Dual Battery setup?

[frank rabbets]

Don't let the smoke out of the wires Chris. Toyota don't do replacement smoke.

 

[Chris]

Don't worry Frank, Milners sell it.

 

[Towpack]

Guys, not a hijack but a sort of side step. If you had a 12 set up and two batteries (well like a Collie for example) but wanted to run something that was 24volt, could you take a feed from both batteries (ie in series to give 24) to the device and earth to chassis? I get a bit misty here. Let's say it was a CB or something like that. I am guessing not, but curious as to where the volts would go. I suppose it would only be fed when switched on. Is there anyway to do this and say feed back to one or other earth terminal to prevent the current escaping?

You could using a 12-24v switchover relay!
No seriously. Wire it in pretty much as in the 24v start setup but not via the ign key, by a separate switch and feed the 24v output to your 24v equipment. The 12v stuff would run from the offside batt as it does on the OE 24v start setup. JMO

 

[Towpack]

Or even easier, something like this for a low current application.....
http://www.ebay.co.uk/itm/DC-DC-600..._Measurement_Equipment_ET&hash=item20e703d5cc

 

[Dave2000]

Any mod to vehicle wiring has to be really thought through. The volts whether 12 or 24 may be low but the current they carry can run into thousands of amps! The low resistance in a battery means it could dump the whole lot in a few seconds into your vehicle wiring and a fire would be inevitable if you get it wrong. When looking for higher volts I would prefer an inverter for low current gadgets.

For something heavy like a winch I would either copy the LC 80 starter system in it's entirety or, (and this is my preference) install a completely independent 24v system. So that would be two batteries in series and a 24v volt alternator, twin alternators is not uncommon so should be workable? The advantage when winching is your vehicle electrics are under no strain at all, fire risk from an independent system (no change over relays/isolators and so forth) should be less. I have no doubt it could be done?

regards

Dave

 

[Dave2000]

Don't let the smoke out of the wires Chris. Toyota don't do replacement smoke.

IIRC Frank didn't we used to say that about Lucas parts years ago?

regards

Dave

 

[frank rabbets]

I think so Dave.

Milners do free smoke with their wiring harnesses as well Chris.

 

[Steveindar]

As appie's we were taught that all electrics were made out of smoke, the trick was to keep the smoke on the inside...

 

[Towpack]

Any mod to vehicle wiring has to be really thought through. The volts whether 12 or 24 may be low but the current they carry can run into thousands of amps! The low resistance in a battery means it could dump the whole lot in a few seconds into your vehicle wiring and a fire would be inevitable if you get it wrong. When looking for higher volts I would prefer an inverter for low current gadgets.

For something heavy like a winch I would either copy the LC 80 starter system in it's entirety or, (and this is my preference) install a completely independent 24v system. So that would be two batteries in series and a 24v volt alternator, twin alternators is not uncommon so should be workable? The advantage when winching is your vehicle electrics are under no strain at all, fire risk from an independent system (no change over relays/isolators and so forth) should be less. I have no doubt it could be done?

regards

Dave

I think you mean a converter and not an Inverter for low power gadgets Dave. An Inverter gives AC from DC.

The 24v starter system components would handle the current for a winch OK IMO, subject to the duty cycle of the switchover relay being high enough. It's design intention is for relatively short engine starting/cranking events so prolonged use for other devices like winches could potentially overheat it. Some testing/experimentation of the unit would be required. JMO

 

[Dave2000]

I think you mean a converter and not an Inverter for low power gadgets Dave. An Inverter gives AC from DC.

Thanks for the correction, you are of course right, I had already edited my post to replace voltage with current so should have been on the ball and seen that cock up as well.

The 24v starter system components would handle the current for a winch OK IMO, subject to the duty cycle of the switchover relay being high enough. It's design intention is for relatively short engine starting/cranking events so prolonged use for other devices like winches could potentially overheat it. Some testing/experimentation of the unit would be required. JMO

I still have my old change over switch and when I get five minutes I will see if there are numbers/spec on it that might give us an idea, the only problem I see is if the engine is running that the alternator will be looking to charge a 12v source and the batteries will at time be in series so not sure about this, from a redundancy point of view I prefer a separate system.

regards

Dave

 

[Towpack]

I still have my old change over switch and when I get five minutes I will see if there are numbers/spec on it that might give us an idea, the only problem I see is if the engine is running that the alternator will be looking to charge a 12v source and the batteries will at time be in series so not sure about this, from a redundancy point of view I prefer a separate system.

regards

Dave

If I understand the system correctly, in the OE 24v start setup of the 80, the alternator is connected across the + of the offside battery and earth. When the batteries are in parallel then both will be charged. When the switchover relay operates and the batteries are in series the only battery charged will be the off side one as the the + of the nearside battery will be connected only to what is hooked up to the output terminal of the switchover relay, in the case of the 24v starting system, the starter itself. A separate (2) batteries to give an isolated 24v supply together with their own alternator and charging system may well be simpler and potentially less problematic but a whole lot more challenging (and expensive?) to fit in the space available. JMO

