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Battery Balancer/Monitor


Stephan
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Hallo
I am new to the field, so might questions might sound stupid 
I have the following already installed in a mobile coffee unit:

  •     24v 3kw Devel Pure Sine Inverter with a DC charging current of 20-75A.
  •     2x 12v Narada AGM batteries with a charging current limit of 50A.

My scenario: I will be using it for about 5-8hrs per day with an estimate usage of 300Wh. The batteries will then be fully charged again at night. I am considering getting a solar panel just to top it up, as I have space for one, but for now I’ll only use the battery system.


My questions:
1)    Is a battery balancer needed? I am considering the Victron one.
2)    I am also considering buying the Victron | BMV 702 | Battery Monitor with the Bluetooth device to monitor while working. Is anything else needed for the setup?
3)    Since the batteries are max of 50A charging current, will the inverter monitor that so that it does not exceed this or will the battery balancer do it?


Thank you
Stephan

 

Narada.pdf

Inverter LPT-manual-EN.pdf

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Welcome Stephan.

Question 1: Nope.
Question 2: Good investment. If you get the Ve.Direct to USB cable, you can record the data. Not sure if that can be done with a Blue"teeth" device. Anyone else?
Question 3: What is the Narara's AH? Normally it is 10% of the C20 AH for best charging. Maybe 50amps max is for a larger 500ah bank. Anyone else?

Based on the battery banks Ah, the panels can be specced to ensure proper charging of the bank. Note. you will have to buy a charge controller to charge the batteries.

Last comment. It has been discussed ad-nausium on the forum that batteries will not save you any money if you have Eskom. So the question I have for you: What is your goal with the inverter / batteries and potential panels?

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2 hours ago, Czauto said:

As I understand he's got the installation in a mobile coffee unit so I guess this is some kind of trailer which is not close to grid power during the daytime?

I like !!!

Solar or gennie ... solar wins. Add a Victron MPPT controller :D and panels to match the batts and load, and there you go.

O, and spec the panels for cloudy'ish weather, early mornings / later afternoon (8 hour days) so the more the panels the longer the batts will keep / business can run.

Next step, if the above is confirmed, we need to make sure of the load, spikes could be covered with the 3kva inverter.

I would have preferred Trojan T105Re's or some such than Naradas for they are not exactly matched for off-grid usage.

Similar price as like T105RE's but I think 800(?) cycles as they are standby batteries?

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7 hours ago, Stephan said:

My scenario: I will be using it for about 5-8hrs per day with an estimate usage of 300Wh.

Is this ^^ accurate or a typo?

If your consumption really is 300Wh (50 watts for 6 hours) then I wouldn't bother with solar at all - get a 12v 100Ah battery and a small 600w inverter/charger. Plug the inverter/charger in at night to charge your battery and you are looking at around 30% DoD during the day to satisfy your load requirement. A reasonable AGM/Gel battery will last you years at 30% DoD.

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If on the other hand your usage is 300W for 8 hours then that is 2.4kWh, I would suggest at least 4x 200ah batteries to carry this load at 30% DoD if you are recharging at night only.

The battery balancer is a very good idea. The HA02 is pretty cheap (below R800 from ChrisR on the forum) and it will be perfect for the job. I dont think any other form of monitoring is necessary other than a DC meter to keep an eye on bank voltage. Your inverter is equipped with a 4 stage charger and should do a decent job of charging the batteries.

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If on the other hand your usage is 300W for 8 hours then that is 2.4kWh, I would suggest at least 4x 200ah batteries to carry this load at 30% DoD if you are recharging at night only.
The battery balancer is a very good idea. The HA02 is pretty cheap (below R800 from ChrisR on the forum) and it will be perfect for the job. I dont think any other form of monitoring is necessary other than a DC meter to keep an eye on bank voltage. Your inverter is equipped with a 4 stage charger and should do a decent job of charging the batteries.

I would just add a bmv-700/702 to that recipe to make sure about the battery state.

Not sure how big the trailer is to put panels on top but it would be easy enough to add afterwards if you need a bit of topping up during the day.

