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opinion:frater_secessus:self-heated_lifepo4 [2023/09/03 16:07] frater_secessus [how to think about the decision] |
opinion:frater_secessus:self-heated_lifepo4 [2023/09/03 16:21] frater_secessus [perfect storm for self-heated batteries] |
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* self-heated: | * self-heated: | ||
* DIY: more control, more charging under certain conditions, usually cheaper | * DIY: more control, more charging under certain conditions, usually cheaper | ||
+ | * in practice, warming is combined with other forms of protection: | ||
+ | ===== how the approaches work ===== | ||
+ | **Self-heated batteries** | ||
+ | - sense ~freezing temps | ||
+ | - shut off charging((normal BMS shutoff)) | ||
+ | - allow incoming power only to the internal heaters, typically ~60w | ||
+ | - when cell temps are > | ||
+ | - optional: | ||
+ | |||
+ | This means //warming only happens when charging is present// | ||
+ | |||
+ | |||
+ | **DIY warming solutions** | ||
+ | |||
+ | - use an external temperature controller and temperature probe | ||
+ | - use the lowest-wattage warming mat practical for conditions((for gentlest, most-even heating)) | ||
+ | - and turn the mat on/off with the controller | ||
+ | |||
+ | This means //warming happens whether or not charging is present// | ||
+ | | ||
===== when it's a wash ===== | ===== when it's a wash ===== | ||
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With " | With " | ||
+ | In some specific use cases one approach might be better-suited than the other. | ||
+ | |||
+ | |||
+ | ===== when self-heated might be preferable ===== | ||
+ | |||
+ | When you want a packaged solution. | ||
+ | |||
+ | If you run your bank very low habitually((stop doing that!)) and the warming load is enough to trigger BMS discharge shutdown. | ||
+ | |||
+ | |||
+ | ===== when DIY warming might be preferable ===== | ||
+ | |||
+ | ==== robust charging ==== | ||
- | ===== perfect storm for self-heated batteries ===== | ||
With robust charging (alternator and/or bigger solar) there can be charging opportunities lost with self-heated batteries in freezing conditions. | With robust charging (alternator and/or bigger solar) there can be charging opportunities lost with self-heated batteries in freezing conditions. | ||
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If one was charging by alternator only and only driving to/from work while stealthing in freezing weather it's conceivable the self-heated batt would get *never get charged at all* because it wouldn' | If one was charging by alternator only and only driving to/from work while stealthing in freezing weather it's conceivable the self-heated batt would get *never get charged at all* because it wouldn' | ||
+ | ==== specific configurations ==== | ||
+ | |||
+ | You may want more control over the temperature setpoints. | ||
- | ===== perfect storm for DIY warming ===== | + | Note from Secessus: |
- | You run your bank very low habitually (don't do that) and the warming load is enough to trigger BMS discharge shutdown. | ||
===== how to think about the decision ===== | ===== how to think about the decision ===== |