Question BIM in 2022 LADP?

[redbaron]

fwiw, this discussion might interest you, re dc to dc nor special BIM

Maybe switching to Lithium House Batteries - iRV2 Forums

I'm sure thhe info I am looking for has already been addressed in this great form, but I can't find it so: I have a 2018 New Aire and the AGM house batteries need replacing. Am considering going

www.irv2.com

Thanks…that does help.

 

[redbaron]

Well, not really! It's said a lithium battery acts much the same way a capacitor reacts! It will completely discharge very fast!

I could see modifying the relay system to switch the starting system from one battery to the other. But to introduce a short circuit to a lithium battery is pure suicide!!! Thank God your lithium battery has short circuit protection!!!

And the additional DC to DC charger will also protect against reverse /short

 

[Kevin D Pem]

And the additional DC to DC charger will also protect against reverse /short

We are not even talking about the same circuit!!!
The only time the load circuit touches the charge circuit is at the batteries!!! What the charge circuit offers is independent from, therefore does not apply to the load circuit!!! Diagram it out!!!

 

[redbaron]

I am talking about the house side at the solenoid. Putting a dc to dc there facing the solenoid will prevent reverse flow to the lithium but will allow the lithium to power the solenoid and thus power the chassis battery.

If a short occurs, it’s limited to 50amp before protection kicks in.

 

[Ddmo]

This?

https://www.victronenergy.com/dc-dc-converters/orion-xs-12-12-50a-dc-dc-battery-charger

Sure looks interesting.

Yes. That’s it.

 

[Kevin D Pem]

I am talking about the house side at the solenoid. Putting a dc to dc there facing the solenoid will prevent reverse flow to the lithium but will allow the lithium to power the solenoid and thus power the chassis battery.

If a short occurs, it’s limited to 50amp before protection kicks in.

Clearly we are reading a different book! I'm still talking about using a boost circuit, on the load circuit. Connection from lithium to "weak" agm or other battery, is by definition a short!

 

[redbaron]

So am I.

Boost is what activates the solenoid to provide the functionality.

Using my design would allow this feature to work for boosting the chassis and let it start safely off the lithium house battery.

The existing circuit for charging the house from alternator would have the DC to DC facing the house battery. This provides for the function as originally designed, while offering protection of shorts and ensuring current draw doesn’t exceed 50amp.

If the chassis battery’s are internally shorted or truly dead, then the boost feature is irrelevant and won’t help anyway. But if they are just very low, it will work the way it did prior to lithium.

 

[Richpatty]

Clearly we are reading a different book! I'm still talking about using a boost circuit, on the load circuit. Connection from lithium to "weak" agm or other battery, is by definition a short!

Huh?

 

[Kevin D Pem]

Huh?

A quote!

"

In the context of a battery (or any power source), we usually mean it to be a load that is far too large for the source. Any battery, whether a high voltage or low voltage battery, will be 'short-circuited' by putting a low or zero resistance load on it.

A short circuit usually produces damaging conditions for the battery, and the load, if maintained for enough time. At best, the battery will be run down quickly. At worst, the battery may catch fire, burst itself or its container, or the load start a fire."

 

[redbaron]

Kevin, one of us is clearly confused on the purpose of the DC to DC charger I have mentioned.

I will do some more research because right now I feel pretty confident in my design and intended usage.

 

[flyboy013]

There’s probably a way to configure the Silverleaf system to disable the automatic activation of the charge bridge with various configuration options. Doing this should retain the boost switch function in which the Silverleaf TM102 would still activate the charge bridge for the boost capability.

 

[Kevin D Pem]

Kevin, one of us is clearly confused on the purpose of the DC to DC charger I have mentioned.

I will do some more research because right now I feel pretty confident in my design and intended usage.

Like I said! We must be reading different books.i am confident you will run the numbers, and double check you circuitry.

I would be amiss if I didn't share what I see. Remember I do KISS simple jobs, and you? Well, you're starting with complexity! I could start that way, I just don't wana!!!

