LR4 - Disconnect BMS to enable full battery charge

DerekV87

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Hello All,

First post… Given the LR4 charging profile related to the battery management system https://expeditionportal.com/forum/...ile-measured-with-iid-really-this-bad.163106/

I am considering disconnecting the BMS sensor on the negative battery terminal while camping when I need full battery capacity to run a fridge.

Its my understanding from extensive searching but but little objective data that the battery will be charged to full capacity as the BMS is not able to do its thing and only charge battery to about 80% when it chooses to save fuel.

Has anyone played this game with BMS? It’s true there are a couple of warning signs on the dash as soon as this sensor is disconnected. I am mainly concerned about causing any other issues with this practice. I don’t have a scan tool to know exactly what is going on when disconnecting the sensor.

Hope this work around is the ticket otherwise not sure how to run a fridge on main battery. I have 95 amp hrs of capacity but with only being charged to around 80% and mostly not charging when driving or idling, I end up getting the low battery warning on the dash in the morning. Thanks All!
 
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jlach993

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an 80% charged H8 battery with an alternator putting out 13.5 volts vs a 100% charged battery with an alternator putting out 14.7 volts would probably run your fridge when the engine is off for 10 mins less? It's not going to be a huge difference even with the higher alt voltage. Your best bet is to run a secondary battery or just start your car and use it as a 5700lb expensive generator for your fridge after an hour or so of running the fridge. I think you meant to say your battery has 95 minutes of reserve capacity. That depends on how many amps your fridge pulls. Your battery will most likely run it for 60 mins at best? i'm not too sure. 95 reserve capacity is true maybe for a radio or some interior lights, but not a fridge. Anyone could correct me on all of this if i'm wrong. This is just what i think in my brain lol
 

DerekV87

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I meant to say my battery has 95 amp hours. As a general rule of thumb, the Dometic CFX3 35 fridge I am running draws 1 Amp p/hr. I think the problem is my battery is only let’s say 60% charged when I pull into camp cause I’ve seen 12.3 or 12.4 volts at this point (57 amp hrs available), I drawn some by having the door open for an hour, then the fridge is pulling 1 amp hr for 20 hours, which results in low battery warning in the morning. At this point in time my battery would be roughly at 39% capacity (37 amp hours left out of 95).

Trying to have the battery be 100% charged by camp time assuming I’ve been driving for awhile.
 

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