Aux. battery charging

[ralph62]

How long does it take to charge the aux. battery from the van charging system. Also how can you tell if it's charging?

[Ford_6L_E350]

Sportrsmobiles come with a little plug voltmeter. Plug it into a 12v outlet that is on the house batteries. Check the voltage. Start the engine and check the voltage again and after a few minutes. If the number goes up, you are charging. If not, you have problems.

Depending on how low the batteries are, it could take1-4 hours of driving to charge the house batteries.

Mike

[John and Dana]

Ralph,

How long your battery to charge depends on many factors. The first are the size of your battery and output capacity of your alternator. If it a 4D it will have approximately 200 amp hours, at 50% discharge if your alternator put our 100 amps it could potentially recharge the battery in one hour. Here is the problem, you van uses some of that 100 amps just to run plus every thing that is on in your van, headlights, wipers, A/C, ets. uses up some of that 100 amps. Most of the vans have at least a 115 Amp alternator but this is the maximum output and you may not be getting this unless your engine is turning high rpms. So if you are only getting 20 amps of charge capacity from your alternator it will take you a little more than 5 hours to replace the 100amps and bring your battery to full charge. (100 amps of battery current/20 amps charge current = 5 hours.

This past winter I had spent a week in cloudy weather camping, so my house battery was pretty low. I drove three hours home in the dark, cold and rain, so there was a pretty heavy load on the alternator. As soon as I got home I plugged the van into shore power and the inverter/charge immediately went to heavy charge mode. So after 3 hours of driving the batteries were still not charged.

[ralph62]

Originally Posted by ralph62

How long does it take to charge the aux. battery from the van charging system. Also how can you tell if it's charging?

I bought my SMB used and it did not have a volt meter. I'll try to find one at an auto supply.
Thanks,
Ralph

[daveb]

Originally Posted by John & Dana

Ralph,

How long your battery to charge depends on many factors. The first are the size of your battery and output capacity of your alternator. If it a 4D it will have approximately 200 amp hours, at 50% discharge if your alternator put our 100 amps it could potentially recharge the battery in one hour. Here is the problem, you van uses some of that 100 amps just to run plus every thing that is on in your van, headlights, wipers, A/C, ets. uses up some of that 100 amps. Most of the vans have at least a 115 Amp alternator but this is the maximum output and you may not be getting this unless your engine is turning high rpms. So if you are only getting 20 amps of charge capacity from your alternator it will take you a little more than 5 hours to replace the 100amps and bring your battery to full charge. (100 amps of battery current/20 amps charge current = 5 hours.

This past winter I had spent a week in cloudy weather camping, so my house battery was pretty low. I drove three hours home in the dark, cold and rain, so there was a pretty heavy load on the alternator. As soon as I got home I plugged the van into shore power and the inverter/charge immediately went to heavy charge mode. So after 3 hours of driving the batteries were still not charged.

This is a very important point and why I had to add a 200 amp alternator. Many new owners like me at delivery were not informed what is needed to actually run the van while supplying a realistic charge to the house battery. Add a second house battery and it becomes more critical.