100AH Lithium cant handle start up draw
- Thread starter RichieFromBoston
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shade
Well-known member
Wouldn't you rather use data coming directly from an internal BMS to derive your custom charge parameters? Seems like internally measured cell temps & voltages would be more accurate than external readings.
I do not know what an "internal BMS" would look like. Voltages measured right at or near the cell terminals is as good as it gets.
There are many ways to get per-cell voltage readings.
Any such circuitry needs to be easily removed, replaced, isolated from the cells as needed.
I have also never heard of cells with embedded temp sensors, but would be an interesting idea. In fact temperature measured between cells within a pack is really just as useful.
If your use of the bank is causing temperature issues, you're doing it wrong.
There are many ways to get per-cell voltage readings.
Any such circuitry needs to be easily removed, replaced, isolated from the cells as needed.
I have also never heard of cells with embedded temp sensors, but would be an interesting idea. In fact temperature measured between cells within a pack is really just as useful.
If your use of the bank is causing temperature issues, you're doing it wrong.
shade
Well-known member
By "internal BMS", I thought we were discussing the management systems built into LFP batteries, like Battle Born offers.
Frequently Asked Questions
In this section we've compiled facts, frequently asked questions and tutorials to help you answer any questions you may have about lithium-ion batteries.
battlebornbatteries.com
Anyone using both lead acid and lithium (battle born) through d250s b2b charger?
Hi everyone! Here is some info that is not in the marketing materials. The BMS is not bucking or doing any voltage regulation. It is simply monitoring the voltages, current and temperatures and acting as a high current switch, when things are out of whack. Charging and discharging circuits may...
www.expeditionportal.com
shade
Well-known member
To broaden my palate, what LFP battery in the 100Ah range would be suitable for you for use as a house battery in a camper?
shade
Well-known member
Do you own a system based on any of those, or do you just use them at work on your submarines and rockets?
Sorry, I thought you were sincerely asking my advice. I certainly answered sincerely.
I have never worked in submarines, but yes some aviation.
Most of the systems I've installed are on boats, but off-grid homes and liveaboard land vehicles as well.
I choose what details I want to share, usually as much as possible given the circumstances. If I remain silent on an issue it means I have nothing to contribute on that specific matter.
I've been revising my standard write-up for care factors designed for maximum longevity, will post in due course.
I realize there are those here with commercial interests to protect, but hope the intention of the forum management is to allow objective information and a wide range of opinions be presented to the membership as a whole.
I have never worked in submarines, but yes some aviation.
Most of the systems I've installed are on boats, but off-grid homes and liveaboard land vehicles as well.
I choose what details I want to share, usually as much as possible given the circumstances. If I remain silent on an issue it means I have nothing to contribute on that specific matter.
I've been revising my standard write-up for care factors designed for maximum longevity, will post in due course.
I realize there are those here with commercial interests to protect, but hope the intention of the forum management is to allow objective information and a wide range of opinions be presented to the membership as a whole.
shade
Well-known member
I appreciated your post in the spirit it was made. I really was curious about what's available. I was kidding about the submarine and rocket, but the sources you listed make that grade of products.
I've read enough of your posts to know you were going to point to the high end, and I'm completely ignorant about that space. If I go LFP, I'll end up somewhere in the middle of the quality/price spectrum. I doubt I can justify the cost of top tier gear, but I also don't want to buy no-name junk destined to burn my truck to the ground.
Since you mentioned Bruce Schwab, I'm also curious about Firefly carbon foam AGM batteries. One of those might be a good fit for me.
Firefly Oasis Battery - Carbon Foam AGM
The only Carbon-foam AGM battery is the Firefly Oasis Battery. Now available for marine applications, it is capable of deeper discharges and longer life
oceanplanetenergy.com
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luthj
Engineer In Residence
John61ct is using his previous standards. Personally I think they are much to stringent. We aren't working on deep water marine vessels or aircraft. We have a much higher tolerance for failures. He is also comparing early quasi experimental drop-ins (somewhat unfairly) to the newest crop of drop-ins.
While I agree that they are not perfect, the consistency of cylindrical cells has improved dramatically in the last 4 years, and electronics quality control scales with volume. While drop-ins are fully not mature, they are passing the early adopter stage, and moving towards mainstream in our applications.
While I agree that they are not perfect, the consistency of cylindrical cells has improved dramatically in the last 4 years, and electronics quality control scales with volume. While drop-ins are fully not mature, they are passing the early adopter stage, and moving towards mainstream in our applications.
Cylindricals are a whole 'nother category.
While widely used for eBikes and skateboards, I would not use those chemistries for DIY House banks inside a living space.
LFP in that format is hard to find at reasonable prices per kWh.
And per-cell monitoring gets unweildy when you are working with hundreds of them.
While widely used for eBikes and skateboards, I would not use those chemistries for DIY House banks inside a living space.
LFP in that format is hard to find at reasonable prices per kWh.
And per-cell monitoring gets unweildy when you are working with hundreds of them.
shade
Well-known member
The main failure that concerns me is something catastrophic, like a fire. From what I've seen, as long as a battery isn't sourced from a no-name supplier, that doesn't seem likely. Beyond that, I'm sure using the very best LFP batteries & chargers yields the highest performance and battery life, but I'm not sure the cost is worth those benefits for me.
I have installed many FF banks over the years, start a new threadFirefly carbon foam AGM batteries. One of those might be a good fit for me.
Firefly Oasis Battery - Carbon Foam AGM
The only Carbon-foam AGM battery is the Firefly Oasis Battery. Now available for marine applications, it is capable of deeper discharges and longer life