Split charge and security advice for travelling.

[16 RN 49]

Hi all,

I think I'm going to need a 2 battery system in my Land Rover but I'm after some advice first. It could be I'll get away with one good battery.

It's not going to be used in challange events or anything like that and won't have a winch. It will be used for travelling though. Last year I flattened my battery when I accidently left the fridge on overnight. However, turning off the fridge everynight left me with a pretty useless fridge!

So, I want to run a fridge for at least one night. If it'll run for two nights and a day that would be better, but I can always plumb in the gas for that length of time. I want to be able to listen to music (PDA and amplifier), charge my PDA and laptop etc while driving and while stopped. I want to be able to use interior lights when stopped for a good length of time (upto 2 nights would be good but I can always get the Tilley out for some of that).

I do not want to run the risk of not being able to start the engine.

From a security point of view, the vehicle is hopefully going to be a full soft top. Do I need any kind of battery isolation switch, or anything?

If 'VentureOverland' is around I know his company do a '2 batteries in the seatbox with gubbins' system. I would be interested to kow if that might fit my needs (and wallet!) and if there are similar alternatives around.

Many thanks all!

Pete.

[mrcheese]

This is what I have. Under the seat are two batteries. The main one for starting and a leisure battery.

Both are connected to ground. The positives are connected together via a big 100A relay. With the engine off the leisure batter is isolated. I power what I need from it using a cable to a cigar lighter socket.

The relay only connects the two positives when the engine is running. In this way the second battery is charged and it won't matter if you have run it flat.

To activate the relay you will need to find a source of 12V that is only live when the engine is running. I have a V8 and I use a feed from the fuel pump. You can also use a feed from the charge light. If you search there are threads on here with some drawings (not had a chance to look yet).

You will find what you need here.

http://www.vehicle-wiring-products.co.uk

Paul.

[16 RN 49]

Thanks again. I'll have a look at that site. Which batteries do you use?

[mrcheese]

The main battery is something bog standard and the leisure one is about the same size and came from a camping show. They fit nicely side by side.

You can see them in this picture. This was taken after an electrical fire. The winch cable shorted out. The isolator switch melted! The white powder is from the extinguisher. Perhaps not a good advert for my expertise.

[SimonWH]

A split charge system is simplicity itself to install if you just want the big, dumb relay affair.

Essentially it just connects the spare battery when charging and disconnects it when the engine is off, you then connect all your in-car electrics to the spare battery thus preserving the main battery for starting the engine.

The ideal solution for long trips is a deep-cycle battery. A starter battery will not take kindly to being drained and recharged very often, in fact you'll kill it in record time. If you're on a budget I'd have a look at a leisure battery designed for a caravan of at least 85ah (amp hours) and make sure it'll fit under the seat next to your existing battery.

I fitted THIS ONE from OEC International as it comes with everything pre-wired and everything cut to length. (you could build the kit yourself for less with parts off ebay but I like the simplicity of getting everything in one box with full instructions!)

I also fitted a DUAL MATE battery management system from the same company but that may be a bit over the top for what you need.

Don't forget to run all the connections to the spare battery through a fuse!

[16 RN 49]

Thanks all for you help. I was expecting something a little more complex and a fair amount of re-wiring.

So, keep my existing battery as the starter, grab a small caravan battery and then a kit like the one Simon linked to (which sounds perfect).

Sounds easy!

I know there's a thread round here somewhere that goes into AHR ratings so I'll find that and have a read.

[16 RN 49]

Oh, one more thing, what size fuse would you recommend, or is that dependent on the things I want to run? Some of them already have their own fuse.

[mrcheese]

Peter - For the leisure battery fit a fuse as close to the positive terminal as you can get. I use 20A as this is the max supply I need.

London Luke - The cable over the bracket is a ground cable. The one with the fuse just got moved out of place during the event. The underneath of the seat cover is also plastic coated as there is not a great deal of clearance.

Paul.

[The Original Tom]

I would fuse everything individually. find their wattage ratings and work out the current at 12v, and select a fuse higher than the value. e.g if an appliance pulls 11A, use a 15A fuse etc.

If you're going to be wanting to run a fridge, charge laotops and phones and use lights, for 36 hours you'll surely need a pretty huge battery?! My laptop power supply is 3.65A at 20V which is 6.08A at 12v!

