Coach Batteries Depleted after 1.5 Weeks

[Desert Boat]

Originally Posted by hwobs

Seems to be conflicting information in this thread as to whether or not the solar charges both chassis and coach batteries or coach only batteries.

Welcome to asking questions online.

I stand by my claim on the BIM functionality, based on reading the BIM manual, the Dynamax 120 and 12V diagrams, and hand-over-hand wire tracing on my coach.

Here is a post on how my coach is wired. Any coach may vary. I do not believe there are any significant differences in the 28 and 30 wiring for major items.

https://www.forestriverforums.com/fo...ml#post2537770

Below is a diagram of the 12 v connections.

Dynamax adds a few connections to the chassis 12V system. I would start with these looking for parasitic problems:
- connection to BIM/LI-BIM for cross charging
- BIM control line (via aux switch)
- docking lights (via aux switch)
- step & door power
- leveler power
- connection to firefly for 12 V monitoring
- not shown, but my coach also has a line running to the middle of the coach to power a TPMS repeater that they used prior to OEM TPMS

I would start with these in the search for parasitic loads. Is the step light going off when the door is closed, for example.

There is no way to completely power off the leveler without pulling a fuse (not recommended). But they use so little power should not be an issue. (Will measure current next visit to the coach). Safety issue - you want the leveler to scream at you if you start with a leveler down (really not fully up).

This is also why the steps are powered from the truck battery - you always want the steps to retract when the engine is running.

The diagrams and descriptions in the attachment above might help in tracking down the parasitic loads.

Separate post coming for BIM functional test.

[Desert Boat]

This tests BIM closing on command, and with a charging potential on either side vs load on other side.

Start with both truck and house batteries charged, but all charging sources off. Disable house charger, truck engine off, turn solar disconnects off.

Static Test

You want dissimilar voltages to start. If both truck and house are are at 12.7 volts, you cannot tell when the BIM has connected. Add a DC load if necessary to pull down one side (say truck headlights or several house fans and lights, maybe an inverter-powered 120 volt load).

LIon coaches should naturally have a static voltage difference.

Press the cross connect button on the dash (typically Aux 2). Voltages should equalize. (If quiet, you might hear the BIM contacts close.)

Release cross connect button. After 30ish seconds, you should see voltages start to drift apart toward unconnected values.

Turn off loads used to test.

Charging Test

Put some DC load on the house, as above. Start truck engine & engage high idle. After a few minutes, the house battery voltage should rise to equal the truck voltage.

(with LIon batteries, this might not show anything if the truck voltage doesn't get higher than the static LIon voltage.)

Stop truck. Battery voltages should drift apart once BIM opens.

Turn on headlights for a truck load. Enable charger. After a few minutes, truck voltage should come up to match the house voltage.

Disable charger. Battery voltages should drift apart once BIM opens.

Turn off all loads used for testing. Put charger and inverter back to desired settings. Turn on solar disconnects.

My coach is BIM, not LI-BIM, but this should work on LI-BIM with the caveat above.

[hwobs]

Originally Posted by Desert Boat

This tests BIM closing on command, and with a charging potential on either side vs load on other side.

Start with both truck and house batteries charged, but all charging sources off. Disable house charger, truck engine off, turn solar disconnects off.

Static Test

You want dissimilar voltages to start. If both truck and house are are at 12.7 volts, you cannot tell when the BIM has connected. Add a DC load if necessary to pull down one side (say truck headlights or several house fans and lights, maybe an inverter-powered 120 volt load).

LIon coaches should naturally have a static voltage difference.

Press the cross connect button on the dash (typically Aux 2). Voltages should equalize. (If quiet, you might hear the BIM contacts close.)

Release cross connect button. After 30ish seconds, you should see voltages start to drift apart toward unconnected values.

Turn off loads used to test.

Charging Test

Put some DC load on the house, as above. Start truck engine & engage high idle. After a few minutes, the house battery voltage should rise to equal the truck voltage.

(with LIon batteries, this might not show anything if the truck voltage doesn't get higher than the static LIon voltage.)

Stop truck. Battery voltages should drift apart once BIM opens.

Turn on headlights for a truck load. Enable charger. After a few minutes, truck voltage should come up to match the house voltage.

Disable charger. Battery voltages should drift apart once BIM opens.

Turn off all loads used for testing. Put charger and inverter back to desired settings. Turn on solar disconnects.

