My Split Charge Thread

[fridayman]

I now have most of the major bits bits that I need to build my split charge system:
2000W inverter
105ah battery
Cyrix 400A relay
Reya battery monitor

Still to get:
All the cables
Cable sheathing
New battery terminals
Fuses / circuit breakers
Dust proof housing for relay

Lots of questions to follow...

 

[Chris]

Good choice on the Cyrix. Mine works absolutely perfectly. Very pleased with it.

Chris

 

[fridayman]

I have started doing some sums to work out what cable and fuses I need, and I think my 2kW inverter may be a bit excessive...

Anyway, my alternator only puts out 80A, which at 14V would provide around 1kW to the batteries/accessories. Now I'm wondering if I should upgrade to a 120A alternator. I know, I know... what accessories am I going to have attached...? Well the honest answer is that I don't know yet, but I do know that it will include a 2kW inverter running off a 105Ah battery that will also be powering my fridge/beers/meat. Maybe I should get the upgrade, then I have the old one as a spare I think it was Greg that said you should carry a spare starter and alternator in an auto on overland trips.

 

[Nuclear Chicken]

Yes do the upgrade. Better running 70 or 80A from a 120A unit that from an 80A unit, especially if it's an old 'un. Gives you some 'breathing' space.

 

[Chris]

But how often will you be pulling 2Kw? Why would you be running a fridge off an inverter anyway? What's wrong with running it at 12v off the battery? I'm not a vehicle electrics technician by any means, but I don't run my inverter directly from the alternator. I run it from the battery - yes with the alternator connected in parallel via the splitter, but I figured that this would be the best way. For your alternator to be sending 80 amps to the inverter, it would not have to be sending power anywhere else would it. Like the main batteries etc. The Cyrix only cuts in when there is sufficient over current in the main system. If I have mine engaged then stick main beam on, X-lights and then KC Daylighters on, the Cyrix disengages.

I only got the 600w inverter which is 1000w peak. The 1000w might have been nice, but then the 2k ones are massive aren't they? I don't think that there is anything I'd really want to run at that output.

Watching with interest. Don't forget to put some fuses in line there. Somewhere easy to get at.

Chris

 

[Paul]

On the inverters i sell, generally they are listed at the constant wattage and not peak watts (unlike some of the cheap ones ) so you can go over for short periods.
I am told by my supplier that the 2000w model at peak could draw 120A which is why it must be used in conjunction with a good sized battery extra to the normal vehicle one to provide a buffer.
With the Mastervolt it is considered so efficiant (97%ish) that you can run items from the inverter rather than the 12v vehicle supply with minimal loss of power, this is something i will do as the decent compressor fridges we all love are also available in 240v only and are about half the price, so with the price of inverters it makes good sense.

 

[fridayman]

But how often will you be pulling 2Kw? Why would you be running a fridge off an inverter anyway? What's wrong with running it at 12v off the battery? I'm not a vehicle electrics technician by any means, but I don't run my inverter directly from the alternator. I run it from the battery - yes with the alternator connected in parallel via the splitter, but I figured that this would be the best way.

I worded it poorly above, the inverter and the fridge will both run off the leisure battery, not the alternator.

For your alternator to be sending 80 amps to the inverter, it would not have to be sending power anywhere else would it. Like the main batteries etc. The Cyrix only cuts in when there is sufficient over current in the main system. If I have mine engaged then stick main beam on, X-lights and then KC Daylighters on, the Cyrix disengages.

This is why I was wondering if I should upgrade the alternator. Are your additional lights running off the leisure or main battery? It sounds like the main. How many watts are your lights combined? I am a little surprised that they draw so much current that the Cyrix disengages, but this is exactly why I am considering upgrading the alternator - I want mine to still be charging the leisure battery (to keep meat frozen) even if I am trying to create daylight, or if I am only using moderate lighting to see where I am using my power drill running off the inverter (as an example)...

 

[fridayman]

I am told by my supplier that the 2000w model at peak could draw 120A which is why it must be used in conjunction with a good sized battery extra to the normal vehicle one to provide a buffer.

Did he say what a good size is?

 

[Paul]

I will check for you but the ones he installs is fecking huge, but i know it is wired into alot of other circuits.

 

[Chris]

Yes, lights run from main battery, alternator feed. In total, not including dashboard, side lights, indicators etc and anything else running from the engine, I had over 700 watts on the front. With the triple headlight (uprated bulbs) effectively on the 80 plus 4 X Lites and 2 130 W Daylighters, I don't think there was much surplus to go to the leisure battery. It clicked in and out depending on what I was doing. But the leisure battery was still powering the fridge etc. As the LB runs the fridge at 0 degrees for nearly a week, I don't think that sticking my lights on will make any difference. It will get a top up once I knock some of the lights off. It's a pretty big reservoir.

Chris

 

[Crispin]

Paul,

More than that. 2000/12 = 175. Add some for losses.

Alternator should be fine unless you continuously pull the 2kw. For any decent length if time, you'll kill the battery.

Sent from TapaTalk

 

[Paul]

Not sure if they all do, but my 100 has a 120A alternator on it already

 

[fridayman]

I have decided that I will fit a 120A alternator, but it can wait until later (it is straight swap).

Does anyone know what the spade terminals on the left side are for (the ones marked micro/com/nc/no on the white sticker)?

All I can think is that it is a switch that I could use to power on/off LED's in the cab..? Any ideas?

Also, is it better to have a push button (connects the batteries for 30 seconds) or an on/off switch (batteries stay connected when on) for the start assist? Or maybe a switch that can do both like an electric window switch...

 

[AndyCook]

All I can think is that it is a switch that I could use to power on/off LED's in the cab..? Any ideas?
yes its a microswitch (not powered though) and i used it for LED's on dash


Also, is it better to have a push button (connects the batteries for 30 seconds) or an on/off switch (batteries stay connected when on) for the start assist? Or maybe a switch that can do both like an electric window switch...

i found once i activate this it stays on and doesnt turn off at 30secs, i use a on-off switch so i can keep batteries linked for winching etc

 

[Chris]

Yes, it's just for an indicator. If you use the power of Google you will find a whole instruction sheet on this unit including all the wiring options and the different profile settings that you can set in the inside cover. I went with profile 2 which I think we all found to be the best.

Chris

 

[fridayman]

Anyone got any suggestions about where to locate the Cyrix relay in the engine bay? Both batteries will be upfront, so the relay needs to be there too. Or... can I mount it behind the dash somewhere to keep it away from dust/moisture?

 

[fridayman]

Anyone got any suggestions about where to locate the Cyrix relay in the engine bay? Both batteries will be upfront, so the relay needs to be there too. Or... can I mount it behind the dash somewhere to keep it away from dust/moisture?

Presumably, if I use 50/60mm cable it will be fine behind the dash somewhere (as opposed to near the main battery)?

 

[AndyCook]

I used 50mm2 cable, but mounted the relay in engine compartment in a waterproof (old ice-cream tub).
It is bolted to a "L" bracket that bolts onto the firewall, on drivers side between wing and break fluid reservoir.

In hindsight i could just as easily mounted in cabin in the large acreage of space behind dash and above drivers feet. would have been very little additional cabling. I put a mega fuse on each +ve feed from main and auxillary battery.

 

[fridayman]

I hadn't even thought of using a round tub in the corner... Are those extra fused red wires for a battery monitor?

Did you solder or crimp the ring terminals onto your 50mm cable?

 

[AndyCook]

I used Crimp

the fuses are for the LED lights I have on dash to indicate if the relay is engaged or not. and also on feed to voltmeters.