second Battery charging

[axeman]

I want too set up a second battery in the doka as sort of resurve battery, dose any one know if a rectifier would be suitble, as i under stand it should act as a one way valve. If this is posible what sort of rating ret+ifier should i look for?

Thanks neil

[tonytech]

I'd be looking at a relay (switched from your alternator or a dashboard switch) or even one of the automatic charging systems.
The diode would work ( dropping about 0.7 volts) but would really need to be rated at 20A or more.

T

[jed the spread]

I used a cut off switch in my doka (the red key type) and turn it on every now and again to top up the second battery. As you have no camping interior in your van and you wouldnt really need a leisure battery only a spare starter one to use it in emergencies if you are really lazy you could always fit a relay out of a towbar that will charge the second battery when the alternator is running, then a cut off switch like I have to connect the two in times of need when the first one is flat. Really easy to do.

jed

[Red Westie]

Intelligent split charge relay that only connects the two batteries (Starter and leisure) WHEN charge from the alternator is sensed.
These relays are real simple to wire in, only requiring a length of heavy duty wire, soldered eyelets and a heavy duty fuse holder and 40 amp fuse.

Example:

http://www.rawcomponents.co.uk/all-cust ... ystem.html" onclick="window.open(this.href);return false;

Martin

[jed the spread]

Intelligent split charge relay that only connects the two batteries (Starter and leisure) WHEN charge from the alternator is sensed.
These relays are real simple to wire in, only requiring a length of heavy duty wire, soldered eyelets and a heavy duty fuse holder and 40 amp fuse.

Example:

http://www.rawcomponents.co.uk/all-cust ... ystem.html" onclick="window.open(this.href);return false;

Martin

Hence the need for a breaker switch to connect the two for starting power when needed.... I will pop round and help you with it if you want Neil although i know your more than capable. Have a look where i put my switch next time I see you.

jed

[Red Westie]

Jed...why would you need MORE than one battery to start the van when the starter battery is isolated by the relay?
AND.....if you intend to link the two batteries under starting the wiring and relay between the two batteries would need to be VERY heavy duty, potentially 200amp cabling/relay and fuse.

Martin

[jed the spread]

Correct, I have used bastarised jump leads.... I can understand why Neil wants this set up, it could come in usefull in situations that go beyond tame sitting in a field for a weekend VW show situations. You wouldnt understand its a Syncro thing

Have this set up and it gives you more of an option for extra Syncro buisness, winch, engine coolant heating systems for winter off roading events in the Alps in temperatures down to say -12 plus loadsloads of other shnizel...

jed

[Red Westie]

On second thoughts....I can understand where you are coming from and without any normal camping consumers heavy wiring and a big switch makes sense. Just be sure the cabling and connections are up to the job otherwise things will be melting.
Martin

[jed the spread]

Thanks for your approval (must resist the roll eyes Smilies)

jed

[bigherb]

The best option is still to fit a split charger then the auxilary battery is always charged, not much good out in the boonies having the slave battery flat as well because you forgot to charge it or forgot to switch it off and flattened them both.

[Red Westie]

Jed....us mear mortals in our 2WD vans just wouldn't understand, I know.

[axeman]

right i have set up a relay as per what people have been saying and following the diagram in the wiki, that is trigered vai th alternater signal wire so all is good, i will be conecting a large gauge wire via an isolater some point soon, the next question is if i dont have any thing that is dicharging the second battery, is there any posibilty of damaging the battery? ie over charging it, this was the reason why i first asked about rectifiers/diode. as i know from my bikes (old and british) that has a zener diode although it has a dynamo not an alternater, the zener diode effectivly dumps excess electricity at any thing over 13.8v.

thanks neil

[bigherb]

The zener diode is built into the alternator regulator so the battery will not overcharge.

[jed the spread]

Cant overcharge as it is being charged just like a regular car battery. Just make sure you fuse the thick cable both sides.


jed