Charging systems

[windyjools]

I'm trying to find a more efficient method of charging the leisure batteries when the engine is running!
I currently have the standard split charge relay which works but have read abou the Sterling Battery to Battery charger which claims to charge the betteries quicker and to a higher level. The price however is a bit of a shocker, so has anyone found a better way of charging the leisure batteries using another relay system?
I wild camp all the time so 240v hook-up is not much good for us. Any thoughts would be good!

 

[Bernard Jones]

Just a matter of minimising the resistance in the connections between the main and leisure batteries. Cable ratings tend to be based on the maximum current the cable can carry without risk of catching fire, but will produce a lot of resistance at the maximum rating. The cables supplied in the split charging kits sold by the likes of halfords are just too thin for fast charging. Fuses priovide further resistance. I use a 100amp relay, connected with 25 sq mm copper cable, and no fuses, so the leisure batttery charges just as fast as the main battery. Of course, if you omit the fuses, you have to be sure it is very well insulated so there is no chance of a short circuit. Anywhere the cable touches metal I feed it through hose for an extra layer of insulation.
If you need to buy thick copper cable from a retail outlet, it will probably be cheaper to buy a set of jump leads, and use the cable from them.

 

[David & Ann]

Normally your Alternator charges your battery while on the run. Solar panel will charge when engine is off. Someone with electrical and wiring knowledge will come along and advise you. If you can afford a Solar panel and a second battery, your problem for not wanting to stay at campsites will be solved.

 

[Bernard Jones]

I've never needed a solar panel, but it does depend on the capacity of the alternator fitted to your van. The X2/50 has 160 amp alternator as standard, which is plenty to fast charge a leisure batery, even on tickover, providing there is low resistance (thick cable) connecting it to the main battery.
Of course, the 'experts'/salesmen will advise you to buy something more expensive, because most of the free advice on the internet derives from those in the business of selling expensive equipment. They will consequently ridicule my suggestion of omitting fuses through using extra insulation, (no profit for them in that) and others will repeat their advice

 

[Admin]

I use a CTEK d205s which charges up to 300ah of batteries using the alternator. Before this my inverter batteries were on split charge. I have a NASA Marine battery monitor installed so the results I give are based on its readings not just my personal opinion. Before the d205s the batteries charged to about 78% of capacity and now they charge to 105%. That is 105% of rated capacity (250ah).

The charger outputs 20A @ 14.4v and also does multi stage charging.

Another plus is the second input for solar panels, so it regulates your solar charging too (up to 22v input)

[h=3]CTEK D250S DUAL General Information[/h]

• Input voltage: max 22VDC
• Output voltage: 14.4V at 25°C
• Charging current: 20A
• Ripple: <4%*
• Ambient Temperature: -20 deg.C to +50 deg.C
• Charger Type: fully automatic 5-stage charger
• Batteries: Suitable for all types of 12V lead-acid batteries (Wet, MF, AGM and GEL).
• Battery size: 40-300Ah
• Dimensions (L x W x H): 192x110x65 mm (LxWxH)
• Insulation: IP 65

* The quality of the charging voltage and current are very important. High current ripple heats the battery and ages the positive electrode. High voltage ripple can also damage other equipment connected to the battery. CTEK chargers produce a very high quality voltage and current with low ripple.
[h=4]General Information:[/h]Charging without grid power increases the opportunities for those living a battery dependent lifestyle
A battery banks' ability to maintain sufficient energy to meet consumption requirements is a crucial issue for those dependent on solar energy or wind power, for example, boat, caravan, car and leisure home owners.
A charger permanently connected to your battery bank, automatically selecting the best energy source (generator or solar panel), and charging when the generator is on or when the sun is shining makes life easy.
The addition of an intelligent energy management unit, which controls and optimizes the energy produced and later distributes it to the battery banks or consumers which require the energy, makes everything completely worry-free.
It's good for your batteries too. They will last much, much longer.
The D250S DUAL charger obtains its energy from DC sources such as alternators, solar panels or wind power and optimises this power to meet the charging requirements of different battery banks. The D250S DUAL automatically selects the best connected DC energy source (of 2) for the purpose and switches between these energy sources to achieve high efficiency multi-stage charging.
The D250S DUAL is particularly suitable for charging caravans, motor caravans, boats and second homes that do not have access to grid power supplies. Charging automatically starts as soon as DC energy is provided to the charger, such as from alternators when a vehicle is started or from solar panels when connected.
The D250S DUAL has a temperature sensor which ensures optimal charging voltages at all temperatures. The D250S DUAL ensures that your batteries are always in good condition, quick charging and long battery lifetimes.
The D250S DUAL is a fully automatic 5-stage charger that supplies 20A to 12V batteries of 40-300Ah. The charger is IP65 classified (water jet and dust protected and approved for outdoor use), protects vehicle electronics and is suitable for all types of lead-acid batteries (Wet, MF, Gel, AGM). It is supplied with a 2 year guarantee.

