Valence XP Super Thread

mannytheseacow said:

Why not just use one of the high voltage Valence BMS? Travis got me one with a simple step-up to supply the higher voltage and it's working like a dream.

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Hello folks. Had a couple questions re: using the HV Valence BMS units, of which, there are currently a number available on eBay:

• Can you recommend a step-up converter? There seem to be a lot of questionable products out there and I'm looking for something that will be reliable and not start any fires
• Did you have to flash the BMS to get it to work? I'm running a relatively simple system w/ four batteries in parallel at 12V.
• Any other pointers on getting this set up / questions you would have asked knowing what you know now?

Thanks so much!

Travis said:

they are second hand batteries so yes they've been balanced but they were also balanced when they were new before the first seller got a hold of them. The problem now is that most of these batteries have been sitting for years and so any cell block that has a slightly faster self-discharge rate is severely behind. On your initial top balance it would be beneficial to get the voltage higher then your normal daily charge. The higher the voltage gets the more extremely obvious the voltage differences become and the more obvious they become the more finely balanced they'll be.

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My charge controller's highest LiFePO4 setting is 14.6V. I believe it doesn't hold this voltage for longer than 1 hour per day though, falling back to 13.8V, and floating at 13.5V once it determines the batteries to be fully charged. I'll give this mode a go, and leave it for several days if needed.

After I fully charge the batteries like this, then I guess it will be good to discharge down to 80% SOC or so for storage since I don't plan to use the van much until next Spring (I'm currently building the interior).

Had to reupload video


HOW TO: USED Valence U27-12XP Lithium batteries. Repair, Communication & Software issues

seb303 said:

This doesn't seem to be the case (at least not most of the time).

I am measuring 0.5mA on the RS485 5V wire regardless of whether the 2 batteries are asleep (20secs LED flash) or awake (5secs LED flash). The current usage jumps around a bit while the RS485 data is transmitting, so I stop the comms to take the reading. Strangely, I occasionally see a current draw of 29mA, as if stopping the data at a certain point causes the internal BMS to switch to drawing external power.

My whole external BMS draws 12mA at 13.8V, and this doesn't change noticeably if I disconnect the RS485 to the batteries.

So I would conclude that the battery BMS *can* draw power externally under exceptional circumstances which I can't predictably reproduce, but in normal operation it does not (although the RS485 5V must be present for comms to function),

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You could easily take a side cover off and measure various things

Travis said:

You could easily take a side cover off and measure various things

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Well I could if the batteries weren't already bolted into a tight little space under my passenger seat

But it's pretty clear from the current measurements that in normal operation, the internal BMS is not being powered from the RS485 5V line. The fact that the internal BMS stays active for a couple of minutes after the RS485 is disconnected seems to support this.

This thread is great, thanks for all the work. I am using 6 U27 12XP batteries plus 600w solar, with a backup 5kw generator in my RV. I have a Victron charger for shore-based charging, and an MPPT for solar charging, both set to a lower max output then 14.6v. I have ordered a MIUSA-BMSLV, it may be a bit overkill since I am running a 12v parallel system, but with 6 batteries it seems worthwhile to keep them as healthy/happy as possible. I am thinking that using two contactors, one as a backup to prevent overcharging, and one as a backup to prevent over-discharge, I have a couple of Victron battery protect units I was planning on using between the batteries and my 12v system. I have been able to follow the directions (Thanks Again) and use the valence software to ensure internal balancing and check the status of my batteries. I am looking for suggestions for contactors/relays, and also I want to plan for how to setup the MIUSA-BMSLV once it arrives. I have RTFM but, I am unsure of next steps. From what I can tell I will need to make my own cables to connect to J2 and also the XP internal BMS. Anyone have have any pointers?

dcadaret said:

