Charging a second battery bank

[gkerlin]

I'm not sure if the Classic 150 has the capability to charge a second battery bank.

I'm using it in a Motorhome to charge a 900ah house bank, but need a solution to charge my chassis (starting) batteries when off grid.
I know that I can put in another device like an AmpL start to trickle charge them from the house bank but am curious if the Classic 150 can do it directly.

If I've read my manual correctly it looks like the max output of the Aux output would be 200ma which is not enough.   I'm looking for a min 1 or 2 amp charge capability.

[zoneblue]

There are several possible solutions for that:
- use a battery charger that runs off your inverter
- use a 24V house bank and 12v starter with a dc to dc converter, or
- use a DC boost converter to charge a 12v bank from another 12v bank.
- use the aux port to controll a contactor to join matching voltage banks togther when the controller is in float, or using waste not.
- use the dual battery devices that use MOSFETs or relays to join the banks based on voltage differences.

[gkerlin]

Wow...  thanks for the answer but some seems like a pretty complicated fix for a simple problem.  Change to 24v banks and dc to dc converter??

I'm really just interested in charging my chassis bank off of the solar.    A simple fix is to buy a Trik l Start for $50 and connect across my charge solenoid and be done in 5 minutes.   I just figured if my Controller had that capability I'd like to also consider that option.   

My original question however was simply if the Midnite Solar Classic 150 has the provision to charge a second bank.   I've owned A blue sky Solar boost 3000  and Tristar MPPT60 and both had outputs for a second bank.

I'm new to the the classic and the manual is about twice as thick as either of those so I thought with all the complexity perhaps I was overlooking something.   As I said from what I can gather - the best that I could do would be 200ma off of Aux 1    Aux 2 is being used by Whizbang.

Am I missing something?

[zoneblue]

Feel free to pick the ones that work and discard the rest. As i said, the classic can charge one bank. However you may use the aux port to control relays to connect the banks upon certain conditions. Waste not is one example, however float, or voltage threshold are other solutions. Just be sure to use quality contactors or SSDs. DC arcs are hard on those things.

[keppelk]

As I said from what I can gather - the best that I could do would be 200ma off of Aux 1    Aux 2 is being used by Whizbang.

Am I missing something?

Yes - I think you are missing something here. Use the 12V 200mA off Aux 1 to control a relay or SSD. The output from Aux 1 is for control/signalling purposes - not for supplying power directly. Any of Zoneblue's suggestions would work.

I would buy an AC rated relay that is actuated by 12VDC and use this to supply power to a decent plug-in AC lead acid (assume your chassis battery is lead) charger. A quality charger will ensure the chassis battery is charged properly (not over/under charged) and go to float once the battery is charged. Use the Classic's Aux1 diversion to control AC power supplied to the charger when house pack reaches the voltage you define in the Classic settings. This is a pretty cheap way of setting it up, but also reasonably simple/safe/reliable. ymmv

[gkerlin]

OK... thanks for the replies.  I figured from them that the answer is no - it cannot charge a second bank directly.

I went with a simple AmpL start device (which I think is Zone Blues final suggestion).  Connected it across my charge solenoid.  $50 and about 10 min work and done.  Works great - simple fix.

Thanks again.