House and Engine Battery -Update 2-Surge? REGEN threat!

[BFL13]

Update 24 Oct, Update 2- 28 Oct

I have not worried before about alternator charging with House and Engine both being flooded or even when I had AGM House and flooded for the Engine.

That included while driving and also while parked where the Engine batt is connected to the House batts and both being floated. (Same with leaving both on the same solar)

However, I am getting an SiO2 battery for the House in the TC, and am nervous about having it in parallel with the very different type of battery for the engine (flooded).

I could disconnect the parallel connection and maintain the Engine battery separately while keeping the solar and House charger just for the House. That would mean no alternator charging even as an emergency method if the House battery got too low. (no gen with the TC)

What are folks with Li batteries (also very different from flooded) for the House doing in this regard? Thanks.

[BFL13]

Been a while, so reminder what that guy said:

"They sent a 60amp Lithium battery charger for generator/shore power and a Sterling power battery to battery DC charger for chassis battery/alternator charging while driving. It’s also a surge protector for overload surge back feed to alternator. Both designed for use with their battery. Put my trust in their knowledge and expertise and hoping for the best. So far so good ??"

It seems to be not just for ensuring the Li gets a good charge, but for if the regen high voltage spike triggers the BMS into shutting down the Li, making for a load dump on the alternator. Question is whether this would happen in a Class C with the House in parallel with the Engine Battery, or only with the House directly on the alternator, or not at all.

The DC-DC would be for all types of House battery including Li to get a good charge regardless of the alternator's voltage 12.x-15.x during regen or if the alternator voltage is always too high for the House battery.

(Si can stay undercharged too, but has no BMS. I chose to not have it in parallel with the Engine for other reasons, not to do with this regen voltage variation or whatever, so I do not have a stake in this aspect- If I had a new vehicle with regen and Li, I would be more than curious. )

[MEXICOWANDERER]

The OEM SYSTEM should work just fine unaltered. Breaking camp and starting with low Li. Charge at worst means arriving with less than full lithium batteries. Big deal charge them or have a power miser evening. The manufacturer of the gizmo harps about its importance but fails to reveal why. Lithium's strong point is it's ability to thrive at partial charge conditions. Charge them at the camp site. The gizmo is like wearing steel toed dress shoes just in case.

[BFL13]

time2roll wrote:
That alternator protection is pure snake oil. All voltage above 13 volts is created by the alternator. How on earth does this device protect the alternator from itself? Complete nonsense for an RV.

No clue except that Li load dumping which might not do that ?

I only posted about that device as a possible example of alternator protection; AFAIK BB did not sell one to the fellow with the C.

They did sell him the Sterling DC-DC. He posted something about it doing surge protection for the alternator (his post linked earlier from the C thread)

Sorry for the mix-up. It boils down to learning why BB said his C needed one with the BB house batts. He said he doesn't know and just trusts BB

Over here in Tech Issues, we want to know why about everything 🙂

So does everyone with Li House batts need one if there is alternator charging with his set-up? Why or why not? Only those with regen braking? Then must you do it via Ignition as mentioned in that blurb, or does that not apply to an RV but only to boats? If you don't use the Ignition method in the RV, then how can it do its job? ( Whatever its job is!)

[time2roll]

That alternator protection is pure snake oil. All voltage above 13 volts is created by the alternator. How on earth does this device protect the alternator from itself? Complete nonsense for an RV.

[BFL13]

Sterling says about their $89 Alternator Protection Device:

"If the spike is excessively rough, it can lead to APD damage (which can’t be fixed) but, your alternator / regulator has been protected."

(Link in earlier post)

Mex said:

"I read the description in the link and it gives zero justification as to why voltage would surge in an automotive circuit. Load dump occurs when a substantial load is utterly cut off. If the Gizmo is connected closer than the break in the load path, say goodbye to the gizmo."

I gather that substantial load being cut off is your Li BMS doing a shut off?