My coach is BIM, not LI-BIM, but this should work on LI-BIM with the caveat above.

Desert Boat, Thanks for all of the Li-BIM info. I’ve downloaded the Li-BIM 225 info sheet and I had found the cross connect button you mentioned. We were not briefed that this button had any function when we picked up the RV, but when I was testing earlier (before I saw your two recent posts) I was able to hear it click in when I pressed the button. It is setup, in the commercial settings on the instrument panel, as a momentary switch, not latched. I was able to monitor chassis battery voltages before and after pressing and the voltages came up significantly when the switch was engaged indicating the BIM had linked the chassis and coach batteries. That said, the BIM does not seem to provide any automatic control to charge the chassis batteries off the coach batteries, only the other way around when the engine is running. At least that’s the way I read it. It would be possible for me to program the switch to be latched such that the BIM would always keep the chassis and coach batteries connected thus providing solar charging to the chassis batteries when the coach isn’t being used. I do not know if this is wise though. I’m going to paste the ‘description’ of the Li-BIM 225 in my vehicle below. I’ll post the wiring diagram link from their webpage below that.

Description

The LiFePO4 Battery Isolation Manager (BIM) monitors voltage and connects batteries when needed. Under normal charging conditions, the BIM will connect for 15 minutes every 35 minutes. That means that the BIM will connect for 15 minutes, disconnect for 20 minutes, and repeat this cycle until the coach battery is charged.

If the coach battery resting voltage exceeds 13.4 V then the BIM will disconnect. A resting voltage greater than 13.4 V indicates a fully charged battery. Note that “resting voltage” means that no current is flowing to the coach battery.

The BIM will disconnect if the alternator voltage exceeds 14.4 V. This protects the coach battery from overcharging. The LiFePO4 Battery Isolation Manager will disconnect if the voltage difference between the alternator and the coach battery is less than 0.1 V. If the voltage difference is too low, then there is a negligible charging current, and no need to connect to the coach battery.

The BIM will disconnect if the alternator voltage drops below 13.3 V. If the alternator voltage is too low, then it cannot adequately charge the coach battery, so there is no reason to connect.

Wiring Doc:

https://1t1pye1e13di20waq11old70-wpe...uick-Guide.pdf

[Phreak480]

Originally Posted by hwobs

Not block heater, grid preheater for the intake. Similar function to glow plugs in other vehicles such as Fords. Not a block heater. It take a lot of amperage initially for a cold start up though. The grid preheat only operates during ignition on at engine startup.

The grid heaters actually can cycle on and off to provide additional intake air heating even once the engine starts running. It helps make those cold starts less obnoxious.

[Desert Boat]

Originally Posted by hwobs

That said, the BIM does not seem to provide any automatic control to charge the chassis batteries off the coach batteries, only the other way around when the engine is running.

In the data sheet you linked to:
- scenario 1 is truck charging house
- scenario 2 is house charging truck
- scenario 3 is depressing the pushbutton.

In scenario 2, the LI-BIM does not care where the voltage comes from, charger or solar or whatever, it should provide charge current to the truck batteries.

It would be possible for me to program the switch to be latched such that the BIM would always keep the chassis and coach batteries connected thus providing solar charging to the chassis batteries when the coach isn’t being used.

No. You want the automatic functions of the LI-BIM to do their job. In the automatic case, when something goes wrong, you should only have one dead battery. If you keep them cross connected, you will have two dead batteries.

Automatic mode also avoids the overcharging situation - you don't want to boil your truck batteries with extended time at the LIon charge voltage.

And thanks for the link to the LI-BIM data sheet. I was familiar with the regular old BIM. While the LI-BIM has some different parameters, the basic functionality is the same. The data sheet gives you the specific voltages to watch for cross connecting during the functional test.

[hwobs]

Originally Posted by Desert Boat

In the data sheet you linked to:
- scenario 1 is truck charging house
- scenario 2 is house charging truck
- scenario 3 is depressing the pushbutton.

In scenario 2, the LI-BIM does not care where the voltage comes from, charger or solar or whatever, it should provide charge current to the truck batteries.



No. You want the automatic functions of the LI-BIM to do their job. In the automatic case, when something goes wrong, you should only have one dead battery. If you keep them cross connected, you will have two dead batteries.

