another 24v question

Posted: Sun Apr 11, 2004 7:17 pm

I wish to use 24v to start my hilux, but have the rest of the vehicle (except maybe winch) remain 12v. What is the best way to set this up/what parts are reuired,particularly to ensure batterys charge off 12v alternator. I imagine a few solenoids or some kind of heavy duty changeover relay.

Reason is simple with my engine setup, car is sometimes hard to start even on a fully charged 12v battery, but will start first go every time with 24v. I know where the problem lies but it is a biatch to fix due to room constraints.

cheers
craig

Joined: 21 Oct 2003 Location: North East Melbourne

is it a 24V starter motor? if not i dont think it will last long.

not too sure how you would go about charging off a 12V alternator either.

have you tryed putting a larger size cable to the starter?
dont think going to 24V is the answer.
how were you runing 24V to it last time?

MaccA

Posted: Sun Apr 11, 2004 7:35 pm

will be using two 12v batteries in series for start only, 12v rest of time, it is just the best options for changeover wiring i need.
Yes i have tried all sorts of different cables batteries etc and no 12v sytem will start it easily everytime. It is a voltage problem not a current problem I need to spin the starter quicker. dont know how much it will effect the wear of the starter but cranking it for 10mins without a spark on 12v prolly isnt going to treat it too good either.

Joined: 21 Oct 2003 Location: North East Melbourne

is it a new starter? im not trying to be stupid or anything, its just that i cant see why everyone elses starters work fine and yours doesnt.

if you were to do it probably run a 24V alternator and that way you can run a 24V winch too.

Posted: Sun Apr 11, 2004 7:57 pm

problem is due to the fact that i have a supercharger which loads the motor at startup and have carby motor converted to efi and the distributor gives a very weak signal to aftermarket computer at low(cranking) revs. I can amplify signal, but it induces noise and causes engine misfires.

Joined: 21 Oct 2003 Location: North East Melbourne

ah k. if you have room i believe the easiest way would be putting in the 24V alternator and running its own circuit to the starter. you wont need to run new switch wires or anything as that can be done from the original circuit. just a cable from the alternator to the battery to the starter and your done.

MaccA

Posted: Sun Apr 11, 2004 9:38 pm

I have no room for anything else in the engine bay that is why i am hoping to series my 2 12v batterys only to start car. just toying with ideas.
problem is system becomes a bit intense if i want to parallel em for winching etc.

I could also convert everything to 24v and use dc-dc converters to get all 12v stuff to work, but i imagine it would become expensive doing it this way. and considering the load of some of my 12v stuff id need a big converter

Joined: 21 Oct 2003 Location: North East Melbourne

hmmm, i just had a brain storm, ill draw you up a diagram and see what you think. it uses solenoids. charges the batteries in parallel (12V), and cranks in series (24V)

it probably wont work tho because of all the other accessories attached.

Joined: 19 Dec 2002 Location: Sydney

would it not be a better option to put a clutch onto your supercharger, like an aircond style one, this will allow you to turn it on and off, thus helping you start the motor unloaded,

just an idea, i believe it can be done,

Joined: 25 Oct 2003 Location: Melbourne Australia

cplux wrote:

I wish to use 24v to start my hilux, but have the rest of the vehicle (except maybe winch) remain 12v. What is the best way to set this up/what parts are reuired,particularly to ensure batterys charge off 12v alternator. I imagine a few solenoids or some kind of heavy duty changeover relay.

Reason is simple with my engine setup, car is sometimes hard to start even on a fully charged 12v battery, but will start first go every time with 24v. I know where the problem lies but it is a biatch to fix due to room constraints.

This would be quite complicated to do, and it would be far preferable to get a replacement starter motor that has more get up and go if such a thing exists.

Do you already have the dual battery set-up or is it just planned? If you already have it set up, we need to know what you've got. If not, then you can design it to suit your plans.

Either way, it's going to be pretty difficult and it's going to kill starter motors repeatedly.

Lessee... what you want is two possible battery states:

1. (for starting) all wiring runs of a single battery for 12V operation, 2nd battery is in series with first and only operates to run the starter motor.

2. (for every other condition) the two batteries are in parallel.

It's also imperative that the set-up never tries to do BOTH, ie, it has to be designed so that if a relay should fail, or whatever, it doesn't blow things up.

And, a starter motor could easily draw 600 - 1000kW (I'm guessing). That means you need a pretty beefy connection between the two batteries.

Hmm. I am thinking about this. I believe it can be done, but first tell us what you've got already set up and definitely suss out a replacement starter motor instead, because what you're asking for won't be simple.

Jason

Joined: 21 Oct 2003 Location: North East Melbourne

heres my idea of how to run a 12/24 volt battery setup at the flick of a switch.

tho im not too sure if you can get normally close solenoids. or N/C relays with high enough amp ratings.

but this is what i came up with.

Joined: 25 Oct 2003 Location: Melbourne Australia

And this is what I came up with... at the same time.

It's probably the same...

Definitely same problem though - you need some double-throw relays with heavy, heavy current ratings. Ideally, you want a single double pole, double throw relay, because you really DON'T want one relay to trip and the other one not to, or one to get stuck and the other one not... or whatever. If that happens, there's potential for an earth-shattering kaboom.

Jason

Edit: the switches shown would be single pole, double throw relays/switches, or 1x double pole double throw relay/switch

Joined: 25 Oct 2003 Location: Melbourne Australia

chimpboy wrote:

And this is what I came up with... at the same time.