This thread is great, thanks for all the work. I am using 6 U27 12XP batteries plus 600w solar, with a backup 5kw generator in my RV. I have a Victron charger for shore-based charging, and an MPPT for solar charging, both set to a lower max output then 14.6v. I have ordered a MIUSA-BMSLV, it may be a bit overkill since I am running a 12v parallel system, but with 6 batteries it seems worthwhile to keep them as healthy/happy as possible. I am thinking that using two contactors, one as a backup to prevent overcharging, and one as a backup to prevent over-discharge, I have a couple of Victron battery protect units I was planning on using between the batteries and my 12v system. I have been able to follow the directions (Thanks Again) and use the valence software to ensure internal balancing and check the status of my batteries. I am looking for suggestions for contactors/relays, and also I want to plan for how to setup the MIUSA-BMSLV once it arrives. I have RTFM but, I am unsure of next steps. From what I can tell I will need to make my own cables to connect to J2 and also the XP internal BMS. Anyone have have any pointers?

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The Victron Battery Protect units will act as relays and require only a low current 12V signal, so should be able to run directly of the external BMS (I've no direct experience with the MIUSA-BMSLV though - I wrote my own BMS running on inexpensive Arduino hardware).

You might be able to control your charger directly, and eliminate the need for a 2nd battery protect / relay.

I have Votronic VBCS which handles all 3 charging sources: solar, mains hookup, and vehicle when driving (it also trickle charges the starter battery from solar). In my set up the BMS will disable the VBCS via a 12V signal if any individual cell goes over voltage or over temperature (or if placed into "storage" mode where I don't want to keep the batteries fully charged). Then I have a single Victron Battery Protect to disconnect the load in a low voltage situation - as well as the internal low voltage threshold of the Battery Protect, my BMS sends a disconnect signal if any individual cell goes under voltage or over temperature.

One thing to bear in mind about the Victron Battery Protect is that it will not prevent reverse current flow, so you can't use it for battery to battery charging for example. Vin must always be > Vout.

Thanks seb303, I wondered if I should put a relay in place between my PV panels and the MPPT to interrupt charging in case individual cells get overcharged? I will need to look into my MPPT and if I can control it directly from the BMS, I had bad information initially about the XP batteries and did not understand the need for a BMS, luckily I used victron battery protects for UV, and manually set my MPPT to 14.4v max. I already have several battery protects, I was thinking I would power my BMS using a battery protect as a UV failsafe, so that I can keep the BMS powered even after I have turned off the rest of the load via relay/contactor. Your work with a DIY BMS using arduino hardware is impressive, I opted for a Mueller BMS mostly out of fear that I wouldn't have time to keep up with it, being that I am a grad student, and time is precious.

You don't need to place a relay between your panels and charge controller. To protect against over-charging/over-voltage you would put a relay between the charge controller and the batteries. Or if your charge controller supports it, directly signal it from the BMS to stop charging in an over-voltage or over-temperature situation. Some charge controllers will drop the voltage to something low like 12.8V in this situation so your appliances can continue to draw power from the solar without over-charging the batteries.

The only caveat is that your system be voltage matched appropriately so the charge controller can handle the no-load voltage from the panels (which will be higher than normal operating voltage).

seb303 said:

You don't need to place a relay between your panels and charge controller. To protect against over-charging/over-voltage you would put a relay between the charge controller and the batteries. Or if your charge controller supports it, directly signal it from the BMS to stop charging in an over-voltage or over-temperature situation. Some charge controllers will drop the voltage to something low like 12.8V in this situation so your appliances can continue to draw power from the solar without over-charging the batteries.

The only caveat is that your system be voltage matched appropriately so the charge controller can handle the no-load voltage from the panels (which will be higher than normal operating voltage).

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Yeah, I was only thinking about something between the PV and controller, since it is bad for the controller to have the batteries removed while still connected to PV... or am I making it too complicated? My charge controller has high/low temp shutoff. I was just starting to get worried about cells independently of total voltage being a problem with over voltage, or is that well controlled by the BMS?

