BIM160 not charging chassis battery when on shore power

[keefd]

Howdy all,

So I've owned my 2018 Axis 25.2 for a couple months now. When I park it at my house and connect it to 120V 15A shore power (AC, fridge, and microwave off), it'll keep the house batteries well charged at around 13.1V.

Problem is, it does not charge up the chassis battery and it goes dead after a coupe days. There's around a 1 amp parasitic draw from the chassis battery from what I've tested. I put in an aftermarket radio but the other electricals are all stock.

If I hit the Emergency Start switch I hear the clunk from the BIM160 and if I hold it down the radio will turn on after about 20 seconds. If I let go I hear another clunk and the radio dies after a few seconds. It doesn't seem to keep the chassis and house tied together. This is all with the engine off.

I bought a Noco Gen5x1 charger to keep the chassis battery charged, but it didn't seem to keep up, I wonder if the "smart" electronics can't deal. I had a cheap 8A charger that would keep it charged if I left it connected.

Any ideas as to what I can do to troubleshoot?

[Mr Sunshine]

Check out the section on charging in Ed Felker's excellent crowd-sourced manual for Vegas/Axis under the Motorhome Tech Topics section. It was collated for earlier models, but I bet your electrical system is similar. Charging is all about BIRD and trombetta.

I just last week replaced the BIRD in my Vegas. I had the same problem, batteries not charging from engine or post. A little too soon to be sure, but I believe this solved my problem. Although the factory that makes them is only an hour away, since I only needed one I had to order it from M&M in California.

[16ACE27]

Do a search for BIM problems on the forum and you'll see that many have had their BIM wired incorrectly from the factory. Basically the IGN and SIG wires are backwards. Swap them on the terminals and see if that doesn't fix it.

[keefd]

@Mr Sunshine -

Unfortunately I don't have a BIRD/Trombetta - in about 2018 they changed to the BIM160. Ed's guide is invaluable, though!

@16ACE27 -
I thought I checked it, but it may have been the battery leads that I checked, which were wired correctly. House side went to house, chassis side to chassis battery. Thanks for giving me something to try.

BTW - when not using your RVs long-term and not on shore power like on a RV storage lot, do y'all completely disconnect the batteries? I would think so. Sorry if it's a dumb question.

[DavidEM]

The problem is that Thor installs the BIM incorrectly. They connect the chassis battery to terminal B, it should be connected to A. See the attached Precision Circuits document to confirm this.

Switch the leads so that the chassis is connected to A and the coach to B and it should work fine.

David

[Judge]

Search is your friend....

I have posted numerous times on this issue that others have experienced. Here is one recent example.....

https://www.thorforums.com/forums/f1...0-a-26220.html

Read my posts in this thread.

[keefd]

I did verify that the house/chassis batteries are going to the correct terminals as per Precision's documentation. That's not the problem (I hope). Have not yet checked the ignition and signal wires.


BTW, can anyone recommend an inexpensive in or on dash volatage monitor that can show both house and chassis batteries at the same time? My GPS/speed monitor shows the house voltage, but not chassis.

[Judge]

Originally Posted by keefd

I did verify that the house/chassis batteries are going to the correct terminals as per Precision's documentation. That's not the problem (I hope). Have not yet checked the ignition and signal wires.


BTW, can anyone recommend an inexpensive in or on dash volatage monitor that can show both house and chassis batteries at the same time? My GPS/speed monitor shows the house voltage, but not chassis.

Forget the documentation.....

The chassis battery needs to go to the BATT-A post and the house batteries need to go to the BATT-B post.

Then be sure the Emergency Start Switch goes to the SIG post. That leaves the IGN wite above the BATT-A post and the chassis battery.

[RACarvalho]

Ressurecting an "old" post...
I checked the BIM on my unit and it was connected wrong, like Judge said.

I fixed that but from Davids testing I have a question:

Is it possible that the Solar Charger is making the BIM stop charging the house batteries?
My thinking is: If the Solar Charger is keeping the battery at 13.6V, for example, the BIM will not charge the house batteries from the engine alternator....
This may be a problem for the solar may be keeping the battery at 13.6V but only charging 3amps while if the alternator was charging the house batteries it could be dumping 40 amps in them....
Is it possible?

