CTEK D250s, when is the smartpass really needed?

[JCDriller]

I'm planning my 12v build out in my 4R. I plan on utilizing a D250s, dual batteries under the hood, 1 100w solar panel mounted full time to the roof rack and a CTEK shore charger. This fall I hope to tie the system into a Conqueror 490 extreme trailer using a rear Anderson plug. I'm using the B2B since I don't think the 4R puts out high enough voltage to properly charge AGM batteries. However, I'm still not crystal clear when a Smartpass is needed. Can anyone shed some light on this? Anyone use the D250s/Smartpass combo?

 

[john61ct]

The main unit has limited amps.

Best design is to charge House directly from all charge sources, then the DCDC to just keep Starter topped up, hardly any current required.

If you don't want to do that, then the SmartPass allows high-amp current to bypass the main unit for Bulk CC stage.

Once Absorb CV starts to ramp down the amps, then the main unit takes over the charging algorithm.

Read the manual, PDF available online, they give lots of different scenarios.

 

[JCDriller]

The main unit has limited amps.

Best design is to charge House directly from all charge sources, then the DCDC to just keep Starter topped up, hardly any current required.

If you don't want to do that, then the SmartPass allows high-amp current to bypass the main unit for Bulk CC stage.

Once Absorb CV starts to ramp down the amps, then the main unit takes over the charging algorithm.

Read the manual, PDF available online, they give lots of different scenarios.

That is what I was thinking, the smart pass only boost the amps for faster charges for big batteries or big consumers. So basically I'll hook my solar and alternator up to the D250S, AC Shore Charger to the House Battery. I guess If for some reason the charge isn't keeping up, I can always add a smart pass later...

 

[john61ct]

I've read a few times the solar controller built into that CTEK isn't so great, if you get a chance to A/B test against a quality standalone please report back.