Aux setup with solar that keeps both batteries topped up?

[sphet]

What isolator/dc-dc chargers, or other electronic appliances can let me install solar with an aux battery, but allow the solar to keep both batteries topped up? I don't drive my van often enough to keep the starter fully charged, so I was hoping if I install a solar panel it could keep both batteries charger.

I park on the street so shore power tender isn’t an option which is why I am wondering about trickle charging the starter.

I know the Renogy MPPT DC-DC charger is an option but it has mixed reviews. Are there any other options?

Sorry if I missed an existing thread but I couldn't locate any.

S
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1982 Diesel Westfalia 1.6 NA - The Shellakabuukiee

[valvecovergasket]

The Blue sea ACR, or really any ACR or combiner should work the same, should combine both once it senses the raised voltage on one side from the solar.
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MegaSquirt resource - SpitfireEFI.com

gone, but not forgotten: '83 tdi westy - swap thread

[bobbyblack]

This may have been covered before, I'm a bit foggy on it.

BUT, in my imaginary world, these two functions are separate animals. The Solar stuff is a jack rabbit, and it is set up to keep the House system as charged up as is good (you know, of course that House battery is a moving target, in terms of how charged up it should be, depending on how you use the stored energy, right?) Anyway, the Start battery looses about 1% of its stored energy each day, if completely disconnected from any draw, so, there is already a Newt or a Slug sucking on it, and its is just internal to the nature of that beast.

Best scenario is to keep the Rabbit and the Newt in separate cages. They don't' want to be together anyway! They think that the other one is totally gross.

Get yourself a transfer switch, and wire it up so that when you get to a site that has shore power, you can flip it over. The Start battery should have it's own Maintainer charger. Use an Inverter or shore power setup, with that transfer switch to power that battery charger, it doesn't need to be much, a 2A maintainer would probably do what you want.

BUT, the two systems should be separate, no doubt about it.
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'87 Westy 'Flossie','86 Westy 'R1','86 tintop GL - Subi2.2 'J2','83.5 stock tintop L 'ZoomBus','74 Karmann Ghia, '63 Notch

[sphet]

Bobbyblack, thanks for your response. I forgot to mention that I park on the street so a shore power tender isn’t an option.
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1982 Diesel Westfalia 1.6 NA - The Shellakabuukiee

[fxr]

[sphet]

[kourt]

I'm going to echo bobyblack on this one.

My SLA group 41 starter battery is charged by the alternator only.

My LiFePO4 200AH house battery setup is managed by a Redarc DC/DC charger. That charger accepts inputs from the alternator or a 240W solar array on the roof. I also have a Victron IP22 blue smart charger for shore power charging of the house battery bank.

In this setup, there is no combination. The house battery serves its various purposes. The start battery starts the van. Period.

The fundamental problem with your subject is the inherent differing chemistry of the best starter battery (which is still sealed lead acid) and the best house battery (which is now Lithium Ion). There are one or two products out there that try to manage both battery systems. Those systems don't accomplish anything, really.

Build your van so that the starting battery just starts the van, and keep your engine's charging system (alternator) healthy.

After seven years, and several other complicated setups, I have landed on the system I describe above, and it's the best. The rabbit and the newt should be kept separate.

kourt

[sphet]

[kourt]

Yes, the Victron shore power charger can still charge batteries while they are under load. It's a recent addition to my system--completely unnecessary, really--but I've always maintained a shore power charging setup for the house battery, "just in case".

The starting battery is something I leave to a healthy alternator to manage, and it works best that way (and plan to replace a starting battery every five years is also good).

kourt

[fxr]

[Howesight]

If you plan on going to LiFePo4 batteries anytime soon, then the DC-DC chargers make sense. Here in Canada, they are not cheap, but I happen to love my Redarc 40 amp unit (next size up from Kourt's Redarc unit).

If all you want is to enable battery separation plus solar charging, then the Surepower 1314 will do the job. When it senses that 13 or more volts is available (I may have this spec slightly wrong), then it connects the house battery to the starter battery to allow the house battery to charge. The Yandina and the Samlex battery separators both work on the same principle.

