smart alternator vs aux battery

Submitted: Tuesday, Apr 01, 2014 at 10:10
ThreadID: 107019 Views:2326 Replies:5 FollowUps:14
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Hi, well after 16yrs we're upgrading the tug so we're now into the latest technology brkt, our NEW 4wd will have a smart alt and to get around the lack of space for an aux battery I thought using the ALLROUNDER would do the trick (from previous 4wd) but having trawled thru past forum chats we may have a charging rate problem. Only the fridge would be running from it, the van(s) run 2x 100a/h AGMs thru a REDARC BCDC 1240. The ALLROUNDER being calcium will it be getting the total charge required. cheers
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Reply By: HKB Electronics - Tuesday, Apr 01, 2014 at 10:50

Tuesday, Apr 01, 2014 at 10:50
Hi Mudguard,

What is the model of your new vehicle?

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Follow Up By: Mudguard - Tuesday, Apr 01, 2014 at 13:11

Tuesday, Apr 01, 2014 at 13:11
I bought a JEEP, the V6 Diesel, Grand Cherokee Limited with off-road pack
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Follow Up By: HKB Electronics - Tuesday, Apr 01, 2014 at 13:44

Tuesday, Apr 01, 2014 at 13:44
No idea what sort of charging system they have, talk to the dealer, see if it has an ECU controlled type or a constant voltage alternator, if it is an ECU type then see if they can turn the smart charge function of, if not then you'll need a DCDC charger.

If constant voltage type then you'll need to monitor the voltage to see what you have to work with.

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Follow Up By: Tony F8 - Tuesday, Apr 01, 2014 at 18:37

Tuesday, Apr 01, 2014 at 18:37
You bought a jeep
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Follow Up By: Ross M - Tuesday, Apr 01, 2014 at 20:26

Tuesday, Apr 01, 2014 at 20:26
Some like to refer to them as a Chrysler Premium Product.
Still have the farm gate on the front though.
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Follow Up By: The Bantam - Tuesday, Apr 01, 2014 at 22:59

Tuesday, Apr 01, 2014 at 22:59
You baught a sheep?
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Follow Up By: Member - nrb1748 (VIC) - Tuesday, Apr 01, 2014 at 23:55

Tuesday, Apr 01, 2014 at 23:55
The Jeep charges at 14.0 volts when the main battery requires a higher charge rate. It then drops to 13.0 volts. If the main battery is already fully charged when the engine is started then it charges at 13.0 volts from start up.
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Follow Up By: Mudguard - Wednesday, Apr 02, 2014 at 01:44

Wednesday, Apr 02, 2014 at 01:44
Yeh I know after having Nissan 4wds for 29yrs I'm copping some flack for going to Jeep (the front looks better than the new Prado)!
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Follow Up By: Member - John M (NSW) - Wednesday, Apr 02, 2014 at 15:24

Wednesday, Apr 02, 2014 at 15:24
You are gunna need a bigger boat!!!
Life isn't about how to survive the storm, but how to dance in the rain!

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Reply By: John and Regina M - Tuesday, Apr 01, 2014 at 11:46

Tuesday, Apr 01, 2014 at 11:46
If you are using the 'allrounder' for the starting battery then I hope it will be getting sufficient charge as there are no options for modifying an existing new vehicle charging system without voiding your warranty.

So as they say.....who you gonna call?


An 'allrounder' is just another name for a slightly different configured standard battery. No big deal. In fact they're old hat nowadays. Better options available.
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Follow Up By: Mudguard - Tuesday, Apr 01, 2014 at 13:17

Tuesday, Apr 01, 2014 at 13:17
and those options would be? thinks are looking a might tight
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Follow Up By: John and Regina M - Tuesday, Apr 01, 2014 at 14:33

Tuesday, Apr 01, 2014 at 14:33
You asked about charging. You will have additional questions and can ask them based on all the answers to your original post. Compile your answers and ask them together is the best option.

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Reply By: Member - Frank P (NSW) - Tuesday, Apr 01, 2014 at 14:02

Tuesday, Apr 01, 2014 at 14:02
Mudguard,
I'm not sure you'll do yourself any favours with the Allrounder as your only battery.

I have the battery manufacturer's instruction sheet for the Allrounder. It says:

1) Select a charger that will deliver a current of one tenth of the C20 amp-hour rating.
So if you have an MRV70 with a 105 Ahr rating, it should be charged at about 10 amps - not the 40 or 50 that your alternator might deliver to a low battery.

