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Old 06-14-2019, 10:49 PM   #1
Junior Member
Brand: Thor Motor Coach
State: California
Posts: 3
THOR #14705
Battery charge - Gen vs Alt

I have four six-volt batteries in my 2017 Thor Outlaw 37RB.

It seems the batteries take a better charge and last longer when charged with alternator vs generator.

Am I crazy?

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Old 06-14-2019, 11:05 PM   #2
Senior Member
Miramar Owner's Avatar
Brand: Thor Motor Coach
Model: Miramar 34.4
State: Iowa
Posts: 665
THOR #4488
I believe the alternator has higher output so should charger faster.

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Old 06-15-2019, 12:13 AM   #3
Senior Member
Brand: Thor Motor Coach
Model: Hurricane 31S
State: Texas
Posts: 1,854
THOR #6411
Your converter is probably a three stage one. So, the first 80% is bulk charge using the full 55 amps. When at 80% of the charge it switches to an absorption mode which takes 3 to four hours to charge the batteries fully. This is necessary for deep cycle batteries as it extends battery life. Your alternator is rated at 175 amps (Ford engine) but probably only puts out 150 amps. While it does fast charge the house batteries, it does shorten their life. Deep cycle batteries should be charged at a max of 10 to 13% of the amp-hour rating. More current lessens battery life.
Jim & Roy Davis
2016 Hurricane 31S
1961 Rampside in tow
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Old 06-15-2019, 02:05 AM   #4
Thor Palazzo 33.3 diesel
TurnerFam's Avatar
Brand: Thor Motor Coach
Model: Palazzo 33.3 34'bunkhouse
State: Georgia
Posts: 2,339
THOR #4735
I think you need to tell us 'how' you are arriving at your hypothesis...as neither should be relatively different than the other, given the same charge rate for the same amount of time... are you comparing traveling all day with the Alternator charging the house batteries, versus running your generator for only an hour to charge them? etc.,,,,,
the Turners
'14 Palazzo 33.3 bunkhouse 34' diesel
KingTailgater2 Dish HD, 100w/5a SOLAR, BlueOx
100,000+mi since '14 - US, Alaska, Canada - Hiawassee, GA! (also, '14 Gulfstream Amerilite and '07 ForestRiver Rockwood) : )
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Old 06-16-2019, 03:21 AM   #5
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Brand: Thor Motor Coach
State: California
Posts: 3
THOR #14705
Thank you

Thanks one and all for your input.

I'm going to test batteries. They are probably original and in need of replacement.
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battery charging

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