# question

## Why is the solar volts higher then the volts going to charge my batteries in Bulk mode never getting to 14.4 volts

Hi All;

I will have plenty of solar amps as high as 23 amps at times but the charger is on bulk charge and never gets higher then 13.9 volts going to the batteries? I have set float to 15 volts along with Bulk at 15 and still doesn't change. I have the mppt 30 amp charger with Bluetooth.

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Paul B answered Â·

The volts will only increase once the batteries are charged fully especially if they are LIPO4

also you mention why are the solar volts higher

this is how the MPPT works and gets full output from your panels.

it keeps the voltage of the panels as high as it can to achieve the highest amps as a example 24V and 5 or 120Watts amps and then it converts this to the Battery side and thus you get 12V and 10 amps thus 120 watts

the older style PWM would clamp the PV volts down to the battery voltage or if you directly connected the panels to the battery (ie with no regulator) thus 12 v and 5 amps watts 62 watts into the batteries

in this case the MPPT is close to giving you 100% extra power from your panels.

1 comment

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Â·

I guess i still dont understand. My battery voltage reading at the posts was 11.9 volts. The MPPT said i had over 15 volts from solar but was only putting 12.59 in Bulk mode or so in the batteries. I confirmed this at the controller because I thought I may be losing volts thru the wire but was not. So is there a setting I should change in order to get 14.4 Volts in bulk mode that I haven't done?

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When you state that the MPPT shows over 15volts from solar, is this shown in the upper half of the display?

How many volts do your solar panels generate? How many in series and parallel?

The MPPT needs to see 5volts more solar voltage than battery voltage to start charging and one volt more solar voltage than battery voltage to continue charging.

If your solar panels are only outputting 15 volts, the batteries will never get over 14 volts.

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For the solar charger to raise the terminal voltage of your batteries (that are quite discharged from what you posted), requires two things ... 1) Current (amps) from the solar charger and 2) Time.

Think of the battery like it was a bucket of water. If your bucket is nearly empty, you need a hose with a good flow of water AND time to fill the bucket. It is also important that you do NOT take more water out of the bucket than you are putting in - if you do, the bucket will never fill up.

Terminal voltage is NOT reliable indicator of battery state of charge while the battery is charging or discharging UNLESS the battery is very full or very empty.

I suggest that you research the correct settings for your battery, set these into the charger - then let the charger do its job. Remember - a battery is only a bucket for electrons. You can not take more out than you put in.

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