How to accurately monitor the leisure battery?

DaveS

DaveS

Joined
Jan 2, 2012
Posts
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Location
Bristol
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19,303
MH
Knaus Van Ti 640 MEG
Exp
Had a variety of tents, tipis, motorhomes, caravans and now back to a coach built motorhome!
I’ve got a 2023 Knaus Van Ti with an OEM Banner 80AH leisure battery.
I have a Truma 100W solar panel fitted by the dealer when we bought it, plus a Battery Master that charges the vehicle battery.
The problem is I have no idea what is going on with the battery. The control panel seems pretty useless and almost instantly tells me the battery is at 50% capacity when I don't think it is.
I tried a Battery Monitor BM2 from Amazon, but that doesn't really help a great deal and it's a bit clunky with the app.
Is there a device I can buy that will do this?
 
Best device will be to fit a shunt. This is usually fitted on the negative side of the leisure battery. One side of the shunt is the sol connection to the negative battery terminal, other side is the connection to everything on your habitation wiring (lights, power, solar and chargers).

The shunt "sees" every bit of power going into and out of your leisure battery. So, unlike most gauges that can just estimate based on voltage, this knows how many amps are being drawn from the battery or put back into it. From that, when it also knew to start with that your battery was full, and you programmed it with it's full capacity in Ah (Amp Hours), it can calculate how much you still have left.

The shunts do work better with lithium batteries as these tend not to lose their charge when not being used for a while (lead- acid types will gradually lose their charge), and also last much longer without capacity loss (lead-acid types will hold a diminishing amount of charge over time based on their charge and discharge usage).

Some of the shunts have a little remote display you can mount somewhere. Others will link to a bluetooth type app on your phone. The Victron Smartshunts are popular.
 
Kannon Fodda said:
Best device will be to fit a shunt. This is usually fitted on the negative side of the leisure battery. One side of the shunt is the sol connection to the negative battery terminal, other side is the connection to everything on your habitation wiring (lights, power, solar and chargers).

The shunt "sees" every bit of power going into and out of your leisure battery. So, unlike most gauges that can just estimate based on voltage, this knows how many amps are being drawn from the battery or put back into it. From that, when it also knew to start with that your battery was full, and you programmed it with it's full capacity in Ah (Amp Hours), it can calculate how much you still have left.

The shunts do work better with lithium batteries as these tend not to lose their charge when not being used for a while (lead- acid types will gradually lose their charge), and also last much longer without capacity loss (lead-acid types will hold a diminishing amount of charge over time based on their charge and discharge usage).

Some of the shunts have a little remote display you can mount somewhere. Others will link to a bluetooth type app on your phone. The Victron Smartshunts are popular.
Click to expand...
Ahh ok. I now realise that I fitted a similar NASA BM1 to my Bongo when I had one 12+ years ago. The Victron Smartshunt looks just like what I'm after... but if I did get a Lithium battery it seems that some have this functionality built in.
 
The Victron Smartshunts do not appear to have a display.

The NDS Energy Meter from RoadPro has a display and works very well with Lithium (LiFePO4) batteries.
 
LithiumConvert said:
The Victron Smartshunts do not appear to have a display.

The NDS Energy Meter from RoadPro has a display and works very well with Lithium (LiFePO4) batteries.
Click to expand...

If you have a Bluetooth capable phone, then you have a display for a Victron Smartshunt. (y)

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I have been told that the NDS Imanager Battery Control System (also from RoadPro) will do the same thing also with a display for Non-Lithium batteries (athough more expensive)

Some GPS trackers will also report battery voltage. I use the Queclink GB100. (needs a 2G SIM card with credit)
 
Victron Smartshunts use the bluetooth app for the monitoring. This can tie in well if you have other Victron smart stuff like their solar controllers as it all links in with the same app and integrates into one system. Even the little mains battery charger I have from Victron links in too. But you can spend too much time wondering what your gadgets are up to ....

There are alternative Victron Shunts that have a remote display, such as the BMV-700, or there are also displays that can be remotely fitted to the SmartShunts which supplement the app functionality.

Many lithium batteries will have a built in BMS (Battery Management System). That may be sufficient to allow remote monitoring of charge / discharge, instead of a shunt, using a phone app.
 
LithiumConvert said:
I have been told that the NDS Imanager Battery Control System (also from RoadPro) will do the same thing also with a display for Non-Lithium batteries (athough more expensive)

Some GPS trackers will also report battery voltage. I use the Queclink GB100. (needs a 2G SIM card with credit)
Click to expand...

A Victron Smartshunt is programable for all battery chemistries in the same unit at the same price, and it's your battery SOC that is far more important than your battery voltage, especially with lithium having a near flat line voltage from 85% to 20% SOC. (y)
 
Just fitted one. Very easy.

IMG_20231226_124654.jpg
 
Battery monitors need to be adjusted to the specific efficiency and Peukert factor for the battery in use. When I bought mine only the Victron ones could do this.
 
