Which leisure battery ... not what oil

Go on google and find-out Lazy!

 

I reckon the cheapest / easiest option for me would to be sacking the AGM off like you have Neil and just buy a decent lead acid and not drain it flat like I normally do

 

Shurrup

 

Campers place unusual demands on their batteries.

1. Camper is often not used for long periods

2. Camper uses considerable power while on site.

Molteni Mike's modifications.

1. Two batteries (NOT leisure ones) bought from a breakers yard for £15 - £25 each. They're huge, 80+AH each and I've always got more than 4 years good use out of them.

2. Hardwired the +ve terminals together with heavy duty jumper lead cable. Then sent both earth cables to a heavy duty (300Amp!) "boat switch" placed in a rear cupboard. This gives a choice of OFF - batt 1 - batt2 - both. The choice of using the "earth" for this system is in case of a short circuit, the system is safe. Never ever turn the switch to OFF with the engine running, you'll fry the alternator diodes! I've never used the "both" option as charging more one than one battery in parallel results in the "better" battery only being charged to the level of the "worse" one.

3. Wired a solenoid (standard Leyland starter solenoid) so that when the starter is turning, BOTH batteries are momentarily called into action.

4. When parked in the drive, the electrics are plugged into a "Smart" charger which safely keeps the battery charged without risk of overcharging.

Protocol when away from home.
As soon as the vehicle is parked for the night, the battery is "switched" to the other one. In this way the battery just charged by a long drive will be fresh for the following day. The one just connected can be used overnight without concern about the following morning's start.

Touch wood, this setup/protocol has worked 100% for several years.

Here's a picture of the boat switch, they're about £25 from chandlers. Good Smart Chargers are available from various suppliers on eBay for £15+.


The traditional "split charge" system has the "overnight" camper electrics wired to the leisure battery and a relay to charge both batteries together when the alternator is turning. It's a great system when everything is working! But there's a small risk that something to do with the vehicle's electrics will be left on (sidelights, courtesy lights etc), causing the engine battery to drain on site.
Additionally, if the leisure battery is in poor condition, after a long drive the engine battery will become drained.

But on an old vehicle, starting needs every help we can give , hence the decision to use two engine batteries which are used in tandem when cranking. In my set up, the system has controlability in that I decide where the charge goes and which battery is used overnight. Actually I don't use much power on site, in the days when I had just one battery, I could remain on site for several nights and the engine would (just about) start.

For the majority of the time the camper is not used for holidays, so it can be driven without regard to charging. Just swap batteries via the switch every couple of months.

I like the peace of mind which comes with knowing that the fully charged battery is completely isolated overnight from any current drain.

It's a bit of hassle to remember to switch over batteries but it soon becomes instinctive.

 

My last leisure battery lasted 9 years the trick is a good mains charge with decent multistage charger before you go and when you get home.

 

Anyone tried Banner batteries? I need to replace both of my leisure batteries and I liked the quality and the reviews.

 

Excellent use of your 2am wake time ... Thank you!

 

@sANDYbAY for one...
7 years ago now!

 

That's a monster!!! I was looking at two of these smaller ones.

https://www.tayna.co.uk/leisure-batteries/banner/95551/

 

I'll just throw this into the pot.
It's accepted in the boaty world that almost every smart charger goes into float too soon - before the battery is fully charged. This is to prevent batteries that are not so depleted from over charging - you can't have it both ways and the charger cannot see the rested voltage, just charging volts. If you leave it permanently connected and switched on, it will get there eventually, but if you use it to charge your battery from well used after you've been camping then switch it off, the overwhelming chance is that it won't be fully charged. So, if this is you - when you see your smart charger has "finished" switch it off then switch it on again. Then repeat another time. If you don't so this your battery will sulphate.

I can cut and paste the technical explanation if required.

 

That's interesting, I have long thought this has some truth based upon empirical evidence of open circuit voltages after a single charge only versus multiple charges; I tend to rotate my charger across my various batteries over the winter.

 

Apparently this is numero uno reason for peoples short leisure battery life. Solar controllers do the same... or some do. I suspect mine didn't and that's why left permanently in the sun for months on end with no drains it boiled my battery instead!

 

If you want to know if your battery is fully charged it's not straightforward and you can't judge it by the rested battery voltage either haha. Your best hope may well be to use a carp charger that is not smart. Ironic eh! That's not dissing smart chargers.
You would need to accurately monitor the charging amps until either the amps going into the battery (which gradually fall) reach 1-2% of the battery capacity around 14.4v, or stop falling for about 1 hour. Continuing to charge after that point will damage the battery, hence the existence of smart chargers which do this for you... except that they do it too soon and the more depleted your battery is the more "too soon" that is. Here is why for anyone not already glazing over...

There is no direct correlation between state of charge, and ability to absorb current. Think of the battery plates as sponges, the material at the surface is easy to reach /easy to react, the stuff deep inside is much harder to reach /slower to react.

So if you take a battery at 50% SoC and apply a large charger, let’s say you get 150A charging current. By 75% SoC you will perhaps be getting 75A and by 90%, perhaps 15A. This is because the chemicals deep inside the plate have been discharged, and it takes a long time for the charging reaction to penetrate deep into the plates.