It's probably the same...

Actually mebbe not. I may have made a mistake, or there may be several ways to skin this cat.

You can do what I've outlined there with a number of relays interacting, but I don't like this idea because if one fails something could conceivably short out. I suspect that a manual switch could be used if relays couldn't, but running the big cables to the cabin could be a hassle...

I really think a replacement starter motor is the go here Smile

Jason

Joined: 21 Oct 2003 Location: North East Melbourne

chimpboy wrote:

And this is what I came up with... at the same time.

It's probably the same...

Actually mebbe not. I may have made a mistake, or there may be several ways to skin this cat.

You can do what I've outlined there with a number of relays interacting, but I don't like this idea because if one fails something could conceivably short out. I suspect that a manual switch could be used if relays couldn't, but running the big cables to the cabin could be a hassle...

I really think a replacement starter motor is the go here Smile

Jason

im with you jason. and yeah running less relays has less chance of that kaboom which would occur in your pocket.

Joined: 25 Oct 2003 Location: Melbourne Australia

383FJ45 wrote:

and yeah running less relays has less chance of that kaboom which would occur in your pocket.

Every kaboom ends up in your pocket really, eh?

Jason

Joined: 09 Nov 2002 Location: Traralgon Vic Aust.

These Diagrams shown will supply 24v to the alternator. If it's a 12v alt this will be bad. Also the second battery will not be charged.
I may be wrong, it's just how I see it.

A beefier starter and sort out the ignition problem and engine starting problem would be a better path to follow.

Joined: 25 Oct 2003 Location: Melbourne Australia

DAZZ wrote:

These Diagrams shown will supply 24v to the alternator. If it's a 12v alt this will be bad. Also the second battery will not be charged.
I may be wrong, it's just how I see it.

A beefier starter and sort out the ignition problem and engine starting problem would be a better path to follow.

Nah I think the diagrams are okay but you're still right; it would be much better to solve this another way. Even if it were all wired up as suggested, you'd be roasting the starter motor by putting too much voltage across it, which is the fundamental problem with the plan.

Jason

Joined: 21 Oct 2003 Location: North East Melbourne

in my diagram the alternator is connected across 1 of the batteries therefor is still 12V when in 'series'. and the system is in 24V for only a short period of time anyway.

the alternator isnt getting 'supply' its supplying.

all the other accessories like distributor and fuel injection should be linked to the first batteries + terminal.

what sort of engine is it anyway?

MaccA

Joined: 09 Nov 2002 Location: Traralgon Vic Aust.

would the Alt need a diode to protect it when cranking as it isnt suppling at this time. And wouldn't the whole system voltage be 24v at crank causing damage??

Joined: 21 Oct 2003 Location: North East Melbourne

its not the best way to solve this problem. but i broke my diagram into the different sections.

Joined: 09 Nov 2002 Location: Traralgon Vic Aust.

Yep. can understand it now. Just a bit confused with relay switching. This should operate. Reliability and complexity would be the main issues....

Wasn't doubting, just needed a push in the right direction..... Smile

Joined: 21 Oct 2003 Location: North East Melbourne

yeah no worries, always glad to push Laughing

yes reliability is the main issue as jason suggested with the earth shattering kaboom.

i wouldnt like to be around when it goes.

the starter motor will smell funky sooner

and availability/cost of setup wouldnt be worth it.

MaccA

Posted: Mon Apr 12, 2004 8:14 am

will be trying to sort a heavier duty starter this week, my ignition problem lies in the distributor signal, many tricks have already been already employed to get it to start, once it starts it runs perfectly with the exception of the computer getting error counts at low revs. These can be eliminated with the computers filters but if done the car wont start because it doesnt get a strong enough signal from dizzy.

If i can spin the dizzy rotor spinning quicker at crank then all is well. I do not have any room to change dizzys unles it is one of virtually the same size.
Motor is a 4y petrol.

The problem is not a huge one just frustrating sometimes, expecially when its cold or the vehicle has sat just long enough for the battery to discharge a little. (main battery is brand new 660cca)

Main reason I want to fix it is because i dont wanna be stuck in a prick of a place and the motor wont start because i cannot crank it at enough speed.

I'm currently not running dual batts but had before, crude direct setup in parallel. will be fixing properly soon with solenoids.

I have heard of people with drag/race cars using 24v starting and 12v running circuits so it can be done.

I would much prefer a quicker spinning starter, but if i cant find one??

Joined: 19 Dec 2002 Location: Sydney

bac to my idea, is there any possibility of p[uttin a clutch onto your supercharger, so that you can turen it off and start the motor unloaded, when running, you can turn it back on, i do not see why this wont work, depending on your supercharger, and comp set up, you computer might give you errors withlack of air presure, and running rich, but all depends on what sensors your comp runs

Posted: Mon Apr 12, 2004 8:36 pm

ozy1 wrote:

bac to my idea, is there any possibility of p[uttin a clutch onto your supercharger, so that you can turen it off and start the motor unloaded, when running, you can turn it back on, i do not see why this wont work, depending on your supercharger, and comp set up, you computer might give you errors withlack of air presure, and running rich, but all depends on what sensors your comp runs

sc has a clutch, it works and motor is still hard to start with it off or on.

Joined: 09 Nov 2002 Location: Traralgon Vic Aust.

Does the ignition system have a Hall sensor to trigger the Ignition module. If so has this been replaced. Had a car at work the other day with a simular starting problem. At normal cranking speed the Hall sensor would not generate enough signal.