DC/DC charge controller
- Thread starter rick2b
- Start date
fat_old_sun
Solar Enthusiast
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- Nov 16, 2019
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multiple options - renogy has a 20 amp @ $125 & a 40 amp @ $190. Sterling 60 amps @ $370 & bogart 30 amps @ $120 and .....
RandyP
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- Sep 21, 2019
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.....and renorgy RBC50DS1 dc-dc battery charger with mpp solar controller, and RedArc BCDC1240D dc-dc battery charger with mppt solar controller. Make sure your truck alternator can handle charging the liFePO4 battery, might have to upgrade the alternator or duty cycle the dc-dc charger depending on the charge current delivered to the second battery by the charger and the alternator output current rating.
RandyP
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Most good dc-dc battery chargers have some logic built into them. They generally do not take power from the alternator until it has recharged the vehicle starting battery to 13.2v or more.
You can cheat on the wire size from the starting battery to the DC-DC battery charger a little. a little voltage drop there is usually tolerable, the dc-dc charger can boost it back up to the desired charging voltage for the aux battery within limits. you do loose some power in the wiring, but it still works if the alternator is rated at sufficient amp output and you can keep it cool enough.
You can cheat on the wire size from the starting battery to the DC-DC battery charger a little. a little voltage drop there is usually tolerable, the dc-dc charger can boost it back up to the desired charging voltage for the aux battery within limits. you do loose some power in the wiring, but it still works if the alternator is rated at sufficient amp output and you can keep it cool enough.
RandyP
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Battleborn sells a load modulator for dc-dc chargers where the LiFePO4 batteries are big enough to kill the alternator during continuous charging. But if you are carefull I think charging one 100AH LiFePO4 battery thru a 40a dc-dc battery charger from an alternator works most of the time without burning the alternator up.
battlebornbatteries.com
LiFePO4 Battery Isolation Manager (BIM)
LiFePO4 Battery Isolation Manager (also known as the BIM) monitors voltage and connects and disconnects batteries when needed. Click here to read more!
battlebornbatteries.com
hiuintahs
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- Nov 19, 2019
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First time post here. Have liked what I've seen here and so thought I'd sign up. I'm a semi-retired electrical engineer or maybe that is underemployed, LOL and having a lot of fun with projects. I have always been interested in power control throughout my career and have designed my own lithium ion battery chargers (the 18650 size) and NiMh charger. I've done other projects like design the entire solar and electrical system for my nephew's sprinter van and right now I'm designing a portable setup for use in the back of my F150 truck which will have one of those overland looking type of campers on it. (Snap Outfitters). I wouldn't consider myself a solar expert, but with the electronic background.........doesn't take me long to catch on.
So here is my first comment to this thread: If wanting to charge an auxillary battery from the vehicle's battery/alternator, you really need to have a DC-DC charger which will compensate for the loss of voltage in the cable run, manage current and do the whole charging process properly without draining your vehicle's starter battery. I chose the Kisae Abso DMT1250 50 amp charger. I don't need that much current, but this charger allows you to set the charge current in 5 amp increments. That pretty much allows me to chose whatever battery I want. Also it has solar input too.
So here is my first comment to this thread: If wanting to charge an auxillary battery from the vehicle's battery/alternator, you really need to have a DC-DC charger which will compensate for the loss of voltage in the cable run, manage current and do the whole charging process properly without draining your vehicle's starter battery. I chose the Kisae Abso DMT1250 50 amp charger. I don't need that much current, but this charger allows you to set the charge current in 5 amp increments. That pretty much allows me to chose whatever battery I want. Also it has solar input too.
hiuintahs
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- Nov 19, 2019
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Ah yes you figured it out....LOL! My other interests have been with the outdoors, backpacking etc, so thought the name fit. hiuintahs is also my forum name on candlepowerforum and budgetlightforum. Have had a huge interest in LED flashlights ever since they first started coming out. This is only the 3rd forum that I have ever signed up for. Hope to learn more from here.
Oldtimer
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- Nov 23, 2019
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What is a good DC to DC charger for a 24 Volt Alternator say for instance i am using a 40 Amp 24 Volt Alternator. Do they make a Solar Charger all in one with a DC to DC converter ? also if anyone has a diagram to add a DC to DC converter to a Solar Charging System.
hiuintahs
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- Nov 19, 2019
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The Kisae Abso DMT1250 that I mentioned above will handle either 12v or 24v alternator. Also it's solar input can be either 12v panels or two in series for max voltage of 45v. I'd suggest downloading the manual which talks about it in more detail.
JeepHammer
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- Nov 15, 2019
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The issue with a vehicle alternator is the voltage regulator.
Newer alternators don't have the voltage spike issues (pre-computer cars) had, but they are very capable of 120-200 amps, or more,
That can be a problem 'Charge Controllers'.
A vehicle alternator is designed for lead/acid batteries, which are very tolerant, metal batteries not so much, they like clean, consistent power at a slow charge rate.
