/ Leisure battery as a super duper powebank?

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wilkie14c - on 11 Oct 2016
Anyone done anything similar to this?

i'm looking for a solution to iphone, ipad, vape units, camera battery charging. at the moment i have 5 of the 'one shot' power bank things that are cheap and cheerful but not really suitable for my needs.
i'm wanting to have many charges of our stuff while camping and on multi day fishing trips. i bought an isis solar charger but it really was pants and i've had the idea of buying a 75ah leisure battery, battery box, flush fit 2 amp usb sockets and a charger, all of which would set me back about £100. it needs to provide power for 3/4 days of charging 2 or 3 things a day.
anyone??
wintertree - on 11 Oct 2016
In reply to wilkie14c:

Lead acid leisure batteries are not light. I'm assuming you're walking in as you're not using your car for power. A 70 Ah lead acid leisure battery from Halfords weighs in at 17 kg for example.

If you want a lead acid battery to last you want a decent charger (££). A lead acid battery will degrade over time if it's not on a float (or even lower) charge through the unused months. If you regularly discharge a cheap lead acid leisure battery to > 50% depth of discharge you'll knacker it. Cheap lead acid leisure batteries are full of nasty spillable liquid acid. Gell or AGM alternatives are safer but are ££ (Yuasa do lower capacity ones for stairlifts etc, many people - e.g. Victron, Rolls etc do larger ones).

What-ever you do make sure to fuse the battery appropriately, it's really quite amusing/scary (depending on circumstances) what a shorted lead acid battery can do.

I'd just get some decent lithium ion rechargeable power packs with USB for power in and out. Lighter per unit energy, likely safer, can be distributed between packs, can be connected to a solar charger with USB output, can be easily recharged in a pub or cafe etc
Post edited at 22:35
1
richprideaux - on 11 Oct 2016
In reply to wilkie14c:

Go for a smaller gel lead acid (burglar alarm type) and a cheap trickle charger. I use one in the way you describe or several days at a time and it works well. I use one with an inverter to run studio lights when on location shoots.

This sort:

http://amzn.to/2ed7BLY
1
Philip on 12 Oct 2016
In reply to wilkie14c:
Do you need such power? For 3/4 days you could carry spare battery packs for your camera. I take 4 for my canon ddlr and that lasts me a week usually. I don't know what a vape is. If you're only using it in the evening in a tent if have thought an iPad would last - mine does.

That leaves just your phone, which you could do from the lightweight battery packs you have.

Otherwise, as said, lead batteries are heavy. Also 75Ah at 12V without loss is 90 hours at 5V/2A. That would charge a phone 180 times, or roughly for a year.

What about this, less than £100.
https://www.solarpowersupply.co.uk/goal-zero-venture-30-recharger

Or 2 of these, only 0.5kg total
http://www.gooutdoors.co.uk/freeloader-isis-solar-charger-p307773
Post edited at 07:22
arch - on 12 Oct 2016
mike123 - on 12 Oct 2016
In reply to wilkie14c:
I'm think you mean fitting a leisure battery into your car / van ?
Edit : if not , this probably doesn't help !
This summer I finally got around to hooking up the 80amp/hour leisure battery / split charge relay that's been sitting unused under the passenger seat in my van in since new (9 years ) . I put in an eight way fuse box and hooked up 3 double usbs ( just because they ere cheaper than single 2 amp ones ) and a 12v socket / usb socket / voltmeter in the back . During the summer holidays we used all the above for 2 iPhones and 3 iPads , generally while on the move but occasionally without moving the van for a couple of days. After 2 days not moving (and hence not topping up the battery )and reasonably usage / charging of all the devices the voltage drop on athe leisure battery was minimal , 13.7 v to 10 ish v . I had done some back of the envelope calculations that suggested this would be so. However , unsurprisingly , plug the three way fridge into the 12v socket and the voltage drop is large . Also our Tom Tom sat nav is surprisingly power hungry , but since its only in use when we're moving / charging that's not s problem .
I got the fuse box and some nice flat twin core , from 12v planet , pricey but really well made and also good advice on the end of the phone. All the usb s , voltmeter and 12v socket were from eBay .
I a fully charged 75 amp hour battery should be plenty for your needs .
Post edited at 09:44
Cú Chullain - on 12 Oct 2016
In reply to mike123:


Good post!