 

[SteveMA]

Just completed the maiden voyage (7900 miles in April and early May) after changing the house batteries to LiFePo, 2 new inverters and support gear all Victron. Working on getting the 2 Victron Multiplus-II units to read via SilverLeaf but now think I have gained the "missing info links" to get this resolved in the next 2-3 weeks.

Right now the chassis batteries stay fully charged and trickle from the house batteries and the house batteries are doing very well driving long days and when we stop.

I went with 2x DC-DC converters - one each way so that charging works from Alternator (Victron DC-DC 12|12-50) and from House to Chassis Victron DC-DC 12|12-30 (but going to change this 12|12-30 as soon as I can get another 12|12-50 as 12|12-30 is Bluetooth only vs. the 12|12-50 uses VE-Direct and reads on the Cerbo GX MK-2 display and via the cloud). The Victron settings for the DC-DC going 2 ways was a bit of experimentation but good community support on the forums and in the end it was not too difficult (other than the bluetooth that will not work in our coach unless I am sitting the the recliners and then I fall asleep...)

I still have the boost feature from the dash - when you boost you are linking for mere seconds, and the only goal is more amperage and to get the DC voltage up to start the engine, therefore the added voltage is not going to have any negative effect on the alternator or the chassis batteries in that short time. The alternator is not spinning, and the chassis batteries just see a charge coming at them at a typical voltage (14.5v) for a few seconds. the LiFePo BMS limits output to 250A and they are each fused in the Lynx distributors at 350A for safety so in reality it is 1000A theoretical maximum being drawn from the entire House LiFePo battery bank. I disconnected the "Bridge" feature in SL with Omniscope and also removed the 1 wire connection from SL to the "boost solenoid" in the electrical bay. Added a new 6ga Chassis battery 12V+ line up to the house battery bay just for the connection for the DC-DC converters so from the chassis V+ post on the boost solenoid to the new breakers and fuses added to the House battery bay just for this. Breakers at both ends of this cable and also to the chassis side of the 12|12-50

Doing a complete write up on the new system with photos and schematics of this all as well as the 1840AH of LiFePo, Lynx distributors and 1000A shunt and the 1800W of solar (9x200w) in the next few weeks now that I am home.

 

[MarkMaxPayne]

As pointed out by Joe Hogan factory installs of Lithionics lithium batteries (even with 3 320Ah batteries for a total of 960Ah configurations) by Newmar has relied on SilverLeaf to trigger combining the batteries (through combiner solenoid) for alternator charging. I have myself pined over converting to a Victron DC-to-DC charger for alternator protection in other forum threads. Especially given how many units Newmar incorrectly built with the wrong solar charge controllers for lithium (now a service bulletin), lowering my trust in their engineering of this.

One thought I have had is to trace to see if the battery combiner switch goes through SilverLeaf as an input or if it is instead a second trigger wire connecting to the same trigger post of the combiner solenoid. If the latter, adding DC-to-DC converter would be as simple as removing the trigger wire from the SilverLeaf but leaving that from the combiner switch connected at that solenoid trigger post (but you'd then lose how it also uses house to charge chassis by combining them).

Why do I suspect this? The SilverLeaf Technical Reference Manual (downloaded from SilverLeaf) shows the pinouts for the main, input, and output connectors. The output connector shows the pin that goes out to the combiner solenoid (output pin 4) and describes how this works. However, the 12 pin input connector doesn't have any pin labeled as an input from the combiner switch. With no input from the switch in the dash I doubt SilverLeaf has any idea when that switch is depressed and that means it most likely also goes directly to the combiner solenoid. I also suspect this due to SteveMA's results.

I also researched the Lithioncs battery combiner as a possible solution, but then realized it works almost the exact same way SilverLeaf does, so I quit chasing that path and left the factory SilverLeaf/solenoid solution in place (for now).

My rig is currently at the dealer at this time for yearly service and replacing factory solar with a floating solar array (leaveraging Girard awning mounts for no new holes in the roof) so I cannot trace the combiner switch wire from the cockpit to see if my suspicion is correct or not.

