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12v power source for electric steering

Posted: Sat Dec 15, 2018 5:38 pm
by Derrickbwg
Will someone explain the difference between a 24v/12v converter and a 24/12v charger? Ive tried to keep the trucks all 24v (winch,usb chargers, cb's, compressor) due to my experience losing 2 inverters on rv's. I'd rather not count on a converter to run a winch or something critical. I don't have much choice with the power steering and worst case if it fries I'm back to good old armstrong power steering, not a critical issue.

After reading every post about converters...I'm still confused. Some say a big enough converter will be fine stand alone, others use a 24/12 charger to a battery, then battery to the steering. Converters being able to be used as chargers comes up as well.

Whats the difference between the two? Are they essentially the same and offer similar reliability/ruggedness or would one be a better choice for the pinz?

One post on the steering was based on the converters inabilty to supply enough juice to turn the wheels easily(or at all) when on rocks. I'm not sure if this was an isolated issue....would the charger/battery setup improve this condition on a pinz?

Thanks!

Re: 12v power source for electric steering

Posted: Sat Dec 15, 2018 7:07 pm
by rmel
A converter will produce a DC output that is intended to be used with a direct
connection to a load, e.g. electronic devices etc. etc. there are two types
"Buck" and "Boost". In the case of 24V IN and 12V OUT that is a Buck converter,
the flip would be a Boost (12V to 24V). They need to be sized properly to the load.
A good rule of thumb would be never have the total consumed load current exceed
80% of the converters capability -- that's called margin, this extents the reliability
of the converter SIGNIFICANTLY and guarantees a clean DC output with low ripple
voltage. Second, IMHO use converters that are convection cooled e.g. no internal cooling
fan -- for obvious reasons dusty trials eats fan bearings. Though, convection cooled
electronics do need proper airflow. Converters are an excellent choice for electronics,
EFI/ECU's, and your power steering motor. There are several companies out there are
are very high quality, there are many companies out there that are total crap.

A charger is "battery" aware, they know they are charging a battery and don't give a
rats arsk about the load. A proper charger goes through several charging cycles;
Constant Voltage, constant Current, trickle -- simplistically speaking, some are more
complicated. A charger is only a charger and is not capable of stand-alone use. One
would use a charger over a converter if you already had an Aux 12V Battery. A charger
can be GROSSLY undersized to the load and still be fat dumb and happy as the Battery
is what is serving the load NOT the charger. For instance you could have a 100AH
Battery with a 15,000 lb Winch with a 500A peak current -- with a 2A charger and all
would be good. Of course it would take eons to re-charge the Battery with only 2A but
it would and all would be cool.

Re: 12v power source for electric steering

Posted: Sat Dec 15, 2018 10:15 pm
by edzz
Ron, very nice explanation I wish some of my EET instructors would have had the ability to word their explanations in a manner as understandable as what you provided. :D

Ed
73

Re: 12v power source for electric steering

Posted: Sun Dec 16, 2018 1:53 pm
by Hotzenplotz
Back to the initial question re: power steering.
I use the EZ tech 12 V system sold by EI in the US. It requires a max of 40 amps on 12 V, but I have additional consumers in the 12 V subnet.
So i decided to install a 12 V panel behind the passenger seat. This panel holds a 25 ams 24 to 12 v charger and a 20 Ah motorcycle battery.
The one thing you have to be careful about such a setup is common ground for both systems.
I had reverse currents on the charger originating from the batter, so I installed a relais that disconnects ground from the 12 v system when igniton is off.
Now everything runs as expexted

Re: 12v power source for electric steering

Posted: Mon Dec 17, 2018 8:28 am
by 63rover
With the power steering needing variable amperage draw up to 40 amp, I would suggest wiring a feed off the down-stream battery and adding a battery equalizer to maintain the voltage balance between the two batteries. An equalizer is relatively inexpensive. I found mine for $20. It is capable of a 5 amp draw in either direction which would equalize the demand of the power-steering very quickly. I added a 4 circuit fuse panel and two pairs of 12 v outlets for the accessories. The fuse box is mounted on a piece of wood so that a ground point could be added that was insulated from the body. (Don't try to run the 12 and 24 with the same ground.) I would offer photos but my truck is stored for the winter with too many things in the way.

