Search found 2716 matches

by weber
Mon, 03 Feb 2020, 12:16
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 441
Views: 69206

Re: Low cost BMS

T1 Terry , It's possible that some old models of the EV Power CMUs started bypassing at a higher voltage, but the present-day specification clearly states that it starts bypassing at 3.5 V. But I agree that the present-day EV Power spec of not turning on the alarm until 4.0 V leaves much to be desi...
by weber
Sat, 01 Feb 2020, 14:04
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 441
Views: 69206

Re: Low cost BMS

T1 Terry , Why are you wasting your time telling us not to do things that no one in this thread is proposing to do? No one in this thread is proposing to bypass LFP cells at a voltage above 3.6 V. And no one in this thread is proposing to use the cell as a heatsink for the bypass resistors. I'll be...
by weber
Sat, 01 Feb 2020, 12:59
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 441
Views: 69206

Re: Low cost BMS

T1 Terry You still haven't told me what to do voltage-wise, to demonstrate internal heating of a cell at minimal current. I note that I am not willing to hold any LFP cell at a voltage of more than 3.65 V, because I know this will accelerate the rate of loss of capacity. Our LyteFyba BMS will not a...
by weber
Fri, 31 Jan 2020, 07:37
Forum: Renewable Energy and Storage (Non-EV)
Topic: PIP-4048MS and PIP-5048MS inverters
Replies: 2697
Views: 631722

Re: PIP-4048MS and PIP-5048MS inverters

mojo Please post photos of the labels on the sides of the two inverters. Block out the rightmost 6 digits of the serial numbers if you wish. What is the maximum value of setting 26 (when setting 5 is USE) on each inverter? If one is 58.4 and the other is 64.0, then you will not be able to parallel ...
by weber
Thu, 30 Jan 2020, 15:13
Forum: Renewable Energy and Storage (Non-EV)
Topic: PIP inverter repairs and hardware modifications
Replies: 485
Views: 55469

Re: PIP inverter repairs and hardware modifications

Roman khan Good photos. The capacitors for the battery-voltage DC bus are certainly not where I expected them to be. Can you post a photo of the tracks on the underside of the board. And also post the text on the 35 V 1000 µF capacitors. It's likely that all six of these 35 V caps are across the ba...
by weber
Thu, 30 Jan 2020, 14:54
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 441
Views: 69206

Re: Low cost BMS

Terry, You sound like you're making excuses as to why you haven't done this experiment yourself. ;) I note that your proposed cell opening, to insert a temperature sensor, would not only require a low temperature, but also zero humidity and no oxygen, if you don't want to damage the cell. But measur...
by weber
Thu, 30 Jan 2020, 14:21
Forum: Batteries, charging, management and monitoring
Topic: Weber & Coulomb's LyteFyba BMS
Replies: 72
Views: 34572

Re: Weber & Coulomb's LyteFyba BMS

Would these use optic fibre links or wire links? They can use either optic fibre or wire links. They can also use line-of-sight free-space infrared comms (like a TV remote control, but deliberately reduced in power to work only over typical inter-cell distances). Since the fibre and IR require addi...
by weber
Thu, 30 Jan 2020, 13:19
Forum: General EV Discussion
Topic: How to tell a kilowatt hour from a kelvin week henry
Replies: 34
Views: 4412

Re: How to tell a kilowatt hour from a kelvin week henry

Here's another fine point of symbol usage that relates specifically to batteries. The relative rate of charge or discharge of a battery is often described as a multiple of its capacity, by using the letter "C". For example a "2C" charge or discharge of a battery with a capacity of 100 amp hours, cor...
by weber
Thu, 30 Jan 2020, 08:29
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 441
Views: 69206

Re: Low cost BMS

Terry, I'd be happy to test your theory, that voltage, without current, can cause internal heating of an LFP cell. Can you describe a simple experiment I can do, involving say a single (possibly sacrificial) cell, a thermometer, some thermal insulation, a power supply and some multimeters? What volt...
by weber
Thu, 30 Jan 2020, 07:06
Forum: Renewable Energy and Storage (Non-EV)
Topic: PIP-4048MS and PIP-5048MS inverters
Replies: 2697
Views: 631722

Re: PIP-4048MS and PIP-5048MS inverters

The website https://solarmonitor.enapter.com/ describes a DIN-rail mounted device, currently available for pre-order at €70, that connects to a PIP serial port, and to Wi-Fi, and gives a dashboard over the net, as an alternative to Watchpower. No endorsement is implied.
by weber
Wed, 29 Jan 2020, 21:58
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 441
Views: 69206

Re: Low cost BMS

Ummm..... the whole purpose of a BMS is to extend the cycle life and retain usable capacity isn't it? No. That's only part of its purpose. Another part is to stop your house burning down. Another part is to extend the calendar life and retain low internal resistance. But a BMS can't control everyth...
by weber
Wed, 29 Jan 2020, 14:28
Forum: Renewable Energy and Storage (Non-EV)
Topic: PIP inverter repairs and hardware modifications
Replies: 485
Views: 55469

Re: PIP inverter repairs and hardware modifications

Yes i mean battery side mosfets,they works for some days and blowing up.i replace them with csd19505 and make all drivers and replace 4427 ic ,but the same result. Mosfet along with driver transistors and resistors blow up. You need to replace the DC bus capacitors that are associated with the MOSF...
by weber
Wed, 29 Jan 2020, 12:06
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 441
Views: 69206

