5 Battery Management - Porsche 356 Electric Conversion

Battery management issues with LiFePo4 batteries. Management/monitoring. Dangers of current shunt balancers. Digital monitoring in EMI harsh environment.

Category:

Autos & Vehicles

Tags:

• BMS
• Porsche
• battery
• management
• monitoring
• balancing

[lpgas1]

thankyou for the great videos! i am glad you treat them as batteries instead of just cells! a lead acid has 6 cells but because they are in one case we treat them as a unit. your doing the same with lithiums and i love the simplicity of it. i will be doing exactly what your doing in the 356 next time my lead acids die in my car! just one question mate...what sort of charger are you using? sorry i am slowy looking at your videos. you may have one on it already!

regards blair

[marionrickard]

We use a Brusa NLG-511 charger on the Speedster. It is quite programmable as to charge curves and voltages, which is the important part with these cells.

[resal3000]

hello Richard :) Nice video.Very Informative. But I must say, to be on the safe side, a non-microcontroller based LowVolt Cutout and a Chrg balancer is required on every cell.

From my experience, checking on the terminal gives absolutely no evidence of what is happening inside. At capacity difference of 10% with off-throw the batteries during charges and discharges.

I absolutely respect the fact that you mentioned we should buy extra batteries. And I realised that too from practical experience

[marionrickard]

Well, we've driven the car for a year without all that and it is working very nicely thank you. I know you guys think its needed, but I cannot match that with what I see and experience directly.

Jack Rickard

[erroneus]

Something that I have built, but haven't implemented yet is a low voltage indicator. This is more useful with lithium batteries, (i'm using lead acid). but it simply closes an isolated switch (optocoupler) when the voltage drops below a certain threshold. I am going to enable an LED to turn on at that point to show that there is one battery that is lower than the rest, thus catching a failure before anything gets destroyed. this analogue circuit is also immune to noise.

[marionrickard]

Not a bad idea all in all.

[maddexter]

Great project and nice car but is there a video of the car running?

[maddexter]

Is there a video of  the car running?

[resal3000]

I generally work with RC lithium batteries.

Each cells are 5Ah, and I am preparing a 100V 100Ah pack(26S20P). They are Turnigy cells from HobbyKing.

These cells are more sensitive to overcharging and discharging.. And its is more of a NECESSITy to monitor each cell voltages.

Right now I am working on designing a affordable active balancing system. It is going to be microcontroller based. Noise filtering Algorithms will also be put into action.

[7926645]

Very interesting, thank you.

[marionrickard]

You charge using a CONSTANT CURRENT source and the charger monitors the pack voltage. As it charges this voltage will rise. When it reaches 130 volts, it switches to a CONSTANT VOLTAGE source and holds that voltage there using whatever current is necessary. That current level will then gradually fall while holding 130v. As it decreases to below 2 amps, the charger shuts off.