[SimonWH]

When I mentioned fuses I meant what Tom said, make sure everything you connect to the battery is fused. It is very easy to run a live wire direct to the batter and connect something to it. (I've seen lots of people forget about a fuse)

If you really wanted to go to town you could invest in a fused distribution block like this:



Just connect this to the live terminal on your spare battery and fit the appropriate fuses for each item you're connecting, that way all the fuses are close to the battery and all in one place. (the streetwires one is designed for boy racers and fairly expensive but there are cheaper versions on ebay)

[16 RN 49]

Now it's starting to make sense. This is very helpful.

Well, most of the distribution boards on eblag are chav type ones. Not really what I'm after.

What about something like these?:
http://cgi.ebay.co.uk/ABI-Caravan-Zig-Unit-Dist...itemZ270116580930
http://cgi.ebay.co.uk/ABI-Zig-CF9-Distribution-...itemZ330118029141
http://cgi.ebay.co.uk/ZIG-MARQUE-1-CONTROL-PANE...itemZ130109125653

Some of these 'Zig' units offer mains charging of the battery, mains / 12v switch for the fridge, switching from car to van battery, charging from mains or car and 12v fused distribution.

I think!

This sounds ideal as it would handle the split charge and allow mains charging and allow the fridge to run on 230v. I could plug it all into the mains before setting off and make sure everything is tip-top. Have I missed anything? It sounds too good to be true!

[SimonWH]

Hi Peter

Everything you say is possible . . . but . . .

Those ZIG units are massive and not really suited to fitting in a vehicle. I sold one like your 2nd link on ebay last week (£55). There are also a few reliability issues with buying something that's been ripped out of a caravan. I bought it for my campervan but never got around to fitting it, I just couldn't find a good place to fix it without sacrificing valuable storage space.

I can send you a PDF copy of the fitting instructions and manual if you want to have a look at it, they are very easy to fit and use if you did decide on it.

I've spent literally hundreds of hours researching electrics and batteries for my vehicle, this is what I decided to do:

main starter battery (under passenger seat)
2 x 150 ah leisure batteries (under drivers seat)
split charge relay
Dual Mate battery management (more details below)
100w Solar Panel and charge regulator
Sterling 40amp Mains battery Charger (more details below)

Everything in the vehicle will be 12v or have the ability to run off a 12v supply. I decided the extra expense, weight and loss of storage space for fitting a 240v system wasn't worth the hassle. I might fit an invertor as a temporary measure to run anything that isn't 12v while we're in the UK but we won't take mains equipment on our foreign travels.

This set-up is not cheap, the full retail price of all that kit is getting on for £2k but it is - for me - the most efficient and flexible.

If all you need is a basic mains hookup for occasional use I'd thoroughly recommend one of these off EBAY:


Dual Mate Battery Management system is a stunning box of tricks. The standard split charge relay is just a big dumb switch that opens when the engine is running and closes when it's not. Once the main battery is charged the leisure battery will no longer be charged either. The Dual Mate is an intelligent device that monitors your batteries condition and switches between them to prioritise the charge as required. It also gives you the option to temporarily bring the leisure batteries online to act as a starter backup if the main battery has failed (a split charge cannot do this)

Sterling Battery Charger This unit is designed for ocean going boats. It can take a mains supply anywhere between 80v and 300v and charge your batteries - very important when travelling through countries with dubious mains supplies or different voltages. It also has the option to act as a power centre. So when your batteries are fully charged but you are still drawing power (eg to the fridge) the power will come DIRECT from this unit and your batteries will remain untouched.

It is also important to make sure the battery charging system is matched to your battery - might sound obvious but not all chargers can cope with GEL or AGM batteries.

I am writing an article about on-board electrics that may appear in LRO very soon, as I said, I've become a bit of an armchair expert on all the possibilities.

[Bermuda Import]

give these ppl a try

http://www.vehicle-wiring-products.co.uk

used them many times

this is what i think ur looking for

http://www.vehicle-wiring-products.co.uk/VWPweb...elays/relays.html

part number

Ref: RB4U under Relay boxes

and
http://www.vehicle-wiring-products.co.uk/VWPweb...use-1/fuse-1.html

Ref:FBB16U

nice bits of kit makes the job A LOT easier

[16 RN 49]

Hi Simon,

Thanks again for a very informative post. I would be very interested in a copy of the installation instructions. That would give me a clearer idea about their potential usage and whether one would suit. I'll PM you my e-mail address.

I didn't know that a simple split charge relay would not charge the aux battery if the main battery was fully charged. That would surely prove problematic if the aux battery is used extensively for longer stops. Not good. Would a Zig system work the same way or would that still charge the aux battery when the main battery is charged?