Re: Low cost BMS

No Terry. Even if my batteries die tomorrow, it won't prove anything about our respective BMSs because there are way too many other variables. I never said there was anything harmful about having 5 amp balancing currents, or the idea of inductive charge shuffling. I just wanted to make sure that oth...
by weber
Wed, 29 Jan 2020, 11:24
Forum: Batteries, charging, management and monitoring
Topic: Weber & Coulomb's LyteFyba BMS
Replies: 72
Views: 34572

Re: Weber & Coulomb's LyteFyba BMS

LyteFyba can be modified to work with LTO cells without any artwork changes, only component and firmware changes. The 1N4004 reverse protection diode can be replaced with an ultra-low forward voltage Schottky (although this may only have 20 V to 60 V reverse withstand). The voltage regulator should ...
by weber
Wed, 29 Jan 2020, 11:05
Forum: Batteries, charging, management and monitoring
Topic: Weber & Coulomb's LyteFyba BMS
Replies: 72
Views: 34572

Re: Weber & Coulomb's LyteFyba BMS

Your use of a low cost optical fibre is interesting. Adds about $30 to total cost? no problem with that. What is the main incentive to use this, the high volt isolation - then noise immunity? You got it. High voltage isolation and noise immunity. The additional cost depends on how many fibre hops y...
by weber
Tue, 28 Jan 2020, 13:07
Forum: Batteries, charging, management and monitoring
Topic: Weber & Coulomb's LyteFyba BMS
Replies: 72
Views: 34572

Re: Weber & Coulomb's LyteFyba BMS

Are they going to have a second life as house bank? Yes. Regarding Brisbane weather and 5C discharge.    • What's you thoughts on battery cooling? Great idea. One theory says you can double the calendar life of pretty much any battery chemistry by lowering the temperature 10 °C. It's usually just t...
by weber
Tue, 28 Jan 2020, 12:30
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 441
Views: 69206

Re: Low cost BMS

The induction balancers we use switch off once the cells are within 10mV and don't switch back on until the differential is greater than 100mV. Ah yes. That was the other reason I told my customer/friend that these balancers are useless for LFP. One cell could be at 80% SoC and 3.33 V and its neigh...
by weber
Tue, 28 Jan 2020, 10:51
Forum: Batteries, charging, management and monitoring
Topic: Weber & Coulomb's LyteFyba BMS
Replies: 72
Views: 34572

Re: Weber & Coulomb's LyteFyba BMS

Very nice guys, how did you go the PCB material compressing and loosening connections? Not an issue? That's right. Not an issue. We're currently about half way through replacing all the cells in the MX-5 (but reusing the CMUs). The 218 cells have been bolted up for 7 years now, and travelled 23.5 M...
by weber
Mon, 27 Jan 2020, 18:48
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 441
Views: 69206

Re: Low cost BMS

Alternatively, the master can tell the CMUs what the average cell voltage is, and they can all bypass at that voltage, provided that voltage is above the rested 98% SoC value. Ah, now that is interesting. And something that I could implement... In my case the master tells each CMU when and how much...
by weber
Mon, 27 Jan 2020, 17:28
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 441
Views: 69206

Re: Low cost BMS

The cheap inductive balancers I saw, always worked over the whole voltage range. There was no way to tell them to only work above a certain voltage. If there was a sufficient voltage difference, they shuffled charge. But yes, if you were designing them into your own CMUs you could make them work for...
by weber
Mon, 27 Jan 2020, 13:04
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 441
Views: 69206

Re: Low cost BMS

Good point about these inductive charge-shuffling types of balancers, which seem to have become available recently at low cost. Somebody asked me about them recently. I pointed out that they would be worse than useless with LFP cells, for the reason you gave. But they might work OK with NMC cells (o...
by weber
Mon, 27 Jan 2020, 10:10
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 441
Views: 69206

Re: Low cost BMS

Coulomb and I have packets with CRCs in our system too -- containing various commands and their responses. But every module still forwards every byte the instant it receives it. So the latency is only ever one byte-time per module. When the packet is complete, if the CRC doesn't match, the packet is...
by weber
Sun, 26 Jan 2020, 14:31
Forum: Renewable Energy and Storage (Non-EV)
Topic: PIP-4048MS and PIP-5048MS inverters
Replies: 2697
Views: 631722

Re: PIP-4048MS and PIP-5048MS inverters

That's what we like to hear. :) Thanks @daimyo.
by weber
Sun, 26 Jan 2020, 14:29
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 441
Views: 69206

Re: Low cost BMS

Hi Andrew. What do you mean when you say Coulomb and I break it up into smaller groups? Our BMS is strictly daisy chain, like 4Springs'. The only reason we have two strings of 109 CMUs in the MX-5 is that we have a separate charger for each half-pack. We have a 15 Hz update rate. The rate is not aff...
by weber
Wed, 22 Jan 2020, 22:35
Forum: Renewable Energy and Storage (Non-EV)
Topic: Nickel Iron Batteries real data
Replies: 42
Views: 4436

Re: Nickel Iron Batteries real data

Yes, the iron and nickel hydroxides will turn to carbonates after they have been exposed to air for long enough, same as the potassium hydroxide.
2OH⁻ + CO₂ → CO₃⁻ + H₂O