Lthium charged with mppt controler

mena661 wrote:

Gdetrailer wrote:

Run without this protection and the result is nothing short of a spectacular 2300F degree fire..

Unless you really have top notch understanding of all the charge/discharge parameters of Lithium batteries it is best to leave them in profession hands..

Perhaps another 10 or 15 yrs they will find better ways to deal with the potential hazards but not as of yet..

your batteries BMS system would have to fail at the same time to allow this to happen.

That IS why the battery cells MUST HAVE A BATTERY MANAGEMENT SYSTEM.

The reason EV folks did not experience any "fires" was for the fact that EACH INDIVIDUAL Lithium cell HAS a BMS CHIP BUILT INTO IT. The built in BMS chip monitors the cells temp, voltage and how much current is being drawn or put back in.. That chip will disconnect the cell if it detects anything out of the design parameters.

The only way around getting cells without a BMS chip is if you yourself find a manufacturer which you could sweet talk them into selling you RAW CELLS.. and that is not going to happen.

BMS chips are not fool proof and they DO FAIL, typically they fail in the disconnect mode but they CAN fail and not disconnect..

A company I worked for had several cases in which a product we sold HAD several documented cases of the LI battery bursting after being freshly charged in the proper charger causing burns to hands and even one that caught fire in a pocket.. We didn't manufacture the product, we bought it prebuilt from another well known company and added our software package to it.. then resold it with our software package.. My company discontinued that product shortly after that..

Back a few years ago there was a spectacular recall for MANY laptop brands which used a certain manufacturer for their LI batteries.. The reason.. A manufacturing defect which allowed impurities to create a electrically conductive "whisker" which would short out the affected cell causing the batteries to overheat or even start a fire..

Don't hand me any BS that a different LI based battery is "better" for safety than others.. They can and do fail and due to the shear energy storage in that little package even an accidental short by a person can trigger an event which just may not be a good thing..

While the iron phosphate are more stable it doesn't mean they are totally safe either.

Gde, seems we are mostly in agreement. There is no BS here. Not sure why you don't understand that a different chemistry can have different characteristics. LiFePo4 is an order of magnitude safer than LiCo. That's just a fact. If you choose not to accept it, that doesn't make the battery any less safe.

The reason EV folks did not experience any "fires" was for the fact that EACH INDIVIDUAL Lithium cell HAS a BMS CHIP BUILT INTO IT.

Incorrect! Didn't see this before. The EV guys build their own battery packs (hence DIY EV). They take the raw cells, strap them together, and connect a BMS of their choice. Some don't even use BMS's. Those tests were done without BMS's connected. They didn't catch fire (so scary that fire word) because they're simply not as energy dense as LiCo.