freeman avatar image
freeman asked

Battery charge status


I am working on a project where I want to provide a portable power solution.

To achieve this I am considering using the Victron MultiPlus and a 12V AGM battery.

In order to make the system user friendly I would like to display the condition of the battery.

This needs to be simple for the guys using it.

To achieve this the best way I had imagined was a display with 4 LEDs which indicate would indicate charge level* i.e.:

LED1 - 90% - Over 75%

LED2 - 70%

LED3 - 40%

LED4 - 25% Recharge at this point

% levels are approximate and could go from 0 - 100% if easier.

A screen which could display this information would be suitable.

When charging this same display could be used to indicate charge progress.

LED1 - Charged

LED2 - Float charging

LED3 - Absorbtion

LED4 - Bulk

Appreciate that % of battery charge is hard to precisely determine but I am basically after an indicator for how much useful charge remains for usage or whether it needs charging.

Am wondering if there is someone who is familiar with Victron products.
Is there a Victron product that can achieve this functionality or something similar?

It is important that the interface is simple to use.

My alternative option is to put a simple battery meter (I believe this works on preset voltage levels to approximate capacity). However am unsure what this shows whilst charging, imagine it would show over 100%

Hope someone has a suggestion.

Thanks in advance for your help.


BMV Battery Monitor
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2 Answers
wkirby avatar image
wkirby answered ·

That's an interesting project John.

As you are aware, using Voltage as SOC indicator is vague and may cause more confusion than you are trying to eliminate.

I don't know of any products like you describe. Midnite do something with coloured LEDs, but it needs to link in with their solar charge controller if I remember right.

The Victron BMV gives an accurate SOC but it's an LCD readout. It is possible to remove displayed information screens from the BMV user menu so that the only thing that can be displayed is SOC, 0 - 100%. Is that useful in any way or does it need to be readable from afar? The BMV does not display the stage of charge though, only the LEDs on the front of the Multiplus do that.

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freeman avatar image
freeman answered ·

Thanks for your help.

Having an LCD showing the state of charge would be acceptable.

Would like a way to alert the user that the battery voltage is low though believe I could use the alarm output from the Multiplus 500 to achieve this combined with a buzzer or some sort.

This then leaves displaying the state of charge to the user.

As the inverter/ charger will be relatively inaccessible in an internal structure we cannot rely on the LEDs on the front of the multiplus.

I wonder if anyone has come across this problem before?

In our usage scenario the user has the option to keep the unit charging from a mains supply if required. Our desired scenario is to choose a fully charged unit rather than a partially charged unit.

Appreciate any advice.


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