100AH Lithium cant handle start up draw

[67cj5]

Voltage "potential".

Those big chargers are pretty simple. When you switch the "amps" what you are actually doing is switching the voltage from a multi-tap transformer, and a current limit controlled by the circuit board.

Yeah when you first switch in on the Amps rocket up on the meter and then it creaps down fast for a few seconds and then as the Amps go down the volts go up to around 12.7 volts on the lowest setting once it gets gown to about 1 Amp where it disulphide the battery, On the highest setting it will go over 15 volts where you have to cut it back before damage occurs , even on the low 9 Amp setting it is still faster than my 26 Amp Noco Smart charger when charging one of my 115Ah DC batteries.. Regardless of the Amp setting As the Amp meter drops the volts go up, and the higher the Amp setting the higher the Volts go.

 

[dwh]

This is what Sean from BattleBorn said...

https://www.expeditionportal.com/fo...-d250s-b2b-charger.173120/page-2#post-2317523


So for BB at least, the BMS is restricting (limiting) current (for both charge and discharge), and also keeping an eye on temps.

 

[shade]

EV BMS systems usually communicate with the charger. This is to allow max safe charge rates. The BMS will throttle back the charger if there is an overheat, or balancing issue.

I should revise my previous post to include "for applications discussed here". As fully integrated EV and high power systems do use bi-directional communication between BMS and load/sources.

For applications discussed here that is not applicable, as we don't need to get 4 hours of driving from a 20 minute charge...

I was just curious if a manufacturer had gone as far as to have integrated a charger with the internal BMS for this application. I'm guessing there isn't an advantage as long as a good charger is used and the BMS is well designed. The cost involved would be prohibitive, too.

This is what Sean from BattleBorn said...

https://www.expeditionportal.com/fo...-d250s-b2b-charger.173120/page-2#post-2317523


So for BB at least, the BMS is restricting (limiting) current (for both charge and discharge), and also keeping an eye on temps.

Thanks for the link. Pretty nice of BB to speak to the internal operations instead of defaulting back to a spec sheet.

 

[dwh]

I was just curious if a manufacturer had gone as far as to have integrated a charger with the internal BMS for this application.

No real need with "drop-in replacement" types intended to replace regular 12v lead-acid.

But it wouldn't surprise me to see Victron "gettin' jiggy wid it" by sticking bluetooth in their batteries and tying them into the Victron net.

 

[shade]

No real need with "drop-in replacement" types intended to replace regular 12v lead-acid.

But it wouldn't surprise me to see Victron "gettin' jiggy wid it" by sticking bluetooth in their batteries and tying them into the Victron net.

If they can do it in a meaningful way and still keep competitive pricing, why not? Seems like something the marketing folks would love to club the competition with in every ad.

 

[john61ct]

Victron's LFP packaged systems do indeed of course plug in perfectly well with their ecosystem of monitors and displays.

Their comm protocols are pretty well open to integration with DIY systems.

 

[john61ct]

In normal daily cycling I would not allow any LFP bank to charge to over 13.8V (3.45Vpc).

If the BMS required higher than that for balancing, then I'd balance another way.

If that were not possible I would look elsewhere for my battery supply.

 

[luthj]

I am extremely dubious that BBs BMS has a way to regulate current flow. That would require either a resistive load, or some kind of PWM, both of which have serious problems. The only option the BMS has if there is an over-current condition is to disconnect the pack.

 

[dwh]

I am extremely dubious that BBs BMS has a way to regulate current flow. That would require either a resistive load, or some kind of PWM, both of which have serious problems. The only option the BMS has if there is an over-current condition is to disconnect the pack.

Which is exactly what Sean said it does in that post I linked to. Which is a limit. Or a restriction.

Unless we want to take this over to the ExPo semantics division for a ruling.

 

[dreadlocks]

Bodycam footage from the last ExPo Semantics Court ruling:

 

[luthj]

Lol. I would still argue any regulation that drops the whole pack out, is really an emergency brake...

 

[john61ct]

I am extremely dubious that BBs BMS has a way to regulate current flow. That would require either a resistive load, or some kind of PWM, both of which have serious problems. The only option the BMS has if there is an over-current condition is to disconnect the pack.

I agree, did someone express otherwise?

 

[john61ct]

Limiting current output is rare enough with charge source devices, e.g. alternator VRs.

I've had ACRs that do so, but roughly.

Building such into a battery's electronics is actually a very interesting idea.

Let the user go over, but start beeping, flash a red LED, and of course lets them know they're voiding their warranty.

 

[shade]

Lol. I would still argue any regulation that drops the whole pack out, is really an emergency brake...

Sort of like having a two-speed motor: on & off.

 

[shade]

Limiting current output is rare enough with charge source devices, e.g. alternator VRs.

I've had ACRs that do so, but roughly.

Building such into a battery's electronics is actually a very interesting idea.

Let the user go over, but start beeping, flash a red LED, and of course lets them know they're voiding their warranty.

With an on-board BMS already in place, I can see additional features being added, even if they're only passive or used for documentation. ABS has followed that path. Once the system was there, adding ABS derived stability & traction aids was a natural progression.