24v charging questions

[Arfur's World]

Hi All,

Now that I know my van a little better and have built it a bit more, I have a few questions about charging that you may be able to offer advice on.

In my previous thread I was expecting to need a 24v > 12v charging system, but this is not the case. The reason for this is because my van came with a 3000W/24v invertor that I decided was too good not to use, so I have installed my batteries as 24v to accommodate this. Unfortunately, the charger that the van came with seems to have gone on the blink (Maypole 50S), so I'm going to use the opportunity to upgrade from a "garage" charger to a proper in vehicle charger. I just need to decide which is the right option, thinking Sterling 24v>24v battery to battery charger?

Also, I have a question regarding the red key that is located at the base of the drivers seat in the Vario. Does anyone know what this switches on or off? I think it may be connected to the leisure batteries but haven't traced it fully yet. Could it be a split charger?

If I go for a Sterling, how do you guys hook up to a power supply when on a site? Can that source be routed through a Sterling to charge the batteries then?

Cheers,
Martin

 

[canals1164]

Martin
we have a 24 2 24v battery to battery charger and the feed batteries are either charged by the engine or the mains charger. I don't think it matters how you put charge in as the B2B charger then sorts it all out and then charges the house batteries.
I have now got some solar panels to fit and that seems to be just as confusing!

 

[ianc]

Martin,
First of all - that red switch is not a standard Vario fitment. If I was to guess, I'd say it was either a main battery isolator turn it off and the ignition will not come on) or a secondary battery isolator. You'll have to trace it to find out.
On the charging - what are you looking to achieve? Charging from a mains supply or charging from the existing alternator or from a second alternator?

If it's from the mains - then check if you're inverter is just an invertor of is it a combo unit (inverter + mains charger). If not - then consider a good 3 stage mains charger from Sterling or similar
If you want to charge from the existing alternator then the most effective would probably be a battery to battery charger (24v) with amps rating based on your house battery amp/hour size. A much cheaper option would be to use a Voltage Sensitive Relay.

Let us know what you're looking to do.
Regards

Ian

 

[surfer4life]

i Use a sterling 24v to 24v for the battery to battery and a sterling 240v to 24v for when charging off mains, you cant connect the mains to the battery to battery charger, i imagine you would fry it :-(

 

[Arfur's World]

On further investigation, the red switch comes from the positive of the van batteries and connects to the positive of the leisure batteries. I guess this will charge the leisure batteries at the same rate as the van batteries, from the alternator, and once the van batteries are charged on a run, all of the alternator capacity will go towards the leisure batteries.

I'm pretty sure my mains charger is dead, and it could be because I had not wired everything back correctly so perhaps it has been fried as suggested could happen by surferforlife.

So, assuming the alternator will help charge the leisure batteries when running, I just need to replace my mains charger. I think :/ Anyone have any ideas on a high end unit for that? I'm not convinced on the Maypole being the best solution.

 

[ianc]

Martin,
Interconnecting the starter and house batteries (with the red switch) will only give a partial charge to the house batteries at best. There are two difficulties
1) The alternator output does not adjust based on the level of charge in the battery and so while it may get the first 50% of charge in reasonable time, it will take forever (never) for it to deliver the 2nd 50%
2) Many standard alternator systems apparently* are set to back off charging after a short time because they only have to top up the starter battery after the start.

*I say apparently because I've not managed to measure this myself.

The other thing to watch out for is if you forget to flip the red switch and drain both your house and starter batteries. This is one of the things a Voltage sensitive relay will protect against.

If you are interested in the subject see the documentation here: http://sterling-power.com/downloads.htm Obviously keep in mind that they are trying to sell stuff to you.

Sterling also do very good mains based chargers.

 

[Arfur's World]

Thanks for your excellent input Ian. After doing some more digging and now understanding a little more, I've decided my mains charger is priority one, and *think* I'm going for a Sterling Pro Ultra 2430. I've decided the larger capacity charger will be beneficial if I need to "splash and dash" charge at anytime, rather than being on site overnight.

