split charge relay help

[glenandemm]

hi guys im building a window cleaning system in the back of my van and seen a cheap split charge relay on ebayhttp://www.ebay.co.uk/itm/321148454905? ... 1423.l2649 and was wondering if anyone used one of these before and of anyone had any links to cheap decent wiring about 20-30 amp!

[rabbithunter]

Hello mate. I am also a window cleaner.

I had somethi g similar, and similarly cheap too.

It was no good.

What i have done now is just put a second battery in, with a 10mm cable from positive to positive. And earthed the 2nd battery to the metal. I run my water pumps obviously off the 2nd battery.

The 10mm cable provides a trickle charge to the 2nd battery. Iv never had a problem this way.

But it depends how much you use your system, i only use it on a few jobs. But if your 100% wfp thrn id reccomend maybe going to your local auto electrician and grtting a good split charge system.

[jls security]

Hello mate. I am also a window cleaner.

I had somethi g similar, and similarly cheap too.

It was no good.

What i have done now is just put a second battery in, with a 10mm cable from positive to positive. And earthed the 2nd battery to the metal. I run my water pumps obviously off the 2nd battery.

The 10mm cable provides a trickle charge to the 2nd battery. Iv never had a problem this way.

But it depends how much you use your system, i only use it on a few jobs. But if your 100% wfp thrn id reccomend maybe going to your local auto electrician and grtting a good split charge system.

You haven't created a split charge system. All you have done is increased the battery Ah rating. The two batteries will charge pretty much at the same rate all the time. If you have a load connected to the 2nd battery it will still discharge the first battery at the same rate as the second because there is no split between the two batteries. ( if that makes sense)

[glenandemm]

seen these 30 amp relays,http://www.ebay.co.uk/itm/161230993372? ... 1423.l2649 are these any good?
at the moment im just using a duff spare battery i got and charging it every night but its lasting me the day, as soon as i turn my pump controller on in the van in the morning its giving me 12.1 volts but by the end of day its down to 11.1 volts, my controller has a built in battery saver thats cuts out at 11volts so need something thats gonna keep charging my battery plus i know a new battery will hold more charge than this old thing i got!

[whitemice]

you are doing a high drain and it's unlikely the second battery is going to get enough juice back driving to and fro each day.

maybe just isolating the second battery completely and fitting a socket for the battery and a plug on your 240v charger will make it less hassle?

[Leeday]

Hi,

You can make your own split charge system if you have some electrical knowledge.
The rate at which your batteries charge depends on what alternator output you have and how long the engine is running. Ideally when you start the van the starter battery uses up some of its power, once started the alternator will then put out its max amps to recharge the battery, when the battery is re-charged the alternator then reduces its output and only increases when you use electrical equipment (wipers, lights etc), if you have a second battery on a split charge, the alternator would continue to run at max output, re-charging the starter battery first then continuing to recharge the 2nd battery, the higher output alternator you have, then the more chance of recharging your 2nd battery. Split charge systems were originally intended for caravans and motorhomes on long drives thus charging the 2nd battery effectively. 30 minutes from job to job is not ideal.
I have 2 split charge systems on my van for starter and 2 separate leisure batteries (see topic: viewtopic.php?f=2&t=72990 )
To make your own you will need a heavy duty relay (rated higher than your cable), I used 50 amp cable and I think 70 amp relay, 2 x inline fuses.
Connect 1 side of your fuse (rated at lower than your cable: 40 - 45 amp) to the positive of your starter battery, other side of fuse to pin 30 of your relay, then from pin 87 of relay to other inline fuse (rated at lower than your cable: 40 - 45 amp), other side of fuse to positive of auxiliary battery, pin 85 of relay to alternator trip wire (live when engine is running, not- live when engine is off) using 5 or 8 amp cable, pin 86 of relay to earth using 5 or 8 amp cable. Auxiliary battery negative goes to earth on van body.

With this your 2nd battery is isolated from your starter battery, so if you flatten the 2nd battery your starter battery is still fully charged, when you turn on engine the relay operates and your 2nd battery will start charging.

[mjsroofing]

Google, intelligent spilt relay charger.

I can get 70amp ones for 14 quid.