I'm not really after a mains supply in the vehicle at all times but running the fridge on mains where possible would be nice (it's colder on mains than 12v) but I wouldn't run that from the battery through an inverter. I will have an inverter with me, however, but only for very occasional use / emergencies.

Your setup does sound excellent. I can well imagine needing that when going to more remote places. Hopefully I'll not need anything quite so sophisticated. Yet.

Picking up on the different types of leisure batteries:

Lead Acid - Unsealed
Lead Acid - Sealed
Gel
AGM

Is there any particular type I should go for, or any that I should avoid? I should imagine unsealed in a Land Rover that's going to end up in the rough stuff isn't a good idea! But then, what do I have currently? Mmmm...

Pete.

[16 RN 49]

[VentureOverland]

Peter,
Are you planning on going to the Spring Adventure Show in Driffield this weekend?

If so pop in and have a word. As you've gathered, this is a fairly big subject and your ideal solution is largely dependent on your immediate requirements and how crucial your batteries and ability to start is.

On the face of it though you should be able to keep your existing start battery and drop a good second battery in and link with a split charge system. How good a split charge system you need again depends on your requirements.

How big a battery you need depends on your fridge and how much power that drags. With my Engel I can leave it going all weekend on an Odyssey PC1700.

If your not going to Driffield, feel free to give me a call.

[SimonWH]

Jons Odyssey batteries are the dog's reproductive organs!

Something else to remember is that the ZIG units do not include an RCD trip switch and if you are intending to use a hook-up on a commercial camping site they will insist on an RCD. It's best to fit one anyway.

An alternative option is something like this:



Available from Oleary Motorhomes for £165. It hasthe RCD built in and does everything the ZIG does. They are also available with an upright control panel (ie tall and narrow rather than wide like the photo)

Go to their website
>>click on Online Store
>>click on Electrical Systems

They also do the full range of ZIG stuff

Then you'll need a hook-up plug, etc, etc, (the list soon adds up!)

I'll try to compile everything together to give you a few more pointers.

[16 RN 49]

Thanks all.

I've read through the manuals for the Zig unit, Simon. Many thanks for posting those. I'm sure there's a typo or mistake in there somewhere, regarding the connection of the 12v fridge supply. No matter. It's certainly cleared a lot of things up for me and something like that would work.

Mmm. RCDs. Well, I guess there's no point in having mains hook-up (even for emergencies or rare usage) without an RCD. I gather they can be expensive. So an all in one unit might be useful. Pricey, though.

Anyway, I had a quick look at the fridge last night, and other things that'll be plugged in at some point. Here's what I found:

Fridge:...........4A (actually just under I think) at 12V
Laptop:..........3.36A at 16V (4.48A at 12V???)
PDA:..............2.4A at 5.4V (1A at 12V???)
GPS:..............1A at 5.4V (0.45A at 12V???)
AMP:..............Don't know. It's a 200W amp but would never be at that load when stationary. 5A at 12V???
Strip Lights:..2 of. Approx 1.2A each at 12V I guess.
Phone:..........0.45A at 4.9V (0.18A at 12V???)

So, unless I'm way off base, I'd need a 160Ah battery to power the Fridge for a 40 hour stop (2 nights and 1 day). Or two 85Ah+ batteries.

How are my calculations?

Also, anyone any thoughts on battery type?

I might be able to make Driffield at the weekend. I was considering it anyway.

Pete.

EDIT: Surely the fridge won't be running at full tilt all the time? Maybe during the day, but not at night. It did manage to drain my old 110's battery (70Ah), to the point where it wouldn't start the engine, in a night and a bit (20 hours ish), however.

[:)]

[SimonWH]

The general rule I found was that motorhome manufacturers calculate that a fridge (like most other equipment) will only be used for a total of 8 hours in any given 24 hour period (IE a third of the time) But it is VERY much influenced by the type of fridge.

The most efficient types are compressor fridges but they start to add mucho wonga to the price list, less efficient 'coolers' are much, much cheaper but need to run constantly.

What fridge have you got?

As for batteries, I can thoroughly recommend the Odyssey range as they have the ability to be both deep-cycle and can be used as a starter if the main battery fails.

For a weekend stay I reckon you'd get away with a single 65ah (like the Odyssey p1700) It would certainly be worth trying it first before buying TWO batteries - you can always just take the motor for a quick spin to boost them if they are running short.