Sounds like a very similar split charge set up to what I have. I just upgraded my battery to a 115Ah monster that gives me an extra day or so of charge.

Really looking to install a 'pop up 'solar panel system on the roof but still doing my research as I fear I am reaching the limit of my electrical engineering DIY capabilities.

What vehicle do you have?
RyanOsborne - on 12 Oct 2016
In reply to wilkie14c:

I'd second the idea of looking into Golf cart batteries. I've been looking into it quite a bit for my boat, and decided upon some Trojan batteries (2 x 6v batteries in series). They're probably a bit overkill for what you need, but if you get even a 'leisure' battery, then it'll be pretty knackered if you discharge it regularly more than 30%, so the usable AH is actually pretty low, whereas the true deep cycle batteries can be completely discharged quite a few times before they're knackered.
mike123 - on 12 Oct 2016
In reply to Cú Chullain:
Thanks.
transporter window van ( yes I know ......dogging boy of this parish calls them clitoris vans, but I suspect this is because he doesn't know what one looks like ) ( I just need one of those floppy prrvuvisn hats, or a multi colured bobble hat and a collie with a necker chief on some climbing rope ) . Bought it with a view to converting down the line hence the leisure battery , but realised that for us it s a much better family bus / practical van , without all the furniture built in . The next addition will be some LEDs lights and maybe a solar panel .
Cú Chullain - on 12 Oct 2016
In reply to mike123:

I did have a few LED external strip lights under the awning but at first they were so sodding bright there was a serious chance of either going blind or having an airplane land on you. Ended up seeing a string of outdoor 'soft light' bulbs down a garden centre for about £25 so bought those and they have worked out grand as a cheapo solution and are quite nice to chill out with a beer under in the evening.
wilkie14c - on 12 Oct 2016
In reply to wilkie14c:
Thanks to all so far!
Feel i should expand on the subject. the power pack wouldn't be moved out of the car so weight is not an issue. i could move it from car to tent if required perhaps to run some basic lights or even a 12v TV so weight isn't an issue really.
i go one of the freeloader isis solar pack/charger and ended up taking it back. 20 odd hours on bright summer sunshine and it would t charge itself past 2 bars!
thanks for the suggestions of smaller batteries, i'm going to look into these today.
i'm going to aim to have all my devices charge directly rather than via a battery to inverter, then 3 pin plug then to device. i'm aware that this is a wasteful and unessesary conversion process. laptop and possible TV would be straight from the battery via a 12v to 5v step down that uses less power, creating less heat etc
oh, although i have a biggish car (mondeo estate) this power pack won't be wired into the car at all. it'll be charged up in the garage before trips. i don't want to use the car to charge stuff while it's not running and not prepared to have it burning fuel running simply to charge stuff!.
the wife could easily charge her phone 2 maybe 3 times a day if using it for music or playing games. the vape batteries are hungary too but better for us than 40 benson and hedges!
Post edited at 10:48
winhill - on 12 Oct 2016
In reply to Philip:

> I don't know what a vape is. If you're only using it in the evening in a tent if have thought an iPad would last - mine does.

Sex toy, I think.
winhill - on 12 Oct 2016
In reply to wilkie14c:

A huge leisure battery sounds like overkill, get a small one and charge it off the car when you're out and about if it needs charging. Easy to rig it in the boot.

How far from the car are you going to be?