Automatic mode also avoids the overcharging situation - you don't want to boil your truck batteries with extended time at the LIon charge voltage.

And thanks for the link to the LI-BIM data sheet. I was familiar with the regular old BIM. While the LI-BIM has some different parameters, the basic functionality is the same. The data sheet gives you the specific voltages to watch for cross connecting during the functional test.

I will monitor the system over the next 2 days. Currently my chassis batteries are down to 12.83V (just measured). The house batteries are now at 13.4V. I’ll look check the chassis batteries tomorrow morning. If they are < 12.5V then the BIM should begin allowing charging of them once the house batteries are > 13.5V. We should have a nice sunny day. If the chassis batteries are well below 12.5V tomorrow morning then I’ll probably need to get the RV in for some warrantee work to see why the chassis batteries are draining so quickly. Hopefully I can find that the BIM will provide power to the chassis batteries as in scenario 2.

[aircommuter]

Originally Posted by hwobs

Vehicle is essentially brand new. Just picked it up Aug ‘21. As of the 1.5 week timeframe in question, the chassis batteries were fully charged at the time the RV was parked down in back. It is in full sun all of the time here in Albuquerque, NM. We have very few non-sunny days and even recently only had about 2 days just prior to this where we had some weather with overcast days. Chassis batteries are, obviously, new and terminals are clean. I agree that parasitic loads are likely the problem, but how to track them down is the question. We’ve had some interesting light wiring problems (2 specifically I know of and one is still outstanding) amongst a few other quality control issues from the time we obtained this RV. I’m not 100% confident all wiring is correct. Just my suspicion. I don’t like the idea of having to keep the chassis batteries charged if there are parasitic losses, but may have to do that in the time being if I am unable to track down such a problem. I will look at the BiM to see if that’s actually setup correctly. Perhaps that’s the problem if it is supposed to provide solar charging to the chassis batteries as well. Seems to be conflicting information in this thread as to whether or not the solar charges both chassis and coach batteries or coach only batteries.

Seems like it should be under warranty. But at any rate, to test for loads on the chassis battery. Install an amp meter between the battery ground post and the cable. Then remove one fuse at a time and see what the loads are. You may need to wait a few minutes for the load to show up or go away. Keep in mind that loads like the door locks you need to look up what it is supposed to be. That type of load is actually a ghost load. One you know is there but can’t see. A parasitic load is one that should not be there, like a leaky diode in an alternator.
I once had a customer with a battery becoming discharged and people had tried numerous things to no avail. Turns out his son had used the vehicle and the horn stuck on so he pulled the wire off to silence it. The computer was constantly searching for the missing device and slowly discharging the battery. A discharged battery is one that can be recharged, a dead one cannot.

[bclemens]

Originally Posted by hwobs

I will monitor the system over the next 2 days. Currently my chassis batteries are down to 12.83V (just measured). The house batteries are now at 13.4V. I’ll look check the chassis batteries tomorrow morning. If they are < 12.5V then the BIM should begin allowing charging of them once the house batteries are > 13.5V. We should have a nice sunny day. If the chassis batteries are well below 12.5V tomorrow morning then I’ll probably need to get the RV in for some warrantee work to see why the chassis batteries are draining so quickly. Hopefully I can find that the BIM will provide power to the chassis batteries as in scenario 2.

Chassis batteries are "down to" 12.83? That is not "down to", that is topped off and likely a "surface charge". The chassis batteries are still lead acid batteries and fully charged (at resting state) should be in the 12.6-7 range. They may show 14.4 when they are charging, but that is a charging voltage. Only the lithiums will sit above 13V.

The house batters and chassis batteries will NEVER be the same actual voltage other than when charging.

The BIM is di-directional. The alternator will charge chassis and house, the house "charger" will charge house and chassis. However, when reading the "theory of operation" on the BIM (and this should be a "Li-Bim" by the way) it will not pair the batteries in certain scenarios where one side might pull down the other. It will protect ONE power source.

First off, we have to make sure we understand what voltages they should be at....a lead acid battery at 12.5v is still 90% charged.

[hwobs]

Originally Posted by bclemens

Chassis batteries are "down to" 12.83? That is not "down to", that is topped off and likely a "surface charge". The chassis batteries are still lead acid batteries and fully charged (at resting state) should be in the 12.6-7 range. They may show 14.4 when they are charging, but that is a charging voltage. Only the lithiums will sit above 13V.

