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redrover avatar image
redrover asked

BlueSolar MPPT 100/30 leaves BULK too early

I have a BlueSolar MPPT 100/30 charging Sentry 300AH Lithium battery. I have set user defined settings and selected charge voltage of 14.6, float voltage of 13.8 and absorption voltage of 14.8. When I reboot the MPPT 100/30 it stays on bulk for a few minutes then goes to absoption. Battery is at 39%. I increase the absoption voltage to 14.9, then 15.0 then 15.1 and 15.2, and same thing happens. The maximum battery voltage recorded for the day was 14.94. Goes to absoption after a few minutes then stays there for 1 hour before going to float. I have upped the absoption voltage to 15.3 and then it works fine. Stays on Bulk all day and the next.

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4 Answers
JohnC avatar image
JohnC answered ·

So 39% SoC? Reading that as gospel is/may be a mistake. It may just need 'syncing' or 'resetting'. Notorious for misleading..

Your batts may already be fully charged, and you may be flogging them to premature death.

Ignore the charge stage that you're in, that's really just a throwback to Pb's. Observe the max V your maker states, and watch your Amps. If they taper away, then there's fair chance they're full.

By all means check the V with a multimeter to confirm. And there's always a possibility that the BMS isn't right.

Take care when telling your batt supplier what you've been doing, because it's likely you've voided your warranty already.

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redrover avatar image redrover commented ·
I don't think so. I believe 39% was correctly reported by the battery. I roughly measured amps-in and amps-out for 6 days and observed a battery loss of about 10% per day from a fully charged 100% (on 240v charger). Battery can also not be flogged beacuse of inbuilt BMS. There must be another reason why charger is switching to Absorption prematurely.
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JohnC avatar image JohnC ♦ redrover commented ·

Hi Red. Perhaps my faith is lesser than yours? :) Re SoC, note that Victron don't recommend their installers provide multiple SoC sources to customers, because they can often conflict and prompt queries/complaints (don't ask me to find a link, too hard). That's even between Victron sources, even without exotic bms's.

'Absorption' will be reached simply by it's V setpoint being achieved. For me, the earlier in the day that happens the better (Pbs though). Look hard at your bms..

Maybe think of 'Bulk' as a leadup to the 'Absorb' optimum.

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redrover avatar image redrover JohnC ♦ commented ·

Hey John

Thanks for that. So when absorption happens early in the day then after 1 hour it goes to float where I'm not getting enough into the battery to bring it back up to 100%. It loses 10%every day. I've got a RV with 300W solar and only running a compressor fridge sitting out the front of my house in full sun. Battery should recover to 100% by afternoon every sunny day. Something is causing the solar charger to think that the V absoption setpoint has been reached. It's like some sort of a voltage spike that happens. Or something else, I'm still looking for help.

cheers

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JohnC avatar image JohnC ♦ redrover commented ·

Yeh, so set your float V to the same as your absorb V. So it should just continue on as you or your bms demand. But it's not a good idea to exceed recommended specs on batts.

Even a spike? should be ignored by your Victron. It will simply continue to target your set Absorb/float V.

If it doesn't reach that V, then be concerned. It seems you're worried it happens too fast? That's not a concern, it's a target. 'Absorb' is really your target, and if you've achieved that over most of a day, job done.

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bluepowershop avatar image
bluepowershop answered ·

@RedRover

Assuming you're talking about SNL12V300BT ...

It is not very clever to raise the absorption voltage to 15.3V as the specifications of this battery state that the maximum charge voltage is 14.6V +/- 0,1V.
As @JohnC says when the charger reaches the selected absorption voltage the charger goes from bulk into absorption.
If you dial in a voltage that the battery simply can not reach the charger stays in bulk.
Needless to say this will ruin the battery!

Please reset the value back to the advised voltage and check the current flowing to the battery with a clamp meter.
If the SOC is legit you should see a reasonable amount of power going into the battery.
But if the current stays low and the voltage is 14,6V your battery is fully charged or broken already...

You say: "I have set user defined settings and selected charge voltage of 14.6, float voltage of 13.8 and absorption voltage of 14.8."

Charge voltage and absorption voltage is the same so how can you dial in separate values?
Or do you mean you have selected 14,8 at the equalization voltage?
Please set this value to the float value and disable the automatic equalization!
This is for other type of batteries.
(float value for safety, if someone hits the manual equalization button)

Regards

Mark

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redrover avatar image redrover commented ·

Hi Mark

see my latest comments below,

cheers

Red

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redrover avatar image
redrover answered ·

Hi Mark

Thanks for that! I'll reset the values to absorption 14.6 and float of 13.8. I mis-stated above the 14.8, please ignore and I'll restate. I was only upping the absorption voltage as requested by the battery manufacture, but then he was probably only guessing.

My original problem still stands and I'll state it in my layman’s term cause I'm not a battery person, just a user/consumer.

I've got a RV with 300w solar and the 300ah lithium with the Bluesolar MPPT 100/30. It sits outside my house in full sun with a compressor fridge drawing power and some minor other stuff. Total amps out should be about say 60AH-80AH per day. I noticed that the solar charger goes into absorption state as soon as it boots up, then runs for 1hr and goes to float. So I'm getting 1hr of a larger current following by the rest of the day of only about 2-3amp/hr on float. This wasn’t enough to keep the battery at 100% and was losing 10% per day.

Then when at 39% I upped the absorption voltage and bingo, it stayed on BULK all day for 3 Days and battery went to 100% and on charger went to float.

Your help in solving this issue is greatly appreciated as the previous solution of upping the absorption voltage was clearly wrong.

cheers

Red

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holle avatar image
holle answered ·

Hi.

Need some help on this issue as my 100/30 also leaves bulk/absorption to soon to fully load the battery.

For my understanding the solar day starts with bulk till the preset V (14.2 in my case) is reached and moves to absorption. The duration depends on the measured Voltage right before solar day starts (max 6h, min 1h). When this time is reached, system switches to float with a load according to V specified in settings (in my case 13.5V). Is this right?

Looking at my history this shows values which do not match that definition. Battery max is always below absorption Voltage (but system turns into absorption) and battery min. V is measured around 11,5V by Victron 100/30 but was was never below 12.5V as Masterpanel shows.

Is there something wrong with the firmware??

Many thanks for a short reply,
Holger

@Bluepowershop


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redrover avatar image redrover commented ·

Hi

I fixed this problem by buying and attaching a Victron "Smart Battery Sense"

I found that the MPPT 100/30 was not measuring the voltage correctly and the smart battery sense does measure the battery voltage and transmits it to the MPPT 100/30 via bluetooth. Thus all problems of leaving Bulk too early have dissapeared. I have been even been able to lower the voltage slightly to prolong battery life so I reach 98% full not 100% which is fine in my application.

cheers

Red

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holle avatar image holle redrover commented ·

Hi.

Thanks for your tip. In general it sounds like a solution but my MPPT 100/30 is around 4m /13ft away (across the motorhome) from the battery which seems to be too far for a stable bluetooth connection.

Best, Holger

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Tim van Dam avatar image Tim van Dam holle commented ·
I realize that this response probably is not useful for you anymore, but perhaps other People can benefit from it. What cable thickness do you use? Cables of 4 meters might result in a significant voltage drop, depending on the thickness, which might be the reason that the behavior of the charger does not match your expectations. It (possibly) simply cant read the actual voltage due to energy loss caused by the cable.


Did you manage to find a solution to your problem?


Cheers, Tim

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