Request - Disable / Reconfigure BMS

[Phimosis]

Have you considered running a big cap at the amp? I've never done that but you could explore if they really work.

They do really work. It might even solve his problem. I had a system that would make the headlights dim on each bass beat. So what that means is that the entire car’s electrical system was dropping from 13.5 to 11 volts or so on each bass beat. And when voltage drops by 20%, that means that current goes up by 20%, which can be the source of blown fuses when the volume is cranked up. I put a 6 farad capacitor on it and the dimming headlights issue went away. The capacitor will keep the voltage supplied to the amp steady at 13.5v, even when the amplifier is asking for 500 amperes on bass beats.

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[tysonbisme]

Quick follow up for any whom are interested -

Removing the BMS sensor (current shunt + wire) altogether and replacing for a solid 2 AWG copper ground has resulted in a stable 13.8-14.0v (when I measured) at all times. The only message on the dash is to "Service Charging System Soon" at startup, but no battery light.

To answer a couple things here, yes - ultracaps work. I used a SB630 XS Power unit on about 2.5k RMS clamped & a 180a alt, never dropped below 13.8 on a car that charged @ 14.4v. There are no other ways to bump up our charging voltage and make it consistent (as far as I tested) without removing BMS altogether. Past this, we'd need some sort of redone HO alternator with a different regulator to adjust voltage past the 14.0v range.

I'm planning to add a jp630 bank when they go on sale for $2-300 again

 

[colinl]

Quick follow up for any whom are interested -

Removing the BMS sensor (current shunt + wire) altogether and replacing for a solid 2 AWG copper ground has resulted in a stable 13.8-14.0v (when I measured) at all times. The only message on the dash is to "Service Charging System Soon" at startup, but no battery light.

To answer a couple things here, yes - ultracaps work. I used a SB630 XS Power unit on about 2.5k RMS clamped & a 180a alt, never dropped below 13.8 on a car that charged @ 14.4v. There are no other ways to bump up our charging voltage and make it consistent (as far as I tested) without removing BMS altogether. Past this, we'd need some sort of redone HO alternator with a different regulator to adjust voltage past the 14.0v range.

I'm planning to add a jp630 bank when they go on sale for $2-300 again

I'm quite curious to know how your battery lasts because I believe the Battery Monitoring System is integral to the alternator charging.

I could easily see it over or under charging without the BMS Sensor. But I don't know, and you'll find out the coming weeks and months, I suspect.

 

[Bill Quattlebaum]

I like the idea of leaving the BMS unplugged. That means no stop/start function, also. Will that hurt the battery in the long run?

 

[tysonbisme]

@colinl & @Bill Quattlebaum

I've had an autostop eliminator installed since I purchased the truck. I suppose I can sell it if it doesn't function without the BMS, lol

It's been probably 3 weeks now with no ill effects. I imagine the battery here will last longer than one using the stock charging logic. Undercharging causes deep sleep and other lifespan / operational issues, and overcharging marginally reduces lifespan in AGM batteries. AGM are very receptive to higher charging voltages (13.5v minimum charging voltage is recommended, 14.8v max).

FWIW, the BMS sensor (factory) setup charges between 12.5 and 15.1v, both of which are respectively too low and too high. Without the BMS sensor, the alternator is "always charging", and the PCM does the voltage control at that point, hence the stable 13.8-14.0(ish)v.

Both the battery and the alternator should / will have a reduced life, but that is the price you have to pay when you want to shake down the block. You should expect to spend money on batteries and charging systems more often with a larger (>500W) audio system installed.

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