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Upgrading to Lithium iron phosphate Battery that new M3 is using?
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07-20-2020, 01:46 PM | #23 |
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jeeze, 30ah? Seems really small. I just swapped in the old battery from our X5, which i think is 100ah, because my 330i couldn't run the radio for more than a couple minutes with the engine off anymore - and the fan was starting to run crazy at low speeds due to lack of power. I knew the battery was on it's way out for a while (measures consistently under 12v) but the fan not running properly was the last straw, especially when I want the AC to be functioning.
But damn, is it heavy. The hardest part of swapping it was muscling it in place without damaging anything. |
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07-20-2020, 05:57 PM | #24 | |
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“ Models Available in 24Ah, 30Ah, 40Ah, 60Ah but Cranking Performance better than a 90Ah Lead Battery” I would say this is true. My car has never cranked as hard as it does now and I had a new diehard gold 60a/h AGM as my last battery before I started playing with lightweight batteries. Also using the battery monitoring software included with the battery the longest my car has sat since install was 5 days and it didn’t drop below 99% charged during that time. That’s with comfort access and the oem alarm activated too.
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07-20-2020, 07:15 PM | #25 | |
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07-20-2020, 07:30 PM | #26 |
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It’s pricey but they claim it will last 10 years so I figured that eases some of the pain. Outside of the price I can’t see any reason you would not be as thrilled as you can be... with a car battery... lol
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07-21-2020, 04:35 AM | #27 |
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The Ah rating for LifePo4 is different to lead acid. I think lithium can discharge lower than lead acid before engine will not start.
I've got a lithium 12.8v battery with 42ah and supplies 900cca. You notice the engine kicking over faster with the lithium battery. Best to find out what cells are being used in the battery you are buying. https://www.aliexpress.com/item/3300...37254c4dEZQcjD This battery uses A123 system cells. AHP14M1Ultra-A 14ah cells in 4S3P configuration. Note battery listed is not 60ah for $1000. China likes to make up there own specs and unrealistic pricing. I paid $440 AUD for battery with 10a matching charger. And be careful if you overcharge battery in car, over voltage protect will kick in and disconnect battery from car while it is still running. |
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07-21-2020, 04:52 AM | #28 | |
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05-20-2021, 09:12 AM | #29 | |
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This.
My experience parallels yours. I don't know how to measure perceived cranking power, but the Li battery does seem to crank with more authority than traditional lead acid technology. Quote:
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05-25-2021, 11:21 AM | #30 |
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Can you explain what you mean by this?
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05-25-2021, 02:11 PM | #31 |
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If the car ever won’t start there’s a button you can hit on a wireless remote (there’s also a button on the battery itself) and it will give you enough juice for one start.
I have had the battery for a year now and never needed to use this feature but it’s nice to know it’s there. So in theory if your car ever didn’t crank because you left something on and the battery was dead, you would just hit a button on the remote right from the drivers seat and it would start.
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05-25-2021, 03:30 PM | #32 | |
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05-25-2021, 04:39 PM | #33 | ||
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Once the battery drops below a set voltage threshold the BMS will disconnect the battery from any loads. Usually the set point is something like 10 volts or about 99 percent depleted. At some voltage below this the battery becomes unstable and "bad" things can happen. The industry likes to phrase these things as "thermal events". The BMS system also manages the recharge cycles insuring that each bank of cells is recharged evenly. Uneven charge levels will dramatically shorten the life of the battery. I like the idea of a higher cut off voltage and the ability to press a button to pull up reserve capacity but in-practice it scares me. A reasonable cut off voltage would be closer to 12 volts or higher and I sure to hell don't won't my battery cutting off at a traffic light and night on a raining day. I've done a lot of research on these batteries and we've started using a 100 amp product as standard equipment so I'm spending an easy 500k a year on them. So far they are great the ability to absorb current and quickly supply heavy loads is phenomenal. Sorry these are heavy duty and not available for resale. Beware, there are lots of cheap Li batteries on the market with poorly designed or even no BMS system at all. Another important topic never discussed at the auto parts store is cell balancing, when building a Li battery all of the individual cells must be matched with cells with similar storage capacity. This is quality control during the assembly stage. |
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05-25-2021, 05:11 PM | #34 | |
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Thanks for the information on the BMS. Maybe it is a breaker with a shunt trip and you press the button it just reconnects the battery to the entire system, all loads. I really doubt it is at 99% depletion for what it is worth. I work with Lion batteries for grid storage and in most use cases you never go below 20% of the nameplate or the warranty is instantly voided. Then again maybe they don't care much about the life of the battery?
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05-25-2021, 07:06 PM | #35 | ||
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I think you will find most of the BMS systems are using MOSFET for power control. MOSFETS are expensive and known to generate heat with large currents and this is why some of the cheaper batteries don't have them. Imagine the heat build up when you over crank a difficult motor. Years ago there were a few brands that used relays to control the current but not many of those left. Good riddance. Most BMS systems seem to cut out around 9 volts. With Li chemistry there is very little storage capacity left at that point. |
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06-06-2021, 02:15 AM | #36 |
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hi all,
accidentially saw that my post few years ago appears, and a lot of new information is generated in this thread. for my journey with the LiFePo4 the battery i installed few years ago, and after 3 years with around 60,000km of running, it's still start and cranks the car fine. and around few months ago, when I am driving back home, and battery red light shows up. after checking, my 4 years old brandnew OEM valeo alternator is toasted, and afterward, it's discovered that it's the pulley goes bad, instead of the regulator, so i replaced the pulley and it's running fine since. but with this incident, i discover 1 issue that makes my battery goes weak even after alternator is replaced. i am just guessing with my personal understanding on bmw dme logic: - for the bmw to report the bad alternator, the charging voltage has to be lower 13V over few minutes? - and for the LiFePo4 battery range 12.8V - 13.2V, so it is running at around 12.8 to 12.9V battery power. - and then it just drain most of the battery, before we receive the warning. and after that incident, my battery isn't cranking as strong as before, even i tried to fully charged it, i didn't do in-depth voltage drop test. so it's a points to note for all people enjoying the battery. another sign that recently happens(probably one month ago) to my car, the idle rpm is not stable around 660, but 80% of time is now at around 800rpm, even with AC off, i saw some documentation says there some logic in the MSV70, that detects if the battery is starting weak, and it will automatically increase idle rpm, so i believe my 3 years old 60AH battery is probably getting old and start losing AH capacity. another case I encountered during this 3 years, is I also recommended one of my friend driving mercedes w204, while the battery is installed in the engine bay area, that battery dies within half year, so definitely no good to install this kind of battery in engine bay area. |
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06-06-2021, 02:13 PM | #37 |
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This post really lacks specifics. Battery type, current charge voltages, float voltages etc.
No good Li battery will be damaged with voltages below 12.5 volts. They will go far lower then that without any damage. However, if you battery does not have an internal BMS system and was allowed to go below 4 volts, you could have seriously damaged the cells. Charge it and check the residual voltage, If it does not hold 13 volts, get rid of it. There are just so many types of Li batteries available and so many rebranded products it's very difficult to know the quality of the product you purchased. As a guide you are not going to find a well built 50 amp Li battery for less than $500 retail. The 100 amp hour units we use are $1,200 retail and they are not the "best" available. High engine idle can be caused by things other than low battery voltage and low battery voltage is not always a battery fault. Li batteries are sensitive to temperate extremes heat or cold, Limits are specified by the manufacturer. If you had one die within a year, get it replaced under warranty. Quality brands will carry multi year warranties. We negotiated 5 year 100% replacement |
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