Possible bad li-bim225

[Oldnapapartsguy]

I recently installed lithium batteries in my 2018 Dynamax series 4 31 DS and used a li-bim 225 and upgraded my progressive battery charger. All seemed perfect until recently. What I am noticing is the charging especially when plugged in. It used to charge the house battery to about 14.5 and stay there. Starting battery would fluctuate between 12.6 and 14.5. Now the starting battery just stays at the same voltage as house, 14.5. Also when driving the vehicle would kick in after house batteries used a couple amp hours, and charge them. This was a cycling event. Now it keeps the house batteries charged within just a few amp hours. Hope I have explained this correctly. I feel maybe the li-bim is acting up or maybe it is working correctly know.

This is what my panel keeps showing. Any thoughts are appreciated.

[TomAR]

I suggest you check the voltage from a dash cigarette lighter socket while driving. Compare that to the voltage as measured from a cigarette lighter socket back in the you coach, while driving. (This is a job for your co-pilot
This is how I found out that I needed to install a Li-BIM, after being told otherwise.

[KRedburn]

just curious

do you have the diode in place on the ignition lead?

[Oldnapapartsguy]

Originally Posted by KRedburn

just curious



do you have the diode in place on the ignition lead?

No, I do not. When I did all the checking no one mentioned a diode. I think the problem is the emergency start button. I think it was passing some current keeping the l-bim connected. I disconnected the switch and it straightened out

[KRedburn]

You may want to add the diode in.

attached is Dynamax pdf for retrofitting.

The diode is a 1n4007 available almost any electronics store.

BIRD to BIM (retrofit).pdf

[Oldnapapartsguy]

Originally Posted by KRedburn

You may want to add the diode in.



attached is Dynamax pdf for retrofitting.



The diode is a 1n4007 available almost any electronics store.



Attachment 249432

Is the diode used to stop back feed to the chassis charging? When I researched the installation the diode was mentioned for BIM to lithium. I assume diodes are non directional. Appreciate your thoughts.

[Phreak480]

Diodes are absolutely directional which is how they prevent any backfeed.

[Bill Davis]

Just think of a diode as a one way check valve.

[KRedburn]

Originally Posted by Phreak480

Diodes are absolutely directional which is how they prevent any backfeed.

Exactly ^^^^^

[mjbenedict]

With the old BIM-225 the battery connections didn't matter on the A and B terminals. The new LI-BIM-225 is specific because the batteries operate at different voltages. I had to flip my LI-BIM-225 upside down to make sure the chassis battery was connected to the chassis (AGM/lead-acid) side and the coach to the coach (lithium) side. If connected incorrectly the BIM would operate improperly. Since you stated you upgraded yourself I thought I would point this out.
I created this reference sheet for my motorhome so I could watch the voltages and see if operating properly. Remember the BIM automatically operates by monitoring voltages. When the two batteries are connected they will display close to the same voltage (charging or discharging).