Idiot guide to battery monitoring required!

Garyf123

Garyf123

Member
VIP Member
T6 Pro
Hi all, I apologise in advance for not trawling through all the previous posts regarding this subject but did a search and wow! So deep!
Basically, I have a 2019 camper conversion T6. It has a PMS3 black box under passenger seat housing the rcd/fuses, switches for van/car, pump etc. There is a Sterling B2B charger under drivers seat and a 110ah leisure battery somewhere! There is also a 60w solar panel. I am wanting to fit a battery monitor for obvious reasons but would like it to cover both van and leisure batteries and maybe provide some information about solar panel charge rate if that is even possible? I have read Dellmassives excellent articles regarding the BM2 Quicklinks monitor but this was an oldish post so was wondering if this is still one of the best options? Also, is fitting as simple as connecting live and neutral to battery posts?
Thanks in advance,
Gary.
 
BM6 is the newer updated BM2.

Which adds temperature.

The BM2 is still a very good voltage logger.

And can be used by conectinh direct to the batterys.
 
I bought a BM6 having seen that it was the new version of the BM2.

Had lots of weird Bluetooth notifications that are clearly wrong as if the starter was 9.7v surely it wouldn't then start?

Mine is wired to the large set of fuses on top of the battery as I was trying to avoid having wires coming directly off the positive terminal (for neatness).
I thought these feeds were a direct feed from the live terminal so ALWAYS live however I guess maybe there are not?

I added an inline fuse as well and maybe that could be an issue?
IMG_7420.jpeg
 
Last edited:
I’m also after a battery monitor, but need it to connect to wifi.
I have wifi setup with a GL.iNet Slate Ax and 5G modem on permanently.
I can monitor Lesuire battery’s via Global Telemetrics tracker but have no way of monitoring starter motor BATT….
 
Garyf123 said:
Hi all, I apologise in advance for not trawling through all the previous posts regarding this subject but did a search and wow! So deep!
Basically, I have a 2019 camper conversion T6. It has a PMS3 black box under passenger seat housing the rcd/fuses, switches for van/car, pump etc. There is a Sterling B2B charger under drivers seat and a 110ah leisure battery somewhere! There is also a 60w solar panel. I am wanting to fit a battery monitor for obvious reasons but would like it to cover both van and leisure batteries and maybe provide some information about solar panel charge rate if that is even possible? I have read Dellmassives excellent articles regarding the BM2 Quicklinks monitor but this was an oldish post so was wondering if this is still one of the best options? Also, is fitting as simple as connecting live and neutral to battery posts?
Thanks in advance,
Gary.
Click to expand...
At 60w dedicated monitoring for the solar may not be economically viable unless available from the MPPT controller.

But you should be able to see the effect on a decent battery monitor, especially if you look at the state of charge over time on a day the van is "idle"

If you just want to get a good mental picture of what is going on and making sure it's all working then I really like this clamp meter which can show you DC currents, plus it's small and handy to keep around for those electrical conundrums in a van.

 
Many thanks for all advice. I have ordered a BM6 and will give it a go. Do I need 2 if I want to monitor both van and leisure batteries?
Thanks also Roadtripper and I will bear this in mind for future.
I appreciate I should probably create a new post but hope it will be ok this time. You can probably guess that I know next to nothing about the van electrics but as I mentioned earlier, my conversion has the following components:
PMS3 management system
Sterling (B1230 I think) B2B charger
60w solar panel
110ah leisure battery
We are away for 3 nights this weekend and it will be the first time on EHU (only slept in it two separate nights off grid!)
When hooked up, Does the switch on the PMS3 want to be on van or car battery position?
Does the EHU mean that the leisure battery is not been used at all and the mains is powering the sockets, lights,fridge etc.
Please excuse my ignorance but I am very new to campervanning but eager to learn!
 
PMS3 confusion cropped up in a recent thread. They key to understanding it is that it is a very old design built for caravans.