Best,
-Mark

 

[MarkMaxPayne]

Doing a complete write up on the new system with photos and schematics of this all as well as the 1840AH of LiFePo, Lynx distributors and 1000A shunt and the 1800W of solar (9x200w) in the next few weeks now that I am home.

Looking very forward to this!!! Can you include how the battery boost wire ties into the combiner solenoid after disconnecting the combine trigger wire from SilverLeaf?

Thanks!

Best,
-Mark

 

[SteveMA]

Mark,

At least on my 2020 MA, the high side of the bridge solenoid coil had 2 wires on the single coil connection post (the other side of the coil being 12V chassis Ground) - 1 was from the dash switch and 1 was from the KIB relay board in the AC electrical bay (directly below where the Bridge relay is located).

I disconnected the wire from the KIB Board/Silverleaf relay signal and left the dash connection intact. The Bridge solenoid still engages when the dash boost switch is activated. As the dash switch is a momentary contact, as soon as you release the dash boost switch the Bridge relay opens. Given the output of the KIB board is a relay to drive the bridge solenoid you are correct that Siverleaf does not get feedback on the status of the solenoid coil and the coil only cares that it gets 12V+ on that contact - where it comes from is irrelevant.

I have to go back into the SilverLeaf programming (with Omniscope) now that I am home and see why Silver leaf thinks it is still periodically bridging (IE supplying +12V to the bridge solenoid) but I have confirmed that the bridge solenoid is not activating when SL thinks it is sending the demand to it's coil via the KIB board as there is no connection (wire removed leading to the solenoid coil)

 

[MarkMaxPayne]

Mark,

At least on my 2020 MA, the high side of the bridge solenoid coil had 2 wires on the single coil connection post (the other side of the coil being 12V chassis Ground) - 1 was from the dash switch and 1 was from the KIB relay board in the AC electrical bay (directly below where the Bridge relay is located).

I disconnected the wire from the KIB Board/Silverleaf relay signal and left the dash connection intact. The Bridge solenoid still engages when the dash boost switch is activated. As the dash switch is a momentary contact, as soon as you release the dash boost switch the Bridge relay opens. Given the output of the KIB board is a relay to drive the bridge solenoid you are correct that Siverleaf does not get feedback on the status of the solenoid coil and the coil only cares that it gets 12V+ on that contact - where it comes from is irrelevant.

I have to go back into the SilverLeaf programming (with Omniscope) now that I am home and see why Silver leaf thinks it is still periodically bridging (IE supplying +12V to the bridge solenoid) but I have confirmed that the bridge solenoid is not activating when SL thinks it is sending the demand to it's coil via the KIB board as there is no connection (wire removed leading to the solenoid coil)

This is great news for those of us wishing to add DC-DC chargers to protect our alternators while at the same time maintaining the function of the battery boost/combine switch at the dash. Thanks for confirming some of my suspicions. I had naively thought that output pin 4 would go to the combiner solenoid trigger terminal, but it sounds from your description it instead goes to the KIB and then that sends the +12V voltage back to the combiner solenoid trigger (through a relay on the KIB?). When I get my rig back from the dealer, I think I know what one of my next projects will be once I confirm my combiner solenoid is wired the same way. Now that it is a couple of weeks out of warranty...

As far as why your SilverLeaf may still be wanting to supply +12V to the bridge solenoid to turn it on, it appears from what I've seen while checking out my Omniscope settings that SilverLeaf may also do this when it thinks your chassis batteries should be charged by the house batteries. I've often wondered if that scenario could set up for a "deadly embrace" where both chassis and house eventually get drained until the BMS shuts off the lithium when the SOC falls below its cutoff threshold. With old school batteries, SilverLeaf could just look at the voltages on both the house and chassis batteries to make this decision, whereas with Lithium it should be looking at the SOC as well. That said, they may not care if they assume the BMS will protect the Lithiums regardless.

Best,
-Mark