First Post! Batrium Watchmon Plus OR Tenergy 5-in-1 Battery Meter

[lance]

First of all: I've very little but, not zero, knowledge of things electrical. I'm in the early stages of designing my Sprinter build and am working on the electrical designs now; initially just trying to get a list of all needed components. I feel I've got a pretty good handle on that so far using Will's videos and also The Mortons. The Mortons reference these two BMS units but, the Watchmon Plus is not available at the time his video was made. It is available now for about $800.... The Tenergy unit is about $15. SO: I'm willing to spend money to do this right and well but, I wanted to see if anyone with more knowledge had a sense for the advantages gained by spending for the Watchmon. My sense of it is that the Tenergy essentially does the same thing but, has to be done manually, and it takes much longer to balance the cells. The advantage of the Watchmon is that the battery's health is better maintained with continuous balancing and that the Watchmon is capable of doing it much faster. Do I have this approximately right? Does anyone have any input they're willing to share? Thank you! Oh... the system I'm aiming for is 24v with a single Tesla 5.2kw battery, solar charging and probably shore power but, not alternator charging.

 

[snoobler]

Welcome to the forum.

One is a BMS that protects the cells from damage. The other lets you watch it happen.

There are dozens of options with price points in between. How much current do you need?

 

[Rocketman]

If you are looking at Batrium- check out the leafmon. I believe that unit is designed for leaf batteries and Tesla batteries.

I choose the Batrium watchmon4 + expansion board. I will be getting 8 of the listen 271ah cells (when my boat comes in). Set up as a single 2p4s 12v battery.

The Batrium makes it easy to start fans and heaters automatically ( and lots of other stuff). For me it will connect to my Victron CCGX with the Can-Bus. This will (I believe) allow better charging of the batteries.

This is my plan. As the batteries get full the charge current will drop way down - for balancing. Then it will shut off. Power will be used until the batteries drop down a ways - then the solar can start back up. This (to me) seems the best.
The other reason I choose Batrium is because I will have access to the full amperage of the battery pack to boost my chassis battery in my MotorHome (for starting a diesel motor).
For me Batrium fit what needed to be done, For others, it would just be an expensive bms that doesn’t fit their needs. Find the unit that fits in your system needs the best.

 

[lance]

Welcome to the forum.

One is a BMS that protects the cells from damage. The other lets you watch it happen.

There are dozens of options with price points in between. How much current do you need?

Thank you. I'm pretty sure I'm going to go with door A, Bob. Let's go for protecting the cells from damage. ;-) Really? I'm reading that as the Tenergy as being essentially useless....

I've not done this Energy Audit yet but, I did do one with Nate over at Explorist.life and, I believe this is the figure you're looking for when you ask how much current I need, I come up with 189.14 amp hours/day needed, a recommended 400w of solar, and a 2000w inverter for my 110v needs. I am leaning towards going with a 3000w inverter to cover the possibility of my 110v needs increasing at some point.

 

[Rocketman]

I think what he was trying to say - is they both protect the cells - but you can watch the results and all that stuff with one. The other is just happening. (At least that's how I took it)

 

[snoobler]

I think what he was trying to say - is they both protect the cells - but you can watch the results and all that stuff with one. The other is just happening. (At least that's how I took it)

I wasn't saying that at all. The Tenergy is just a monitor. It takes no action should a cell voltage go out of limits, but it will show it happening if you happen to be looking.

Thank you. I'm pretty sure I'm going to go with door A, Bob. Let's go for protecting the cells from damage. ;-) Really? I'm reading that as the Tenergy as being essentially useless....

I've not done this Energy Audit yet but, I did do one with Nate over at Explorist.life and, I believe this is the figure you're looking for when you ask how much current I need, I come up with 189.14 amp hours/day needed, a recommended 400w of solar, and a 2000w inverter for my 110v needs. I am leaning towards going with a 3000w inverter to cover the possibility of my 110v needs increasing at some point.

Nope. I'm looking at your peak current, i.e., how many amps are coming out of the battery at once. 3000W/24V = 125A assuming you actually use the 3000W simultaneously.

Rather than a Tesla module, which is "meh" at 6S (that chemistry is closer to 24V at 7S), you could buy 40% more storage for 20% less and reduce your fire risk to zero.

8X LFP cells for 24V at 7kWh will run you about $900 delivered (about 7-8 weeks) and another $120 for a 100A BMS with cell monitoring via bluetooth, balancing voltage protection and temperature protection. 100A may be a little light, but since it almost sounds like 2000W would do it, maybe it will work for you.