[16 RN 49]

I fear my fridge is the none-compressor type. It cost me in the region of £40 - £50 from CCC in Sheffield. It runs on either 230v, 12v or Butane / Propane. I will be running it on gas anytime I pitch my tent but I'd like the option of sleeping in the Land Rover for up to two nights without going anywhere.

Buying just one battery and seeing how I get on makes a lot of sense. A PC1700, however, is a little pricey for my needs at over £200. I could get a 100Ah Elecsol, for example, for around £100 which would hopefully power my inefficient fridge for around 24 hours. Adding a 2nd, if needed, would see me good for a weekend.

Options and choices...

[SimonWH]

The elecsol is a good choice. They are physically smaller than similarly rated batteries from other manufacturers so you can fit it under the passenger seat.

With a gas backup you'll be fine with a 100ah for the weekend. I estimated that 200ah would see me through a whole week running the laptop and DVD player etc

There is a bloke on ebay that sometimes sells Elecsols. It'd be worth a search.

[16 RN 49]

Cheers, Simon. Yep there are a couple of ebay shops selling Elecsol batteries. £100 will see a 100Ah one delivered.

Unfortunately I've just checked my fridge and it's actually 6.25A at 12v.
So, looks like it's going to be two batteries after all...

[mmgemini]

[quote="Simon@Difflock"]
The standard split charge relay is just a big dumb switch that opens when the engine is running and closes when it's not. Once the main battery is charged the leisure battery will no longer be charged either. The Dual Mate is an intelligent device that monitors your batteries condition and switches between them to prioritise the charge as required. It also gives you the option to temporarily bring the leisure batteries online to act as a starter backup if the main battery has failed (a split charge cannot do this)

[
Why not.
Mine does.

You can't fully charge a leasure battery from flat with an alternator. Nor is it always possible to charge a vehicle battery from flat with an alternator.

A leisure battery WILL not start your engine, it doesn't have the cranking ability, that's why I bought an Elecsol as it's not just a leasure battery.
However if your system is wired correctly then your aux battery should go flat and not your vehicle battery. Well mine works that way.

IMO the best system is a VSR. That's what I would fit now. My split charge relay is very old. It works very well and it is bush repairable. It's all very good having an intelligent system working but when it's not you have nothing.

Fridges should be wired DIRECT from the battery. Do not use the vehicle earth.

Be aware also that not all alternators can be used to trigger a split charge system

For those of you that can get hold of a copy of SA 4X4. magazine. There is two very good articles this month. One on alternators/batteries and one on fridge use.

[The Original Tom]

Leisure batteries will start an engine. My battery was drained by a dodgy central locking fit and I had places to be, so I borrowed the neighbors old battery from their caravan, with "Leisure battery" written on the side. Worked fine when mine wouldn't even turn the engine over.

[16 RN 49]

mmgemini, what's a VSR?

Anyway. There's little price difference between a 100Ah and 110Ah Elecsol battery (£10). There is a difference in size, however:

LxWxH mm
100Ah - 277 x 175 x 190
110Ah - 352 x 175 x 190

In your learn'd opinions do you think two 110Ah batteries will fit in the drivers seat box? Will one fit along side the normal battery in the passenger seat box?

I probably will only buy one to start with, and put it in the passenger seat box, but I'd like to make sure I can take two of the same.

Ta!

[SimonWH]

[SimonWH]

[mmgemini]

Voltage Sensitive Relay.
Look at http://www.merlinequipment.com/industries.cfm All the information should be there.

Speak to Matt. He will also discuss batteries with you.

You will get a 110 Elecsol battery under the seat box with the vehicle battery.

I suggest you do what I suggested to Simon some time ago and make the battery box deeper. I can't get to my positive terminal on my Elecsol when its fitted.

[matisamd]

Hi just reading this great thread, i was reading about batteries elseware and something mentioned was if you have batteries in the cab make sure they are ventilated as hydrogen can build up, or other faults occur could cause i guess in rare occasions the battery to explode not good if its under your seat ?! (unless its steel lined or something i remember that story of a car bomb going off but the seat was steel plated or something maybe it was TV, any way) just wanted to mention this as i didn't see anything mentioned and don't want to read about it later .

Something that confused me is that if you use a 230v system you use less current for the same power so does that mean its better to use 230v because if you draw the same amount of amps on 12v as 230v you get much higher power output on 230v ? i am looking to run alot of AV and PC equipment.