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Old 10-27-2020, 10:33 AM   #21
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How about a solar controller with two-bank charging? Something like this:

https://www.custommarineproducts.com...ut-series.html

https://www.amazon.com/EPEVER-DuoRac.../dp/B08534T16Q

I don't know anything about the brand but I'm sure others have them as well.

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Old 10-28-2020, 01:06 PM   #22
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I ended up following my own advice. The inexpensive Renogy Voyager 10A controller I'd installed failed after two days. Even though Amazon's return window had closed, they nicely agreed to a full refund.

Fortunately I had a 30A, dual battery bank, GoPower controller sitting around, waiting to be installed in my motorhome so I've installed it in the van instead. It's a PWM, which is fine for my van and its 100W panel even if it can handle more watts than I'll ever need on my van. I'll get an MPPT controller for my Motorhome and its 320W of solar that's yet to be installed. I'll save the Amp-L-Start for something else.

I installed it yesterday afternoon and things look good today. I don't drive the van that often so having the starter battery charge via solar will be great.
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Old 10-28-2020, 02:42 PM   #23
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Originally Posted by boywonder View Post
..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?
My solar controller is the Victron 100/30 mppt
I have it set to charge the agm starter. the dc dc charger set to charge the lithium house. If there is possible complications about this set up I’ll just have to deal with no solar going to my starters.
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Old 10-28-2020, 08:23 PM   #24
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You should check the solar charger to understand what phase of the charging cycle it is in. If both you house and starters are full you would want it to show a float voltage. I would the check when the starter was full and the House was at varying SOC levels, to see if the DC to DC charger actually makes the Solar controller go into Bulk or Absorption levels. Either one of those would could possibly be overcharging the starter battery and defeating the whole reason you doing it this way.

It make work fine, I haven't ever tried it myself, but I can certainly come up with scenarios that may be problematic.

If you see that you are always seeing the solar charger stay in float once the starter is full, then I would again go and check to see what amount of charge you are putting into the house batteries at different SOC levels. Being in float not only reduces the charger output voltage but also reduces current. In this case your solar system wouldn't be doing justice to your house system.

You may be able to mess with the charging parameters (absorption time, tapered charge level) and get some different results.

-greg
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Old 11-01-2020, 12:39 PM   #25
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You could run at 300 watt or better inverter off the house battery. And then plug a high-quality AC battery charger into that and use that to charge the starter battery.
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Old 11-02-2020, 06:56 AM   #26
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We are in the process of switching our house bank from AGM to lithium, also not liking the loss of the dual connectivity from our ACR. In rereading the manuals for our existing components, we installed the original system over 5.5 years ago, we discovered that our Blue Sky charge controller has a 2 amp auxiliary output for a second battery bank. We have removed the ACR and have replaced it with a 30amp Victron DC-DC charger (non-isolated). We have also installed connectors for a 110 battery charger, also a Victron, with the plan to use it only when necessary but the charge unit itself is not installed. That will enable us to also connect the charger to the van batteries if we feel we need to put a charge on them. As it is now, our primary solar output from the charge controller is connected to the house bank and we have decided to not connect the auxiliary output to the van batteries at this time.

What we do want to share is that we have installed an on/off switch for the DC-DC charger and a blue seas circuit breaker switch between our 255 watt solar panel and the charge controller. This enables us to disconnect all charging sources from the lithium bank since lithium should not be recharged daily, the opposite of what our previous AGM bank preferred. Today, we will be replacing our battery meter and negative shunt with a Victron Smart Shunt, giving us expanded metrics via Bluetooth only. We don’t have a separate BMS so we will manually re-charge by turning on the appropriate source as needed, usually turning the source(s) off once the lithium bank is close to 85% and only fully recharging the house bank every 20-25 days. If you have installed a BMS you can configure it to do this automatically by setting minimum and maximum set points with a full charge exception every 25 days...kind of what the latest smart phones do to extend the battery life. Since we live in the van, manual is fine for the time being.
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Old 11-02-2020, 10:07 AM   #27
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What's an ACR?
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Old 11-02-2020, 10:18 AM   #28
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Automatic Charging Relay , The usual suspects are the Blue Sea 7620 or 7622 but they have others.

-greg
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Old 11-02-2020, 10:45 AM   #29
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Yes, an Automatic Charging Relay...sorry for speaking in acronyms. The advantage of an ACR is they will automatically combine the banks when either one hits a certain voltage, 13v in the case of our Blue Sea Systems 7622. In essence, charging both banks on either solar, the alternator, or both. There is an override switch on the top of the unit, the 7622 also has a remote button to make joining or manually disconnecting the banks easier. In a pinch, you can join the banks to jumpstart yourself. Blue Sea Systems now has a Battery Link which is an ACR combined with a world charger. If we were to stick with AGMs we would have switched to it but it requires the system to be completely 12v, which ours is.
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