Stand alone 12V system for a 24V TD42

[safarifern]

So as the first mini project for the truck is complete, I thought I best give back so info and my experience to the forum as you guys have given a lot of help over the last 2 years .

Some back ground history …. I brought a Safari back in Dec 08 for one purpose only … 4WD Touring. “Touring” meaning out for 1 to 4 weeks in the bush. So I brought a whale … LWB with high roof (she has a queen bed in the back, for me and the misses thus the high roof ), she came with a 50mm lift, snorkel and warn winch and previous owner drove it from Bangkok to the UK so she had a lot of touring experience already.

The project was to make a 12V standalone system from the 24V system in the Safari. “standalone” meaning even when using all the power in the 12V system, when turning that key my Safari will always start first time! Also make sure other than some driving lights and the winch everything else electrical is 12V.
When I got the truck, the previous owner was up front and said both batteries are shot. He had been tapping 12V from the 2nd battery and if you been reading forums here you know that a no no!! So new batteries had to be brought, but also knew I would be charging a 3rd (house) battery which was to be big and deep cycle.



So the system set up:
To power all batteries and keep up with a winch / lights working very well! I had to upgrade the 35 amp alternator to a 70amp alternator. Just a quick side note, my 1st plan was to mount a 12V alternator below the original, but research and talking to people found that the low mounting got a lot of mud in it and became a continuing cleaning mission (plus no air con and my partner wasn’t too happy about that) this wasn’t a hard one, a place in Rotoura did a straight overhauled replacement for a decent price and I got reasonable bucks back from my old one. Note: the big black cable is the parallel cable to battery (goes to 50amp fuse and turns into blue cable)



To charge the house battery I got a 24V to 12V 3 stage charger unit. Note the “3 stage”. A lot of people charge a house battery with a reducer, this is a bad idea. It doesn’t drop voltage so will cook the battery in time and deep cycle one will only give out 70% power (if you’re lucky) if you don’t charge at absorption state (1 of the 3 stages is absorption). So after 2 to 3 months of searching I found a company in Auckland that does a 24V to 12V 3 stage charger @ 40amps … plenty of power for my deep cycle. (just in the last few months they now do the same unit on TM)



This unit has a small CPU that will see the 24V income and start to charge (12V output) @ 28V and stop @ 25.5V (this caused me some small issues, see below) and the 3 stage charge is fully automatic. This means when you turn off the engine the unit will shut down and isolate the 12V system, and doesn't matter how much power you use, the 24V system is always ready to start your engine again!

Next was the 12V fuse board and cut off switches. I put in 2 cut offs switches in. One isolates the charger unit with the 24V system (for maintenance / faults); the other was a 3 way switch (all off / 1 on / 1 and 2 on). I’m running a 12V compressor with tank thus the draw is around 40 amps at peek (has its own inline fuse) so I can’t go though the fuse board (fuse board is 30 amps per fuse max) so I can isolated that and / or the fuse board from battery. From those two switches I can isolate all the major parts of the system if needed. The fuse board is an 10 way, 30 amp max, 150 amp total max, this feeds all other 12v equipment needed and fused independently.



Now the setup was in … the problems start … the first problem I had was voltage drop, now I’m an electrical engineer and feel pretty competent when dealing with electricity, but I don’t deal with DC very much and the voltage drop was a bitch to find! I really did feel it was the alternator (which it was half the problem, but come to that later). The problem was the loom from alternator to battery and was resolved very quickly with a blue 12mm core cable (fused 50amp) running from the alternator (the black cable) to the battery (the blue cable) direct. Now I had the 28.8V @ 1200 RPM!



Next was the problem of not getting 28V at 600 RPM. The alt would only give 28V at 1200 RPM. Now this was causing the problem of every time you stooped at a set of lights or roundabout the unit would go below 25.5V and turn off, then you accelerated it would go over 28V and turn on. Now this constant on / off doesn't do you charger any good, and could perpetually burn it out.

I also wanted 600 RPM as most trips we are 4WD driving in somewhere and then walking for a few days, to and back to camp, so we need power for around 3 to 5 days. Now the battery will run without charge for 3 to 4 days but good if you can charge it before this. So I wanted to put truck on tick over and charge without driving anywhere (good for camping also).

