Drop-in car battery DIY?

[Sean Very North]

A correctly configured Batrium does just what I said.
If you have a runner it will shut down the entire bank.
There is only 1 connection to a Shunt trip from the supervisor.

I don’t know where you’re buying your cells but all of them even from the same batch and manufacture have variances.

The only way you can “lower” the charge rate is to be able to talk to the inverter or CC.

Batrium doesn’t talk to Every AIO or CC.

@sunshine_eggo care to weigh in here.

I exclusively use Victron equipment, which communicates perfectly with Batrium/RECC, so changing the charge rate when a cell hits its target volts is simple, effective and proven to be entirely dependable for years. If the cell, for any number of reasons, rose or was reduced to a point deemed to be critical, you then have the option to cease charge or discharge, or failing that, fire the shunt trip.

The only cells we use are what seem to be known here as EV grade cells.

 

[Nobodybusiness]

I exclusively use Victron equipment, which communicates perfectly with Batrium/RECC, so changing the charge rate when a cell hits its target volts is simple, effective and proven to be entirely dependable for years. If the cell, for any number of reasons, rose or was reduced to a point deemed to be critical, you then have the option to cease charge or discharge, or failing that, fire the shunt trip.

The only cells we use are what seem to be known here as EV grade cells.

Well there ya go.
Not everyone uses Victron gear.

 

[Sean Very North]

Well there ya go.
Not everyone uses Victron gear.

Indeed, nor do many check to see if their BMS abc speaks the same language as their xyz AIO untill after they've purchased and proven they aren't compatible, usually through lengthy and costly experiments, and then moan that they aren't doing what they expect, and eventually conclude that they are better off with a BMS that simply decides to charge or discharge.

 

[Nobodybusiness]

Indeed, nor do many check to see if their BMS abc speaks the same language as their xyz AIO untill after they've purchased and proven they aren't compatible, usually through lengthy and costly experiments, and then moan that they aren't doing what they expect, and eventually conclude that they are better off with a BMS that simply decides to charge or discharge.

Granted there have been cases of that but Batriums lack of support and documentation lends itself to those kinds of mistakes.

If you buy a Batrium you better be prepared to figure it out in your own.

 

[Sean Very North]

Back in the early days, Batrium assumed that end users knew what they were doing, their lack of response wasn't a problem, just more of an annoyance, which is why we ended up not placing any sizable orders with them, but the systems we did buy have proven to be fine, but certainly not plug in, configure and walk away.

 

[TomC4306]

series FETS

HUH?
Parallel.
If you're trying to sound like a know-it-all at least try to know it all.

 

[Sean Very North]

HUH?
Parallel.
If you're trying to sound like a know-it-all at least try to know it all.

Fets in series with the current flow, it's multiples of parallel FETs that dictate the amount of current they'll pass.... if you're wanting to score cheap points then crack on there.

 

[TomC4306]

Fets in series with the current flow

Hmm. Interesting. I guess as opposed to perpendicular?
Cheap point? No.
I already know who you are.
That guy.

 

[Sean Very North]

Hmm. Interesting. I guess as opposed to perpendicular?
Cheap point? No.
I already know who you are.
That guy.

Great, I'm happy for you.

 

[sunshine_eggo]

A correctly configured Batrium does just what I said.
If you have a runner it will shut down the entire bank.
There is only 1 connection to a Shunt trip from the supervisor.

I don’t know where you’re buying your cells but all of them even from the same batch and manufacture have variances.

The only way you can “lower” the charge rate is to be able to talk to the inverter or CC.

Batrium doesn’t talk to Every AIO or CC.

@sunshine_eggo care to weigh in here.

Your description is correct. It effectively treats two batteries arranged in 16S2P as 2P16S.

BMS control of the system means there can be layers of response. A runner doesn't shut down the entire bank. It simply stops charging analogous to a BMS that prohibits charging without the actual cut-off. The charger never sees the load removed. It simply receives instructions to charge at 0A. Critical levels can be defined that do actually open a relay to cut off the battery entirely, but there is ample opportunity to avoid that.

With 0.5A of passive balancing, runners are rarely a problem.

I would also assert that the Batrium is a poor choice for LFP. It does not support float charging as a concept. One can overcome this, but it is a nuisance and requires iterative customization to find the right solution for the system.

@Sean Very North,

This debate is context specific - having been on this site for a bit, I would assert that 90%+ of users on this site use a FET based BMS with no inverter communication, 9 percent using AiO/Server Rack Battery communication and 1% or less use Batrium or REC; therefore, the default advise is to NEVER rely on the BMS for routine charge termination and treat it PURELY as a safety device.

The concept doesn't even apply to AiO/rack batteries, Batrium or REC as those BMS are actually in control of the hardware.

 

[Sean Very North]

....... and 1% or less use Batrium or REC; therefore, the default advise is to NEVER rely on the BMS for routine charge termination and treat it PURELY as a safety device.

The concept doesn't even apply to AiO/rack batteries, Batrium or REC as those BMS are actually in control of the hardware.

I'm not disagreeing, my opinion is that many folks aren't aware of what a quality BMS can provide in terms of control, data and stability, I disagree with the "default advice" but I'm long enough in the tooth to recognise that folks seem to enjoy doing what the off grid garage chap seems to do so I'm not intending pointing out the futility of playing lucky dip with random components.

 

[400bird]

This is just your opinion, I believe the opposite to be true, but I suppose it'll depend if you trust your BMS.

So here's the thing, it sounds like you are saying that using a communicating BMS to control the charger/inverter is your preference. (This is a fine strategy)

But, as already stated, most BMS's don't do that. So, everyone is hearing you recommend using a FET based BMS to control charge/discharge by opening the FETs to stop current flow. (This is a bad strategy)

I hope now you can see why you're getting the push back on your opinion.