 

[lance]

Got it, regarding Tenergy. Somehow my memory had picked up and stored from the Morton's video that it had the capacity to balance the cells as well.

I believe it is safe to say that that 125A draw you deduce would be the max I'd ever hit. That would require the oven, H20 heater and pump, iMac and Nutribullet to all be running simultaneously and even then not hit that mark.

Searching "6S" and "7S" on the site I'm seeing the terms used regularly but, have not a clue as to what they reference.

I believe it is safe to say that the primary thing that draws me to the Tesla is the compactness of the unit. My understanding is that it packs more power more cubic inch than any other battery out there. That said, the fire hazard and all the redundant devices needed to reduce the risk of that fire hazard are intimidating.

Can you tell me if something along these lines is what you're recommending? And, 8 of these 3.2v units to achieve 24v? I'm not necessarily suggesting this exact unit (I'm doubting I'd be buying from Alibaba) but, something along these lines. Just trying to gauge the dimensions of my finished product taking the route you're suggesting. (https://www.alibaba.com/product-detail/lifepo4-battery-cell-for-RV-Solar_62500104295.html)

Thank you.

 

[snoobler]

It does, but at a very low rate. Properly configured low current balancing is typically enough to keep already balanced cells in balance, but the unit provides no protection at all. Someone on this board set their charger to Lithium on a Tesla module and destroyed it. Fortunately, there was no fire. Had he been running a BMS, no damage would have occurred, and he would have learned a valuable lesson without any pain.

6S, 7S = 6 and 7 cells in series. Tesla -type cells provide the best approximation of a 24V system at 7S. LFP cells need 8S due to their lower operating voltage.

For some reason, I can't access that site at the moment. What I'm recommending are the Eve or Lishen 280Ah 3.2V cells. 8 of them in series (8S). There are trusted sources on this forum. If you go to Resources at the top of the page, there are data sheets for both of these cells that include dimensions.

 

[lance]

It does, but at a very low rate. Properly configured low current balancing is typically enough to keep already balanced cells in balance, but the unit provides no protection at all. Someone on this board set their charger to Lithium on a Tesla module and destroyed it. Fortunately, there was no fire. Had he been running a BMS, no damage would have occurred, and he would have learned a valuable lesson without any pain.

6S, 7S = 6 and 7 cells in series. Tesla -type cells provide the best approximation of a 24V system at 7S. LFP cells need 8S due to their lower operating voltage.

For some reason, I can't access that site at the moment. What I'm recommending are the Eve or Lishen 280Ah 3.2V cells. 8 of them in series (8S). There are trusted sources on this forum. If you go to Resources at the top of the page, there are data sheets for both of these cells that include dimensions.

<sigh> I think I'm starting to let go my OCD with the Tesla. I don't like the weight gain, I don't like the size gain. I love the fire risk reduction/elimination. I like the $$ savings. I like, what I'm thinking will be a slight simplification of the components needed. I like the added capacity. It looks like, without a major redesign, I can fit these 8 modules into my current allotted space for the electrical cabinet. I will do some more in-depth reading and exploring on this board on this topic and come back with my next round of questions once I've exhausted my comprehension of what I'm reading here. Thank you snoobler.... hugely appreciated.

 

[lance]

It does, but at a very low rate. Properly configured low current balancing is typically enough to keep already balanced cells in balance, but the unit provides no protection at all. Someone on this board set their charger to Lithium on a Tesla module and destroyed it. Fortunately, there was no fire. Had he been running a BMS, no damage would have occurred, and he would have learned a valuable lesson without any pain.

6S, 7S = 6 and 7 cells in series. Tesla -type cells provide the best approximation of a 24V system at 7S. LFP cells need 8S due to their lower operating voltage.

For some reason, I can't access that site at the moment. What I'm recommending are the Eve or Lishen 280Ah 3.2V cells. 8 of them in series (8S). There are trusted sources on this forum. If you go to Resources at the top of the page, there are data sheets for both of these cells that include dimensions.

Hey.... are either or both of these the Eve cells you are recommending?

Alibaba.com

www.alibaba.com

3.2V280ah LiFePO4 Battery 4S/12V Pack FOR Solar Energy Storage Inverter EV Marine RV Golf US/EU TAX

3.2V280ah LiFePO4 Battery 4S/12V Pack FOR Solar Energy Storage Inverter EV Marine RV Golf US/EU TAX

senbry.com

 

[snoobler]

They are that type, but not that supplier.