Renogy dc to dc Charger with existing 400 w solar charger.

Rhodeisland

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Jun 10, 2021
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I have a 400w solar set up that charges a 206ah SOK battery. Every thing works just fine.
I want to install a Renogy 20 amp Dc to Dc Charger to charge the battery during rainy/ cloudy weather.
is 20amp Charger large enough. I don’t want to burn out my factory alternator.
what I can’t figure out is how do I use the charger with my solar set up? Any help would be great.
do I still use my mppt charge control with the solar or dose the dc to dc take that over.
 

MisterSandals

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Nov 5, 2019
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is 20amp Charger large enough. I don’t want to burn out my factory alternator.
How big is your factory alternator?
Whether 20A is big enough depends on how fast you want to charge. 1A is big enough if you want to charge for an
hour per Ah (by definition in fact).

I would think if you were just idling the engine to charge, with radio, lights, ... everything you can power down you'd be just fine.
You would know if you were going to burn out your alternator by monitoring how hot it gets. Anything you can do to improve airflow will help, so folks open their hood a bit.
 

Rhodeisland

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Jun 10, 2021
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Do you need to turn off the solar system to your house battery when you are using the dc to dc
 

Rhodeisland

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Joined
Jun 10, 2021
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well now that I know that I can use solar and DC to DC Charger my next question is this.
I have a SOK 206amp Hr battery. And my Nissan truck has a 130 amp alt.
would I need a 20 amp charger or a 40 amp. Needles to say I don’t want to damage the trucks alt.
 

chrisski

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Aug 14, 2020
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3,395
Only thing I will add is if the spec sheet says not to charge past 50 amps, I would stay controllably under that.

Had a 15 amp BMS and a 15 amp charger and the BMS at times would would shutoff charging. I limited it by setting the SCC to 14.9

The specs I looked at said max charge rate of 50 amps. Don’t know if this is an internal BMS limit or a cell limit.

A 400 watt panel could produce 24+ amps and a 40 amp charger will produce 40 amps. Either alone is fine, together they could exceed 50 amps. What happens then, I don’t know.
 
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