[16ACE27]

Originally Posted by RACarvalho

Ressurecting an "old" post...
I checked the BIM on my unit and it was connected wrong, like Judge said.

I fixed that but from Davids testing I have a question:

Is it possible that the Solar Charger is making the BIM stop charging the house batteries?
My thinking is: If the Solar Charger is keeping the battery at 13.6V, for example, the BIM will not charge the house batteries from the engine alternator....
This may be a problem for the solar may be keeping the battery at 13.6V but only charging 3amps while if the alternator was charging the house batteries it could be dumping 40 amps in them....
Is it possible?

BIMS don't charge anything, they just connect two circuits.

If you solar charger "keeps" the battery at 13.6 VDC then the batteries are fully charged. How much current goes into a battery depends on basically two things:

The voltage of the battery, and
The output voltage of the charging source.

As a battery charges, its voltage will raise to the voltage of the charging source.

When a charging source is connected to an uncharged battery, it's output voltage drops to close to the uncharged battery's voltage until the battery becomes more charged. How low it drops depends on the wire resistance connecting it to the battery and the current capability of the charger.


DC sources and loads in parallel will all have the same voltage across them (except for minute differences due to wire resistance and current).

[Judge]

Originally Posted by RACarvalho

Ressurecting an "old" post...
I checked the BIM on my unit and it was connected wrong, like Judge said.

I fixed that but from Davids testing I have a question:

Is it possible that the Solar Charger is making the BIM stop charging the house batteries?
My thinking is: If the Solar Charger is keeping the battery at 13.6V, for example, the BIM will not charge the house batteries from the engine alternator....
This may be a problem for the solar may be keeping the battery at 13.6V but only charging 3amps while if the alternator was charging the house batteries it could be dumping 40 amps in them....
Is it possible?

When the engine is running and the coach is not on shore or generator power, the BIM relay will not engage until the house battery voltage drops below 12.6v. If your solar system is keeping the house battery voltage above 12.6, you are correct. The BIM will not engage.

That should really not be a problem. If the house batteries have ample capacity and the voltage is holding about 12.6v under load from the inverter, there is no need for the BIM to engage.

If your house batteries are deeply discharged, then the alternator will provide a charge along with your solar.

[RACarvalho]

Originally Posted by Judge

When the engine is running and the coach is not on shore or generator power, the BIM relay will not engage until the house battery voltage drops below 12.6v. If your solar system is keeping the house battery voltage above 12.6, you are correct. The BIM will not engage.

That should really not be a problem. If the house batteries have ample capacity and the voltage is holding about 12.6v under load from the inverter, there is no need for the BIM to engage.

If your house batteries are deeply discharged, then the alternator will provide a charge along with your solar.

Here is what I see it can happen:
Lets say your battery is 30% SOC when you leave your overnight and hit the road before the sun rise, without the generator running, for a 4 hour trip to your next destination... In this case, the BIM will connect the batteries and the engine alternator will charge the house battery...

Then sun goes up and the solar charge controller starts charging the house battery at 14.7V (bulk charge for my solar charge controller)...
In this case, because the house battery is not at or below 12.6V, the BIM will NOT connect the batteries and allow the engine alternator to charge the house batteries... I think we agree on this point BUT:
If my solar is dumping only 0.5amps (~7.3W) because it is too early, it is a cloudy day, the latitude is too high, etc etc the amount of Ah that I will get during my 4 hours drive is 0.5A*4h = 2Ah while if the BIM had made a connection from the start, I could have potentially (depending on the batteries C rate and other loads) get 210 x 4 = 840Ah of power available to charge the house batteries....

In this case the solar controller is preventing my batteries from being charged ...

In fact at 0.5amps from solar charging the house batteries are being discharged for I'm sure I have more than 0.5amps of load at any given time while on the road....

This is what I'm trying to check if it can happen for I have only 100W of solar and usually, on a good day, I see peaks of only 4A from solar...