2) Charge (at C20/10 amps) until the battery voltage comes up to 15.5 and hold it constant for 2 to 4 hours.

If your Jeep has a low output charging system it will never get there - it will be about 2 volts short. Also, the 2 to 4 hour timing at that voltage - your alternator can't do that either. You need a multi-stage smart charger to do it properly. (DC-DC for your vehicle or mains powered for maintenance)

3) Float charge at 13.0 to 13.1 volts. Your alternator might do that when it's hot.

4) Avoid charging at battery temperatures above 45 deg C.

Typical engine bay temperatures are well above that, and your alternator will keep charging regardless. My Prado aux battery (Allrounder) gets to over 60 deg on a trip on a hot day. (My charger shuts off at 50 deg - a bit high for the Allrounder, but at least it shuts off - but continues to record peak battery temperature so I know the battery temp for a fact.)

For your information, mate.

Options?

Leave the engine bay standard and put a battery down the back with a dc-dc charger for it.

Can be a conventional lead-acid type (properly tied down, of course) but doesn't have to be. Have you thought about Lithium Iron Phosphate - a third the weight, smaller physical size and twice the useable amp-hours. These batteries are now going into Bushtrackers and Kimberley Kampers, Karavans and Kruisers with fabulous results. None of this lead-acid multi-stage charging stuff - just a simple dc-dc charger that fills it flat out until it's full, then goes to float. Only drawback is cost, but you'll get 3000 to 7000 cycles from it, provided you don't abuse it, which offsets the cost compared to a number of lead-acid replacements for the same number of cycles. All depends on use/abuse, of course.

Cheers
FrankP

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Follow Up By: Mudguard - Tuesday, Apr 01, 2014 at 14:50

Tuesday, Apr 01, 2014 at 14:50
Thanks Frank now I know why the charging will come up wanting looks like our son gets the battery (for a carton) and Im up for another battery & charger
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Follow Up By: Member - Frank P (NSW) - Tuesday, Apr 01, 2014 at 15:30

Tuesday, Apr 01, 2014 at 15:30
Mudguard,

A number of our club members have converted their older Karavans from lead-acid (AGM) to lithium batteries. Without exception, they are ecstatic. Lithiums are so much easier to manage properly.

If you want more info, PM me or if you can't do that drop me a line at frankp79 at hotmail dot com

Cheers
FrankP

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Reply By: The Bantam - Tuesday, Apr 01, 2014 at 22:58

Tuesday, Apr 01, 2014 at 22:58
Firtsly don't get obsessed with this whole "calcium battery" thing, if it is a sealed battery appart from a cylindrical cell battery like an optima..it will have calcium in the plates.

If the standard battery is a sealed battery, it will have calcium in the plates.

Secondly, don't get obsessed with this smart alternator thing without knowing how that particular alternator behaves.....not all smart alternators are a bad thing.

third..no matter what type of battery you select.....you will not increase the capacity in the same space unless you do to some exotic technology like lithium.
The changing from the factory battery may not give you any real advantage...in fact you may well reduce capacity.

Remember the if you run the fridge too long, with a single battery you may well not be able to start the car.

cheers
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Follow Up By: Mudguard - Wednesday, Apr 02, 2014 at 02:03

Wednesday, Apr 02, 2014 at 02:03
Thanks all for your input I've always used a cranking battery for an auxiliary (remote camping spare) its only in the past year I"ve started using the ALLROUNDER (in the Patrol) which isn't going to be suited to what we need it for now with the Jeep
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Reply By: Trevor P4 - Thursday, Apr 03, 2014 at 20:50

Thursday, Apr 03, 2014 at 20:50
Mudguard,

When you work out how you are going to charge your Aux battery in the car then do not connect your trailers charge wires (for the REDARC BCDC1240) to the Aux but to your start batt in the car.
It stops any smart chargers getting confused when the vans batteries are connected about what it is they see in terms of voltage.
As you will only draw power from the start battery when the engine is running and you have your trailer connected it is not a problem provided you disconnect your anderson plug when the engine is not running.

This leaves what ever set up you have in the car seperated from the van circuit
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Follow Up By: Mudguard - Friday, Apr 04, 2014 at 12:53

Friday, Apr 04, 2014 at 12:53
The REDARC acts as a isolator when it senses no charge from the alternator the unit turns off
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