Solar and Engine Charging

[rizzabove]

I hooked up the solar to the starter side of my dc/dc charger seems like it’s all working like I want it to be. I have the dc/dc charger-isolator set to turn off at 12.6v so there’s no drain from my starter battery’s. Thanks again Boywonder!

[BCam]

I'm wiring mine as follows:

1. DC-to-DC charger, charges house batteries from alternator.
2. Solar Controller connected to house batteries only.
3. Amp-L-Start, charging starter battery from house batteries. The Amp-L-Start protects the starter battery from overcharging and shuts off when the house batteries aren't receiving a charge from the solar controller.*

*It may not be necessary but I'm installing a relay so the Amp-L-Start won't be connected when the alternator is running since Renogy wasn't sure if it was OK to use an Amp-L-Start their DC-to DC charger.

[Scalf77]

Originally Posted by CDACamper

My van has an MPPT solar charge controller hooked up the house battery and the house battery is also connected to the engine alternator (stock SMB set up with Sure Power 1602 islolator). Is it ok to start the engine when the solar system is connected and charging via the MPPT or does this backfeed the MPPT and cause problems/overload/short?

There will be no backfeed from the solar charger to your starting system. You are using 1602 isolator, this is diode based so it would stop current going from the solar to starter.

Once the alternator is charging it will provide charging along with solar. It will not be additional charge, as the alternator will throttle back it charge based on the output of the solar.


If you were using a sure power separator(1315 bi-directional) or blue sea ACR then it could be possible that the solar controller charge was already connecting the two battery systems together, thus you would be starting the vehicle with both batteries. On the Sure Power the start assist could also do this. The Blue Sea ACR can be wired to isolate during start if you have sensitive equipment tied to the house battery.

Again, after the alternator is fully up and running solar and alternator charging can happen at the same time, but it will not be anymore than the alternator could put out (unless your maxed out)

Originally Posted by rizzabove

I have a question regarding the similar part of my electrical system. I have the “Victron dc/dc 30 isolated“ charger. it’s charging my house battery from my starter battery. It does not allow my solar power to charger my starter battery because of the isolator. My question is... can I hook up my solar input on the starter battery side of the dc/dc charger and have the solar power charge my starter battery then run though the dc/dc Charger to my house battery? Or do I just want to replace my dc/dc Charger with the non isolated version?

I love Victron products, but they are late to the table on DC to DC chargers. And then when they do, they confuse it by calling it an isolated DC to DC charger. DC to DC chargers are by their nature isolated, but while they can replace an isolator, separator, or ACR, they don't perform the same function.

They do have a remote on-off, which would allow you to put a charge on the starter and not invoke the DC to DC charger , or force it on. Some new functions probably nice if using their mini-BMS. I'm sure I might have missed something. If your goal is to use solar to charger your house battery with solar, putting on the starter side of the DC to DC charger could be problematic. Especially, if you solar capacity is lower than the DC to DC capacity. It might work but is not really efficient, and any gain your getting by charging starter is negated by the fact that the turn off is 12.6

Originally Posted by BCam

I'm wiring mine as follows:

1. DC-to-DC charger, charges house batteries from alternator.
2. Solar Controller connected to house batteries only.
3. Amp-L-Start, charging starter battery from house batteries. The Amp-L-Start protects the starter battery from overcharging and shuts off when the house batteries aren't receiving a charge from the solar controller.*

*It may not be necessary but I'm installing a relay so the Amp-L-Start won't be connected when the alternator is running since Renogy wasn't sure if it was OK to use an Amp-L-Start their DC-to DC charger.

I would expect that you need to isolate the input of the DC to DC charger while the Amp-L-Start is running when the engine is not running. Again, the output of Amp-L-Start could invoke the DC to DC to fire up and defeat the purpose of the Amp-L-Start. If the Renogy DC to DC charger has a off switch that is possible to tap into or use a high power relay on the input of the DC to DC. If Renogy can't answer that question I would send it back.