If my above hypothesis is true, then It would be better for me just disconnect the solar panel during travel days and or when in shore power....

Do you see a flaw on the above logic?

[Judge]

Originally Posted by RACarvalho

Here is what I see it can happen:
Lets say your battery is 30% SOC when you leave your overnight and hit the road before the sun rise, without the generator running, for a 4 hour trip to your next destination... In this case, the BIM will connect the batteries and the engine alternator will charge the house battery...

Then sun goes up and the solar charge controller starts charging the house battery at 14.7V (bulk charge for my solar charge controller)...
In this case, because the house battery is not at or below 12.6V, the BIM will NOT connect the batteries and allow the engine alternator to charge the house batteries... I think we agree on this point BUT:
If my solar is dumping only 0.5amps (~7.3W) because it is too early, it is a cloudy day, the latitude is too high, etc etc the amount of Ah that I will get during my 4 hours drive is 0.5A*4h = 2Ah while if the BIM had made a connection from the start, I could have potentially (depending on the batteries C rate and other loads) get 210 x 4 = 840Ah of power available to charge the house batteries....

In this case the solar controller is preventing my batteries from being charged ...

In fact at 0.5amps from solar charging the house batteries are being discharged for I'm sure I have more than 0.5amps of load at any given time while on the road....

This is what I'm trying to check if it can happen for I have only 100W of solar and usually, on a good day, I see peaks of only 4A from solar...

If my above hypothesis is true, then It would be better for me just disconnect the solar panel during travel days....

Do you see a flaw on the above logic?

I don't see that..... I installed 320W of flexible solar panels as one of my first upgrades and have never had an issue.

Before I did an LiFePO4 upgrade, I had four 6V 235Ah batteries. We could boondock overnight with the Inverter running two fridges plus a fan with phones charging overnight as well. The in the morning we would make two pots of coffee. My batteries would be fairly discharge after all of that. I never had an issue with the BIM not engaging to charge up the batteries. I could drive 12 hours with the Inverter running the two fridges and I never had any low voltage warnings.

[RACarvalho]

Originally Posted by Judge

I don't see that..... I installed 320W of flexible solar panels as one of my first upgrades and have never had an issue.

Before I did an LiFePO4 upgrade, I had four 6V 235Ah batteries. We could boondock overnight with the Inverter running two fridges plus a fan with phones charging overnight as well. The in the morning we would make two pots of coffee. My batteries would be fairly discharge after all of that. I never had an issue with the BIM not engaging to charge up the batteries. I could drive 12 hours with the Inverter running the two fridges and I never had any low voltage warnings.

I understand your experience but I'm assuming the BIM logic works only based on voltage...
If that is the case I can't see how what I wrote would not happen, that is the reason I'm asking.

Your previous set up and my current one have very significant differences.
1 - your solar is 3x mine so even if the above is happening, you are still dumping 3x more amps into the batteries than me and potentially covering your use and some more ...
2 - Your 6V batteries probably had a way better C than mine current ones, being able to absorb energy faster than mine 2 x 27Ds from the factory...

I'm thinking on installing a quick solar disconnect and test this next year but I'm reaching the conclusion, so far, that 100W of solar only works for trickle charge the batteries when the MH is not in shore/generator/on the road and if the above is confirmed it can lead to discharge the batteries while on the road...

PS:
You have two fridges but my boys bring their XBOX which, I found out, works as an electric heater too...

[Judge]

Originally Posted by RACarvalho

I understand your experience but I'm assuming the BIM logic works only based on voltage...
If that is the case I can't see how what I wrote would not happen, that is the reason I'm asking.

Your previous set up and my current one have very significant differences.
1 - your solar is 3x mine so even if the above is happening, you are still dumping 3x more amps into the batteries than me and potentially covering your use and some more ...
2 - Your 6V batteries probably had a way better C than mine current ones, being able to absorb energy faster than mine 2 x 27Ds from the factory...

I'm thinking on installing a quick solar disconnect and test this next year but I'm reaching the conclusion, so far, that 100W of solar only works for trickle charge the batteries when the MH is not in shore/generator/on the road and if the above is confirmed it can lead to discharge the batteries while on the road...