Well, now I feel silly, I just checked my MPPT, looks like I can have it control a few relays, without trouble.

dcadaret said:

Yeah, I was only thinking about something between the PV and controller, since it is bad for the controller to have the batteries removed while still connected to PV... or am I making it too complicated? My charge controller has high/low temp shutoff. I was just starting to get worried about cells independently of total voltage being a problem with over voltage, or is that well controlled by the BMS?

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It's not necessarily bad for the controller to have the batteries removed while still connected to PV. You need to check the no-load voltage spec of your panels and compare this to the maximum voltage spec of your controller. I'm no expert on large PV systems, but for an RV system I would have thought the charge controller should be chosen so it can handle the no-load PV voltage.

The charge controller will obviously regulate the total voltage going to the batteries, but you need a BMS to take care of the individual cell voltages.
(1) To keep them balanced with each other (which the internal BMS on the XP batteries does, but *only* when connected to an external BMS).
(2) To provide a safety shutdown of the charge controller if an individual cell goes over voltage or over temperature - which can happen if you have a particularly weak cell or cells that then cause the other cells to have too much voltage (the internal balancing takes care of things to an extent, but it can only bleed off so much current).

The same is true on the load side: a Victron Battery Protect will disconnect the load if the total voltage falls below a certain threshold, but this doesn't prevent an individual cell going down to a harmfully low voltage if it happens to have a lower capacity that the other cells. So you need the external BMS to control the load disconnect relay too.

Any particular contactor recommended for use with the Thunderstruck BMS? I see these 200-500 amp dc contactors on Amazon but not sure if those are the correct ones. I've used battery isolators before but that's the opposite of the intended outcome.

jeremyjeremy said:

Any particular contactor recommended for use with the Thunderstruck BMS? I see these 200-500 amp dc contactors on Amazon but not sure if those are the correct ones. I've used battery isolators before but that's the opposite of the intended outcome.

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The Ev200aaana is rated for 500 amps. make sure you get the one that has the economizer board on the side. It's basically a pwm board that reduces the power necessary to keep the contactor closed after it initially closes.


Data sheet https://www.te.com/commerce/Documen...200_Ser_Contactors&DocType=CS&DocLang=English

seb303 said:

It's not necessarily bad for the controller to have the batteries removed while still connected to PV. You need to check the no-load voltage spec of your panels and compare this to the maximum voltage spec of your controller. I'm no expert on large PV systems, but for an RV system I would have thought the charge controller should be chosen so it can handle the no-load PV voltage.

The charge controller will obviously regulate the total voltage going to the batteries, but you need a BMS to take care of the individual cell voltages.
(1) To keep them balanced with each other (which the internal BMS on the XP batteries does, but *only* when connected to an external BMS).
(2) To provide a safety shutdown of the charge controller if an individual cell goes over voltage or over temperature - which can happen if you have a particularly weak cell or cells that then cause the other cells to have too much voltage (the internal balancing takes care of things to an extent, but it can only bleed off so much current).

The same is true on the load side: a Victron Battery Protect will disconnect the load if the total voltage falls below a certain threshold, but this doesn't prevent an individual cell going down to a harmfully low voltage if it happens to have a lower capacity that the other cells. So you need the external BMS to control the load disconnect relay too.

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Ok, thanks that helps a lot. I am re-reading my manual for my MPPT. I have ordered a couple of large contactors based on Travis's recommendation.

Was wondering if anybody has a recommendation for active module balancing of these batteries I have 6 batteries running in a 24v system and 2 of the batteries consistently fall 25mv behind any help would be appreciated.

So your getting say 26.4 but one pair in series is reading 26.2? After giving up on a practical BMS on my Valence batteries I ordered this 48V balancer "https://zhcsolar.com/product/ha02-battery-equalizer/. You can use it for 24V as what it does is brings each 12V battery in balance to the others by routing power to the lower one. You can attach up to 4 12V batteries. Their schematic for the 24V scenario is a little confusing. I'm picking up one to check out. You can also search and fing the same unit with a different manufacturer.

