New Van what capacity <span class="highlight">AGM</span> <span class="highlight">Batteries</span> do I need

Thank you for that but we wont be isolated for any length of time.

Its more about fitting and capacity needed

I can only fit the two 100ah in if I put one inside the van and I think 32 kilos on the ply floor may be a bit much.
Am thinking of a smaller one inside and as large as possible ,up to about 150ah in the A frame hatch.

We dont bush camp as its a bit hard in a 25ft van
What I really need to know is , with the stuff in the van how much capacity do I really need given we are usually in camping grounds and the van has a smart charger built in.

Thanks

If you aren't going to be isolated for any length of time, why so big a capacity ??

Are you going to be without power at all ?? Overnight ?? 2 days ??

You don't need batts at all if you only ever go to powered sites..

One 100a/h batt will be plenty to run things for a couple of days....without power !!

Well its like this We have a semi offroad van and it had two batteries and solar when I got it. The two marine 80ah carked it due to being stored for nearly 2 years.
I replaced them with two 100ah AGM.
We are on a trip that I thought we may do more free camping than we have.
Reason being that wife is not really an outdoors type and so we have ended up in camping grounds mostly.

Did the deal on the new van which is a tarseal only.

The deal allowed me to keep my nearly new AGM,s.

Then the probs started of where to put them due to the shape of the front of the new van.
However have decided to put one in the tray provided and extend the wires and put the other in the boot so problem solved .

Just need to now how big a cable from car aux to Anderson plug.


Ta

Cant do that in a Princeton as it has a sculptured fibreglass front and the battery is slung crossways between the A frame

The max width is 600mm which is 20mm short of two N70's placed lengthwise.

There is not enough height under the lid to turn them .

I think I will put one under there and one in the boot.
Seems easiest solution.
I will probably use 10mm from the car to the battery.

Graham
Give me the length of the cable run and the expected amps you think should reach the caravan battery and I will look up my chart of voltage droip and give you some ideas on cable size.
Ian

Thanks have saved you the trouble.
Went and saw a knowledgable sparky and he said to use 4 B&S so thats what I have done .
Not sure if the car charges the battery which runs the fridge or it just runs the fridge. If so will probably upgrade the van wiring as well as its only 6mm automotive I think and if it goes to the fridge it will be about 6 metres long and wont be heavy enough would it??????


Thanks

4GGe is a wise choice.

If the 6mm auto is only to run the fridge it will do it but at say 20A the voltage drop would be 0.822V and would not be much good for charging.
4GGe over the same distance would only produce 0.204V drop and would do both.
Ian

Thanks dont get the van till next week so will find out exactly whats what and sort it out.

Will probably put heavier in whichever way.
At least if it charges will run the 4 B& S to the batteries and link them with that as well.
Thanks for advice

Graham
Is the 6MM what is on the van itself and you say it is 6M and that does not include the run of 4GGe on the vehicle then my figures will not be correct .

For example if the 4GGe cable on the vehicle is 5M to the Anderson Plug you would have a total of 11m and that length with 4GGe would give a voltage drop of close to 0.36V so it is within the ball park to do both as long as the amps available is not higher to say 30A to around 0.53V and 40A to around 0.715V and with these increased amps you would them suffer charge capacity.

You deduct the volt drop from your alt output to see what you will get.

If you did not replace the 6MM then you have to add to volt drop of the 6MM basically to the volt drop of the 4GGE and see what efficiency you have with the fridge.
The higher the volts the more efficient it runs.
Ian

You can use 120A Anderson plugs for 4GGE they normally go from 6GGe to 2GGe.

They are smaller than the 175A which are more suited from 2GGE to 1/0GGe.


Ian

Okay went to Sparky this morning and told him that I was advised to use 175amp plugs.

He said ******* whatever for.

Found out that the car charges the van batteries and the batteries run the fridge.

He said replace the 6mm in the van to the batteries with the 4B&S and the 50 AMP Anderson plugs would be fine.

So I dont know, he makes his living at it and said that I wouldnt be putting anywhere near 50 amps through anyway.

Graham
*********4GGe will not fit in a 50A Anderson plug.(LOL)

Technically 6GGE is the largest cable for a 50A anderson Plug.

If he wants to cheat then thats fine as the difference between a 6GGe and a 4GGe is not much and if you trim a few strands on the 4GGe it will fit and the outside diameter of the contact will be around the same as the od of the cable so the contact will compensate the small loss .

If you had 50Amps available from the alternator you would not be using 4GGE unless you only wanted to run the fridge as the voltage drop at 50A would be around 0.8V and would only produce a float voltage for charging on a standard alternator but on a unit that reduces charge after warm up woulld not give efficient charging.

The correcst procedure would be to check the vehicle at the anderson plugs for both volts and available amps after warm up a then go from their to maximse efficiency. That is unless he already knows these statistics from previous installs.

A lot of auto electricians know their jobs but their jobs but do their jobs really cover auxilliary batteries and proper charging methods and I hope this chap does as a lot do not and are R&R workers.

Ian

Ian