So, essentially, you never want the switch in "car" as that will drain your starter battery, you want it in "van" (caravan i.e. leisure battery). Seriously never use the "car" setting. To add to the confusion the battery gauge will always show the leisure battery even if you are draining the starter battery stone dead.

EHU will mean all the mains will be live. So long as you make sure the charger is switched on the PMS3 supplies something like 12A on the 12v rail to support the leisure battery so it's unlikely to discharge and if you do it should charge back up again. Do make sure you have switched the charger on though!

If you don't have a manual grab a PDF one from here

www.jacksonsleisure.com

Bonus electrical PMS 3H Power Management System (Horizontal)

The Bonus Electrical PMS 3H (Horizontal) Motorhome Control Panel is a high quality, easy to install all in one electrical control unit which is perfect for new builds or van conversions!
www.jacksonsleisure.com www.jacksonsleisure.com
 
roadtripper said:
PMS3 confusion cropped up in a recent thread. They key to understanding it is that it is a very old design built for caravans.

So, essentially, you never want the switch in "car" as that will drain your starter battery, you want it in "van" (caravan i.e. leisure battery). Seriously never use the "car" setting. To add to the confusion the battery gauge will always show the leisure battery even if you are draining the starter battery stone dead.

EHU will mean all the mains will be live. So long as you make sure the charger is switched on the PMS3 supplies something like 12A on the 12v rail to support the leisure battery so it's unlikely to discharge and if you do it should charge back up again. Do make sure you have switched the charger on though!

If you don't have a manual grab a PDF one from here

www.jacksonsleisure.com

Bonus electrical PMS 3H Power Management System (Horizontal)

The Bonus Electrical PMS 3H (Horizontal) Motorhome Control Panel is a high quality, easy to install all in one electrical control unit which is perfect for new builds or van conversions!
www.jacksonsleisure.com www.jacksonsleisure.com
Click to expand...
That’s brilliant, thanks for taking the time to explain! So, the plug sockets will only work on EHU? I also have to take the screw out fuse for the fridge from the PMS3 to turn the light off. I just put it back if/when we are going to stay out over night. Does the fridge work from the van or starter battery? I think the light works independently from the fridge though? I saw a suggestion regarding using a NOCO 5 to trickle charge the starter battery when camping due to the doors opening etc. not sure how old the post was so is this still a good shout or is there something newer now? I only have 2 sockets in van, is there a decent multi plug anybody can recommend?
Sorry for all questions but I go away on Friday and getting a bit nervous!
Gary.
 
Unless you have an inverter, and you didn't list one, you'll only get mains out if you put mains in :cool:

Have a read of the manual to get a good idea of what the unit does. It's hard to answer specific questions without knowing how your converter wired the unit in, a picture may help.

What type of fridge do you have? As I said this unit is designed for caravans so ia traditional three way caravan fridge (mains or gas on site, 12v while towing). If you have a more modern compressor fridge it might be powered by 12v and mains, but mostly I'd expect 12v with the expectation on EHU your battery charger is running. You can either check in the instructions I hope you got with the van, or by turning the 12v system off (battery selection to off, charger off) and seeing if the fridge MCB does anything.

Again is your lighting mains or 12, this unit dates from the days a caravan had both for mains on site and limited 12v while towing.

I suggest have a copy of the manual to hand and then have a play with the switches and breakers on your drive.

As a starting point I would suggest:
When on EHU
- Charger ON
- Battery Selector to VAN
 
Trickle charging starter battery

Yes a common DIY trick is to have a small CTEK/NoCo maintenance charger around 5A with the cigarette lighter plug adaptor and plug this in inside from the mains and into the 12v socket by the gear selector (which is conventionally always the starter battery)

This is probably only worth it though if:
1. You use the van a lot in the summer but it's parked up most of the winter and you want to maintain both batteries
2. Your doors are all powered and you have a lot of non LED vehicle (not habitation) lighting that comes on with the doors opening - i.e. you get quite a load on the starter battery

If you are just going away for a few days or you are driving out every day or so from site then having one in the kit box would do no harm but it's probably not worth the bother.
 