So to fix I put a small pulley on the alt that got it down to 800 RPM @ 28V. I'm hoping in the next few weeks to do my injectors which fingers crossed give me the 200 RPM I need to have the alt at 28V at tick over of 600 RPM. Will post up when I get injectors done

Would like to hear what others have done for a 12V system, I know of a few that have done for more power to winches and such like, this set up is more of an RV setup.

Any questions or electrical problems happy to help, as I'm going to be doing the engine side of the truck this year and as being electrical I will be asking a lot of questions as I don't that side
Also anyone in Christchurch area who has done any turbo set ups who fancy giving us some pointers would be great!!

[Swamped]

I run a redarc charge equaliser to balance my batteries and run the biggest batteries I can fit. Don't remember the cca ratings for em. Works fine. They do an equaliser for using a 3rd battery for your application and its a real basic fit. I just draw off one battery and let the equaliser compensate for it as I'm not running any huge lights or touring stuff like a fridge or anything.

I was interested in a pure sine wave inverter to fit to mine but the prices are insane for a reasonable wattage one. If anyone knows of something reasonable I'd check it out.

[safarifern]

I run a redarc charge equaliser to balance my batteries and run the biggest batteries I can fit. Don't remember the cca ratings for em. Works fine. They do an equaliser for using a 3rd battery for your application and its a real basic fit. I just draw off one battery and let the equaliser compensate for it as I'm not running any huge lights or touring stuff like a fridge or anything.

That's pretty good and cheap option. I agree not be best for major power draws but for simple radio, CB, even a low amp cooler / want to be fridge, it will defiantly do the job .... what watt sine were your wanting?

[Swamped]

I was looking at a redarc 700w inverter for 24v. They are like a grand though.
Was just sticking with that brand as the other stuff I've had from them has been pretty good.

[sibainmud]

Yip that is some system
Rv setup alright, or to speak my language, a road going boat
If that was me, I would make a true stand-alone system. No black boxes, compensator's, or stuff like that. You will need separate 12 volt alt. Build a complete 12 volt set up with it's own charging system, with the only thing they have in common is the key switch. i would use a 24 volt relay to supply 12 volt through a warning light to the excitation circuit of the 12 volt alternator.
As I have previously posted, Automotive alternators with internal regulation are a bit too passive for bulk charging and a good external reg should be considered.
My philosophy is Keep It Simple Stupid (kiss).
Your issue with the current 24 volt alt could be related to to compensator
Great looking install.
Small warning, don't expect much CCA out of a deep cycle battery. Though they give out reasonable load, repetitive over-demand with shorten their life considerably.

Cheers,

[safarifern]

If that was me, I would make a true stand-alone system. No black boxes, compensator's, or stuff like that. You will need separate 12 volt alt. Build a complete 12 volt set up with it's own charging system, with the only thing they have in common is the key switch. i would use a 24 volt relay to supply 12 volt through a warning light to the excitation circuit of the 12 volt alternator.

Only problem is mounting it in the safari .... I talked to a few that have done it and they said they had to pull apart every other month due to mud / dust .... not keen ... and lazy

Your issue with the current 24 volt alt could be related to to compensator

Good call! ... will look into that one

Small warning, don't expect much CCA out of a deep cycle battery. Though they give out reasonable load, repetitive over-demand with shorten their life considerably.

All the loads I have are small and constant ... apart from the compressor ... thus why I went for the marine in the end ... I haven't done a full test on her yet ... but we got to 4 days of a fridge / freezer (compressed), lights, radio, cell phone charging ect and she still had power left .... so pretty pleased so far But thanks for the warning, I will make sure I don't jump another truck from it

[sibainmud]

Talk to Monstr, his has two alts. Done well, and since it is on a winch truck, it is in the worst conditions possible.
Until you are not relying on one 24 volt alternator, the system is not "stand-alone".
Put the 12 volt one low, if it stuffs out while out there, use the system you have now as back up
Just my opinion, that's all.
Again, COOL setup
Cheers,

[darinz]

I ran a completely stand alone 12v / 24v system in a Safari. (had repower so no TD42)
The 12v was for the truck as it had an efi motor etc. so everything was 12v except the winch which was 24v.

12v system was 110amp alternator feeding 1000cca battery. This powered motor and all accessories. Including 7 100w lights for night stages.

