Recent content by Aerowhatt

Simply put on a ping BMS the whole battery charges equally until the highest cell reaches a voltage set point where a resistor is switched across that high cell to burn off some of the charging current to just that cell. Since the charger charges faster than the resistor burns off the power, the...

I guess it all depends on what your needs and abilities are. I think at best one should actually have experience with something before trashing it. Two of the ping packs I have ride as a range extender on a bike which peaks out at 9,900 watts DC input. For less than double the price of the...

That's normal. The higher voltage is mostly surface charge so it has no depth to it. Probably 30 to 60 minutes at the 100ma discharge will bring them down pretty close to the others. You will know how close at the end of the following charge cycle of the whole battery. The other thing you can do...

Sounds like a waste of time repairing the BMS. Running the cells up to 73 amps and more with a short circuit, every cell is marginal if not toast at this point. That's why the BMS has current protection to start with. Other LiFePO4 batteries have come down some but are still harder to get what...

It sounds like the BMS and charger are both doing what they are supposed to. As you can imagine with the charger only connected to the cells by the BMS a few seconds every three minutes the effective charge rate on those low cells is in the neighborhood of .15 amps instead of 3 amps. It will...

It just sounds like inexperience talking to me. After thousands of EV miles it's versatility that one really ends up wanting/needing. Sizing and tailoring for a specific commute doesn't give versatility. "Can't take the bike today not enough range while pulling the trailer" . . . "Well probably...

It sounds to me like the BMS is kicking the charger out at too low of a voltage for the balancing circuits to be sending power to the resistors to be burned off on the high cells. Those two resistors on the high cells should be getting warm in just a few minutes after plugging the charger back...

It sounds like you were measuring the voltages right after disconnecting the charger, is that correct? If so then the voltages are low. I've got a similar ping on the bench which hasn't been topped up in a few weeks and it measures 40.4 Volts. Since you have the BMS uncovered one simple check...

That's a good point, calendar life is a significant consideration. Interestingly though the calender life has to be taken with the fine print. For the older LiPO it was said to loose 20% of capacity in 2 years. Well if you figured some head room on capacity initially that helps some. I'm in a...

I don't have it documented online. I'll list basics here and I can answer any other details you need. I also have some external photos I could send you. It’s an ugly little motorcycle but a great performer. Just like the plain girlfriend that treats you right. She gets better looking the...

This combination is just too far apart to make work without some serious intervention. Even if you raise the cell count on the NiMh to compensate for the high internal R you would need a step down converter to avoid overvolting the LiPO at the beginning of the discharge. Sometimes it's just too...

Yeah, making the main pack the low output pack is the opposite of the systems I have done. I've taken systems with enough power on tap already but insufficient range. Then added range with a different chemistry(bonus is you get more power too). To go the other direction and have a Ping as the...

You are correct that the booster pack provides more current if you increase the resistance on the capacity pack (we must also remember how small the change I recommended was). But that's only one aspect of the real world system performance. Urban Ev's spend significant time coasting and stopped...

You're still thinking one battery at a time. It's a system with two power sources. It really doesn't effect the booster pack capacity in practice. Unless of course you are doing nothing but flat out top speed run with no stops, or climbing a mountain pass. Most of the applications are for stop...

Just a note about resistance and paralleling two non matched batteries. If they are both conected to the load then having resistance in between one of them and the load isn't as bad as it seems. Intuatively adding resistance produces alot of heat and wastes power. This is very true in a single...