 

[Dave2000]

Totally agree space is an issue, the trouble is I am always looking to simplify things, this because I like to travel to isolated places where self sufficiency is important. Given that statement if I get a winch then it will be a 12v as per the one on my Discovery, complete with remote never gave me an ounce of trouble, cannot remember the name perhaps Superwinch , I bought it from the main suppliers IIRC in South Mimms? Of course 24v would be better...but then we know that anyway right?

regards

Dave

 

[clivehorridge]

Well I've enjoyed every word of this thread, and I feel like I know all about my 80 starting system (even though I don't really, but it was a good read!).

Anyway, it was -21C here New Year's Eve and it hasn't risen above -8 since. -15 tonight (again) and "getting colder" is the forecast. Touching wood, my truck has never given me starting problems, certainly nowt to do with 24V change-over haemeroids or whatever they are, and I'm glad of it.

Too bloody cold to be standing around waiting for help to come, so it's great to jump in the truck and have it start on a flick of the key.

BTW, I timed it at 8 minutes for the temp gauge to get to normal from a -15C start up at normal city running speed. I was impressed, and I've not had overheating problems either.

I've never felt I needed the rad blind, although it's in good nick and ready for action. Another use for the blind is to reduce the effects of wind blowing through the rad fins whilst stood up overnight. At -30C, it's reckoned that the rad cores can go down to -40C and less, with a stiff breeze blowing past the fins.

Just love the 80 in the winter, ploughing through 1m high banks of snow to nab a parking place, when all the others are slithering around virtually out of control.

 

[Chas]

Just love the 80 in the winter, ploughing through 1m high banks of snow to nab a parking place, when all the others are slithering around virtually out of control.

Is that after getting out to check for a car already there?

 

[Dave2000]

"-21C here New Year's Eve"

"hasn't risen above -8 since"

"-15 tonight"

"Too bloody cold to be standing around waiting for help to come"

"8 minutes for the temp gauge to get to normal from a -15C"

"whilst stood up overnight. At -30C"

"-40C and less"

"1m high banks of snow"

Yeh....know what you mean.........down to er +10 last night, did not get much above +20 today...horrible...really is....

regards

Dave

 

[Steveindar]

Well I've enjoyed every word of this thread, and I feel like I know all about my 80 starting system (even though I don't really, but it was a good read!).

Anyway, it was -21C here New Year's Eve and it hasn't risen above -8 since. -15 tonight (again) and "getting colder" is the forecast. Touching wood, my truck has never given me starting problems, certainly nowt to do with 24V change-over haemeroids or whatever they are, and I'm glad of it.

Too bloody cold to be standing around waiting for help to come, so it's great to jump in the truck and have it start on a flick of the key.

BTW, I timed it at 8 minutes for the temp gauge to get to normal from a -15C start up at normal city running speed. I was impressed, and I've not had overheating problems either.

I've never felt I needed the rad blind, although it's in good nick and ready for action. Another use for the blind is to reduce the effects of wind blowing through the rad fins whilst stood up overnight. At -30C, it's reckoned that the rad cores can go down to -40C and less, with a stiff breeze blowing past the fins.

Just love the 80 in the winter, ploughing through 1m high banks of snow to nab a parking place, when all the others are slithering around virtually out of control.

I must agree this thread produced a lot of info for which I am grateful. Currently baking in the fair Cape in South Africa, too bad about the cold...

 

[flamesnm]

All

I've recently purchased an HZJ81 that has twin ( no brand, cheap ) batteries. Doing research all the roads point to Australian forums with twin battery setups being 12V with the second battery being considered an auxiliary. This thread has thrown me a curveball as I assumed that's what I had ( I'm still a noob under the bonnett ).

So how do I determine whether I have the 12v + aux battery and isolator or the UK 24v charging system setup ?

Thanks in advance.

 

[Towpack]

Look at the starter which will (should) be marked up 12 or 24v, also the changeover relay present on 24v start setup next to the fusebox behind the NS battery.

 

[Chris]

Disconnect one of the battery's +ve terminals (aux battery) and try and start the car. You'll know if it's 24v then. If you are in the UK and it's a UK car then it will be 24v pretty sure. But the HZJ is the non turbo 4.2. Were there any UK variants? Not my area of expertise.

 

[flamesnm]

Thanks Towpack. Starter is marked ( just ) with 24v, so there it is.

I'll now re-read to see whether I want to switch that out for a dual battery 12V with auxiliary battery, which will better suit me. I hate the cold, so have no intention of going anywhere near it