aevans692 · Jan 23, 2019

Hi all . .

I have been fitting my split charge system , bit of a basic system mind ..

now I could connect the relay direct to an ignition , or to put it on a switch ..

Is there any real benefit to have the relay controlled with a manual switch ? or is it just as well to fit and forget ..

cheers

Rodeo Joe · Jan 23, 2019

http://www.agmpartscomponents.co.uk...charge-relay-kit-for-charging-battery-fridge/

For a basic back up battery I have used one of these for years, dead cheap and always leaves the spare battery under the seat fully charged..... just in case.
BTW mines on a series but all the same really.

mick 1986 · Jan 23, 2019

aevans692 said:
Hi all . .

I have been fitting my split charge system , bit of a basic system mind ..

now I could connect the relay direct to an ignition , or to put it on a switch ..

Is there any real benefit to have the relay controlled with a manual switch ? or is it just as well to fit and forget ..

cheers

I use a 70A relay for mine. It’s switched from the dashboard switch panel. I used this system so that if either battery goes flat, I can switch the relay and still connect the batteries. Even if it gives me enough power to transmit on the CB, it doesn’t have to start the vehicle. It was a sort of half arsed backup, for a backup.

owas · Jan 23, 2019

I've just fitted one of those 30amp split charge relay things and put a switch on the 12v wire going to it so I can disconnect it if I need to, seller said I needed to isolate the relay if I want to bridge the batteries to start it if the main battery is dead.

mick 1986 · Jan 23, 2019

owas said:
I've just fitted one of those 30amp split charge relay things and put a switch on the 12v wire going to it so I can disconnect it if I need to, seller said I needed to isolate the relay if I want to bridge the batteries to start it if the main battery is dead.

Only 30A? Are you sure? I wouldn’t use a relay that is smaller than your alternator output, it doesn’t make sense. I would up it to at least 70A, maybe 100A if you have a bigger alternator.

owas · Jan 23, 2019

mick 1986 said:
Only 30A? Are you sure? I wouldn’t use a relay that is smaller than your alternator output, it doesn’t make sense. I would up it to at least 70A, maybe 100A if you have a bigger alternator.

I did think that, but I don't think the second battery is getting the full alternator output through the relay? I've only got 20amp fuses either side

'This voltage sensing split charge relay is used for charging a second battery from your main vehicle (crank) battery. This relay is different from standard split charge relays in that it does not require an alternator connection or ingition switching wire. It simply connects between the two batteries.

When the engine is started, the relay detects the higher voltage from the alternator and will then switch to allow charge to go through to the leisure battery. No over charging can take place and the main battery is charged as normal, so there is no interference with the existing system. Once the engine is switched off, the relay will then open (switch off) and in doing so, disconnects the two batteries so that no matter how flat the leisure battery becomes, it wont affect the main battery.'

mick 1986 · Jan 23, 2019

owas said:
I did think that, but I don't think the second battery is getting the full alternator output through the relay? I've only got 20amp fuses either side

'This voltage sensing split charge relay is used for charging a second battery from your main vehicle (crank) battery. This relay is different from standard split charge relays in that it does not require an alternator connection or ingition switching wire. It simply connects between the two batteries.

When the engine is started, the relay detects the higher voltage from the alternator and will then switch to allow charge to go through to the leisure battery. No over charging can take place and the main battery is charged as normal, so there is no interference with the existing system. Once the engine is switched off, the relay will then open (switch off) and in doing so, disconnects the two batteries so that no matter how flat the leisure battery becomes, it wont affect the main battery.'

I fitted the 70A because if the second battery becomes discharged, and then the vehicle is started, most of the charge current will go to the lowest powered battery. I wouldn’t be surprised if you blow them 20A fuses the first time you start the engine after discharging the second battery.

owas · Jan 23, 2019

mick 1986 said:
I fitted the 70A because if the second battery becomes discharged, and then the vehicle is started, most of the charge current will go to the lowest powered battery. I wouldn’t be surprised if you blow them 20A fuses the first time you start the engine after discharging the second battery.

Hmm I suppose I could always use the voltage sensing relay to trigger a normal large relay instead.

aevans692 · Jan 23, 2019

I have used a 200 amp relay ...

I didnt go for a voltage sensing unit because I wanted to keep things simple , but I wasn't sure if to add a switch so I can manually split the batteries .. ? what benefit is there ..

I may just connect it up to join when I switch the ignition on , and forget about it ..

mick 1986 · Jan 23, 2019

owas said:
Hmm I suppose I could always use the voltage sensing relay to trigger a normal large relay instead.

That’s an option, but it’s adding an extra relay to things. It should work.

aevans692 said:
I have used a 200 amp relay ...

I didnt go for a voltage sensing unit because I wanted to keep things simple , but I wasn't sure if to add a switch so I can manually split the batteries .. ? what benefit is there ..

I may just connect it up to join when I switch the ignition on , and forget about it ..

I wanted my system to be as simple as possible. That’s two fold, it’s easier to diagnose and repair, and has much less things to go wrong.

I fitted a switch because I wanted the ability to isolate the two batteries. Yes an ignition trigger will allow the batteries to be isolated, but only when the ignition is off.

The biggest benefit your system has over mine, is your relay size. You could hold the relay closed and effectively pulse the starter without too much fear of breaking something, so long as your cables are rated at 200A+.

aevans692 · Jan 24, 2019

Sure , I know what your saying .. My cables are 110 amp , I opted for this size as they seemed just easier to work with ...

just checked , 110 - 500 amp rating , so I would guess that would be ok ..

mick 1986 · Jan 24, 2019

aevans692 said:
Sure , I know what your saying .. My cables are 110 amp , I opted for this size as they seemed just easier to work with ...

just checked , 110 - 500 amp rating , so I would guess that would be ok ..

What has a rating 110 - 500A? That’s a very broad range.

aevans692 · Jan 24, 2019

the cable , its listed at 110amp .. ... im guessing maybe pulses upto 500amps , least thats how I read it , tho thinking about it I may be wrong... shouldn't need it anyway , 110 should be plenty ..

.. got it fitted out with fuses on both sides

everything done and finished , all working fine

mick 1986 · Jan 24, 2019

aevans692 said:
the cable , its listed at 110amp .. ... im guessing maybe pulses upto 500amps , least thats how I read it , tho thinking about it I may be wrong... shouldn't need it anyway , 110 should be plenty ..

.. got it fitted out with fuses on both sides

everything done and finished , all working fine

I fitted 70A fuses to each live of mine too, as close to the pos as possible. It’s the only sensible way of protection when dealing with these levels of current.

I would guess it’s ok too, but that’s only a guess. Hopefully we will never have to find out.

aevans692

Active Member

Rodeo Joe

Well-Known Member

mick 1986

Well-Known Member

owas

Well-Known Member

mick 1986

Well-Known Member

owas

Well-Known Member

mick 1986

Well-Known Member

owas

Well-Known Member

aevans692

Active Member

mick 1986

Well-Known Member

aevans692

Active Member

mick 1986

Well-Known Member

aevans692

Active Member

mick 1986

Well-Known Member

Similar threads