charging 12 battery with 24 volt alternator

Submitted: Thursday, Feb 19, 2015 at 21:28
ThreadID: 111172 Views:4060 Replies:6 FollowUps:0
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Can any one point me to dc - dc charger that will charge a 12 volt house battery from a 24 volt alternator. A friend has just brought a coaster bus and wants to set it up as a motor home. I know what I'd use if it was a 12 volt system, but throwing in a 24 volt alternator has me scratching my head.
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Reply By: Member - Bigred13 - Thursday, Feb 19, 2015 at 21:48

Thursday, Feb 19, 2015 at 21:48
Hi Cruznoz, Yes it can be done various ways ,but what I have done is install a Redarc BMS ,battery management system, not cheap but it will take 24V and charge 12Volt batteries also will do solar and 240Volt without any thing to do ,it will decide what is the best charging medium and automatically do it ,it also has MPPT for solar ,I have one in my caravan ,and also fitted one in the Motorhome I built which had 24 Volt in and charged 2x 130ah AGM batteries .They are about $1795 from Redarc but on evil bay I got my last one for $980 .They have a new model out which is a 40Amp at about $1900 ,whereas the old one was 15Amp.It does the same as a dc-dc charger but with 240 V as well.
Regards John
AnswerID: 546208

Reply By: Allan B (Member, SunCoast) - Thursday, Feb 19, 2015 at 22:50

Thursday, Feb 19, 2015 at 22:50
Hi Cruznoz,

Any of the Redarc BCDC charger series will accept up to 32 volt input and deliver a staged 12 volts output to a battery. This series are less expensive than the BMS series but with less features, although possibly adequate for your application.

The Redarc BCDC series can be viewed here.

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AnswerID: 546214

Reply By: Peter_n_Margaret - Thursday, Feb 19, 2015 at 23:05

Thursday, Feb 19, 2015 at 23:05
Couple of cheaper alternatives.....
1. Connect a 24V-240V inverter and use it to drive a 12V battery charger.
2. Fit a second alternator (12V) tuned to a decent charge voltage.

In both cases, add as much solar as possible.

OKA196 Motorhome
AnswerID: 546216

Reply By: Cruznoz - Friday, Feb 20, 2015 at 08:39

Friday, Feb 20, 2015 at 08:39
Thanks for the reply's everyone. The BCDC series that Allan suggested sounds like what I am looking for. Thanks again.
AnswerID: 546239

Reply By: duck - Monday, Feb 23, 2015 at 07:53

Monday, Feb 23, 2015 at 07:53
I have fitted the redarc BCDC (40amp) to my Isuzu 300 4x4 (24V) to give me 12v house battery's (2 x 110amp) & its works & charges well & an easy fit, I have also fitted the BCDC 24 to 24volt charger & its been un reliable & just stops working, have fitted 2 now & the 2nd one has stopped working now again for no reason
good luck
AnswerID: 546423

Reply By: Brian and anne C - Sunday, Mar 08, 2015 at 09:38

Sunday, Mar 08, 2015 at 09:38
Jaycar have a suitable 24-> 12 volt charger. Installed into my mates old Toyota bus about 12 months ago. Have since added a low volt cutout
AnswerID: 549588

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