If it's less than 30 metres have you thought about power over ethernet?

https://en.wikipedia.org/wiki/Power_over_Ethernet

Power over Ethernet or PoE describes any of several standardized or ad-hoc systems which pass electric power along with data on twisted pair Ethernet cabling. This allows a single cable to provide both data connection and electric power to devices such as wireless access points and IP cameras.

If you use an inverter in the car you can plug in a 13amp PoE Wifi router than you can connect to directly with your phone's wifi to charge it or get a second router and convert it to USB to charge other devices.

HTH as recommended by Steve McClaren
Dauphin on 12 Oct 2016
In reply to wilkie14c:

2 X Anker 20100 mah powercores. Quick charging type shenanigans. They are 20-30 quid each. I was going to get one of the those power monkey expedition units but then the fact that it was £300 notes and only held approx 10000 mah kicked in. Why would I want to charge it via solar? Certainly not in the u.k. with any reliability.

D
krikoman - on 12 Oct 2016
In reply to wilkie14c:

If it's just phone and satnav stuff try this is small light and useful http://www.hootoo.com/hootoo-tripmate-ht-tm05-wireless-router.html

This won't power the fridge.
wilkie14c - on 12 Oct 2016
In reply to krikoman:
At the moment its phones several times a day, 2 x vape batteries (e-cig type things but big ones, not the pen type ones) AAA/AA battery charger (USB) and iPad. In the near future it could well be laptop and a 12v TV. At the moment I'm downloading stuff off the iplayer to the iPad to watch in the long winter nights but want to build something future proof and as I'm a carp angler, I often spend 2 or 3 nights by the water waiting for 1 bite! (mad I know but why do we do anything other than we enjoy it?) so I could possibly get a 12volt TV to watch news, footy match etc. A leisure battery type arrangement Im thinking could well run a TV for a few hours, a 12v coolbox and charge iPhone/ipad as many times as we want.
Post edited at 15:46
arch - on 12 Oct 2016
In reply to wilkie14c:

> as I'm a carp angler, I often spend 2 or 3 nights by the water waiting for 1 bite! (mad I know but why do we do anything other than we enjoy it?) so I could possibly get a 12volt TV to watch news, footy match etc. A leisure battery type arrangement Im thinking could well run a TV for a few hours, a 12v coolbox and charge iPhone/ipad as many times as we want.


...............No coiled spring then. ;-)
Gudge on 12 Oct 2016
In reply to mike123:
13.7V to 10V is a HUGE voltage drop for a 12V leisure battery! At 10V it will be completely discharged and if you leave it in that state for long it will be irreversibly damaged.
Post edited at 20:23
wintertree - on 12 Oct 2016
In reply to wilkie14c:

> ... car ...

This makes a lot more sense! Go for it. Make sure to get a high quality gel or AGM lead acid leisure battery and not a "wet" one. It'll last longer, suffer less degradation when discharging more than a paltry fraction, release less explosive hydrogen gas under normal and fault conditions, and pose less of a spill risk for sulfuric acid. These are more of a concern when it's the cabin compared to the engine bay. A battery box is meant to isolate these hazards from you and from ignition (fire) sources, so ideally you wouldn't put the electronics (voltage converters etc) in the battery box itself.

I'd not write off charging in the car itself during journeys. Less invasive (to your car's wiring) than a split charge unit is to use your battery charger fed from a cheap 120W inverter running from a cigar lighter socket. The efficiency loss pales into insignificance compared to the engine and driving, and it sidesteps a lot of problems with modern alternators and split charging, as well as giving you an inverter to supply low power mains from either battery (if you fit a cigar lighter socket to your leisure battery system.). Compared to split charging with a relay it's trivial to control the charge current to a safe level for your battery by getting the right capacity charger.

If you end up using crimp connectors, buy a proper ratchet crimping tool for £20-£30 and save yourself the misery of the cheap pressed steel crimpers.