 

[sunshine_eggo]

I'm not disagreeing, my opinion is that many folks aren't aware of what a quality BMS can provide in terms of control, data and stability, I disagree with the "default advice" but I'm long enough in the tooth to recognise that folks seem to enjoy doing what the off grid garage chap seems to do so I'm not intending pointing out the futility of playing lucky dip with random components.

Few are willing to spend more on the BMS than they are on the battery. Most pursuing DIY are cost driven.

Commercial batteries are sold with FET based BMSs. Would you encourage everyone who buys one to charge to 16V because the BMS will protect the cells at ~3.65, or would you encourage users to program their chargers in accordance with the manufacturer's specifications?

Answers are influenced by the audience asking the questions.

You're a Batrium/Victron Elitist... as am I. I think the difference is that I can read the room. You either can't or aren't willing to accept that there is more than one solution besides the one you have chosen.

 

[Sean Very North]

So here's the thing, it sounds like you are saying that using a communicating BMS to control the charger/inverter is your preference. (This is a fine strategy)

But, as already stated most BMS's don't do that, so everyone is hearing you recommend using the FET based BMS to control charge/discharge by opening the FETs to stop current flow. (This is a bad strategy)

I hope now you can see why you're getting the push back on your opinion.

You've either deliberately, or accidently misunderstood my opinion, I'm certainly not recommending a "BMS" that feature FETs passing the full battery current.

I'll acknowledge that the majority of folks here seem to prefer components, often called battery managements systems, that have an ability to pass current to/from a battery, and stop/start that flow if it detects a cell issue.

I believe they have been somewhat blinded, by the generally poor reliability, features and compatability of these cheap devices, to the advantages of a quality BMS, that has full control of the entire ESS, which is what the likes of a RECC or Batrium will do when combined with a Venus device, it just works.

 

[400bird]

You've either deliberately, or accidently misunderstood my opinion, I'm certainly not recommending a "BMS" that feature FETs passing the full battery current.

I'm pretty sure I understand.
You are staying this, right?

using a communicating BMS to control the charger/inverter is your preference. (This is a fine strategy)

If so, I agree and you are correct. (Assuming a quality BMS)

The rest of my post was just pointing out that is not what people are hearing.

 

[Sean Very North]

Few are willing to spend more on the BMS than they are on the battery. Most pursuing DIY are cost driven.

Commercial batteries are sold with FET based BMSs. Would you encourage everyone who buys one to charge to 16V because the BMS will protect the cells at ~3.65, or would you encourage users to program their chargers in accordance with the manufacturer's specifications?

Answers are influenced by the audience asking the questions.

You're a Batrium/Victron Elitist... as am I. I think the difference is that I can read the room. You either can't or aren't willing to accept that there is more than one solution besides the one you have chosen.

Nope, not a Batrium/Elitist at all, we've used a lot of quality equipment over the years, SMA, Schneider could equally have been added to a list of preferred manufacturers that are well proven.

 

[sunshine_eggo]

You've either deliberately, or accidently misunderstood my opinion, I'm certainly not recommending a "BMS" that feature FETs passing the full battery current.

I'll acknowledge that the majority of folks here seem to prefer components, often called battery managements systems, that have an ability to pass current to/from a battery, and stop/start that flow if it detects a cell issue.

I believe they have been somewhat blinded, by the generally poor reliability, features and compatability of these cheap devices, to the advantages of a quality BMS, that has full control of the entire ESS, which is what the likes of a RECC or Batrium will do when combined with a Venus device, it just works.

You'll find a few threads of Batrium users here who are dealing with serious issues, Core's locking up, needing to be rebooted, poor support outcomes, etc.

Batrium is a strong product, but IMHO, you're screwed if you need support. I've had two support issues. One I had to figure out for myself, and you should have as well as the Batrium instructions for Victron interface is absolutely incorrect. The second remains unresolved, admitted to be a firmware issue with zero commitment to fixing it on the WM5 and only tentative commitment to fix it on the Core product.

Nope, not a Batrium/Elitist at all, we've used a lot of quality equipment over the years, SMA, Schneider could equally have been added to a list of preferred manufacturers that are well proven.

Noted that you ignore relevant questions and only engage in using top tier hardware, spend far more than the vast majority, and have no reasonable perspective on helping those asking the questions. I'll re-label you as a top-tier elitist.

Read the room.

 

[Sean Very North]

The rest of my post was just pointing out that is not what people are hearing.

These days people "hear" whatever they want to "hear", what was actually said doesn't seem to matter.

 

[sunshine_eggo]

These days people "hear" whatever they want to "hear", what was actually said doesn't seem to matter.

You epitomize this behavior.

 

[Sean Very North]

..... that you ignore relevant questions and only engage in using top tier hardware, spend far more than the vast majority, and have no reasonable perspective on helping those asking the questions. I'll re-label you as a top-tier elitist.

Read the rooroom

As i've previously stated, in the early days the miniscule husband, wife and a couple of mates company that was Batrium was selling products designed for folks who know what they were doing, we didn't really need their help, but their general response, or lack of it, when we pointed out documentation and firmware errors, such as their Eltek implementation wasn't ideal, but given they were drowning in trying to support folks who very obviously expecting to string a few cells together, plug in the cheapest AIO and bingo instant ESS we didn't really mind as the instant response we got from RECC when asking for custom compatibility was perfect, which is why they got lots of business, but like an old car I'm quite happy with the Batrium systems still running.

I'm not sure that labelling me simply for buying quality equipment is of any value, buy cheap buy thrice ..... but I guess some folks don't value their time.