How many Amps returned to batteries while driving? - Motorhome Forums, Motorhome Discussion, Motorhome Chat

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post #1 of 5 (permalink) Old 08-10-2011, 14:54 Thread Starter
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How many Amps returned to batteries while driving?

Just out of interest, in the absence of any sophisticated battery monitoring equipment does anyone have a reliable idea on how many amps are returned to the cab and habitation batteries during driving?

We've yet to run out of juice despite running our Laptop from a 12v charger 24/7 for 4 days from our bank of 2 86AH batteries.

We use our cab battery also on occasion since our inverter is connected to it but only for an hour or two max.
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post #2 of 5 (permalink) Old 08-10-2011, 15:14
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I would think the best way would be to test both batteries with a multi meter before and after a run would be interesting to know. Think i will do this next time we use our van
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post #3 of 5 (permalink) Old 08-10-2011, 15:23
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from my meter i see an initial kick up to 230w on batteries used the night before, but its suprising how quickly that drops to a modest charge whilst driving....

Regarding the laptop, i find they are not too heavy on the batteries enless you recharge from flat whilst in use...
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post #4 of 5 (permalink) Old 08-10-2011, 15:51
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On my van, a Burstner, the charging on hookup is 16 amps to the leisure batteries and 2 amps to the vehicle battery.

On engine start up, the ammeter shows the same amount of amps as when on hookup. There will possibly be a difference on how much the vehicle battery takes out of the alternator to replace that lost by turning over the engine.

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post #5 of 5 (permalink) Old 08-10-2011, 16:15
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My Murvi Morello has quite a sophisticated charging and monitoring system.

In an hour's drive I can deliver 20 Amp-hours to the leisure batteries so I guess that means 20 Amps for an hour.

According to Wikipedia, automotive alternators can supply 50-70 Amps for peak demand.

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