Victron Multiplus charge settings for SOK batteries

[offroad]

Will have 3-4x SOK 12v 100ah batteries in parallel charged by a Multiplus 12/3000/120-50
I asked Current Connected and SOK for charge recommendations and got different info.

Current Connected says 14.6v provides better cell balancing, likes higher float voltage and charge current.
What settings should I use to balance performance and lifespan?

Additional settings I should make on the Multiplus?

Absorption Voltage:
CC-14.6v / SOK-14.4v - (14.6v max)
Float Voltage:
CC-13.8v / SOK-13.6v
Charge Current: (per battery)
CC-50a / SOK-20a - (50a max)

Low Voltage Disconnect:
CC-10.5v / SOK-11.2v
Low Voltage Reconnect:
CC-12.1v / SOK-11.6v
BMS Low Voltage Disconnect:
Per SOK - Around 10.4v

 

[sunshine_eggo]

Either will work, but given that SOK is providing the warranty, I would go with theirs.

BTW, who is current connected?

 

[offroad]

BTW, who is current connected?

Dealer for Victron, SOK etc

 

[Koert]

For our small motorhome, I bought four SOK 206Ah batteries with Bluetooth and heating. The batteries arrived yesterday and I was surprised that they were almost completely discharged. Based on other batteries I've purchased, I expected them to be at about 80% full. I understand that It's important to have each of the batteries at a similar state of charge before connecting them together, so I'm charging each of them individually using our motorhome's solar charging and inverter/charger.

Another surprise. I thought I had read that the the 50 amp charging limitation was just a suggestion. It's not. If the charging sources put out much more than 50 amps (about 65-70 seems to be the cutoff) then the batteries completely stop charging. I expected that at some point the battery would stop accepting additional current, but I didn't expect all charging to be completely turned off.

Most 200Ah batteries would have a recommended charging rate of 100 amps and a maximum charging rate closer to 200 amps. A 206Ah battery with limited to 50 amps means the fastest charge rate requires four hours for a complete charge. But, even worse, it seems that if the battery momentarily encounters a charging current that is above specs, it will turn the charging completely off. That would mean on a day with exceptional solar production, if the current got above 50 amps it would prevent the battery from charging for the rest of the day.

This won't be as big of a problem with four batteries because that means the total current they'll accept will be 4 x 50 = 200 amps which is beyond what is usually available. But I would have like to have the option to combine 250 amps from the generator, 100 amps from the alternator, and 90 amps from solar panels for a quick charging rate of over 400 amps, and a charging time of less than two hours. (I was planning on replacing my Xantrex 2000 with a Multiplus 3000 for faster charging.)

I'm hoping to learn that this 50 amp charging maximum is a parameter that can be changed in the BMS.

 

[offroad]

The batteries arrived yesterday and I was surprised that they were almost completely discharged. Based on other batteries I've purchased, I expected them to be at about 80% full.

Interesting, my 100ah SOK's arrived at 13v, which is about 30% and what I've read they ship at.

Another surprise. I thought I had read that the the 50 amp charging limitation was just a suggestion. It's not.
I'm hoping to learn that this 50 amp charging maximum is a parameter that can be changed in the BMS.

I think the 206ah use the same BMS as the 100ah batteries have, so have the same limits.

At 4x 100ah batteries (400ah total) I'd be able to charge at 200 amps, but my Victron Multiplus 3000 maxes out at 120 amps.
If I'm on shore power I wouldn't want to charge them that fast anyway, as slower means longer lifespan. (shore power = whats the hurry)
If I don't have shore power I'd want them to get all the current solar or my generator will provide, but it's not going to be 200 amps then either.

 

[Koert]

Interesting, my 100ah SOK's arrived at 13v, which is about 30% and what I've read they ship at.

I'm in the process of charging #3. The first two were at zero and the third one was at 30%. (But it's possible that the first two had just been triggered off by the BMS and needed to wake up.)

I think the 206ah use the same BMS as the 100ah batteries have, so have the same limits.

Yes, I think that's the correct explanation, and the problem.

At 4x 100ah batteries (400ah total) I'd be able to charge at 200 amps, but my Victron Multiplus 3000 maxes out at 120 amps.
If I'm on shore power I wouldn't want to charge them that fast anyway, as slower means longer lifespan. (shore power = whats the hurry)

In normal use, we consume about 150Ah per 24 hour day and gain about 225Ah through solar charging. So, in a perfect world we could get by with 200Ah.

We purchased the additional battery capacity for situations where we use more than normal (as when we use the air conditioner) or when we have consecutive dark days. In both of those cases, we need to be able to recharge as quickly as possible by combining all of our charging sources. We currently have 220A available (alternator 90A, generator 80A, and solar 50A) but would like to have the option to add an auxiliary alternator or upgrade the inverter/charger.

A few problems here.

First, if we use all three charging sources and exceed SOK's limit, the batteries shut down and all charging stops. Or, if one battery goes into protect mode, it will increase the current going into the other batteries and they'll also go into protect mode.

Second, the low charging rate means that even if we max out our charging capability, we have to slow it down to a rate that would require running the generator for four hours at a time, which is often not practical due to fuel and noise considerations.

Third, the low discharge rate would prevent us from being able to use a 3,000W inverter.

