DC - DC charger for dual batteries with solar

[16CVs]

Has anyone installed a DC to DC charger in their van ? I have been looking at the Redarc BCDC and the Renogy unit.
My application is my work truck with 2 Trojan Deep cycle 12 V batteries that power a 1200 watt Pure Sine inverter I am using an switching relay now but realize that my batteries are not getting topped off as well as the should be.
There is a huge price difference between the two and am looking for any input.

Stacy
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1987 Syncro Westfalia Triple knob (bastard)
1989 Syncro Tristar Triple knob "Swedish"
2013 Jetta Hybrid a true "Zwitter"
Samba member # 14980
Call anytime number 650 722 4914 .
Keep Your van running and upkept tastefully for the love of the hobby.
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[beach_creature]

A Renogy was used in this build.
https://www.thesamba.com/vw/forum/viewtopic.php?t=723621

Seems like a number of people have been using the Redarc.

I’m still waiting for the Victron to come to market and see what it offers before making my purchase. It wa suppose to be on market this month. Hopefully soon.
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84 Westy
1.9TD AAZ
5spd manual with Locking Peloquin TBD

[dgbeatty]

We are quite pleased with Renogy 40amp unit. We have 140 amp hr lifep04 house batteries. A big improvement over our previous configuration. We also use a 1000 watt renogy inverter, but only very occasionally.
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Schau in das Buch

[tencentlife]

No need for such a special item to charge deep cycle lead acids, especially one with such low current as 40A. You'd do better to upgrade the current paths, use a high-current combiner, and install a remote adjustable voltage regulator in the same temperature environment with your secondary batteries.

https://www.240turbo.com/AdjustableVoltage.html
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[dgbeatty]

You do not mention the type of engine nor the type and rating of your alternator.
There are significant advantages to a DC-DC charger.
1. Prioritization. You choose which battery bank charges first and/or strongest
2. Charging profiles. Standard alternators up to about 2012 did not have any charging profiles, none. Many if not most newer cars do have multiple maps to improve several aspects one being fuel economy and charging speed and quality ie lower warranty cost.
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[16CVs]

I have a DJ spec 2.1 and a stock Alternator which is I think is 90 Amp.

Stacy
_________________
1987 Syncro Westfalia Triple knob (bastard)
1989 Syncro Tristar Triple knob "Swedish"
2013 Jetta Hybrid a true "Zwitter"
Samba member # 14980
Call anytime number 650 722 4914 .
Keep Your van running and upkept tastefully for the love of the hobby.
Don't let your van end up in an "abortions" thread.

[dgbeatty]

Stacy let's do a quick little test.
Drop the fuse panel
Connect a voltmeter to the 30 terminals on the left side.
Run the engine for a few minutes and then measure the voltage with the headlights etc on. What was the result?
You now know why a DC-DC charger is needed for optimum performance.
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Schau in das Buch

[rmcd]

Ctek smartpass and d250s dual. Supports AGM (and now lithium) with proper charging profiles for appropriate battery types. There are newer models and the price has gone up to $650.

Plug and play dual batteries and MPPT controller. Seems pretty simple to me.

Here is a good write up.
https://travelcandies-on-tour.com/jeep-wrangler/ctek-dual-battery-and-solar/
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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=

[dgbeatty]

The CTEK items listed above are of the highest quality.
But if you add the recommended M300 charger the price is about $1100! Plus they are large pieces. Ideal for a large motor home with 300-400 amphours of lifep04 batteries but >$5000 which I guess is insignificant in a $300k and up bus.
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Schau in das Buch

[rmcd]

Agreed not inexpensive. But Kind of plug and play -so far. Granted haven’t done a lot of monitoring.

Big footprint? I jammed all the Ctek components, an aux panel With relays, all the shut offs, 90amp hour battery and An iota 110v shore charger under the driver seat. Certainly not easy and took a lot of head scratching.

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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=

[revolution337]

Seems CTEK has since released a newer version of the D250S, the new D250SE. In looking over the specs of the new unit, it seems as though not much has changed. The main difference is the addition of lithium charging abilities. In my searching, most of the installs of this unit I've seen are more overseas in Europe. In fact, most of the reviews on amazon are in languages other than English.

It seems like a very nicely optioned unit though. Pricing wise, it falls right between the lower priced Renogy DCC50S and the higher priced Redarc BCDC1225D. The CTEK is rated at 20amps, the Renogy at 50 amps (also, a 30 amp model available) and the Recarc is 25 amps (also a 40amp version available). All three have built in solar MPPT.

The only downside I can see to the CTEK compared to the others is the lower solar VOC input, at 23 volts. The Redarc accepts up to 32v, and the Renogy manual states it can handle 25v.

https://www.ctek.com/au/all-products/leisure-sport/d250se

https://www.amazon.com/CTEK-Power-40-315-D250SE-charger/dp/B07X4YTP1P

Thoughts on this CTEK unit? I'm currently building an AUX battery setup with a 100AH AGM battery, but would like to "future proof" myself by having lithium charging as an option.
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1982 Westfalia AEB 1.8t
2017 VW Golf Sportwagen
2001 Audi A4 4.2 V8 swapped
2000 BMW Z3 roadster
-Mark

[owokie]

[revolution337]

[owokie]

[revolution337]

[gtinseth]

I use a Sterling BB1230 for the DC-DC charging (with an upgraded 135A alternator in my EJ22) and the Epever 3215BN MPPT for solar. Both are 30A capable and both can deal with LiFePO4 batteries as well as all the other Lead batteries. Around $400 for both and no single point of failure like the all in ones.

[dobryan]

FWIW I am in general not a fan of all-in-one units. If they fail you lose all avenues of charging. Individual components give the ability to charge from solar if DC fails and vice versa. The all-in-ones do allow combining solar with DC charging when applicable however.
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Dave O
'87 Westy w/ 2002 Subaru EJ25 and Peloquin TBD

"To travel hopefully is a better thing than to arrive." Robert Louis Stevenson

MD>Canada>AK>WA>OR>CA>AZ>UT>WY>SD
https://www.thesamba.com/vw/forum/viewtopic.php?t=620646

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https://www.thesamba.com/vw/forum/viewtopic.php?t=695371

The Western Syncro build
https://www.thesamba.com/vw/forum/viewtopic.php?t=746794

[Jamos]

I'm interested in installing one of these Victron units that you link to below.
I have a 120amp alternator, and with a cable run of about 5 feet from my primary battery over to my aux battery location, I'm trying to determine what wire and circuit breaker(fuse) size to use.

The Victron looks like it outputs a maximum of 18amps, so I can't think it would pull much more than that, but I'm not sure.

Can you advise or show how you connected your system?

Many thanks!

[vanagonjr]

[Vanuber]