Priority 2 will be sorting out a split charge or battery/battery from the alternator, or perhaps a second alternator, but I think the battery/battery is a better solution.

 

[Arfur's World]

Hi Andy et al,
I guess to some degree the decision is based around not wanting to chuck out a very expensive and useable invertor, and that the interior systems had been built with 24v from the start by Baileys. The microwave and caravan battery charger will only work on mains, the fridge and wet heating system will work on either mains or gas, and obviously I should not use gas while on the move. So I am using the 24v leisure batteries to feed the invertor and get lots of 240V so I can keep the microwave, fridge and (if necessary) heating on while on the road or when I'm not hooked up. Later on I will be looking to get an Alde heat exchanger so that I can use engine heat to keep the interior warm for nothing but a bit of electrical pump action.
I know there are 12v sockets and 3-pin at the TV points, but I haven't checked if the 3-pin are live without the "mains" being on. Kettle will be 240v when on mains, if I can get the RCD size right, as it kept tripping in France so we used a pan for 5 weeks! (But it is a rapid boil kettle so I just need to size things right). And of course there will be the obligatory hair salon to power - hairdryer, curlers, straighteners etc ... maybe I should just go nuclear!!
I've ordered my Sterling which should be here on Monday, so hopefully I can get some spark back into my van
Martin

 

[LeishaShannon]

24v -> 240v is going to be more efficient than 12v -> 240v , and you get to use smaller cables so i'd stick with 24v. We are using a couple of 24v -> 12v dc-dc converters to power the few 12v appliances we have (thetford toilet, a couple of LEDs, and some USB outlets, etc)

 

[Arfur's World]

My charger arrived this morning, so I have done a temp install and finally have some charge flowing :wings:

 

[Arfur's World]

My charger arrived this morning, so I have done a temp install and finally have some charge flowing :wings:

So I now have fully charged batteries but I need to look at a full install.

In the manual it says I need an 8 amp breaker on the AC and a 40A fuse on the DC. I can rob the 40A fuse from my old Maypole charger so that's cool. But breakers come in 6A, which will trip too easily, or 10A which may trip too late. Does anyone have any suggestions from their installations?

I also got some 4mm stranded electric cable, which the manual suggests I would need 10AWG (approx. 2.6mm), so I figured that too much is way better than too little.

Now I just need to decide where to fit it

 

[Arfur's World]

So I now have fully charged batteries

Well that didn't last long I found out that I wasn't getting mains from the invertor, and the invertor was showing Low Battery warning, which I initially dismissed because I knew I had had the Sterling on for hours before. However ... when I checked the battery levels, it showed that I had 15.9V across the pair, so the invertor was right. Therefore I have 2 questions:

1) Can anyone who has one of these chargers tell me if I can force it to charge? It is showing that I have 29.6V available, but it is not putting that out into the batteries. The LED is on absorption.

2) Does this mean my invertor will only use 30% of my battery capacity?

Any help appreciated ...

 

[Arfur's World]

1) Can anyone who has one of these chargers tell me if I can force it to charge? It is showing that I have 29.6V available, but it is not putting that out into the batteries. The LED is on absorption.

Problem 1 solved ... although the 40A fuse was suggesting that something was getting through, it wasn't, so now by-passed and operational

 

[Arfur's World]

My charger arrived this morning, so I have done a temp install and finally have some charge flowing :wings:

So going back a while to update you all on progress ...

I'm fairly sure my original charger was only a blown fuse, but I didn't realise that until I had stripped it for parts to wire up the new Sterling
The Sterling is great, no complaints at all and now finally, almost 2 years later ...
I'm getting mobile charging installed on Monday. I'm having an Antares ASC+ installed, so I can keep everything topped up while on the road :coffeedrink: