lithium Iron Lead-Acid 999 AH.
www.amazon.co.uk

Just wanted to make sure that we are on the same page!

Thanks again
 
UFO said:
Wildebus – appreciate your comments, very useful. Just to clarify the BM in the Will Prowse youtube video ‘$200 Victron Solar Battery Monitor? Try this $30 Chinese one instead! Great for off-grid Solar’ is the same as the one you provided the Amazon link for.

AiLi Battery Monitor Voltage Tester Voltmeter Ammeter Voltage Current Meter 80V 100A Caravan RV Motorhome UPS Lithium Iron Lead-Acid 999 AH: Amazon.co.uk: DIY & Tools

Free delivery and returns on all eligible orders. Shop AiLi Battery Monitor Voltage Tester Voltmeter Ammeter Voltage Current Meter 80V 100A Caravan RV Motorhome UPS Lithium Iron Lead-Acid 999 AH.
www.amazon.co.uk

Just wanted to make sure that we are on the same page!

Thanks again
Click to expand...
Aha. On a lot of his videos, he shows his testing results on a rectangular monitor and it was that one I thought he was talking about and I said I was not keen on.
I just clicked on the video and watched some snippets and yes, it is the Aili one he is talking about :)

One difference ... the one he is showing in his video is the 350A version and I am suggesting the 100A version is fine for most people, but that is just a difference in the Shunt - the monitor is identical.
Reason why I suggest the 100A model .... the mounting holes are M8 so will almost certainly match the cable to already have going to the battery so it is a easy install. the 350A version uses M10 bolts and most people will have to modify their existing cables - and typically don't have access to a tool to crimp heavy-duty ring terminals. (just a way to keep life simpler ;) )
 
Just for completeness, THIS is the monitor that I thought Will Prowse was talking about. It would have been on a diffrent video I guess

MICTUNING LCD Display DC Battery Monitor Meter 0-200V Voltmeter Ammeter for Cars RV Solar System: Amazon.co.uk: Car & Motorbike

Buy MICTUNING LCD Display DC Battery Monitor Meter 0-200V Voltmeter Ammeter for Cars RV Solar System at Amazon UK. Free delivery on eligible orders.
amzn.to
That unit is stated as being an SOC Battery Monitor and at under £14 would seem to be super value and has loads of great ratings, but I just didn't like it. But as the saying goes ... Your Mileage May Vary and at the price could well be worth a punt?
 
wildebus said:
Going cheaper, the only one I would recommend is this "AiLi" version. Works very nicely and is not too expensive as all

AiLi Battery Monitor Voltage Tester Voltmeter Ammeter Voltage Current Meter 80V 100A Caravan RV Motorhome UPS Lithium Iron Lead-Acid 999 AH: Amazon.co.uk: DIY & Tools

Free delivery and returns on all eligible orders. Shop AiLi Battery Monitor Voltage Tester Voltmeter Ammeter Voltage Current Meter 80V 100A Caravan RV Motorhome UPS Lithium Iron Lead-Acid 999 AH.
amzn.to
Click to expand...
I like that one a lot David for it's simple unfussy display, the green theme should work okay beside my Edecoa remote switch.
Interestingly the Amazon link shows it at £26.50 + £11 delivery so £37.50, but if I sign into Prime it is £44 with free delivery! 🤑
So instead I bought the 100A one from Ebay for under £25 delivered and it will arrive at least 10 days sooner! It's the one Will Prose tested. 👍
I watched a few tube vids about them, most initially set up the SOC with the battery fully charged but one completely drained their battery to set it which seemed a bit odd?
 
There are two ways to set it up. Full and enter the quoted capacity. Or empty and let it calculate the capacity as you recharge it.
The second way maybe more accurate with an battery of unknown age/quality/use, but I have always gone for connecting to a full battery and then if need be, tweak the capacity if the battery drains faster then the SOC says it should.

I have some of these (50A, 100A and 350A) in stock for next day dispatch if anyone is after them, but I don't charge under £25!
 
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