Sycamore said:

So your getting say 26.4 but one pair in series is reading 26.2? After giving up on a practical BMS on my Valence batteries I ordered this 48V balancer "https://zhcsolar.com/product/ha02-battery-equalizer/. You can use it for 24V as what it does is brings each 12V battery in balance to the others by routing power to the lower one. You can attach up to 4 12V batteries. Their schematic for the 24V scenario is a little confusing. I'm picking up one to check out. You can also search and fing the same unit with a different manufacturer.

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I presume he's saying that the voltage of half of the series pair is going out of balance with the other half? The total parallel voltage should not be able to differ unless the wiring is unbalanced.

Peregrine, how are you wiring the batteries. Do you have the mid points of each series pair connected? e.g. like this:


That balancer/equalizer looks like it will do the trick (assuming the mid points of each series pair are connected). There might also be a cheaper option if only 2 channels (24V) are needed.

But it doesn't remove the need for a BMS for the Valence batteries, or at the very least something to keep the internal BMS active. There was an internal balancer/equalizer board posted earlier in this thread which can be fitted in each battery to keep the individual cells balanced. But with 6 batteries that's a fair bit of work. Better to find a way to keep the internal BMS active IMO.

seb303 said:

I presume he's saying that the voltage of half of the series pair is going out of balance with the other half? The total parallel voltage should not be able to differ unless the wiring is unbalanced.

Peregrine, how are you wiring the batteries. Do you have the mid points of each series pair connected? e.g. like this:
View attachment 22090

That balancer/equalizer looks like it will do the trick (assuming the mid points of each series pair are connected). There might also be a cheaper option if only 2 channels (24V) are needed.

But it doesn't remove the need for a BMS for the Valence batteries, or at the very least something to keep the internal BMS active. There was an internal balancer/equalizer board posted earlier in this thread which can be fitted in each battery to keep the individual cells balanced. But with 6 batteries that's a fair bit of work. Better to find a way to keep the internal BMS active IMO.

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If hooked to the midpoints can it see each 12V batt and bleed off or add too for equal voltage in each battery?
What I'm doing is hooking all the batteries communication cables together and going into a laptop with the Valence software. I can see all the data and from what I read the internal BMS is active. I'm running 24V but switching to 48V for a MPP LV5048 110/220 for the house/Shop and a GoWatt SPF 5000ES 220 only for the Mini Split A/C's I'm putting in. The SPF can run the A/C's off a separate 5kw pv string. The SPF has a BMS communication port but don't know if it can interface with the Valence batteries. Purchased my MPP and GroWatt gear from Ean at USA-MPP_SOLAR. You can actually reach him and talk about what your looking to accomplish, pretty rare these days.

seb303 said:

I presume he's saying that the voltage of half of the series pair is going out of balance with the other half? The total parallel voltage should not be able to differ unless the wiring is unbalanced.

Peregrine, how are you wiring the batteries. Do you have the mid points of each series pair connected? e.g. like this:
View attachment 22090

That balancer/equalizer looks like it will do the trick (assuming the mid points of each series pair are connected). There might also be a cheaper option if only 2 channels (24V) are needed.

But it doesn't remove the need for a BMS for the Valence batteries, or at the very least something to keep the internal BMS active. There was an internal balancer/equalizer board posted earlier in this thread which can be fitted in each battery to keep the individual cells balanced. But with 6 batteries that's a fair bit of work. Better to find a way to keep the internal BMS active IMO.

Click to expand...

Absolutely do not tie the midpoints together like in the diagram. Current will not flow equally. Trust me I've done it and measured many points with multiple amp meters and discovered that tying the midpoints together causes imbalances everywhere. it's complicated but when I thought about it more in-depth it makes sense that the power would flow through the path of least resistance and with the midpoint wires it ends up taking what would have been balanced and throwing it off. it seems like tying the midpoints together would help the batteries that were parallel to stay equal but it's not the case. keep each series string completely separate at the midpoints and put balancers on each series string.