Fridge Behaviour

So specifically for the fridge it depends on if the converter has wired something in to the input. Normally this would come from the tow car via the ignition relay to supply power even if the battery selector is off. I wouldn't expect that to be connected in a camper but...

If you have time try the following tests:
1. If you turn charger OFF and battery selector OFF with no EHU does your fridge run?
2. If you turn charger OFF and battery selector OFF with no EHU do your habitation lights work?
3. Do you often need to have the habitation lights working but the fridge off?
4. Do you have a water pump fitted?
 
roadtripper said:
Fridge Behaviour

So specifically for the fridge it depends on if the converter has wired something in to the input. Normally this would come from the tow car via the ignition relay to supply power even if the battery selector is off. I wouldn't expect that to be connected in a camper but...

If you have time try the following tests:
1. If you turn charger OFF and battery selector OFF with no EHU does your fridge run?
2. If you turn charger OFF and battery selector OFF with no EHU do your habitation lights work?
3. Do you often need to have the habitation lights working but the fridge off?
4. Do you have a water pump fitted?
Click to expand...
Just spoke with the converter and he said the Dometic fridge is wired to the leisure battery and permanently on. I can turn the switch off inside the fridge and it will turn off the compressor but the light stays on unless I pull the fuse on PMS3. The habitation lights work with the charger off and switched to ‘van’
Yes, I have a water pump which again works with charger off but switch set to ‘van’
 
Nothing wrong with the BM2 and BM6 battery monitors. If you want a little more detail on your leisure battery performance, solar input and how long its going to last you off grid or on site then maybe consider a Victron Smartshunt. You can do a search on the forum, there is a lot of information about it. It will also monitor your vehicle battery voltage. Hope that helps.
I actually have a BM2 on the leisure battery and a Smartshunt as the BM2 does historical graphs which can be useful to sort charging problems.
 
Farnorthsurfer said:
Nothing wrong with the BM2 and BM6 battery monitors. If you want a little more detail on your leisure battery performance, solar input and how long its going to last you off grid or on site then maybe consider a Victron Smartshunt. You can do a search on the forum, there is a lot of information about it. It will also monitor your vehicle battery voltage. Hope that helps.
I actually have a BM2 on the leisure battery and a Smartshunt as the BM2 does historical graphs which can be useful to sort charging problems.
Click to expand...
Bit worried about 2 results above though. Could it be that I had just connected the monitor and did the test Straight away? Does it need some time to build a history? That’s what I am hoping anyway cos don’t want to be replacing alternator or battery. Wasn’t aware of any issues with either.
 
Garyf123 said:
Bit worried about 2 results above though. Could it be that I had just connected the monitor and did the test Straight away? Does it need some time to build a history? That’s what I am hoping anyway cos don’t want to be replacing alternator or battery. Wasn’t aware of any issues with either.
Click to expand...
If you have a T6 you will for sure have a very complicated alternator/battery system that supports start stop operation and a whole load of other clever shit going on in the background. Your BM monitor is (probably) set to work with a standard vehicle battery system that has a much steadier voltage state. The fancy battery in the T6 will work with a much larger range of voltages that might flag up on the BM as poor results.
In short don't worry about it, its fine. If you want to read more search stop start on the forum :)
 
Farnorthsurfer said:
If you have a T6 you will for sure have a very complicated alternator/battery system that supports start stop operation and a whole load of other clever shit going on in the background. Your BM monitor is (probably) set to work with a standard vehicle battery system that has a much steadier voltage state. The fancy battery in the T6 will work with a much larger range of voltages that might flag up on the BM as poor results.
In short don't worry about it, its fine. If you want to read more search stop start on the forum :)
Click to expand...
Thanks for that, I feel a lot better now
 
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