Victron smart solar, lithium settings.

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Re: Victron smart solar, lithium settings.

Postby davef » Wed May 01, 2019 7:53 pm

1) If the float voltage can be set lower then that might stop the switching in and out of absorption.

From what I have read is that you don't want to float them. I fail to understand how floating a battery at say 13V when its terminal voltage is 13.3V is a problem but I have heard that comment several times. Also, that floating them could reduce their life. Maybe, what people refer to is that if you try to float them at a typical lead-acid float which is higher than bulk or absorption then you might be getting above the 14.4 to 14.6V region where you don't want to go.

When you stop charging, say at 13.8V the terminal voltage will drop a bit but I am surprised that it takes another 30-40AH to get it back up to 13.8V. Are you discharging the battery as well as charging it?

When you get the Winston cells do you also plan to buy new solar panels or try to use the current ones?

I was more interested in why the voltage rises so fast to 13.8v when in bulk mode, even though its nowhere near fully charged, and if a larger pack of cells will do the same thing.


So, fast to 13.8V but from where? 13.4V or 13V? At 13.6V you are hitting the region will it will start to climb rapidly BUT the battery should be somewhere around 90-95% SOC. What happens if you leave the battery sit disconnected for several days? Does the terminal voltage keep dropping?

My SBMS is set up to stop charging when the first cell reaches 3.55V (all other cells will be very close to 3.55V as the active balancing only takes place during charge). Mine is set up so that charging starts when the first cell drop below 3.4V (all the other cells will be fairly close to 3.4V). Everything is fully adjustable. Yes, PV is switched completely off.

He builds very good hardware and has been very helpful.

If you are happy manually balancing the batteries then all you need is HVD and LVD. There are people around who say balance them once a year BUT have the above protection.
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Re: Victron smart solar, lithium settings.

Postby Al510 » Wed May 01, 2019 8:25 pm

So, fast to 13.8V but from where? 13.4V or 13V? At 13.6V you are hitting the region will it will start to climb rapidly BUT the battery should be somewhere around 90-95% SOC. What happens if you leave the battery sit disconnected for several days? Does the terminal voltage keep dropping?


I think it was around 13.2 when i first connected it to the victron. Thats what im getting at, about the voltage climing so fast to 13.8 when it clearly wasn't at 90% soc because it has taken another 40ah without any discharge.

I think we are confusing the battery charging on my projecta charger. Im not charging "to" 13.8 volts im charging "at" a fixed constant 13.8v.

https://www.caravanersforum.com/viewtop ... 11&t=80823

Here is a thread about a lithium pack capacity showin a graph of a charge cycle at a fixed 14.2v, you might find the info interesting.
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Re: Victron smart solar, lithium settings.

Postby davef » Wed May 01, 2019 8:38 pm

I think we are confusing the battery charging on my projecta charger. Im not charging "to" 13.8 volts im charging "at" a fixed constant 13.8v.


If the projecta charger is set to 13.8V and a constant current limit of 10Amps and you attached it to the battery I would expect the voltage of the battery to start at say 13.3V and then rapidly rise to 13.8V.

Are you not talking about CC charging?
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Re: Victron smart solar, lithium settings.

Postby davef » Wed May 01, 2019 8:42 pm

I think it was around 13.2 when i first connected it to the victron. Thats what im getting at, about the voltage climing so fast to 13.8 when it clearly wasn't at 90% soc because it has taken another 40ah without any discharge.


If the charger is set at 10Amps charge rate and it takes 40AH (4 hours) to get to 13.8V then I don't understand how that is "climbing rapidly".
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Re: Victron smart solar, lithium settings.

Postby davef » Wed May 01, 2019 8:45 pm

Agreed ... if it takes 40AH to get back to 13.8V then the battery must have been at 50-60% SOC
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Re: Victron smart solar, lithium settings.

Postby Al510 » Wed May 01, 2019 8:46 pm

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Re: Victron smart solar, lithium settings.

Postby Al510 » Wed May 01, 2019 8:48 pm

Are you not talking about CC charging

No constant voltage.
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Re: Victron smart solar, lithium settings.

Postby davef » Wed May 01, 2019 8:52 pm

Typical day for me:

at 4PM the sun sets behind a mountain voltage is 26.6V and the SOC 97%. When the sun comes over another mountain at 8AM the battery voltage is 26.5V and the SOC is 86%. I have drawn out about 500Watt/hours.
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Re: Victron smart solar, lithium settings.

Postby Al510 » Wed May 01, 2019 8:53 pm

If the charger is set at 10Amps charge rate and it takes 40AH (4 hours) to get to 13.8V then I don't understand how that is "climbing rapidly".

The climbing rapidly was when in bulk mode ( constant current) on the victron charger. It quickly rose to 13.8v then switched to absorption at a (constant voltage) 13.8v.
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Re: Victron smart solar, lithium settings.

Postby davef » Wed May 01, 2019 9:00 pm

If you want to really long thread try cruisersforum. I haven't been back there for a year or so.

Constant voltage. So, the 10Amp current is the maximum that the projecta can put out? And it stays at 10Amps until the battery gets to 13.8V. Or does the current progressively taper off as the battery voltage rises? If it stays at 10Amps until 13.8V then that is CC to me.

Actually. I don't think it makes any or much difference to solving this problem.
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