PS:
You have two fridges but my boys bring their XBOX which, I found out, works as an electric heater too...

Personally…. I think you’re over-thinking it.

If your solar is good enough to charge the house batteries and they have an ample charge to run the Inverter and the solar keeps them charged enough to keep running the Inverter while you’re driving, it really doesn’t matter if the BIM ever engages.

If there’s not enough sun or the solar is unable to keep up, then the BIM will engage so the alternator can provide the necessary charge.

If your solar is not generating enough power and the Inverter is geneating power, the batteries are going to discharge and eventually the voltage will drop below 12.6V and the BIM will engage…. even if the solar is proving some charge.

[16ACE27]

Originally Posted by RACarvalho

Here is what I see it can happen:
Lets say your battery is 30% SOC when you leave your overnight and hit the road before the sun rise, without the generator running, for a 4 hour trip to your next destination... In this case, the BIM will connect the batteries and the engine alternator will charge the house battery...

Then sun goes up and the solar charge controller starts charging the house battery at 14.7V (bulk charge for my solar charge controller)...
In this case, because the house battery is not at or below 12.6V, the BIM will NOT connect the batteries and allow the engine alternator to charge the house batteries... I think we agree on this point BUT:
If my solar is dumping only 0.5amps (~7.3W) because it is too early, it is a cloudy day, the latitude is too high, etc etc the amount of Ah that I will get during my 4 hours drive is 0.5A*4h = 2Ah while if the BIM had made a connection from the start, I could have potentially (depending on the batteries C rate and other loads) get 210 x 4 = 840Ah of power available to charge the house batteries....

In this case the solar controller is preventing my batteries from being charged ...

In fact at 0.5amps from solar charging the house batteries are being discharged for I'm sure I have more than 0.5amps of load at any given time while on the road....

This is what I'm trying to check if it can happen for I have only 100W of solar and usually, on a good day, I see peaks of only 4A from solar...

If my above hypothesis is true, then It would be better for me just disconnect the solar panel during travel days and or when in shore power....

Do you see a flaw on the above logic?

Your solar charger can not stay at 14.7 VDC and only supply .5 amps to a 30% SOC battery bank. If the battery bank saw a charger at 14.7 VDC it will suck up a lot more than .5 amps, to the max current the charger can supply, at which point the charger voltage will have dropped to equal the battery bank voltage - that's just physics. So unless you have a lot of resistance between where the solar charger and BIM together connects to the battery bank (which would allow a significant voltage difference between the charger and the battery bank), your solar charge should not stop the BIM from connecting the two battery banks together.

This is how Precision Circuits describes the operation of the BIM:

The BIM monitors the battery voltage of both the chassis and coach batteries over long
periods of time. If it senses a charging voltage, it connects the two batteries together. If the
charging system is drastically overburdened, the batteries will be isolated, however, if the BIM sees a long term charging of both batteries it will allow the batteries to remain connected and allow the charging system to do its job. Once the batteries have charged for one hour, the BIM will isolate the batteries to prevent overcharging, and will only reconnect the batteries
for charging if one of the batteries drops to approximately 80% charge, and the other is being charged. This long term monitoring of the batteries prevents the annoying relay clicking that exists in simpler isolation modules today. The BIM does not guarantee 100% battery charge, but prevents harmful battery charge levels.

So after an hour of connection/charging by the engine, the BIM will not reconnect if the Solar Charger can keep the house battery bank above 12.4 VDC for a FLA battery bank.

[RACarvalho]

Originally Posted by 16ACE27

... So after an hour of connection/charging by the engine, the BIM will not reconnect if the Solar Charger can keep the house battery bank above 12.4 VDC for a FLA battery bank....

Batteries will not suck up all that the panel can supply and then voltage is reduced... That would only happen if you don't have a charge controller....

Evidently 0.5amps is an extreme example to try to build a case....

But lets get a real one:
Early in the morning my solar panel usually produces 1.5A @ 13+V...
That is more than the 12.6V cut out of the BIM and will lead to it cutting the power supply from the engine alternator....