The house batters and chassis batteries will NEVER be the same actual voltage other than when charging.

The BIM is di-directional. The alternator will charge chassis and house, the house "charger" will charge house and chassis. However, when reading the "theory of operation" on the BIM (and this should be a "Li-Bim" by the way) it will not pair the batteries in certain scenarios where one side might pull down the other. It will protect ONE power source.

First off, we have to make sure we understand what voltages they should be at....a lead acid battery at 12.5v is still 90% charged.

Forgive my usage of ‘down to.’ I had just topped them off and they were just settling out. OP was that they had drained below any capability of lighting the dash lights or even operating the door locks after only 1.5 weeks so they weren’t even close to providing the minimum amount of power to do anyting. In fact they were so low the Firefly was reporting they were at 4V (REALLY?). Seems like an awfully fast drain, in my humble opinion. I’ve put a trickle charger on the chassis batteries to ensure they remain topped off as the BIM requires the house batteries to be > 13.5V in order to provide charging to the chassis. My final analysis is this: for even a couple of days last week (we only had 2, maybe 3 days of overcast here in Albuquerque) it was insufficient to keep the house batteries > 13.5 V so the chassis batteries simply tanked with nothing running other than normal parasitic drains on the vehicle. As far as I’m concerned I’ve closed this issue as I need to pay closer attention to the charging of the chassis batteries than I had realized. Documentation on the vehicle electrical system (battery and house disconnects in the bay behind the driver/in front of the generator - no information in our package as to exactly what they connect/disconnect) and the red battery switch in the coach (I know I shutdown/reconnect all the power in the coach when I push this button, but that’s about all I can tell you) are lacking. Haven’t found, or at least we weren’t delivered) any good documentation on these systems. Seems you have to use the forums to get good info as the documents I did download from Dynamax website also don’t fully match the configurations in our 2021 30FW Xplorer. Schematics, flow diagrams, etc would be helpful. I found information for the BIM and how it works from battle born battery website. I guess it’s what you have to do these days to get enough info to understand/troubleshoot these vehicles.

[clanthon]

What is an emergency battery connect?
Thanks

[Desert Boat]

Originally Posted by clanthon

What is an emergency battery connect?
Thanks

A switch & relay that connects the truck and house batteries to jump start either the truck engine or coach generator from the bank with power.

In the Isata 5s, is a built in capability of the BIMs / LI-BIMs.

[whj469]

Is the battery bypass on or off? It is my understanding that to charge the batteries it needs to be on?

[Desert Boat]

Originally Posted by whj469

Is the battery bypass on or off? It is my understanding that to charge the batteries it needs to be on?

This is coach specific. For the I5s, it should be like the diagram above. No charge current to batteries goes through the main battery disconnect, from inverter, solar, or BIM. Batteries will charge regardless of the main disconnect position. Solar charge does go through the solar disconnects.

[bclemens]

Originally Posted by hwobs

Haven’t found, or at least we weren’t delivered) any good documentation on these systems. Seems you have to use the forums to get good info as the documents I did download from Dynamax website also don’t fully match the configurations in our 2021 30FW Xplorer. Schematics, flow diagrams, etc would be helpful. I found information for the BIM and how it works from battle born battery website. I guess it’s what you have to do these days to get enough info to understand/troubleshoot these vehicles.

Paper manuals are going the way of the dinosaurs. While we do provide what we are given, i can't physically update the owners manual sitting in a drawer, I can however update the ones online.

1. Your dealer should have provided a walk through and explanation of some of how things work.

2. Our online interactive manuals are a living document and get better every day. Any time I get a complaint that something was missing, I go check myself. If it is in fact missing, I add it.

https://forestriverinc.help/#/dynama...als/Electrical

The heart of the interactive manual are the component manuals. That is the digital appliances manuals and unlike paper they can be searched.

In any event, I did check 2021 Isata 5 and found under "electrical", info on the Li-bim and the Firefly manual. I did not see anything on their hard disconnect, so I will have to ask about that one.

I suggest bookmarking this. The "Owner's Manual" itself, yes, is very generic as even many automotive are. They show ALL options available in many cases whether you have it on not. Under the component manuals we also have a folder called "Floor Plan Specific Information" that is where you will find service locations specific to your floor plan"

Then of course there is the video section where we will add product specific videos as well.