tegwin
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| posted on 12/5/15 at 12:42 PM |
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Alternator load to charge multiple batteries
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?
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HowardB
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| posted on 12/5/15 at 01:08 PM |
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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,.... )
Howard
Fisher Fury was 2000 Zetec - now a 1600 (it Lives again  and goes zoom)
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sickbag
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| posted on 12/5/15 at 04:23 PM |
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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.
Finally back on the job!
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tegwin
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| posted on 12/5/15 at 10:58 PM |
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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
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HowardB
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| posted on 13/5/15 at 04:49 AM |
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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 )
Howard
Fisher Fury was 2000 Zetec - now a 1600 (it Lives again and goes zoom)
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MikeRJ
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| posted on 13/5/15 at 07:02 AM |
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quote:
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?
This is not possible using any simple system of diodes or relays etc. The only possible option is a switching regulator to step the 12v up to 24v,
and if you want to draw a significant amount of current from the 24v system this will be expensive.
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tegwin
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| posted on 13/5/15 at 07:34 AM |
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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
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HowardB
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| posted on 13/5/15 at 07:45 AM |
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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?
Howard
Fisher Fury was 2000 Zetec - now a 1600 (it Lives again and goes zoom)
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tegwin
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| posted on 13/5/15 at 07:55 AM |
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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
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HowardB
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| posted on 13/5/15 at 07:57 AM |
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ok,
I have a much better plan,..
more cunning than a cunning fox on his day off,....
can you guess?
Howard
Fisher Fury was 2000 Zetec - now a 1600 (it Lives again and goes zoom)
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tegwin
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| posted on 13/5/15 at 08:05 AM |
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Do away with batteries and use a windup clockwork system instead?
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HowardB
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| posted on 13/5/15 at 08:07 AM |
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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??
Howard
Fisher Fury was 2000 Zetec - now a 1600 (it Lives again and goes zoom)
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tegwin
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| posted on 13/5/15 at 08:10 AM |
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That thought had crossed my mind, could be fairly easy on the landrover. Hmmm cunning indeed
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HowardB
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| posted on 13/5/15 at 08:50 AM |
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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]
Howard
Fisher Fury was 2000 Zetec - now a 1600 (it Lives again and goes zoom)
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DW100
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| posted on 13/5/15 at 09:39 AM |
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How about fitting a second 24volt alternator to charge the batteries.
Split charge systems tend to be very hard on alternators.
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