Look at the depth of discharge vs cycles data for your battery and make sure you don't abuse if to death. At a minimum you'll need a voltmeter to watch it or to fit a suitable "battery guard". Some cheap panel mount led voltmeters on Amazon.

As mentioned earlier 12voltplanet are great. Everything you could need apart from batteries and battery boxes. Marine suppliers often stock the later.

If you're looking to burn a hole in your pocket then there are some lithium ion 12v batteries with built in safety/charge control/management systems. Lighter and smaller per unit energy, and you can discharge them much more without damage so even smaller still in practice.
Post edited at 20:49
wercat on 12 Oct 2016
In reply to wilkie14c:

you could design your own solution - No end of unused govt surplus 4 or 5 Ampere Hour 24 volt Clansman NiCad batteries available on certain auction sites. These pack a lot of punch and can be deeply discharged. You'd need a voltage converter to 12v but these would also increase the current available. (The energy capacity of a 24V 5AH battery is twice that of a 12 volt one - the converter will look after this for you.) You'd need some form of 24 volt NiCad charger.

I know from experience that these batteries have a lot of punch
wilkie14c - on 12 Oct 2016
In reply to wintertree:

fantastic answers, thank you!
wilkie14c - on 12 Oct 2016
In reply to wercat:

interesting info there, will research further, thanks
captain paranoia - on 12 Oct 2016
In reply to wilkie14c:

Your car already has a sodding great lead-acid battery in it. Check the Ah rating on it, and then check the Ah and voltage ratings of your portable devices. Ask yourself how many times bigger your car battery is compared to the portables...

I've seen people leave their engine running whilst charging the phone. Mental.

A car battery is about 100 Ah, at 12V nominal. That's 12*100*3600 = 4.32MJ
A phone battery is about 1Ah at 3.7V nominal. That's 3.7*1*3600 = 13.32kJ
The car battery is 324 times the energy capacity.
How many recharges do you need...?

(edit: you've added a TV, tent lighting and a fridge to the spec. That puts a bit of a different slant on things...)
Post edited at 23:07
1
krikoman - on 12 Oct 2016
wintertree - on 12 Oct 2016
In reply to captain paranoia:

> The car battery is 324 times the energy capacity. How many recharges do you need...?

A lot of modern cars only energise the cigar lighter sockets when the ignition is on. At this point all sorts of power hungry relays are closed and various computer modules power up. It wouldn't surprise me if the quiescent power draw with the ignition on and engine off isn't 10x higher than the power used by a phone charger. Sounds like an excuse to play with my new clamp ammeter...

The other downside to this is that you have to leave the keys in the ignition to energise the power sockets; theft risk?

Also car batteries aren't designed to cope well with being partially discharged for a long time; the assumption is that they'll get recharged in minutes after the starter motor runs. They'll sulfate much faster under deep / prolonged discharge conditions.

Unless you fit a lithium main battery

Edit: but yes, without the fridge and TV the main battery would probably be fine!
Post edited at 23:12
mike123 - on 13 Oct 2016
In reply to Gudge:
> 13.7V to 10V is a HUGE voltage drop for a 12V leisure battery! At 10V it will be completely discharged and if you leave it in that state for long it will be irreversibly damaged.

Indeed . Actual drop was was like to 12.2 with apples finest . Running the fridge for 24 is hours dropped it to 10.2 ( ish) . Don't ( didn't) think this would be too much of a problem very occasionally but will have a look at the actual spec of the battery , which I admit not to having done other than a brief glance. Also happy to be corrected rather than f&?k it. Ta.
Post edited at 06:34
timjones - on 13 Oct 2016
In reply to wintertree:

> A lot of modern cars only energise the cigar lighter sockets when the ignition is on. At this point all sorts of power hungry relays are closed and various computer modules power up. It wouldn't surprise me if the quiescent power draw with the ignition on and engine off isn't 10x higher than the power used by a phone charger. Sounds like an excuse to play with my new clamp ammeter...