Sent from my S60 using Tapatalk

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On 4/27/2017 at 6:03 PM, The Terrible Triplett said:

Not sure if that can be done with a Blue"teeth" device.

At the moment all you can do with it is access it from VictronConnect on your cell phone, so all that is available via that link is what you can get via VictronConnect. So no constant monitoring possible, for that you must use a vedirect cable.

(Well of course it is TECHNICALLY possible, so far there's just no implementation for it).

I used to think the BT link was just rfcomm (serial over radio essentially), but was informed that it is not the case, there is some kind of carrier protocol. The bluetooth link is super useful for installers (using a cell phone to upgrade firmware and set settings), but not so much for monitoring. For that, I suggest sticking with the vedirect cable. You can use the Raspberry Pi version of the CCGX software as a cheap way of monitoring it.

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On 2017/04/27 at 9:24 PM, pilotfish said:

If on the other hand your usage is 300W for 8 hours then that is 2.4kWh, I would suggest at least 4x 200ah batteries to carry this load at 30% DoD if you are recharging at night only.

The battery balancer is a very good idea. The HA02 is pretty cheap (below R800 from ChrisR on the forum) and it will be perfect for the job. I dont think any other form of monitoring is necessary other than a DC meter to keep an eye on bank voltage. Your inverter is equipped with a 4 stage charger and should do a decent job of charging the batteries.

What I currently have is:

- water pump (80w) which probably will work a full 15min in an hour.

- A++ Bosch Fridge at about 100wh

- Espresso Pump 300w which will work around a full 20min in an hour

- Grinder 450w which will work around a full 8min in an hour.

Then also an ipad mini and a bank payment card machine which I am not sure about the wattage, but it probably is very little.

So looking at the above it should be around 300wh.

I suppose I will have then to buy extra batteries. The idea was to get a monitor, then I can exactly see what wattage each appliance/device is using. And maybe also to monitor when a battery is going bad. But if you suggest looking at the voltage I have manage to put the following estimate together rather conservatively with info I have found on the internet. Is it fairly accurate when determining the battery % on AGM?:

100% - 25.4V

90% - 25.2V

80% - 25.0V

70% - 24.8V

60% - 24.6V

Ps: Thanx for the referral of ChrisR.

Stephan

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On 2017/04/27 at 10:42 PM, Czauto said:

I guess that if you're making coffee your 300Wh average is per hour and not per day?

Selling coffee would also mean you'll be making the most coffee when it's cold and cloudy.....so don't depend on panels.

Sent from my S60 using Tapatalk
 

Thanx, I only have space for one 300w panel and much of the coffee will be early mornings, under trees, sport events at night, so I might not really benefit from it. I suppose adding another 400ah battery pack will be a better option.

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On 2017/04/27 at 10:37 PM, Czauto said:


I would just add a bmv-700/702 to that recipe to make sure about the battery state.

Not sure how big the trailer is to put panels on top but it would be easy enough to add afterwards if you need a bit of topping up during the day.

Sent from my S60 using Tapatalk
 

I was think the same with the battery monitor, just to be on the safe side.

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2 hours ago, plonkster said:

At the moment all you can do with it is access it from VictronConnect on your cell phone, so all that is available via that link is what you can get via VictronConnect. So no constant monitoring possible, for that you must use a vedirect cable.

(Well of course it is TECHNICALLY possible, so far there's just no implementation for it).

I used to think the BT link was just rfcomm (serial over radio essentially), but was informed that it is not the case, there is some kind of carrier protocol. The bluetooth link is super useful for installers (using a cell phone to upgrade firmware and set settings), but not so much for monitoring. For that, I suggest sticking with the vedirect cable. You can use the Raspberry Pi version of the CCGX software as a cheap way of monitoring it.

Thank you for the heads up.

I wont have a laptop with me to monitor the through a cable during operation. So I suppose my setup is really small and fairly simple, so I should be OK to periodically check the battery monitoring status, reading, etc. and make my calculations accordingly.