LithiumConvert said:
The Victron Smartshunts do not appear to have a display.

The NDS Energy Meter from RoadPro has a display and works very well with Lithium (LiFePO4) batteries.
Click to expand...
The BMV 712 does have its own little monitor and also works with Bluetooth.

Here is a link to ours:
offgridpower.solutions

Victron Energy Battery Monitor BMV-712 Smart — Offgrid Power Solutions

With Bluetooth built-in, the BMV Smart is ready for the Internet of Things (IoT) era. With Bluetooth being implemented in most other Victron Energy products, wireless communication between products will simplify system installation and enhance performance. This product is stocked in the UK at the O
offgridpower.solutions offgridpower.solutions
 
You don’t need a display with the phone app. I have a BMV 700 and have added a bluetooth dongle so that I can use the app. The display is tucked away in the battery compartment and never looked at.
 
Quick question do you ground the negative to the chasis of the van
Ball point pen shows the negative I refer to

image.jpg
 
Pausim said:
The display is tucked away in the battery compartment and never looked at.
Click to expand...
I prefer a display you can see .....

..... and a system my computer can monitor over the Internet (which means I can see it from anywhere in the world)
..... preferably (essentially) without a tooth of any colour involved.:sick:
 
Last edited:
Two on Tour said:
On mine, the only connection to the battery negative is to the battery side of the shunt, and my cable to the chassis is from the other side of the shunt with the other negatives.
Click to expand...
this is what i am trying to determin whats correct as the instructions dont show any negative to the chassis

The other doubt/unsure of is i need to bring a live from the engine battery to the victron B2B (i have 2 @12-12-30)
a choice of isolated or Non isolated ,I am guessing the negative goes to the load side of the shunt so therefore i must also take a negative from the same load side of the shunt to the chassis
 
So I’ve ordered a victron smartshunt. I note that it doesn’t include a cable to go from the battery negative to the shunt. Can anyone recommend what spec cable I need?

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DaveS said:
So I’ve ordered a victron smartshunt. I note that it doesn’t include a cable to go from the battery negative to the shunt. Can anyone recommend what spec cable I need?
Click to expand...
No simple answer I’m afraid - it depends on your maximum draw.
For standard non-inverter motorhome use (run lights, water pump, Truma/Alde and charge phones) a thin cable is fine (16mm or even 10mm).
If you have an inverter or a charger capable of very high current then a thicker cable is required. I’d not go less than 35mm, prob 50mm or 70mm for a 2kw inverter (to have the lowest loss over the cable).
 
one thing to note is that the victron shunt has 10mm posts. My van electrics were 6mm rings ends, so needed a bit of faf (busbar) to get it all to work (I don’t own a crimper).
I had same problem, old van, not sure how everything worked, how good is battery etc. I’ve had it 24 hours, and already giving me info on: charge rate while driving, which bits in the can draw most amps, how long before I run out etc.
 
DaveS said:
I’ve got a 2023 Knaus Van Ti with an OEM Banner 80AH leisure battery.
I have a Truma 100W solar panel fitted by the dealer when we bought it, plus a Battery Master that charges the vehicle battery.
The problem is I have no idea what is going on with the battery. The control panel seems pretty useless and almost instantly tells me the battery is at 50% capacity when I don't think it is.
I tried a Battery Monitor BM2 from Amazon, but that doesn't really help a great deal and it's a bit clunky with the app.
Is there a device I can buy that will do this?
Click to expand...
Buy a TopDon battery tester for a true test of your battery.
 
I don’t know how the TopDon functions but hopefully it is not a drop tester. Drop testers are designed for engine starting batteries and can damage proper leisure batteries which are designed for slower deeper discharges than engine batteries.
 
DaveS said:
I’ve got a 2023 Knaus Van Ti with an OEM Banner 80AH leisure battery.
I have a Truma 100W solar panel fitted by the dealer when we bought it, plus a Battery Master that charges the vehicle battery.
The problem is I have no idea what is going on with the battery. The control panel seems pretty useless and almost instantly tells me the battery is at 50% capacity when I don't think it is.
I tried a Battery Monitor BM2 from Amazon, but that doesn't really help a great deal and it's a bit clunky with the app.
Is there a device I can buy that will do this?
Click to expand...
Victron Smart Shunt and Victron MPPT controller. Both link to phone via Bluetooth and work in harmony. There's the option with an extra box to check your batts online too.

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DaveS said:
So I’ve ordered a victron smartshunt. I note that it doesn’t include a cable to go from the battery negative to the shunt. Can anyone recommend what spec cable I need?
Click to expand...
The Shunt IS connected INTO the NEGATIVE BATTERY OUTPUT CABLE.... You need a thin positive cable to the battery positive to enable the operation. Connecting to the Engine battery positive is optional and reports engine battery voltage only.
The main negative cable needs to match the existing negative cross section... The Shunt joins the two together..... Beware the studs on the smart shunt are bigger than the battery cable connection holes.
 

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