> The other downside to this is that you have to leave the keys in the ignition to energise the power sockets; theft risk?

> Also car batteries aren't designed to cope well with being partially discharged for a long time; the assumption is that they'll get recharged in minutes after the starter motor runs. They'll sulfate much faster under deep / prolonged discharge conditions.

> Unless you fit a lithium main battery

> Edit: but yes, without the fridge and TV the main battery would probably be fine!

It's a simple job to wire a fused socket into a permanent live feed.
Cú Chullain - on 13 Oct 2016
To all:

When it comes to vehicle modifications (of the camping / off road variety) this book is pretty good. I used it when adapting my LC for overland travel. Has lots of tips/ideas/solutions for any electrical, storage, fit outs, upgrades etc that you have in mind.

http://overlanders-handbook.com/

wintertree - on 13 Oct 2016
In reply to timjones:

> It's a simple job to wire a fused socket into a permanent live feed.

That it is, but then you've got to put a hole through the firewall from the engine bay to the cabin, then somehow hide the wire away through the cabin to the boot it becomes a bit of a carry on.

I'd also have concerns that with a split charging system that one could potentially have very high currents, meaning that one either had to use a high current fuse, or deal with it blowing a lot. To be safe you must then use a wire that won't catch fire before it blows the high current fuse, meaning 30mm^2 or larger battery cable. I'd personally not trust the quality of a body earth for such currents. Further, a 100A fused live feed could cause a lot of mischief before the fuse blows, so isn't something to run lightly through the passenger compartment or exposed underside of the car.

You have to join your battery cable in close to the master battery which becomes quite invasive - probably hacking the cable and adding a splicing box, or changing the clamp on the battery to a post and lug type affair.

12 volts DC may sound a lot safer than the mains however battery charging and short currents are quite serious.
Post edited at 08:44
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timjones - on 13 Oct 2016
In reply to wintertree:

> That it is, but then you've got to put a hole through the firewall from the engine bay to the cabin, then somehow hide the wire away through the cabin to the boot it becomes a bit of a carry on.

> I'd also have concerns that with a split charging system that one could potentially have very high currents, meaning that one either had to use a high current fuse, or deal with it blowing a lot. To be safe you must then use a wire that won't catch fire before it blows the high current fuse, meaning 30mm^2 or larger battery cable. I'd personally not trust the quality of a body earth for such currents. Further, a 100A fused live feed could cause a lot of mischief before the fuse blows, so isn't something to run lightly through the passenger compartment or exposed underside of the car.

> You have to join your battery cable in close to the master battery which becomes quite invasive - probably hacking the cable and adding a splicing box, or changing the clamp on the battery to a post and lug type affair.

> 12 volts DC may sound a lot safer than the mains however battery charging and short currents are quite serious.

I was thinking of a permanent feed to a couple of usb charging sockets for phones, tablets and the like. I've never found a car that doesn't have a permanent 12v feed behind the dash or under the seats.

For split charging systems I'd always prefer to site the extra battery and wiring within the engine bay.

wintertree - on 13 Oct 2016
In reply to timjones:

Right, I understand. Agreed although some care is needed not to overload random wires under a seat...

timjones - on 13 Oct 2016
In reply to wintertree:

> Right, I understand. Agreed although some care is needed not to overload random wires under a seat...

There are usually plenty of nice hefty wires to choose from ;)

The main feed to a fuse box is a good candidate, it's usually possible to find an unused fuse slot that you can use.
MarkJH - on 13 Oct 2016
In reply to wintertree:
> I'd also have concerns that with a split charging system that one could potentially have very high currents, meaning that one either had to use a high current fuse, or deal with it blowing a lot. To be safe you must then use a wire that won't catch fire before it blows the high current fuse, meaning 30mm^2 or larger battery cable.