But if you take the same battery fully charged, discharge to 90% fairly quickly and then apply the same charger, you will get an initial charge of around 150A. The current decrease will follow the same shape as before, but over a much shorter time. (Ie the current will decrease much faster). This is because the battery was discharged by reacting the chemicals on or near the surface of the plates, and that reaction is easily and quickly reversed during charge.

And that my friends is why smart chargers are made to err on the safe side and cut off too soon for a heavily depleted battery. They are made for numpties like us that do not want to monitor charging, CBA to learn how to, and don't want to blow up their batteries by over charging. It also explains why in those circumstances your battery will sulphate, starting deep inside the plates. That capacity is permanently lost but can be rescued to a certain extent by basically boiling your acid with high voltage (15-15.5v) in a controlled manner.

Sorry about the large chargers in the example, most people on boats don't mess around with 5A chargers and 80ah batteries. My own charger is 120A.

 

I am not countering your statement, Zed, I agree, but I should have been clearer, on how I was making my empirical measurements. I was measurng the both the peak and delta open circuit voltages between rotations of the single smart charger across my multiple batteries, usually with multiple days in between, tho' I wasn't as scientific as I could have been as the period wasn't long enough, nor a constant.

Delta OCV is, in the modern world, a typical way to guage SoC and SoH of Lithium batteries during formation, but the same electrical laws/physics applies, I would think, even if the chemistry is different.

 

In a crate on the swim I have a hydrometer! @Zed
Can you believe before all this smart malarky the most accurate method of determining SOC was to measure specific gravity of the battery acid and chart the degradation over a period of time!
That took effort though, and an understanding of the calibration, or not, of the hydrometer.
What was it, weigh the electrolyte and divide mass by volume or something like that

Then each cell had to be monitored and recorded, if you could be bothered. And really nerdy nerds would factor an adjustment for temperature! I did that for one summer whilst we were travelling the system, quite a few years ago. Boat time...

Thank god for smart chargers and to be honest the relative lower cost of batteries!

Don't get me started on lithium and BMS systems...shonky shonkness in my experience and actually more of a faff than fla, because the temptation is to constantly monitor the battery.
I'm over that now! I'm doing a long term test on Lifepo4 batteries in the cratch and powering our travel fridge. They just sit there until I think they need a charge, largely ignored!

 

I wasn't really replying to you directly cat, just adding some (hopefully quite easy to understand) info for those frustrated by their battery short life but do not know why, considering that they are using smart chargers and doing their best. I'm the first to admit I don't totally understand this stuff, I'm a battery murderer myself, but I wish to get out on the cut and be self sufficient so I'm doing my best to gradually learn. You should see the trouble you have to go to when converting to Lithium! Balancing cells, under/over charging etc - you don't get a second chance with those - one false move and £k's of batteries permanently ruined.

 

Absolutely! At the end of the day smart charging and chucking your batteries every few years is likely to cost 50p a day or so... so why bother when a slice of cake in the cafe is £2.50!
I simply could not be bothered to be checking electrolyte regularly.
Apparently now there is a smart battery monitor that does take into account amps as well as volts but it's £200 and sadly none of them seem to be very reliable when it comes to monitoring usage or state of charge. Which ever way you go if you want to maximise your battery life it's going to take user intervention, there just is no fit and forget system.

 

No worries, just trying to clarify things a bit. I know a more (which isn't a lot) about Lithium than I do FLA, to be honest.

And, yes, balancing Li batteries, can be a big deal.

 

Balancing a big bank is essential but also should not be something you have to do too often. The catch seems to be that to err on the safe side you don't deplete under 20% capacity and don't charge over 80%. That immediately kills the extra capacity angle, but you do still get very fast charging.
@tom-bex on here would be the resident expert if he thought there was a point, but as we are little campers... He reports that once the initial head scratching is over and your home-made BMS is up and running, it's actually fit and forget much more so than lead acid - it's the initial headache that puts people off, you do need to be either determined or willing to spend enormous sums on new batteries and a tailor made system around them and for most people the buy it method will simply never ever pay off. One day maybe.

 

After using a split charger and a lead acid battery with solar panels the game changer for me was to fit a B2B charger and a lithium battery. I haven’t used a hook-up since fitting the LiFePO battery and no longer need to take care that the solar panels aren’t in the shade and I no longer have to worry that the fridge will discharge the leisure battery after a day or two camping.

Lead acid batteries are cheap but have only about half the rated capacity and a 400-cycle life, or less. The LiFePO cost about 4 times the price of lead acid but has the stated capacity and 4000+ cycles so instead of about 50Ah I have 180Ah and instead of needing a new battery every 4 or 5 years the LiFePO will probably last 15 years, or more.

I was concerned the 55amp alternator (type4 engine) would not cope with the 30amp B2B but that has not been a problem, the engine battery is topped up and then the B2B charges the LiFePo. When the engine is off the starter battery is completely isolated and is left to start the engine.