The DC-DC chargers are a whole different ball game. They take the power available at the starter battery when you engine is running, and bump up the voltage to the correct profile for the battery type you select. They do the same when you have lots of solar power. In short, without getting too technical, they charge your house battery far faster than simply using a battery separator.

The Redarc units have outstanding reviews. The Renogy units have either great reviews or terrible reviews. It appears that the Renogy units either work or they fail early with poor customer service on returns. Hopefully, they will get their quality control addressed and then keep their lower price point compared to the Redarc.

Sphet, if all you need is a battery separator, PM me as I am selling my Samlex unit and I am in Vancouver.
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'86 Syncro Westy SVX

[sphet]

Howesight,

Your answer has made me rethink the possibility of a 50ah LiFePo4. I like the lower weight and deeper discharge since my van is underpowered, but my 60amp EDIT 65amp alternator only puts out 14.1V, sometimes a bit lower when the fridge is on DC, headlights, etc. Will a DC-DC charger be able to get the voltage high enough for a LiFePo4 battery at the tradeoff of lower amps? If not then yes, I guess just a combiner and a lead battery would work.

S
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1982 Diesel Westfalia 1.6 NA - The Shellakabuukiee

[Steve M.]

[sphet]

[ProspectiveOwnergon]

[Howesight]

Sphet:

The modern DC-DC chargers (of which I really know only the Redarc) are designed to take power from the starter battery (which gets its charging power from the alternator) and convert the voltage up to that which your house battery requires. You tell the charger what type of battery it is charging by the settings. In the Redarc unit, these settings changes are done by connecting certain signal wires together as set out in the installation instructions. In the Renogy unit, as I recall, you set dip switches.

Regardless, these DC-DC chargers charge your battery faster by providing the correct voltages and correct current, unlike using the variable voltages at your starter battery. Whatever the voltage at the starter battery to which the DC-DC charger is connected (to draw power, not to charge the starter battery), the DC-DC charger gives your house battery exactly what it needs to charge quickly and fully. Since LiFePo4 batteries can withstand high charging currents, the combination of a DC-DC charger and a LiFePo4 battery means your drive to the campsite can recharge your battery, depending, of course, on the size of your LiFePo4 battery adn its state of charge and depending on what current rating DC-DC charger you choose.

I would not suggest using only a 50A/h LiFePo4 battery if you are going LiFePo4. Go bigger - - prices are good now. Go for at least 100A/h.
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'86 Syncro Westy SVX

[DeLvxe]

I have similar setup to fxr and it has been working well and as you described.

With 120ah LIFEPO4 aux battery, 100 watt solar, and the Renogy DCC50s, once the aux battery is fully charged, power is sent to the starter battery to top it off. No bluetooth (except in the BMS), but the Renogy DCC50s has some flashing LEDs that let you know when power is going to the starter battery.

IDK about alternator requirements, I have a subaru engine engine and it just works.
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1991 manual camper with EJ25

[rmcd]

Here is a turn key solution that I'm running for DC-DC, Alternator charging, Solar charging and battery combine/separation. I also have an AC Iota for charging off the mains or my portable generator.

I will use it again with my VWLT build (580ah battery bank) except get the CTEK option that supports Lithium and lead acid batteries. Yes. With the correct charge profile(s) to support Lithium, AGM or regular.

And fits under the driver seat.

http://www.thesamba.com/vw/forum/album_search.php?search_keywords=ctek&show_results=summary
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VW LT40 build. Like a Vanagon but 30% larger in every direction and 40% slower even in metric.
https://www.thesamba.com/vw/forum/viewtopic.php?t=749359&highlight=

[Shonandb]

I decided to keep it simple and have the solar panels linked to my Aux battery only so they keep it topped up but rigged in a relay to connect the batteries if needed. (Aux used as a boost or a quick fast charge of the Aux battery if I run it flat)

I've seen others using a small solar panel on their dash to keep the Main battery topped up but haven't tried it myself as it hasn't been needed.

Here is a Link to a simple explanation of 3 options with pros and cons but it really seems to come down to how much you want to spend.


https://youtu.be/TAEzCcayI0g
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76 Westy with a 2.5L Subaru SOHC + Vanagon (010) Automatic Transaxle
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