Sycamore said:

So your getting say 26.4 but one pair in series is reading 26.2? After giving up on a practical BMS on my Valence batteries I ordered this 48V balancer "https://zhcsolar.com/product/ha02-battery-equalizer/. You can use it for 24V as what it does is brings each 12V battery in balance to the others by routing power to the lower one. You can attach up to 4 12V batteries. Their schematic for the 24V scenario is a little confusing. I'm picking up one to check out. You can also search and fing the same unit with a different manufacturer.

Click to expand...

This cheap 4-channel balancer does a good job keeping the 12 volt batteries equal to each other but you still must have the laptop connected to keep the cells balanced. so think of it as a 4 battery balancer it will balance four batteries. it doesn't matter the configuration they don't even need to be connected to a load or a charger. When you hook up the four batteries to this device it will make them all the same voltage. They do have a current draw though so you wouldn't want to leave it connected for months if the batteries were unattended and not hooked to a solar charger. The 4-channel units move more current, they're more capable. But they don't have indicator lights. The 2-channel units basically for 24 volt systems have indicator light so it tells you which battery is charging that is kind of Handy and even though they move much less power and balance slower it still gets the job done with these lithium batteries just fine.
There's some question as to what voltage ranges they will work with. I thought maybe I can get the 4-channel version and hook it straight to the four cells inside the valence battery but I'm not positive that it will work properly at that low of voltage. Some of these units they sell say that it will shut down if the battery gets low. but then at the same time some of them claim to balance lithium voltage levels & they claim they'll work with 6 volt golf cart batteries too and you certainly wouldn't want to drain a 12 volt battery down to 6 volts. remember these things do have a very small parasitic load on the battery when they're connected even after they're done balancing. so who knows maybe there's different models with different low voltage cut offs I'm not really too sure. I own about 15 of these things from three different sources and so far they seem to all behave the same as each other.

thanks for all the responses It is 2 modules that have fallen behind the other 4 now by almost 30mv but they catch up by 10 once charged the internal cells in all six stay within 5mv, I plug the software in every day will one of these work? https://www.amazon.com/PowMr-Batter...id=1599498265&sprefix=24v+battery+bala&sr=8-4

Travis said:

Absolutely do not tie the midpoints together like in the diagram. Current will not flow equally. Trust me I've done it and measured many points with multiple amp meters and discovered that tying the midpoints together causes imbalances everywhere. it's complicated but when I thought about it more in-depth it makes sense that the power would flow through the path of least resistance and with the midpoint wires it ends up taking what would have been balanced and throwing it off. it seems like tying the midpoints together would help the batteries that were parallel to stay equal but it's not the case. keep each series string completely separate at the midpoints and put balancers on each series string.

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Interesting. The diagram for the 4 channel balancer linked by Sycamore showed the midpoints connected, and I've also seen it recommended in other places. Like in this Victron PDF for example:
https://www.victronenergy.com/upload/documents/Wiring-Unlimited-EN.pdf (p21)

I assumed connecting the midpoints would be ok, especially if there is a balancer connected. But I guess any minor difference in cable length and connector resistance could throw the whole thing out. The Valance batteries do have an extremely low internal resistance, which probably makes any cabling differences more significant.

So a balancer channel needed for every battery then. If using 2 of those 4 channel balancers for a 6 battery system, would you parallel 2 of the channels of each balancer?

Peregrine said:

thanks for all the responses It is 2 modules that have fallen behind the other 4 now by almost 30mv but they catch up by 10 once charged the internal cells in all six stay within 5mv, I plug the software in every day will one of these work? https://www.amazon.com/PowMr-Batter...id=1599498265&sprefix=24v+battery+bala&sr=8-4

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I would have said 1 of these would work with the midpoints of the 3 strings connected, but Travis's experience suggests you need 3 of these balancers (1 for each 24V string in your 6 battery setup).

Just saw this and I already ordered one, I emailed powmr and asked they said one is good for six batteries like the victron just buying time untill I can purchase the external bms. hope it works other than those 2 modules slipping back my little system runs like a champ... Thanks for the input