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Old 09-04-2016, 10:34 AM   #1
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DC-DC Chargers. Recommend a good one?

It's time to start building the electrics on my bus.

I'd like to be able to put some charge into the house batteries from the bus's alternator as I motor along. One of the few things I don't have on hand is a DC-DC charger.

What charger works for you? Could you recommend a good one?

Thanks
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Old 09-04-2016, 11:11 AM   #2
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im no electric expert but i'll give you my 2 cents.

to charge house batteries from your alternator, you should just need to run a hot wire from the truck battery to the house battery. on that wire, you'd install a battery isolator, to separate the 2 systems when your key is off. some isolators are electronic, some use a solenoid to seperate the systems.

i've heard, but don't know about possible issues with the size of your altenator. too small an alternator could burn up trying to charge too many batteries.

in my mind, when someone says a dc-dc charger, i think of one that changes voltage, like one that converts 12v to 24v
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Old 09-04-2016, 11:34 AM   #3
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Yeah, turf is right. You should really only need a battery isolator and a beefy length of welding wire connecting your house and chassis batteries if you're doing 12V house batteries. If you're doing 24v or 48v house batteries (which is an excellent, albeit complicated, idea) you then need a DC-DC converter. Those are pricier and harder to find. Sterling-power makes some of the best. Try them. Sterling Power Products
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Old 09-04-2016, 12:17 PM   #4
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I don't believe that you are correct. An automobile alternator is PERFECT for SLA (starting, lights, accessory which are sometimes called Cranking Batteries) batteries, but will not give a sufficient nor proper charge for deep cycle house batteries.

Folks might be doing it, but I don't think they are getting all the life they could be from their Deep Cycle Batteries because an alternator does not put out enough volts properly.

To help explain it, please read this: https://www.caravanworld.com.au/feat...gers-explained

BTW, I should have mentioned:

I have a 2000 GMC Savana van based schoolie. 6.5 Turbo Diesel with a stock 100 amp alternator.

I have 3 deep cycle 12VDC house batteries.

I'd like to install a DC-DC charger in my system. Could somebody recommend one?
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Old 09-04-2016, 01:01 PM   #5
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cool beans, i like the theory of a transformer charging off of the alternator.

i've been resigned to at best, leave home with the battery bank at 100% and and then only be able to recharge up to 80% while on the road, from a generator.

when i google dcdc chargers, i see converters. show some links.
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Old 09-04-2016, 02:01 PM   #6
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Quote:
Originally Posted by turf View Post

when i google dcdc chargers, i see converters. show some links.
I googled dc-dc battery charger 12vdc:

DC Input Battery Chargers for Lead Acid and SLA Batteries, for charging batteries from vehicles and other low voltage sources, 6 Volt, 12 Volt, 24 Volt, 36 Volt, 48 Volt, 12V

Somebody here must be using one of these or something like it.

It's Labour Day. I'll bump this thread when folks get back Tuesday.
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Old 09-04-2016, 04:23 PM   #7
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I have a 140 amp smart isolator (keyline 140amp dual battery isolator on amazon) from my start batteries to 2 auxiliary batteries. Cuts in at 13.3v and cuts out at 12.8 volts. My Aux system is small with a 12v bank of 225ah at 50%. The isolator coupled with 300 watts of solar work well together.
When I upgrade my battery bank I'll do away with the isolator to not overwork my allternator, and add more solar.

I consider my set up temporary and a great test run to figure out our needs power wise.
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Old 09-04-2016, 07:35 PM   #8
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What I would recommend is a charge controller. Sometimes called a solar
charge controller. These come in numerous sizes and types, the best being
MPPT controllers. The one I'm using has inputs from numerous sources like
solar panels, alternators, wind chargers etc. Basically this unit takes various
inputs and combines them and controls them to properly charge the type of
batteries you have on board. Should work good for your purpose and leave
room for expansion in the future.
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Old 09-06-2016, 02:34 PM   #9
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Quote:
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What I would recommend is a charge controller. Sometimes called a solar charge controller. These come in numerous sizes and types, the best being
MPPT controllers. The one I'm using has inputs from numerous sources like
solar panels, alternators, wind chargers etc.
Brand name? Although I don't think I'll get involved in solar ... I learned a long time ago never to say never.

I did find this one. https://www.amazon.com/Flexcharge-NC.../dp/B000C168ZS

Comments indicate that "It can be used with Wind, solar, other DC alternators. It is a hackable / expandable controller.

This unit does not include a blocking diode (this prevents the power from the battery flowing back to your input source)."
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Old 09-06-2016, 06:32 PM   #10
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how does an alternator not charge house batteries well but does charge starting batteries? 14 volts is 14 volts regardless of what battery its going to.. my AGM batteries are 12.6 just like my starting batteries...

I have to think that driving the bus hours at a time is giving my batteries a good charge.. I would say that short trips wont charge an AGM deep cycle battery as much as a standard wet cell.. as the deep cyclers tend to require more time of "trickle charge" than the regular wet cell..

I venture to say a lot of us when we run our buses are running for long periods of time as opposed to a 20 minute trip here and there with dead house batteries between..

-Christopher
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