Double Battery Charging

[isaune]

Sorry for the rather clunky subject line but it was the best I could think of.

Basically, my question is how should I connect my charger to the two batteries in the back of my van which are joined together and used to power up the diesel heater?

It looks like one terminal on one battery is connected to one terminal on the other battery whilst the other two terminals (one on each battery) are attached to the heater.

I just want to know on which terminals should my charger's crocodile clips attach to so that both batteries get charged.

Or is this not possible and I have to charge them separately?

Thanks chaps

Ian

[CJH]

It looks like one terminal on one battery is connected to one terminal on the other battery whilst the other two terminals (one on each battery) are attached to the heater.

Are those the only connections to those batteries? If that's correct, then it sounds like your batteries are connected in series*, which means one of two things:
1) The batteries are both 6V, so connecting them in series makes 12V for the heater, or
2) The batteries are both 12V, meaning your heater is using 24V. No idea if there are 24V heaters out there - others will know.

If your charger is 12V then the question can't be answered until you confirm the battery voltages.

* It's possible that they're connected in parallel, e.g. if the cable that joins the batteries is on the negative terminal of both, AND the batteries are also earthed to the chassis, AND the cables to the heater both connect to the heater's positive terminal AND the heater has a separate earth. Can you check which terminals are connected, and perhaps measure the battery voltages?

[ghost123uk]

And if you are not sure what you are doing, be very careful Exploding batteries are not summat you ever want to be near 99% of batteries will say on them somewhere whether they are 6 volt or 12 volt (or you could use your multimeter).

I believe you can get 24 volt Diesel heaters as they are often fitted to lorries.

Charging 24 volt systems from 12 volt van electrics is not common or garden, but it can be done. Best wait for your answers though before going into that

[Oldiebut goodie]

If you are running a 24v heater - what model and make is it as there could be 2 easy ways of dealing with charging/running heater. (I convert 24v heaters for use on 12v)
Need to know..... Heater running voltage
.....................Model
.....................Make
.....................How batteries are joined at present
.....................Voltage of each battery.

I won't go any further until the basic facts are known

[isaune]

ok - thanks all - i will come back with answers this evening

[isaune]

Here are some answers.

The batteries are both 85AH leisure batteries.

They are connected to each other via the positive terminal on one and the negative terminal on the other.

The spare negative terminal has a brown wire heading towards the heater.

The spare positive terminal has 2 red wires heading towards the heater.

I can't actually see the make of the heater but it is kind of cylindrical, black in colour with 3 backward ticks on the top by way of logo.

I would have found our more but it just started pouring!!

Btw, the heater appears to be in good working order. Also, the previous owner said he seldom used it but often used the 2 batteries as a back up for the main leisure battery. This latter point seems quite handy, hence my desire to keep them topped up.

In other words, it's less about the heater itself. It's more about how to connect my charger crocodiles to the two batteries.

Cheers chaps

Ian

[ghost123uk]

Ian, you have missed out the all important fact. Are the batteries 6 volt or 12 volt ?

[AdrianC]

Ian, you have missed out the all important fact. Are the batteries 6 volt or 12 volt ?

Do 85Ah 6v leisure batteries exist...?

It does sound very much as if somebody's got hold of a 24v Weberspachasto from a truck.

[isaune]

Yep I did look on the batteries for a voltage and it wasn't immediately obvious.

I didn't want to take them out completely.

I am pretty certain Adrian is right. They are both 12 volt batteries connected positive on one to negative on the other.

Everything working fine and, as I say, the heater is not really the point.

All I want to know us do I have to charge each battery separately or can I do both at the same time with my 12 volt charger?

Thanks

Ian

[California Dreamin]

With a 12 volt charger....you are going to have to disconnect and charge them separately......
Otherwise you will need a 24 volt charger (charging in situe)
This setup has obviously been installed just to power the night heater...

Martin

[Oldiebut goodie]

The heater is the point because there is a simple and very cheap solution to running some 24v ones from 12v - knowing which heater you have could possibly mean that you do not need 24v battery power and can just run them as normal 12v supply.

[ghost123uk]

Then you could wire these 2 existing leisure batteries in parallel to get twice the amp hour capacity and a simpler charging arrangement = win win

[California Dreamin]

Am I right is assuming that Oldiebut goodie is talking about some sort of invertor that will bump up 12 volts to 24...but it depends on the amp draw of this particular heater as to whether it is a cheap option or not.

This way you free up the batteries to be reverted back to 12 volts which allows them to be charged from a 12 volt charger or traditional split charge relay from the vehicles alternator making the system much more versatile.

Martin

[Oldiebut goodie]

10 Amp step up to be had for less than £4.

[isaune]

With a 12 volt charger....you are going to have to disconnect and charge them separately......
Otherwise you will need a 24 volt charger (charging in situe)
This setup has obviously been installed just to power the night heater...

Martin

Thanks to everyone.

Martin - I think the above is dead right and answers my question.

Oldie, Ghost - I don't really want to disturb the heater (which is working great) or the two batteries which are conveniently located and which, if kept topped up, make for a handy back up to the main leisure battery.

It's a shame I need to disconnect and charge them individually but at least I now know that I do.

Cheers chaps

Ian