Sunday, Apr 27, 2008 at 21:22
TWJ
I posted this on another
forum, it was written around charging a
battery in a caravan. However this applies to your
battery in the tray of your vehicle. In both cases the
battery is at ambient temperature and not the elevated under bonnet temperature.
Charging deep cycle batteries in a van from the alternator in the tug is not very efficient. If you have a look at the charging voltages that your intended C-teck charger puts out you will see that the maximum voltages are in the order of 14.2 to 14.5 V depending on which type of
battery you have it set up for. The manufacturers of multi stage
battery chargers have established that this is the sort of voltage required to fully charge a deep cycle
battery.
PeterD
The regulator in the alternator has built in temperature compensation. This reduces the charging voltage as the under bonnet temperatures rise. Warm batteries require less charge voltage than
cold ones. If the charge voltage is not reduced with rising temperature then your vehicle
battery would be overcharged and would boil dry. Most vehicle charging systems run at less than 14.0 V with operating temperatures - 13.6 to 13.8 V is a common range.
Whilst your warm vehicle
battery is being well maintained, your van
battery is is still
cool and therefore will not be accepting much current. It will therefore not be charged much over 50% by the alternator. As I said earlier, you need a voltage higher than 13.8 V to charge a batty fully. 13.8 V is the level that
battery experts have established is required to produce a maintenance float charge, not a replenishment charge.
If you need to charge your
battery from the alternator in your tug, you require a
battery booster or an inverter to drive your C-teck
battery charger. These
battery boosters do the same job as an inverter with a
battery charger. There are a couple of boosters on the market. The older model is the Arrid Twincharge
Battery Charger – It has a fixed voltage output which is too high for sealed batteries – I attribute the use of one of these to the demise of my last
battery due to overcharging. The newer model is the RanOx
Battery Booster
http://www.ranox.com.au/401.html which incorporates a 3 stage charger – I now have one of these in my van.
AnswerID:
300832
Follow Up By: Nomadic Navara - Sunday, Apr 27, 2008 at 21:29
Sunday, Apr 27, 2008 at 21:29
I don't know how it happened but my signature ended up in the body text instead of the end.
I also forgot to add that the updated model of the RanOx
battery booster incorporates sensing circuitry that switches the unit on as the alternator starts to charge and off when it stops. This saves having to spend $100 plus on a
battery isolator as well as the booster. (This may be switched off if you already have an isolator.)
PeterD
FollowupID:
566933
Follow Up By: KSV. - Monday, Apr 28, 2008 at 08:17
Monday, Apr 28, 2008 at 08:17
Hi Nomadic Navara!
“The regulator in the alternator has built in temperature compensation.”
I never hear about this – sounds quite odd to me considering that regulator actually sits inside alternator and later one can get much hotter then “underbonet air” because of load. Plus batteries have finite efficiency and also get hotter when charged or discharged with quite enough current. Could you please provide little bit more info on this? Otherwise I completely agree with your point – it is impossible properly charge remote
battery without “step-up” charger.
Cheers
Serg
FollowupID:
566972
Follow Up By: Member - Mike DID - Monday, Apr 28, 2008 at 08:32
Monday, Apr 28, 2008 at 08:32
Putting the temperature sensor in the Alternator has some benefits -
- It protects the Alternator by reducing the charging voltage and hence the current into the
battery as the load increases. It diverts more current to the load as demand increases.
- It allows faster charging of the
battery without overcharging - immediately after starting it puts out the Absorption voltage to replace the used charge quickly, then reduces voltage to the Float voltage when the Engine and Alternator heat up to avoid overcharging. It's a basic 2-stage charger without using current sensing - based on a typical driving pattern.
FollowupID:
566975
Follow Up By: Member - Mike DID - Monday, Apr 28, 2008 at 08:34
Monday, Apr 28, 2008 at 08:34
Plus also -
- One less wire to install, to break, to be wired in incorrectly during a repair.
FollowupID:
566976
Follow Up By: Member - Mike DID - Monday, Apr 28, 2008 at 08:38
Monday, Apr 28, 2008 at 08:38
"Otherwise I completely agree with your point – it is impossible properly charge remote
battery without “step-up” charger."
- unless you use an AGM
battery - they can be charged fully at 13.6 volts.
- I won't be debating it - if you disagree, contact the manufacturers and tell them to change their data sheets (then try to convince me my tests didn't really charge the
battery fully at 13.6 volts)
FollowupID:
566978
Follow Up By: Member - bushfix - Monday, Apr 28, 2008 at 09:20
Monday, Apr 28, 2008 at 09:20
G'day,
the Arrid model I have is designed for sealed batteries. It has a max output of 14.1 V which just happens to be the the max charge voltage of my Apollo AGM. Works well so far.
FollowupID:
566986