24 v charging

[Bruce Lee]

Hi all

I am planning the electrical power for the van (MB 614), and not very sparky orientated. My first thought was to have a split charge relay from the 24v service batteries to 12v house batteries, and just charge the house batts from the solar.

I am now thinking I should run the house batts at 24v, run the fridge and eberspacher at 24v and have a dropper to run the lights, stereo etc. at 12v.

I am told I can get 24v solar panels, or run 2 12v's in series, the question is do I need a 24v to 24v relay to charge the deep cycle gels from the alternator, via the lead acid's, or just run some wires across (with a switch), which will let the alternator charge both together, and the solar keep them all topped up?

Any ideas welcome, thanks

Bruce

 

[loonwheeler]

All great questions and best to get it right in the planning stages.

Moving the thread to the Power Systems sub forum is your best bet. There are a lot of knowledgeable folks there that answer most if not all of the questions you may have.

 

[ianc]

Hi all

I am planning the electrical power for the van (MB 614), and not very sparky orientated. My first thought was to have a split charge relay from the 24v service batteries to 12v house batteries, and just charge the house batts from the solar.

I am now thinking I should run the house batts at 24v, run the fridge and eberspacher at 24v and have a dropper to run the lights, stereo etc. at 12v.

I am told I can get 24v solar panels, or run 2 12v's in series, the question is do I need a 24v to 24v relay to charge the deep cycle gels from the alternator, via the lead acid's, or just run some wires across (with a switch), which will let the alternator charge both together, and the solar keep them all topped up?

Any ideas welcome, thanks

Bruce

Why Deep cycle Gels? Check the difference in cost between normal sealed Lead Acid and the Gel deep cycles and also keep in mind longevity and fragility (particularly in charging)
A plus on running 24V for the house circuits is that you have less loss for a given cabling weight. This can make a big difference if you intend to run a biggish invert for 220V. Plus you can jump start the van from the house batteries in an emergency (But Gels will not like this).
The disadvantage is that it does limit your choice of appliances.
Irrespective of whether you go for 12 or 24v I'd recommend a battery to battery charger like http://sterling-power.com/products/battery-to-battery-chargers if you are sticking to a single alternator.
A second alternator is an alternative approach which gives you some redundancy and is relatively easy to fit on most Mercedes.
I don't know much about Solar (i've not fitted any to my system yet), but I think the output voltage of the panel is misleading and irrelevant as they're usually open circuit figures. Have a read here: https://www.solar-electric.com/solar-charge-controller-basics.html/


I hope that helps a bit.

Ian

 

[thebigblue]

On my MB L608D i have two 100W solarpanels in parallel, they output around 18V, just what the charger (CTEK 250 S DUAL) likes for my 12V house battery.

 

[Neil]

This is my set up and it works well if it helps.

Starter batteries are 24 v lead acid. Cabin batteries are 24v gel. Obviously these have different charging algorithms so cannot really be connected via a relay. I use a sterling battery to battery 24v to 24v charger to get the best charge from the engine alternator. It works very well.but only charges in one direction ie starter to cabin.

My solar panels produce about 36v and the controller is set to gell and they feed the cabin batteries only .

To ensure that the starter batteries are always in good shape a small trickle charge goes from the cabin batteries to the starter batteries via a sterling battery maintainer sending about 1 amp constantly.

This set up ensures the best charging for the whole system . However, I would advise you not to scrimp on the quality of the solar charger. I use a Morningstar TriStar but there are other great chargers . If you get one from eBay for £ 20 then you will get what you pay for I'm afraid.

Most of the big appliances such as fridge, eberspacher, water pumps are 24v . However, all my lighting is in 12v as the 24v lamps were all a bit too agricultural for our taste. The lighting circuits and other auxilliary circuits are fed by a 24 to 12v voltage dropper made by votronic.

Some of you will look at this set up and think it's a bit too messy but it works well.

The solar charges both sets of batteries even though they are different types and the alternator does the same.

Neil