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pianotuna

Regina, SK, Canada

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Posted: 12/01/22 12:07pm Link  |  Quote  |  Print  |  Notify Moderator

S Davis wrote:

I only plan on 350 amps max so two 250amp BMS should cover it.


Yes dual 250'tis will be fine.


Regards, Don
My ride is a 28 foot Class C, 256 watts solar, 556 amp-hours of Telcom jars, 3000 watt Magnum hybrid inverter, Sola Basic Autoformer, Microair Easy Start.

time2roll

Southern California

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Posted: 12/01/22 01:36pm Link  |  Quote  |  Print  |  Notify Moderator

pianotuna wrote:

The "cold" end is the dangerous part. Charge below that, and the batteries become expensive door stops.
Or the BMS stops the charging at low temperature and protects the battery until it can be determined why the heating system has failed.


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pianotuna

Regina, SK, Canada

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Posted: 12/01/22 08:50pm Link  |  Quote  |  Print  |  Notify Moderator

time2roll wrote:

pianotuna wrote:

The "cold" end is the dangerous part. Charge below that, and the batteries become expensive door stops.
Or the BMS stops the charging at low temperature and protects the battery until it can be determined why the heating system has failed.


You left out part of what I said which was there is no need to have heaters cut in at 50 f.

time2roll

Southern California

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Posted: 12/01/22 09:37pm Link  |  Quote  |  Print  |  Notify Moderator

pianotuna wrote:

time2roll wrote:

pianotuna wrote:

The "cold" end is the dangerous part. Charge below that, and the batteries become expensive door stops.
Or the BMS stops the charging at low temperature and protects the battery until it can be determined why the heating system has failed.
You left out part of what I said which was there is no need to have heaters cut in at 50 f.
There was no reason to talk about cold damage at 50f and above and yet there it just fell out.

May as well talk about 150mph speed rated tires for an RV.

wa8yxm

Davison Michigan (East of Flint)

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Posted: 12/02/22 04:28am Link  |  Quote  |  Print  |  Notify Moderator

pianotuna wrote:

time2roll wrote:

pianotuna wrote:

The "cold" end is the dangerous part. Charge below that, and the batteries become expensive door stops.
Or the BMS stops the charging at low temperature and protects the battery until it can be determined why the heating system has failed.


You left out part of what I said which was there is no need to have heaters cut in at 50 f.


Warning.. there is a video where an engineer (We like to take things apart as well as build 'em) took apart a LiFePO4 battery.. Down to the cells (He did not take them apart)

The battery clearly claimed to have both low and high temp sensors and protection (High temp is to prevent thermal runaway and fires.. Rare with LiFePO4, common in some other LiOn types)

IT did have a high temp sensor.. But no low temp at all. He tested.
So just because it says it's low temp protected... Does not mean it is.


Home was where I park it. but alas the.
2005 Damon Intruder 377 Alas declared a total loss
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Kenwood TS-2000, ICOM ID-5100, ID-51A+2, ID-880 REF030C most times


StirCrazy

Kamloops, BC, Canada

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Posted: 12/02/22 06:23am Link  |  Quote  |  Print  |  Notify Moderator

wa8yxm wrote:

pianotuna wrote:

time2roll wrote:

pianotuna wrote:

The "cold" end is the dangerous part. Charge below that, and the batteries become expensive door stops.
Or the BMS stops the charging at low temperature and protects the battery until it can be determined why the heating system has failed.


You left out part of what I said which was there is no need to have heaters cut in at 50 f.


Warning.. there is a video where an engineer (We like to take things apart as well as build 'em) took apart a LiFePO4 battery.. Down to the cells (He did not take them apart)

The battery clearly claimed to have both low and high temp sensors and protection (High temp is to prevent thermal runaway and fires.. Rare with LiFePO4, common in some other LiOn types)

IT did have a high temp sensor.. But no low temp at all. He tested.
So just because it says it's low temp protected... Does not mean it is.


that was a store bought boxed one and what that engineer may have missed is that one temp probe can be used for both high and low limits.. when you build them yourself you know exactly what they have in them. high temp is mainly to prevent charging when the battery is to warm, not for thermal runnaway, as LifePO4 is highly resistant to that. in fact if you have ever seen the vido of what it takes to get a LiFePO4 to actualy catch fire, its pretty amazing..


2014 F350 6.7 Platinum
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Tom_M

New Hope, MN

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Posted: 12/02/22 08:04am Link  |  Quote  |  Print  |  Notify Moderator

The best YouTube source is Will Prowse. He tears apart lots of batteries. Some of the cheaper LiFePo4 batteries have no low temp sensor. He checks this by dipping the sensor in ice water.


Tom
2005 Born Free 24RB
170ah Renogy LiFePo4 drop-in battery 400 watts solar
Towing 2016 Mini Cooper convertible on tow dolly
Minneapolis, MN


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