A nice bonus to this setup is that a 12 v battery charger, up to 12 amp, and even a trickle charger to keep the batteries topped up can feed both of the batteries back through the 12 v system, with the second battery being fed through the equalizer. It is much less expensive than a 24 v charger.

Good luck with the project.

Cheers, Clive

Re: 12v power source for electric steering

Posted: Mon Dec 17, 2018 10:54 am
by rmel
he fuse box is mounted on a piece of wood so that a ground point could be added that was
insulated from the body. (Don't try to run the 12 and 24 with the same ground.)
Although I would agree an equalizer is certainly a workable solution, IMHO it's not the best solution.

As you point out it's all about Ground, and tapping of the midpoint has compromises. With a load
of any kind connected to the midpoint, you now have potentially a ground return path for the top
battery -- which can become a discharge path. You have to make sure things are not only turned off,
but do not have any internal leakage paths.

You could try to connect all grounds of the devices you are powering off the midpoint back to the GND
terminal of the bottom battery so that the ground switch isolates these devices -- that's a MAYBE. You
have to make darn sure anything you bolt to the truck like a radio or the power steering unit is not a
ground itself thus defeating this approach. If that all works out and now you have eliminated any
unwanted paths, you now have a somewhat compromised grounding system. More so for electronic
devices such as Radios. You really want the radios chassis hard grounded to the truck chassis and not
indirectly connected to ground. Otherwise you will fill your truck full of RF and have a lot of noise.

Like I said, you can make this work but you gotta manage ground very carefully, and possibly live
with the fact that interrupting ground with the ground switch may be partially defeated.

Is there a best solution? All depends upon what your trying to achieve.

If this is just for power steering ONLY and perhaps some limited +12V use. I'd go with a DCDC converter.
It can be very robust if you pick the right converter and sized properly. If you have multiple usages for
12V power; power steering, fridge, radios etc etc. Then you may want to go with a more general purpose
solution with a decent sized Aux 12V battery and a 24V-12V charger. You could also get a dual input charger
that supports both Alternator and and solar as input. They ain't cheap, but you could fit a 50AH LiFePO4
battery in the existing battery box. These Lithium Iron batteries are a fraction of the size and weight of a
Gel cell or Lead acid and will NOT catch fire. I've seen a couple of people squeeze a 3'rd battery of this
size in that compartment.

Re: 12v power source for electric steering

Posted: Mon Dec 17, 2018 4:08 pm
by 4x4Pinz
I just used the converter that Ei sells with the power steering unit. Has been working very well and lots of hours of operation both on and off road. I also have a converter for convenience with a fuse block for the individual items in the cab area. I also run a solar system with a couple batteries in the back of the pinz for the camping items. I even went to the trouble to add a 120v plug so that when at a site which provides power I can plug in and charge batteries and run fridge along with other 120v appliances in truck.
Lots of ways to attend to the need for 12v but all require care be taken to not allow crossing of power sources. The best solution is up to the individual and how they use their truck.

Re: 12v power source for electric steering

Posted: Tue Dec 18, 2018 9:10 pm
by tgreening
Pictures or...uhm...none of this happened? Seriously, pics for us electrically challenged folks. :)

Re: 12v power source for electric steering

Posted: Thu Dec 20, 2018 6:06 am
by Hotzenplotz
I'll see my Pinz this weekend and get you some pics

Re: 12v power source for electric steering

Posted: Thu Dec 27, 2018 9:38 pm
by TechMOGogy
I have 2 60 amp converters with 2 12v fuse blocks as both my EFI and power steering use 12v.
The idea was to always be able to power the EFI
No clue about the charger, I just did what Jim L needed for EFI and what EZ and EI recommended for the electric PS.
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