 

[AuldTam]

I bought a 70amp relay from ebay for £8 (for use on a mobility scooter), then I bought a set of 100amp jump leads from poundstrecher (just for the cable), then 2 x 40amp inline fuses, spade connectors, etc...job done for under £20

 

[caspar]

Doesn't a car spotlight relay do the same job?

Phil - never come across that - brilliant piece f kit, just don't like the £214 pricetag! lol

 

[Bernard Jones]

I use a CTEK d205s which charges up to 300ah of batteries using the alternator. Before this my inverter batteries were on split charge. I have a NASA Marine battery monitor installed so the results I give are based on its readings not just my personal opinion. Before the d205s the batteries charged to about 78% of capacity and now they charge to 105%. That is 105% of rated capacity (250ah).

The charger outputs 20A @ 14.4v and also does multi stage charging.

Another plus is the second input for solar panels, so it regulates your solar charging too (up to 22v input)

Must take a long time to charge 300ah batteries with 20A?
Must be quicker to wire it straight through to use all available alternator output (works for me)

I don't know how it measures 105% of charge capacity?
I was taught (admittedly many years ago) that the only way to measure the charge of a lead acid battery accurately is with a hydrometer and thermometer. Just measuring the voltage is notoriously inaccurate, particularly if its within about 12 hours of the battery being charged or used.
In any case, if its 105% of capacity isn't that oovercharging it, and reducing the life?

Pardon my cynicism, but I have read so much stuff designed to sell expensive tackle, and my own simple system works a treat. I have recently had a discussion with a guy who maintains I should buy a generator because it severely damages your engine to leave it ticking over charging the battery. Despite fleets of ice cream vans doing it all day, and having original engines over 20 years old

 

[Bernard Jones]

I bought a 70amp relay from ebay for £8 (for use on a mobility scooter), then I bought a set of 100amp jump leads from poundstrecher (just for the cable), then 2 x 40amp inline fuses, spade connectors, etc...job done for under £20

Whatever is claimed on the pascket you are not going to get proper 100 amp cable in a pound sghop because the copper would cost more than that. 100 amp is most likely the maximum current it could stand for a few seconds without catching fire.

 

[Bernard Jones]

Doesn't a car spotlight relay do the same job?

Phil - never come across that - brilliant piece f kit, just don't like the £214 pricetag! lol

Yes, but they are generally only 30 amp. Again, this light duty stuff will work, but it will create a resistance that will slow down the charging of your leisure battery.
Its like trying to force water through a narrow pipe to fill your bath. It will work, but it will take longer.

 

[AuldTam]

Whatever is claimed on the pascket you are not going to get proper 100 amp cable in a pound sghop because the copper would cost more than that. 100 amp is most likely the maximum current it could stand for a few seconds without catching fire.

Wasnt the poundshop?, I think they were about £5 a set, been fitted a while now and aux battery is always charged. I did a 300 mile round trip a few weeks ago, no problems so far.

 

[maingate]

It is well and good to be able to bang a large charge into a battery in a short time but it will cut down the useful life of a battery. less than a 20 amp charging rate should do no harm to a large battery and it will be capable of more charging cycles before failing. If you have a good quality deep cycle battery, it may last a bit longer but the outlay for one will be a lot more.

The most important thing is to have enough battery capacity and not to discharge the batteries by more than 50%. I can manage fine with 2 x 110 Ah batteries and a 90 watt solar panel.

If you are wildcamping, you should be moving around on a regular basis (not overstaying your welcome) and putting some charge back in that way.

 

[Canalsman]

I am considering this battery-to-battery charger eBay - The UK's Online Marketplace

Take a look ...

 

[Teutone]

Hi, newbie here and it's my first post.
Bought a motorhome recently and working my way through all the bits and bobs.

I am also looking to improve efficiency for the leasure battery.

From younger days I have some experience with in car stereo and wanted to use some of the car stereo stuff.
all the fuses and cables are of high quality (if you pick the right ones) because resistance is the the big enemy of a high power in car stereo and you will get stuff reated high enough, i.e. 100amp blade fuse gold plated.