This all started when I read that guy's post in the Class C forum where Battleborn Li apparently convinced them they needed the Sterling DC-DC gizmo to go along with having Li house batts. and said it would protect against "surge" too. (The poster might have been confused a bit ?)

Several members of this forum have BB Li drop-ins, so I would think they would be curious about this. BB has a chat. (hint) Please post here anything you learn from BB that would add to understanding what this is all about. Thanks.

[NRALIFR]

BFL13 wrote:
So that one "turns on" with input above 13.2v, so it would not boost to 14.4 when the voltage is at 12.x if you used that Dc-Dc with regen braking? The Sterling one claims it will (I think)

Regenerative braking is a momentary rather than continuous condition. When it occurs, if the DC-DC charger is using the “standard” input triggers, and is already actively charging the aux battery, the “Input Loaded Low Voltage” triggers will be used. It will continue charging until the input voltage hits 9.0 volts. If it wasn’t actively charging when regenerative braking causes the input voltage to drop, then it doesn’t matter. If you are using the “Low Voltage” input triggers, it can turn on and off at lower input voltages, but the input loaded voltage triggers are the same.

BFL13 wrote:
Are you saying that if the Li House BMS shut the Li off there would be no load dump damage to the alternator when the DC-DC has input from the starter battery and not directly from the alternator?

I think the most I can say (not being an expert) is that if you install any DC-DC charger according to the instructions, it’s very unlikely you’re going to damage the alternator. The reason these are becoming more common in the automotive and RV world is because of what has happened with the alternator and charging systems. By connecting a DC-DC charger to the starting battery, it’s just another electrical load on it. It’s not the only one. Again, outside of the marine world, I’m not aware of any DC-DC charger that connects directly to the alternator.

BFL13 wrote:
ISTR advice to connect to the alternator to have less voltage drop, but that was not with Dc-DC chargers maybe.

Yes, on my ‘95 F350, I could get much better charging voltage to the camper battery just by running 6 AWG wires from the alternator. It still wasn’t as good as a DC-DC charger can do, but it was much better than the OEM charging wires. But I couldn’t do that on my current truck. I needed something that the truck ECM wouldn’t even know was there.

:):)

[BFL13]

So that one "turns on" with input above 13.2v, so it would not boost to 14.4 when the voltage is at 12.x if you used that Dc-Dc with regen braking? The Sterling one claims it will (I think)

Are you saying that if the Li House BMS shut the Li off there would be no load dump damage to the alternator when the DC-DC has input from the starter battery and not directly from the alternator?

ISTR advice to connect to the alternator to have less voltage drop, but that was not with Dc-DC chargers maybe.

I don't have a clue about all this! IMO those who might be affected by whatever this is all about should take note in case there is something they need to do or not do.

I resign as OP of this thread so people who actually know something can take over this topic. 🙂

[MEXICOWANDERER]

Every motorhome on the market would FRY the electronics if voltage surged to sixteen volts, any time, any where.

I read the description in the link and it gives zero justification as to why voltage would surge in an automotive circuit. Load dump occurs when a substantial load is utterly cut off. If the Gizmo is connected closer than the break in the load path, say goodbye to the gizmo.

Voltage charge control higher than vehicle ECU regulates at puts at risk the higher voltage battery because the ECU voltage amplified may have an entirely different control curve.

Constant undervoltage means constant undercharging. Something lithium is supposed to utterly ignore without shortening cycle life. What about over current protection? For both the Gizmo and the batteries.

AGM tolerates 14.4 volts very well and I know of no OEM charging system that maintains voltage to even 14.40

Unless system voltage differential is .5 higher than the other bank this is an uneeded piece of bank account vitamins for the manufacturer.

The main problem I see today is an OEM charging system that disagrees with the auxilliary battery voltage. Then a DC/DC charger may be needed especially on marine units, but marine charge control wasn't designed by idiots like automotive systems.

