So we know that a normal alternator can charge a typical 12v lead acid battery.

If I fitted an additional two batteries to a vehicle and charge them in parallel so they are both charging to 12v. I then want to swap the wiring over once charged so I have a high current 24V supply.

How would a typical car alternator cope with the extra load of charging two extra batteries?

Anyone know what kind of power output an alternator has and thus how long a battery would take to charge?

modern alternators are more than capable of 90A, and in the caravan type set up a second, or possible a third battery is charged in parallel, and discharged via a switched circuit to ensure that the main vehicle battery is not discharged.

hth

(for caravan,. read also mobile home etc,.... )

As said above a split-charge relay is what you need - depending on the current rating you should pick up a complete kit of parts for less than £100.

Great thanks.

If I wanted to take it one step further and charge the batteries at 12v in parallel and draw off 24v in series at the same time could it be done with diodes or some other clever skulduggery?

Basically so I can charge the batteries whilst driving and at the same time be running 24v systems

not that I know of... the reason bring that for charge two of the + terminals must be connected. .. for 24v one - and one + must be tied together...


Charge => ++ - - Discharge => - +- + so the right hand -ve terminal needs to be at both 0 and +12v.

How about using a single 12 v supply and a high current dc to dc inverter ( inverter to psu )

quote:

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Originally posted by tegwin
Great thanks.

If I wanted to take it one step further and charge the batteries at 12v in parallel and draw off 24v in series at the same time could it be done with diodes or some other clever skulduggery?

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Hmm shame, I'm wanting to draw 40 amps at 24v so an Inverter would be pricey. Looks like il have to be patient and let the batteries charge up

2000 W inverter,.. then a 40A PSU,.

guessing about £400,... atleast for good equipment,.. alternately how about a petrol gen set.... what do you need the 40A at 24V for?

Hmmm that's a bit more than I was wanting to spend but may have no choice.

I need to charge big commercial lipo batteries on the run

ok,

I have a much better plan,..


more cunning than a cunning fox on his day off,....

can you guess?

Do away with batteries and use a windup clockwork system instead?

now that is good, how about a roof mounted wind turbine,....


no seriously,.............











buy and fit a 24v alternator to the existing setup,... simple, cheap and designed to do the job in hand

Guessing about £100 for a recon, £20 for some cunning brackets and £20 for some heavy duty wire






how cunning is that??

That thought had crossed my mind, could be fairly easy on the landrover. Hmmm cunning indeed

Easier on the Landy, loads of space, also WOLF alternators standard at 24V,.

There are loads of aftermarket kits available as bolt on, including 240v gen sets,.....

a whole range of options,..

If it's your vehicle, you could dump your 12v alternator, fit the 24v version, and charge both batteries, and run the Landy off one of them,...


ALT
+ (bat1) - {24v CHARGING }
+(bat2) - |12v LANDY | }

vehicle ground




hth

mines a 61 SII SWB

[Edited on 13/5/15 by HowardB]

How about fitting a second 24volt alternator to charge the batteries.

Split charge systems tend to be very hard on alternators.