Sure this isn't cheap stuff and everybody has to decide of how much one is prepared to spend for the last digit behind the comma.
But even the "cheaper" car stereo stuff is better than the usual low price of the mill stuff.

 

[Bernard Jones]

I appreciate that charging more slowly tends to increases the life of the battery, but restricting a 300 amp hour battery bank to a 20 amps charge rate is ridiculous. My X2/50 van has a 160 amp alternator and a 95amp hour battery as standard equipment. Whatever size battery you add on you are increasing the battery capacity above what the manufacturer deemed necessary. The alternator has its own regulator, you don't need anything else to slow down the charge rate. Just get some good thick copper cables, preferably at least 10mm sq (I use 25mm sq) to couple the batteries together through a 100amp or above relay. Works fine for me.

 

[Bernard Jones]

Wasnt the poundshop?, I think they were about £5 a set, been fitted a while now and aux battery is always charged. I did a 300 mile round trip a few weeks ago, no problems so far.

sorry, I thought poundstretcher was a pound shop. Even so, you won't get much copper for £5. The professionals measure cable by its cross section, in square mm, then there is much debate about how much amps it should cary because it depends on a lot of factors, like how well the cable is ventilated to reduce the heat. Cables rated at 100 amp for jump leads (intermittent use and well ventilated) would probably be rated at 30 amps continuous maximum, much less if you need to minimise the resistance as in coupling to a second battery.
I'll stick my head above the parapet and say that as a very rough guide 1 square mm equates to about 10 amps max. Thats why I said 10 sq mm for 100 amps max, but 25 sq mm to minimise the resistance.
Of course many people will say they use much thinner cable and it works. I don't doubt that. But like filling the bath through a straw, it takes longer.

 

[AuldTam]

sorry, I thought poundstretcher was a pound shop. Even so, you won't get much copper for £5. The professionals measure cable by its cross section, in square mm, then there is much debate about how much amps it should cary because it depends on a lot of factors, like how well the cable is ventilated to reduce the heat. Cables rated at 100 amp for jump leads (intermittent use and well ventilated) would probably be rated at 30 amps continuous maximum, much less if you need to minimise the resistance as in coupling to a second battery.
I'll stick my head above the parapet and say that as a very rough guide 1 square mm equates to about 10 amps max. Thats why I said 10 sq mm for 100 amps max, but 25 sq mm to minimise the resistance.
Of course many people will say they use much thinner cable and it works. I don't doubt that. But like filling the bath through a straw, it takes longer.

Thanks for this advice, you appear to know what your talking about. Better to be safe than sorry!

I had a quick look on the internet for proper 100amp rated cable and found marine cable rated at 110amp at £3.29 per metre, does this sound like the RIGHT stuff? How do I crimp on the ends? Should I cut cable to lengths required and take to an auto electrician to crimp? I dont think soldering the connectors on would be strong enough with all the movement of a vehicle.

I only have a basic hand crimper for auto/household cables.

 

[caspar]

A fascinating post. Keep it coming folks - I'm learning!

 

[maingate]

I appreciate that charging more slowly tends to increases the life of the battery, but restricting a 300 amp hour battery bank to a 20 amps charge rate is ridiculous. My X2/50 van has a 160 amp alternator and a 95amp hour battery as standard equipment. Whatever size battery you add on you are increasing the battery capacity above what the manufacturer deemed necessary. The alternator has its own regulator, you don't need anything else to slow down the charge rate. Just get some good thick copper cables, preferably at least 10mm sq (I use 25mm sq) to couple the batteries together through a 100amp or above relay. Works fine for me.

You should be able to charge batteries at up to 20% of their total Ah capacity without incurring any damage, in your case 60 amps. Alternatively, you could tow a Power Station on a trailer. :idea-007:

What I want to know is what equipment are you using to need 300 Ah of storage and make a big dent in it on a daily basis? A 20 amp charger is usually sufficient for most people. In fact with a 90 watt solar panel, we are self sufficient all summer (it charges at 5.5 amps on a good day). In winter we can last a long time with 220 Ah of battery power and the panel (as long as it is not chucking it down every day).

 

[Bigpeetee]

I've used meter tails from Screwfix to connect to leisure batt.

I soldered to the lugs, I used flux and a kitchen cooks blow torch to heat.

I've got 2x 110 AH batts, but try to never let the batts get too low. If they go low, you still get a voltage drop, not much but makes a difference to charging.

I use a 2000w inverter, but if I'm in doubt, I run the engine.

Preferably reduce the amount of power you use.