You tell me.....

[NRALIFR]

BFL, if you have a DC-DC charger between a Li battery and the alternator, you don’t have to worry about what the alternator output voltage is. The DC-DC will only output what the battery it is charging needs, and can handle a fairly wide range of voltage from the alternator. If the alternator voltage gets too high or too low, the DC-DC charger will drop out.

Most DC-DC chargers are connected to the starting battery, not the alternator. When I was shopping for mine, I only ran across one DC-DC charger that connected directly to an alternator, and it had to be a specific type of alternator. It was a marine unit, and very expensive so I didn’t look into it very long.

The Li charging profile on the Redarc charger I’m using will output a max of 14.5 volts, and float of 13.6. I have AGM, so I’m using a different profile.

Here’s a picture of the Turn On/Off Thresholds for the Redarc. The triggers are switchable between standard (for fixed voltage alternators) and low voltage (for variable voltage alternators).



Edit: not sure why I wrote “your Li battery”. I know you’re not using that type. My point was, as long as your DC-DC charger supports your battery charging requirements, you shouldn’t worry about what the alternator voltage is doing.

:):)

[BFL13]

Three threats.
A. regen braking voltages
B. high standard alternator voltage 14.8-15v
C. voltage spike/load dumping


This DC-Dc is boost/buck so it will output your choice voltage as you set it to, regardless of input voltage higher or lower, for A or B, and for C , more here:

about Li and alternator. Scroll way down to "Alternate Uses"
About "load dumping", BMS, damaged alternator, voltage spikes, etc.

I do not know how this relates to regen braking voltages.

I am not clear if the alternator is on the engine battery too, if it would be a "load dump" if the Li House BMS shut it off.

(Easy for me--I don't have Li, plus with my Si, I don't have alternator charging as a choice I made--pulled the Stud 1 fuse for pin 4.)

So this is for those who might care :)---or start to care after your new, modern set-up fries itself (if it would-)

https://marinehowto.com/understanding-the-sterling-power-pro-batt-ultra-battery-to-battery-charger/

[BFL13]

time2roll wrote:

BFL13 wrote:
It says that makes the alternator voltage drop to 12.x and jump to 15.x at times as you drive.

Even if this is true it will not harm the battery.

Chasing ghosts.

It would not harm my Wet 6s. The issue is Li mostly. Are you saying their BMS will be sufficient defence for them? Some have a charging limit of 14.6, but their high voltage cut-off is 15.x. I am unclear (to say the least) why the two voltages are not closer in values.

They mention AGMs too. I suppose they are thinking of over-voltage venting or perhaps thermal run-away? I don't know.

It could turn on just how sustained the 15.x is? Seems it could vary with stop and go vs highway driving?

[time2roll]

BFL13 wrote:
It says that makes the alternator voltage drop to 12.x and jump to 15.x at times as you drive.

Even if this is true it will not harm the battery.

Chasing ghosts.

[MEXICOWANDERER]

Automatic decoupling pulleys for serpentine cost $15.xx rebuilder's cost and they do break and when they do they fail in the de-couple mode. No charging. What a load of KRAP. They must save mileage like an extra fluid ounce of gasoline in a hundred miles. And add a tangible percentage of unreliability especially if the car is high mileage.

[BFL13]

The regen thing is apparently in new vehicles as described in the Sterling DC-Dc link. It says that makes the alternator voltage drop to 12.x and jump to 15.x at times as you drive.

So that jump to 15.x would harm your House battery by over-voltage if you have a House battery vulnerable to that. (Li say)

I don't know if that is just in cars or also in motor homes. I don't know if it is in all new vehicles that can tow a trailer that would affect that trailer's battery.

Seems kind of serious to me. ?

[time2roll]

Alternator protection from a broken cable? Like if you are in a wreck?

DC-DC is serving as an isolator not a surge protector.

I know Halloween is in two day but don't let the boogieman get you on this.