See that , while on the road during the day I have two sources to charge the house battery:
1 - Solar @ 1.5A
2 - Engine alternator @ 200+A

But because the solar keeps the battery at more than 12.6A, the BIM cut the alternator!!!

So again: If I didn't have solar I would be better off for my house battery would be charged by the more powerful engine alternator while on the road but because the solar controller is there and I have a low power set up, my batteries will charge at lower Amps rate, potentially discharging the house battery - Solar Charge controller BULK voltage is 14.7V so even if my batteries are within the bulk phase (almost dead), the solar controller will trick the BIM and keep the alternator out...

[16ACE27]

Originally Posted by RACarvalho

Batteries will not suck up all that the panel can supply and then voltage is reduced... That would only happen if you don't have a charge controller....

Evidently 0.5amps is an extreme example to try to build a case....

But lets get a real one:
Early in the morning my solar panel usually produces 1.5A @ 13+V...
That is more than the 12.6V cut out of the BIM and will lead to it cutting the power supply from the engine alternator....

See that , while on the road during the day I have two sources to charge the house battery:
1 - Solar @ 1.5A
2 - Engine alternator @ 200+A

But because the solar keeps the battery at more than 12.6A, the BIM cut the alternator!!!

So again: If I didn't have solar I would be better off for my house battery would be charged by the more powerful engine alternator while on the road but because the solar controller is there and I have a low power set up, my batteries will charge at lower Amps rate, potentially discharging the house battery - Solar Charge controller BULK voltage is 14.7V so even if my batteries are within the bulk phase (almost dead), the solar controller will trick the BIM and keep the alternator out...

Sorry, no. The charge controller takes the higher DC voltage from the solar panels and converts it to charging voltage for the battery bank. It may try to put out 14,7 VDC in bulk mode, (and it may have a display panel that says that) but if you measure the actual voltage output it will be the same as the battery bank. It's simple electrical theory, in this case Kirchhoff's Voltage Law.

Consider the simple circuit below:


What voltage does the BIM see? The Solar Charger output voltage? The battery resting voltage?

Neither, it sees the voltage of both which is in between the individual components' voltages. What actual voltage is measured depends on the SOC of the battery bank, it's internal resistance, and the capacity of the solar charger. Charging current at any point in time is calculated by the difference in voltage between the battery bank's resting voltage (say, 12.2 VDC) and the open circuit charging voltage (say, 14.7 VDC) divided by the sum of the wire connection resistances and internal resistances of the battery bank and charge controller (say, .1 ohms to start and to make the math easy). So the charging current is 2.5 VDC divided by .1 Ohms equals 25 amps.

But if the charge controller's capacity is only 10 amps, its internal resistance increases to limit the current to its capacity, so now the sum of the internal resistances and cable resistances has to be .25 Ohms to limit the current.
That extra .15 Ohms of internal resistance in the charge controller multiplied by the current of 10 amps means the true output voltage of the charge controller is 14.7 VDC minus 1.5 VDC which equals 13.2 VDC.

But realize that the battery bank's internal resistance is not static either, nor is its resting voltage, so there are a lot of dynamics going on in charging the battery bank.

And nowhere in Precision Circuit's documentation of the BIM does it say the BIM cuts out when the house battery voltage reaches 12.6 VDC. It just says it won't reconnect after the 1 hour drop out if the battery voltage is above 80%. So unless you have an inverter dragging down the house battery bank you will only get 1 hour of charging from the alternator through the BIM.

[OldWEB]

Originally Posted by RACarvalho

So again: If I didn't have solar I would be better off for my house battery would be charged by the more powerful engine alternator while on the road but because the solar controller is there and I have a low power set up, my batteries will charge at lower Amps rate, potentially discharging the house battery - Solar Charge controller BULK voltage is 14.7V so even if my batteries are within the bulk phase (almost dead), the solar controller will trick the BIM and keep the alternator out...

IF your 'low power' setup will output 14.7V to a discharged battery, then I suggest you have a 'open circuit' in that bank, be it a open cell(s) or corrosion in the connection(s). Cuz, and this has been mentioned before, physics (and logic) will NOT allow it.