Vehicles do NOT have a clean, consistent use of power,
From air conditioning clutches cycling on/off, DC motors creating line noise (cycling), ignition systems cycling, brake/turn signals cycling, it all makes erratic loads on the electrical system.
The second issue is a preset voltage in the regulator, between 13.5 & 14.5 volts.
The 'Optimum' charge voltage for the lead/acid batteries.
-----------
SO FIRST,
You have to clean the power supply up A LOT.
I'm NOT an Electrical Engineer, so the easiest COMMON way I found was with capacitors.
(The same way alternator capacitors take the 'Ripple' out of rectified AC to DC power)
Since high powered ignition systems use capacitors to smooth out electrical system noise, and they are available, I used them.
I used diodes to isolate the the second battery type from the vehicle system.
Then it was a DC to DC power converter, a DC to DC 'Buck' converter.
I had to jack the power around a little to match the charger volt/amp requirement of the charger.
Then the battery charger with thermal sensor.
-------------
No one wants to hear this,
But a second alternator, isolated 'Ground' (Negative) and adjustable voltage regulator is actually the 'Easy' button.
24 volt alternator on a 12 volt vehicle is not an issue with isolated 'Ground' (negative).
12 volt 'Source' will Excite a 24 volt alternator in the event residual magnetism doesn't start the charging process.
Voltage is adjustable means about 20% up or down in voltage output to match charge controller.
With an additional (1) capacitor, the line voltage is maintained, and the line noise is reduced to almost zero.
With line voltage constant, then it's off to the charge controller directly.
As long as you use a charge controller that can handle the volts/amps from the alternator you are golden.
I use a small amp Leece-Neville alternator,
Isolated negative, adjustable regulator, common and dirt cheap, all over salvage yards & rebuilt surplus sites.
I use them for welders, since the AC taps are exposed, they will even produce high frequency AC easily.
With regulator removed and direct access to rotor, it's continuous voltage controllable, an adjustable power supply, assuming constant engine speed, a simple rheostat controlling rotor power, and you can control output voltage/amperage.
A double pole, double throw switch to control rotor, you can switch back & forth between voltage regulator & manual control, with wiring harness attached, it charges batteries,
With welding leads swapped for harness, and manual control of rotor it's an adjustable welder with considerable capacity.
--------
Watts are Watts, what you do with them is your business...
Newer alternators don't have the voltage spike issues (pre-computer cars) had, but they are very capable of 120-200 amps, or more,
That can be a problem 'Charge Controllers'.
A vehicle alternator is designed for lead/acid batteries, which are very tolerant, metal batteries not so much, they like clean, consistent power at a slow charge rate.
Vehicles do NOT have a clean, consistent use of power,
From air conditioning clutches cycling on/off, DC motors creating line noise (cycling), ignition systems cycling, brake/turn signals cycling, it all makes erratic loads on the electrical system.
The second issue is a preset voltage in the regulator, between 13.5 & 14.5 volts.
The 'Optimum' charge voltage for the lead/acid batteries.
-----------
SO FIRST,
You have to clean the power supply up A LOT.
I'm NOT an Electrical Engineer, so the easiest COMMON way I found was with capacitors.
(The same way alternator capacitors take the 'Ripple' out of rectified AC to DC power)
Since high powered ignition systems use capacitors to smooth out electrical system noise, and they are available, I used them.
I used diodes to isolate the the second battery type from the vehicle system.
Then it was a DC to DC power converter, a DC to DC 'Buck' converter.
I had to jack the power around a little to match the charger volt/amp requirement of the charger.
Then the battery charger with thermal sensor.
-------------
No one wants to hear this,
But a second alternator, isolated 'Ground' (Negative) and adjustable voltage regulator is actually the 'Easy' button.
24 volt alternator on a 12 volt vehicle is not an issue with isolated 'Ground' (negative).
12 volt 'Source' will Excite a 24 volt alternator in the event residual magnetism doesn't start the charging process.
Voltage is adjustable means about 20% up or down in voltage output to match charge controller.
With an additional (1) capacitor, the line voltage is maintained, and the line noise is reduced to almost zero.
With line voltage constant, then it's off to the charge controller directly.
As long as you use a charge controller that can handle the volts/amps from the alternator you are golden.
I use a small amp Leece-Neville alternator,
Isolated negative, adjustable regulator, common and dirt cheap, all over salvage yards & rebuilt surplus sites.
I use them for welders, since the AC taps are exposed, they will even produce high frequency AC easily.
With regulator removed and direct access to rotor, it's continuous voltage controllable, an adjustable power supply, assuming constant engine speed, a simple rheostat controlling rotor power, and you can control output voltage/amperage.
A double pole, double throw switch to control rotor, you can switch back & forth between voltage regulator & manual control, with wiring harness attached, it charges batteries,
With welding leads swapped for harness, and manual control of rotor it's an adjustable welder with considerable capacity.
--------
Watts are Watts, what you do with them is your business...