24v was 70amp alternator feeding twin 800cca, 240 reserve minutes (25 plate) batteries. This was purely to feed the winch. The winch was twin motoe 8274 with either 6hp (12v) motors running 24v or twin 7.8 hp 24v Superduty motors.

Both alternators were mounted on top of the motr with custon brackets. they were both almost touching the bonnet. All Battery cables/winch/starter cables were 95mm welding cable. The24v batteries were behind th cab alone with the winch. teh 12v battery was inside the cab. The 12v system had a distrubution board on the back wall of the cab and also one under the dash. These were feed with 50mm cable.

This was massive overkill but as it was a winch truck that relied 100% upon electricity it had to be reliable. The only issue I ever had was melting a 6hp motor that then direct shorted one of the kill switchs which in turn caught fire! Seriously when you have 800cca, 900 amp cable then the weak point is going to be a switch!

Not an RV and nowhere near comparable as it was completely designed for high draw. We (me and battery sponsor) were working through ideal batteries and the gel batteries were too small so would have needed more than 2. They had deep cycle that would handle the current out but you can't charge them too fast. From memory the alternator couldn't be bigger than 30 amps to get rated life and i was feeding them with 70amps.

Through the wole exercise the most supprising thing was that the gel batteries just weren't up to what i wanted and we ended up with big lead acid batteries as the best option. We could have done it with gel but it would have meant 4 batteries and just got too complex. Also the lead acid were only 2 kgs heavier than the gel option. eg 74kgs of batteries.

[safarifern]

WOW .... that's what you call a Winch Challenge set up Must of cost a lot of $$$! Sounds like a great set up .... any pics??

[safarifern]

Talk to Monstr, his has two alts. Done well, and since it is on a winch truck, it is in the worst conditions possible.
Until you are not relying on one 24 volt alternator, the system is not "stand-alone".
Put the 12 volt one low, if it stuffs out while out there, use the system you have now as back up
Just my opinion, that's all.
Again, COOL setup

Cheers ... and your right, not quite a "standalone" but what I meant was more that your able to start the truck any time ... and that's what I was aiming for .... and I love opinions!! Makes you think outside the square

[3VILC]

Has anyone successfully managed to jam a 2nd alt in without taking the aircon out?

[sibainmud]

Monstr has on board engine driven air too, so yes it can be done.
As I don't want to give away any of his secrets, best you approach him
I have had a fairly good look under his bonnet and all I CAN say is that it is quite simple. Just a bit of fabricating of brackets. With marine engines, I have powered all sorts of things off the front of motors. The worst case was, it took a couple of days once to replace 1 serpentine belt
I have fitted systems to power 24 volt bow-thrusters off 12 volt charging by designing my own solenoid pack that latches two batteries together on demand and then disconnects them to be charged at 12 volts. The power demands of a bow-thruster make automotive winches look like toys.
This is why I prefer to try and keep it simple.
10c worth
Cheers,

[3VILC]

I figured there was plenty of room in there, wasnt looking to steal anyones ideas lol. Also contemplating trying to mod the aircon compressor for onboard air hence why I was wondering. Using an inline oiler on the inlet and a fluid trap on the outlet should work, pressure switch connected to the clutch, sounds like a plan in the making at least and i don't doubt been done before. ..now, if only i'd kept the barely run in recon'd alt off my skyline before i scraped it lol

[darinz]

I converted my aircon to air. All I did was take the air from the catch can. This ment a small amount of engine oil vapour went through the compressor and it lasted for several years like that. (until taking motor out) I then used a tank so all air went into that and the oil seperated out there. As the truck was pulled apart fairly regulary I would drain any oil in the tank out but it was so little it didn't matter.

For twin alternaters on a TD42, I've seen guys power the second direct from the factory alternater rather than the crank.

Also an under deck shot of winch batteries and winch

[sibainmud]

For twin alternaters on a TD42, I've seen guys power the second direct from the factory alternater rather than the crank.

Bingo
Had to come out sooner or later.

[3VILC]

That was my thoughts too since the alt has a double pulley which isnt used for some reason

[CLUMZ1]

For twin alternaters on a TD42, I've seen guys power the second direct from the factory alternater rather than the crank.

any chances of pix from anyone with dual alts on a TD42 in its natual habitat??
many thanks

(and sorry for dredging up an old thread, I googled but it ended up bringing me back to ORE anyway)