I should have researched this further and read in between the lines. I don't think the 206Ah SOK's are a good battery for RV's that use anything except solar panels for recharging.

 

[HighTechLab]

Either will work, but given that SOK is providing the warranty, I would go with theirs.

BTW, who is current connected?

I am the owner of Current Connected.
If the batteries are purchased from us, we provide the warranty, and it's an extended 10 year warranty.

From our testing and experience, we recommend 13.8v.
When the cells are fully charged and allowed to rest, they rest at 13.8v. Using a lower float voltage will allow the cells to discharge if other DC loads are applied (such as lights in an RV), at which point they are below 100% and thereby are no longer fully charged. This is despite a charger being connected to the batteries.

Furthermore, this higher voltage provides no degradation. Even @Will Prowse agrees that calendar aging will kill the cells long before running them up to full.

 

[offroad]

With my Multiplus 3000 float set at 13.6v I see voltage is sometimes at 13.7v or slightly above.

Is there an issue with a bit of draw via RV lights etc once the battery is in float?
I do see that but it doesn't last long before I see power going back in.

 

[sunshine_eggo]

I am the owner of Current Connected.
If the batteries are purchased from us, we provide the warranty, and it's an extended 10 year warranty.

From our testing and experience, we recommend 13.8v.
When the cells are fully charged and allowed to rest, they rest at 13.8v. Using a lower float voltage will allow the cells to discharge if other DC loads are applied (such as lights in an RV), at which point they are below 100% and thereby are no longer fully charged. This is despite a charger being connected to the batteries.

Furthermore, this higher voltage provides no degradation. Even @Will Prowse agrees that calendar aging will kill the cells long before running them up to full.

Good to know. I probably already knew that. I would readily accept 13.8V for a long slow absorption, but not a float. 13.6V will hold at battery at high 9X% SoC.

 

[SoCalKevin]

For our small motorhome, I bought four SOK 206Ah batteries with Bluetooth and heating. The batteries arrived yesterday and I was surprised that they were almost completely discharged. Based on other batteries I've purchased, I expected them to be at about 80% full. I understand that It's important to have each of the batteries at a similar state of charge before connecting them together, so I'm charging each of them individually using our motorhome's solar charging and inverter/charger.

Another surprise. I thought I had read that the the 50 amp charging limitation was just a suggestion. It's not. If the charging sources put out much more than 50 amps (about 65-70 seems to be the cutoff) then the batteries completely stop charging. I expected that at some point the battery would stop accepting additional current, but I didn't expect all charging to be completely turned off.

Most 200Ah batteries would have a recommended charging rate of 100 amps and a maximum charging rate closer to 200 amps. A 206Ah battery with limited to 50 amps means the fastest charge rate requires four hours for a complete charge. But, even worse, it seems that if the battery momentarily encounters a charging current that is above specs, it will turn the charging completely off. That would mean on a day with exceptional solar production, if the current got above 50 amps it would prevent the battery from charging for the rest of the day.

This won't be as big of a problem with four batteries because that means the total current they'll accept will be 4 x 50 = 200 amps which is beyond what is usually available. But I would have like to have the option to combine 250 amps from the generator, 100 amps from the alternator, and 90 amps from solar panels for a quick charging rate of over 400 amps, and a charging time of less than two hours. (I was planning on replacing my Xantrex 2000 with a Multiplus 3000 for faster charging.)

I'm hoping to learn that this 50 amp charging maximum is a parameter that can be changed in the BMS.

Another easy method is a Sterling DCDC charger, they come in 30a, 60a, and 120a and will charge the house batteries as you drive.

They are 100% customizeable for different charging profiles and such.

I use the 60a unit and its worked amazing the last 2 years on the road.

Just an FYI

 

[HighTechLab]

Good to know. I probably already knew that. I would readily accept 13.8V for a long slow absorption, but not a float. 13.6V will hold at battery at high 9X% SoC.

It does say in my signature...Lol

 

[mikefitz]

IFurthermore, this higher voltage provides no degradation.

Can you show experimental proof that this is the case?

 

[HighTechLab]

Can you show experimental proof that this is the case?

Sure, I will work out a way to document it in a presentable way. No problem.

With SOK batteries we've never had a single warranty case or report of a battery under-capacity using our figures.

 

[Aly_Oops]

I have the victron system using multiplus The unit itself has parameter to limit the charge current from 120 amp to 15 or less. If you are using multiplus for battery control then you need to set the battery type and parameters. By default they would not be correct.

I am using lynx 1000 bms and cerbo gx. Some parameters still need to be set within multiplus.

But i prefer to install the third party package on my cerbo gx that allow me to change the charger setting as low as 7 amps. On the fly i can change the ac input limits to match the shore power or generator power. The multiplus will assist if needed.

I agree i only notice the 50 amp limit after buying one unit to test first before buying two more. Unfortunately they did not upgrade the bms but use the 100 amp battery bms.

However the option to increase charge or discharge would be to parallel additional batteries. I did ask SOK if that is the case with the 206 but no reply yet. Would like to hear what SOK says. The rule of thumbs may not agree.

Another case of reviewers not doing a proper review or complete. Most are too basic reviews.

Received a reply from SOK and yes, the charge and discharge double with each battery in parallel.