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Judge · 04-01-2020, 10:32 PM

Quote:

Originally Posted by Judge

I'm not convinced the wiring doesn't matter even after Precision told me the same thing.

I have a 2020 Magnitude SV34 with the BIM 160. I have been having issues with the house batteries charging while driving coach.

The BIM 160/225 datasheet's terminology is all screwed up. They call the battery connected to the engine alternator the "coach" battery and they call the battery hooked to the coach converter / charger the "chassis" battery.

The wiring diagram shows the Ignition terminal on the BIM connected to their version of the "chassis" battery, which we would call the house (coach) batteries.

When I look at the BIM version for Lithium batteries it specifically says the left post is for the starting battery and the right post is for the house batteries. The Lithium battery unit looks identical to the BIM 160/225 so the only difference with this model is how the microprocessor controls the Lithium battery charging.

I also found a Forest River site that specifically shows the BIM 160 wired with the left post going to the starting battery and the right post going to the house batteries.

During my last trip the FireFly panel started reporting the chassis battery at 0V when the engine was running and then normal voltage when the engine was off. The BIM was also not boosting the house battery voltage when the Inverter was on for the fridge and the voltage dropped below 12.5 volts and the chassis batteries were showing 14.7 volts on my dash voltmeter.

Today I decided to switch the BATT-A and BATT-B wiring the way the Forest River site showed and the way the Lithium battery version shows. I moved the chassis battery cable to the BATT-A post and the house battery cable to the BATT-B post.

After doing that I started the engine. After a couple minutes I could hear the relay engage while the engine was running and my house battery voltage went up.

I'm still not going to rule out that I have a bad BIM 160 and maybe it just started intermittently working. But after seeing the Precision Circuits documentation being screwy and other indications that it might matter which post goes to the chassis battery and which post goes to the house battery, I figured I had nothing to lose and for the moment it seems to be working.

Here are pics I found from the Forest River site....

I'm becoming slightly more convinced that which battery gets connected to the BATT-A and BATT-B posts might matter on the BIM 160.

Every time I start the coach now the house battery voltage gets boosted after the engine has been running for a few minutes.

I'm also seeing a difference in the the way the converter / charger is working after I plugged into shore power at home. It looks like both the house and chassis batteries are being charged once the relay kicked in. I have a hardwired Progressive EMS installed and with nothing else running I am showing a current draw of 12 amps on Line 1 where the converter / charger circuit is located. I typically don't see the type of current draw after plugging in but it makes sense since the house batteries were drained down a bit and I also had drained down the chassis batteries a bit doing my troubleshooting.

From what the Precision Circuit guys said the relay kicks in if it senses the voltage of one battery bank drops below 12.6 volts and there is an adequate charge on the other bank.

I'll keep testing and see how things go but things sure seem to be behaving differently since I swapped the cables going to BATT-A and BAT-B on the BIM. It still could be the thing has an issue and is only working intermittently but it is a heck of coincidence that it started working more like it should once I swapped the battery cables.