Yet another solar, battery, charging, monitor etc. question

SimonM

SimonM

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I have over the last few weeks uprated my existing solar and battery setup.

I’ve got 2 panels 100w & 120w along with 4 x 110 Banner leisure batteries. What I’ve now added is a MPPT controller, a solar computer panel, along with a 30a B2B charger. Yesterday I acquired a Nasa BM2 battery monitor to enable me to keep an eye on everything.

It’s not that I’ve got a concern about power, apart from a minor hiccup at the end of last year, all of my lighting is LED already, but I do like gadgets and have the time and desire to fit them.

My question, now that I’ve got it all assembled and working well, is this.

After deciding to enter a battery AH value initially as 400, this is because I’m not sure if I should use the 20hr rate or the 100hr rate declared on the top of the batteries. The monitor then showed that after it all settled down that it was at 104% capacity.

I then changed the monitor to 440 which is the “capacity” of my 4 batteries. I left it to its own devices overnight and through the day today.

It’s been quite sunny in between the occasional shower, however, the monitor has been showing 13.4v and 104% charged and negligible charge (I assume that’s because the mppt is saying the batteries are fully charged, so no problem) . My starter battery that also gets a bit of juice from the mppt is showing 12.8v

Should I be worried about it reading 104% charged? Or is it normal?
 
I fitted a BM1 and I have 2 x 100ah batteries, what I was wondering was that that the capacity shown on rhe rhs of the meter is it the useable capacity or the total capacity available?
 
Interesting...have you upgraded from a standard PWM controller? I was wondering if you found the claims of 25-30% more efficient charging are justified?
Finally, which model MPPT charger did you go for?

As you might guess I am considering upgrading my setup form a 100w /PWM controller to a 200W MPPT controlled system.

Thanks
 
I am glad I bought a Victron monitor. It has enough sense to stop at 100% and you can set parameters to automatically synchronise when full. If it is not regularly synchronised then any small errors will accumulate until they become misleading.
 
Berniem said:
Interesting...have you upgraded from a standard PWM controller? I was wondering if you found the claims of 25-30% more efficient charging are justified?
Finally, which model MPPT charger did you go for?

As you might guess I am considering upgrading my setup form a 100w /PWM controller to a 200W MPPT controlled system.

Thanks
Click to expand...
I don’t know if you have seen I’ve a EPever tracer 40amp mppt controler for sale at 40 quid .The only reason it’s for sale it won’t work with my lithium battery’s .dont know if it’s any good for you .+ it has a battery thermostat with it.EFC526E1-0D80-45CA-951F-9F2D35BB039F.jpeg5015A513-79D0-42D5-A02E-F80D8E72860B.jpeg

Jeff
 
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SimonM said:
I have over the last few weeks uprated my existing solar and battery setup.

I’ve got 2 panels 100w & 120w along with 4 x 110 Banner leisure batteries. What I’ve now added is a MPPT controller, a solar computer panel, along with a 30a B2B charger. Yesterday I acquired a Nasa BM2 battery monitor to enable me to keep an eye on everything.

It’s not that I’ve got a concern about power, apart from a minor hiccup at the end of last year, all of my lighting is LED already, but I do like gadgets and have the time and desire to fit them.

My question, now that I’ve got it all assembled and working well, is this.

After deciding to enter a battery AH value initially as 400, this is because I’m not sure if I should use the 20hr rate or the 100hr rate declared on the top of the batteries. The monitor then showed that after it all settled down that it was at 104% capacity.

I then changed the monitor to 440 which is the “capacity” of my 4 batteries. I left it to its own devices overnight and through the day today.

It’s been quite sunny in between the occasional shower, however, the monitor has been showing 13.4v and 104% charged and negligible charge (I assume that’s because the mppt is saying the batteries are fully charged, so no problem) . My starter battery that also gets a bit of juice from the mppt is showing 12.8v

Should I be worried about it reading 104% charged? Or is it normal?
Click to expand...

104% is normal, you should set the capacity at the 20hr rate and don't forget that the BM-2 will have to do a few charge cycles before it re-calibrates.
 
Thanks Phil, I was hopeful that was going to be the case. I’ve just got home from golf and it is still at 104%.

Success, for a change for me, yippee. ?

Now to try to get the wife to retire so we can go off and use up the volts and amps willy nilly. (Perhaps me and Molly could go alone? ?)
 
saxonborg said:
I fitted a BM1 and I have 2 x 100ah batteries, what I was wondering was that that the capacity shown on rhe rhs of the meter is it the useable capacity or the total capacity available?
Click to expand...

That number is the %age of charge that the bank of batteries is currently sitting at. The example pic from their documentation shows 85%C therefore it’s not quite fully charged yet. You need to tell the unit what Ah rating your batteries are when you initially set up the monitor for it to then tell you what state of charge they’re at.
Mine are showing 104% full, and Phil says that’s OK
 
Berniem said:
Interesting...have you upgraded from a standard PWM controller? I was wondering if you found the claims of 25-30% more efficient charging are justified?
Finally, which model MPPT charger did you go for?

As you might guess I am considering upgrading my setup form a 100w /PWM controller to a 200W MPPT controlled system.

Thanks
Click to expand...

Yes I had just a “normal” controller, but then after deciding I needed to add more gadgets I then added a Votronic MPP250 controller for my 220w of panels.
 
Sorry but I think 104% is nonsense. When something is full it is 100% and that is the limit.
 
I know it doesn't sound logical but my BM2 always shows 104% when fully charged. Phil did tell me once why it does that but I've totally forgotten the reason... I just remember that its OK and nothing to worry about :giggle:
 
SimonM said:
That number is the %age of charge that the bank of batteries is currently sitting at. The example pic from their documentation shows 85%C therefore it’s not quite fully charged yet. You need to tell the unit what Ah rating your batteries are when you initially set up the monitor for it to then tell you what state of charge they’re at.
Mine are showing 104% full, and Phil says that’s OK
Click to expand...
Thank you, I did set up the monitor with the total capacity and I was thinking that rhs reading might have been the useable amount of amphours. I have only recently installed it so its early days yet.
 
saxonborg said:
Thank you, I did set up the monitor with the total capacity and I was thinking that rhs reading might have been the useable amount of amphours. I have only recently installed it so its early days yet.
Click to expand...
It’s the uncertainty about a new bit of kit and what to expect, and of course the destructions don’t cover that eventuality. ?
 
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