..charging second/leisure battery simple way..

Hi
Got a question..will this work?..has anyone tried this?..I must admit my electric knowledge is very basic so not sure but it somehow does make sense to me?..just looking for the simplest way to get my second battery charged and to not mess about with any modern and expensive split chargers..

http://vwt2oc.co/wp/2018/12/07/split-charge-relay-charge-your-second-battery-as-you-drive-along/

 

this is how i did my lead acid batteries.. i now have different battery types..


people also use VSR's these days which does exactly the same but doesn't rely on having an ignition live to trigger...


a simple relay, trigger from alternator and some decent cable and fuses between batteries will work fine though

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a vsr is a very simple installation but cost wise usually more expensive that a bog standard relay and trigger cable...

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https://westech-pv.com/Automatic-battery-relay-140A-24V

a few companies make these, Charges the other battery after about 13 V. Has reached , Small, simple, cheap. , , get the 12 V version,





https://westech

 

Just to add to the conversation, perhaps the most important thing to remember is this arrangement won't properly charge your leisure battery on your way home from a weekend camping unless you live in Devon and just did a tour of Northern Scotland... and we all know what happens if you then leave it (and using the simple relay now also your main battery) discharged.

So... I personally have completely abandoned split charging. If it won't properly charge my leisure battery leaving it needing finishing off on another system (mains charger? Solar?) what's the point? Having no access to mains where the van lives it was either lug it indoors to charge or solar on the van roof. I went for solar hoping for a fit and forget solution.

 

I've got a solar set up on my Combo to charge the leisure battery, but looking at this as a supplementary source, just either fit a 12v socket to the leisure battery, or replace the 12v outlet plug for a pair of croc clips and charge as you drive.

 

I use a £20 eBay VSR and have the 12 amp Nordelettronica hookup battery charger/maintainer and the 200 watt epEver solar charger going to the leisure battery.

And when the leisure battery is full, the VSR closes and charges the starter battery.
When I am driving along the alternator finishes charging the starter battery and then the leisure battery starts charging.

Simple, automatic, maybe not amazing battery to battery (B2B) tech, but a proper 30 amp plus b2b charger costs a lot more than £20.., no need for wires apart from 4mm2 fused connections to both batteries and a ground to the VSR.

 

Joke toy. How long does it take ? The wire is too thin to deliver a decent charge in under an hour..

Buy a diesel engine rated set of jump leads.
Start well charged car, connect leads, wait a short while for a few hundred amps to flow, start second car.

 

I've no idea how long it takes and for £18 I don't really care.

And I'd rather not have jump leads hanging out of the bonnet of my van as I drive along (I did say it was for supplementary charging of the leisure battery, not for any starter battery duties).

Can't fault your ability and enthusiasm Mike, but your application and practicality is away with the fairies.

 

and will still notch itself down to 15A or LESS when it gets too hot to provide any more after about 30 seconds... so I've heard. Tis like alternators. Oh yes, rated at 80A but sucking much more than half of that out for prolonged periods will kill it. Both the above are blocks to stumble around charging Lithium banks on boats.

 

I live, love, to overthink this stuff.
Simple split charge as per above.
Durite or similar VSR for 40 odd quid. Appropriate size cable to join the batteries together.
Job jobbed.

No it won't be optimal but it'll work

 

@areksilverfish , One side of Durite to SB positive terminal. I use marine terminals with M8 posts on them so it's easy to connect and disconnect stuff (the cable from the relay is that one coming in on the far right)


The relay comes with an earth tail, just attach it behind the mounting screws.

50 amp midi fuse in line of the cable that goes to LB


Needs tidying after 9 years TE... maybe!

And connection to LB positive terminal. Simples...

 

Spec a relay with a high amp rating. If the LB gets fully discharged, the alternator can spike mega current so the large cable, 140amp relay and 50amp fuse just protects everything in that uncommon, but possible, scenario.

We've done it before with a standard split charge relay many years ago....

 

Personally I’m not keen on the vsr relays and would advise a simple 30amp relay or a battery to battery charger.

have a read of a how too I did
https://thelatebay.com/index.php?threads/leisure-electrics-12v.5390/

 

A VSR does the job for the same price for the relay plus the cost paying for properly rated wires. Your money , you can waste it.


That little charger is a trickle charger, not really man enough for the job that's the point I was making.
For recharging a leisure battery en route it's too feeble. For recharging a starter battery it's going to take ages.

Any cigarette lighter gadget is limited to about 5 amps continuous even if fused for 10 amps. The fuse and connection get hot after a while. Things melt.

 

I'm still not sure even after all these years why one is better than the other. I do know we've popped a standard 30amp one in the past, then ran one for years with no issues
But I'd rather be on the safe side as lots of folk have demanding power requirements these days that can't be fully catered for simply by the space afforded for a std leisure battery.
A big benefit for us, apart from it's literally only 2 cables, is they allow operation in both directions which is useful as a system grows to encompass mains powered hook up charging and solar input

 

Eeeeee.
For ten years camping with 2 kids we had... boom-tish... the Westy flourescent light in the back running off the single starter battery. That was it. How soft we've (including moi) have become in the last 20-30 years!

 

I know. It's called 'progress'.
Stealing time away from work whilst taking work with you to complete outstanding projects on laptops whilst keeping warm with the propex .
Not us I hasten to add, but I recall a fellow member bringing papers for marking one year to a TE.
Being in the field was a preferable chillout to marking for a deadline at home!
Have you seen @MR SAM HODSON mobile projector set up?
It's nuts, but all this stuff needs power

 

Agreed , 20 plus years with just a starter battery . Lights + cassssette player on a night and an inspection lamp outside for cooking - could still get 3 nights from a 60ah (?) battery but best get some sleep if the cassssette starts to slow down .
I only went down the leisure battery route when i got soft and decided to fit a Propex but had the same problem as @Zed in that the only charge it got was via a split charger whilst driving and i had to take the battery off the van whenever it needed topping up which was nearly every time out camping . Buying a cheapo 100w solar panel added to a 20w Epever was an absolute game changer , powers a Dometic CRX50 and propex when needed without any dramas - never needed to charge the battery seperately

 

As my old man used to say: some engineers like to find complicated ways of solving simple problems.......

All I'm looking at is a supplementary solution to top a leisure battery whilst driving, along with the solar I've already got installed. If I ever drain the leisure battery the chances are I'll be heading home anyway, so I'd charge it properly at home when convenient.
I'm not looking for anything other than that so don't see the need to hardwire anything else.

And I do have diesel rated long jump leads and a Nobo pack in the van for starting issues.