30mm cable is rated at 170A. Do you think that the average car has an alternator that can put out that much current! The limiting factor for the cable sizing will almost certainly the voltage drop to the leisure battery (assuming that you aren't using a battery sensed regulator). An unfused 10mm charging circuit to the leisure battery will almost certainly be appropriate and safe for most split charge systems. Move up to 16mm if you have a massive alternator or very long cable runs.
Post edited at 10:26
wintertree - on 13 Oct 2016
In reply to MarkJH:

> 30mm cable is rated at 170A. Do you think that the average car has an alternator that can put out that much current!

Not under normal circumstances but if it's using a split charge relay (as opposed to split charging diodes) then when connecting a severely discharged leisure battery there will be additional current flow from the master battery.
MarkJH - on 13 Oct 2016
In reply to wintertree:

> Not under normal circumstances but if it's using a split charge relay (as opposed to split charging diodes) then when connecting a severely discharged leisure battery there will be additional current flow from the master battery.

Ah yes, see what you mean; I wasn't really thinking of relays. Can't see why you wouldn't use split-diodes these days though. They are much more reliable and not that much more expensive.
wintertree - on 13 Oct 2016
In reply to MarkJH:

> Ah yes, see what you mean; I wasn't really thinking of relays. Can't see why you wouldn't use split-diodes these days though. They are much more reliable and not that much more expensive.

I believe having a diode in the master battery part introduce problems for more modern emmisions compliant vehicles that use automatic voltage regulation alternators. AVRs introduce other problems for split charging as well, which is where the "poor man's DC-DC charger" made with a cheap low power mains inverter and mains charger comes in to its own. The alternative is a proper DC to DC controlled charger which is several hundred quid.
Post edited at 13:52
mick taylor - on 13 Oct 2016
In reply to wilkie14c:

Quick tip: i've had a few leisure batteries (powering a lecy outboard for fishing boat) and highly recommend the CTEK charger, MILES better than normal battery chargers and can almost recover a battery from the dead (when, as someone else said, you've screwed it up by running it flat).

Bloody heavy things mind, and my lecy outboard plus 2 leisure batteries weighed more than my petrol outboard.
MarkJH - on 13 Oct 2016
In reply to wintertree:

> I believe having a diode in the master battery part introduce problems for more modern emmisions compliant vehicles that use automatic voltage regulation alternators. AVRs introduce other problems for split charging as well, which is where the "poor man's DC-DC charger" made with a cheap low power mains inverter and mains charger comes in to its own. The alternative is a proper DC to DC controlled charger which is several hundred quid.

Interesting, I didn't know that. I had seen some of those "battery to battery" chargers for sale and had wondered why you would chose one of them over a standard advanced regulator and split charging system. I guess that is why.

wilkie14c - on 13 Oct 2016
In reply to mick taylor:
Thanks for that Mick, just had a look and they do fall within my price range too.

I have 3 x 12v outlets in my car, dash, rear passenger area and tailgate. I'm well aware that the car battery would charge a few devices many times over without losing ability to start the car however I want to build something future proof. In the future a TV and a fridge may be added simply as luxury items and because I'd already have the means to power them. TV would prob require an active signal booster too so that'd be more power. In the future there may well be longer trips here in the UK and further afield - Ireland, Holland & France. Although my super duper powerbank sounds like overkill for what I want now, I want it to be as future proof as possible.
Post edited at 14:09
BStar - on 13 Oct 2016
In reply to MarkJH:

Just for info, modern alternators can push out 90A quite easily, my Fiat Doblo does. I put a 70A fuse in line with the main power cable and blew it. I put 25mm cable in my camper van, and would not advise putting 10mm2 in unless you are certain that the alternator cannot put out more than 60A.

My leisure battery is charging off a voltage sensing relay (Durite voltage sensing relay, google it). With 130Ahr battery I can change my phone, run my radio and much more for a good few days before it needs to charge it, then anytime I drive anywhere it charges the battery without any intervention.

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