-greg

[rizzabove]

My goal is to charge my starter with solar along with charging house. House is lithium and starter is agm. The way I had it wired before was,
solar was wired straight to house and the dc dc Charger wasn’t allowing solar to get to my starter.

[BCam]

Originally Posted by Scalf77

I would expect that you need to isolate the input of the DC to DC charger while the Amp-L-Start is running when the engine is not running. Again, the output of Amp-L-Start could invoke the DC to DC to fire up and defeat the purpose of the Amp-L-Start. If the Renogy DC to DC charger has a off switch that is possible to tap into or use a high power relay on the input of the DC to DC. If Renogy can't answer that question I would send it back.

-greg

The Renogy DC-to-DC charger only operates when it senses that the ignition is "on" via what the manual calls a D+ ignition cable. I'll be using the voltage from the same cable to turn "off" the relay controlling the Amp-L-Start. Therefore, the Amp-L-Start will be out of the circuit any time the ignition switch is "on" and DC-to-DC charger is operating.

[Scalf77]

Originally Posted by BCam

The Renogy DC-to-DC charger only operates when it senses that the ignition is "on" via what the manual calls a D+ ignition cable. I'll be using the voltage from the same cable to turn "off" the relay controlling the Amp-L-Start. Therefore, the Amp-L-Start will be out of the circuit any time the ignition switch is "on" and DC-to-DC charger is operating.

Got it, make sense.

-greg

[boywonder]

Originally Posted by Scalf77

They do have a remote on-off, which would allow you to put a charge on the starter and not invoke the DC to DC charger , or force it on. Some new functions probably nice if using their mini-BMS. I'm sure I might have missed something. If your goal is to use solar to charger your house battery with solar, putting on the starter side of the DC to DC charger could be problematic. Especially, if you solar capacity is lower than the DC to DC capacity. It might work but is not really efficient, and any gain your getting by charging starter is negated by the fact that the turn off is 12.6

Greg: Are you suggesting to leave the solar on the house battery and use the remote switch to manually connect the battery banks when the desire is to charge the starting battery?


I imagine the 12.6V cutoff is configurable .....

[Scalf77]

No, because he has a lithium house battery, so that would complicate things. I don't think I would look at the starter batteries as my priority. There are a bunch of things that could go wrong depending on the state of each battery system. The solar charger is now looking at the load from the DC to DC charger and the starting battery. It is very possible that you could easily overcharge the starting battery depending on load of DC to DC charger. It would be something that I would want to monitor.

I will say I have never been a huge proponent of always charging the starters especially non AGM starters. The Victron gives him the ability to get around the 12.6 setting, if he chose to use the remote switch.

If I wanted to do this I would probably have a second controller go to the starter batteries. You could dedicate a small panel or divert one from the main controller if needed to top off the starter, or leaving parked for extended period of time. I would make sure that the DC to DC charger was only on when the engine is running.

Or I would look into Amp-L-Start that BCam is using.

There would be a couple of ways to top off starters without possibly compromising and/or loosing the efficiencies of your solar charger. My priority would be to take care of the lithium batteries, they cost to much.

-greg

[boywonder]

Originally Posted by Scalf77

No, because he has a lithium house battery, so that would complicate things.

-greg

..So his solar controller really should have a charging profile for lithium if he's connecting it to the house battery....


Rizzabove: What's the make/model of your solar controller?

[Scalf77]

Yes, or at a minimal be able to set the Absorption and Float settings to the required setting for his lithium battery. I expect he is setting the solar charger for AGM on the starter side and letting the Dc to Dc charger actually charge the Lithium house battery with a Lithium profile.

While this could work, you have the inefficiency of converting the solar panels power twice. Again my main concern is that the load to solar controller is now a AGM starter and the input to the DC to DC charger in parallel. I am just saying it is possible that this could create an overcharge condition, depending on the condition of the House and Starter batteries on the starter battery. It would be something I would sure monitor.


-greg