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On 2017/04/27 at 8:54 PM, The Terrible Triplett said:

I like !!!

Solar or gennie ... solar wins. Add a Victron MPPT controller :D and panels to match the batts and load, and there you go.

O, and spec the panels for cloudy'ish weather, early mornings / later afternoon (8 hour days) so the more the panels the longer the batts will keep / business can run.

Next step, if the above is confirmed, we need to make sure of the load, spikes could be covered with the 3kva inverter.

I would have preferred Trojan T105Re's or some such than Naradas for they are not exactly matched for off-grid usage.

Similar price as like T105RE's but I think 800(?) cycles as they are standby batteries?

TTT, to respond to all of your input:

What I currently have on power:

- water pump (80w) which probably will work a full 15min in an hour.

- A++ Bosch Fridge at about 100wh

- Espresso Pump 300w which will work around a full 20min in an hour

- Grinder 450w which will work around a full 8min in an hour.

Then also an ipad mini and a bank payment card machine which I am not sure about the wattage, but it probably is very little.

So looking at the above it should be around 300wh.

Unfortunately I already bought the Naradas, so Ill stick with them until I get issues. Also looking at the information above, I do not think there would be much of a spike at anytime and the 3kva inverter should be more than enough. Also as mentioned to the others, I only have space for one 300w panel, so considering my scenario of serving coffees real early mornings and also sometimes at night, it probably wouldn't help much.

Thanx

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35 minutes ago, Stephan said:

periodically check the battery monitoring status,

I've never tried the Bluetooth Dongle with a BMV, but it should just work. I used the BT dongle for a short while to read the stats from the MPPT controllers, and it is brilliant for that. It has about a ten meter range, so sadly doesn't quite make it to my normal sitting place in the living room, but I could take out the cell phone, connect to the BT interface, and get the details very quickly. If you have a BMV and a cell phone with VictronConnect, you should be in business.

You could also try getting a USB OTG (on the go) dongle instead and let the cell phone talk to the BMV using a VE-Direct cable. Would probably cost a little less.

Point is, if you just want to check the current state of things and you don't need continuous monitoring (and pretty pictures), the bluetooth dongle will do the trick.

Then again, why not just mount the BMV somewhere where you can see it? :-)

Wire the relay in the BMV to activate an alarm below a certain SOC, one that you can hear.

That should do it, right?

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So to summarize...

  • Add additional battery bank to give you around 8 hours at 20-30% DoD,
  • Add HA02 balancer to look after your batteries,
  • Add BMV-702 to monitor state of charge of your battery bank (bluetooth not required),
  • Charge your battery bank fully at every opportunity,
  • Supply free coffee to forum members on demand!

Good luck, hope it goes well.

 

 

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The 300W solar panel will help some, even under a tree, though not a lot. Do you always park under a tree? If so, could you possibly have a solar panel on ground mounted stand, a few meters away, or could you perhaps get out of the shade, at least with the roof / back-end of the trailer? 

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14 hours ago, pilotfish said:

So to summarize...

  • Add additional battery bank to give you around 8 hours at 20-30% DoD,
  • Add HA02 balancer to look after your batteries,
  • Add BMV-702 to monitor state of charge of your battery bank (bluetooth not required),
  • Charge your battery bank fully at every opportunity,
  • Supply free coffee to forum members on demand!

Good luck, hope it goes well.

 

 

Thank you very much.

Whenever powerforum members are in Potchefstroom, they should look me up for a free coffee :)

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There was a post recently of some guys running some kind of food truck using a Victron setup (BMV, Lithium batteries and the BMS). I think it was an ice cream van, but I cannot for the life of me find it anymore.

But there's also these guys...

So it appears to be a common use case.

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15 hours ago, plonkster said:

There was a post recently of some guys running some kind of food truck using a Victron setup (BMV, Lithium batteries and the BMS). I think it was an ice cream van, but I cannot for the life of me find it anymore.

Yes. The great thing about the espresso machine though is that it is converted to gas, since the boiler pulls almost 4000w which would just not make any sense with a battery system.

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