Alternator charging times

Submitted: Tuesday, May 26, 2009 at 11:39
ThreadID: 69190 Views:4026 Replies:5 FollowUps:11
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Have the duel battery set up with a redark isolator plus a 64 watt solar panel through a 10 amp morningstar regulator that charges the auxiliary 100 amp hour full river agm in the Hilux.Also have a 110 amp hour full river in the camper that is linked to the car through anderson plugs and 8b@s cable while travelling.

During our trip to the GRR will be running 2 fridges in the Hilux with cable to use the camper battery if the need arises.Stops will be mostly overnight or 2 days at most .Have used this system with 1 fridge with no problems but the draw will be double with the 2 fridges.

Anyone got a rough idea how long or how many klms it would take for the alternator to bring the auxiliaries back to full charge.?

Thanks Graeme.
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Reply By: Peter_n_Margaret - Tuesday, May 26, 2009 at 12:14

Tuesday, May 26, 2009 at 12:14
Graeme, it really depends on the output voltage of the alternator and the voltage drop to the house battery.
Charge rate is simply a function in the difference in the charger voltage and the battery voltage (all other things being equal).
If the alternator voltage is down, full charge will be hard to get.
Measure both and then see if there is an 'opportunity'.
We have 14.3V to the crank battery from the alternator and a very low voltage drop (0.2 or less) to the house battery. We get 50A charge into the house from the 80A alternator when the house is down to 12.1V, so charging is quite quick and the solar tops it up. As the house battery comes up, charge rate from the alternator drops off.

OKA196 Motorhome
AnswerID: 366795

Follow Up By: Member - graeme W (WA) - Tuesday, May 26, 2009 at 16:42

Tuesday, May 26, 2009 at 16:42
Hi Peter.

getting 14.13 both sides of the redark at idle.Often wodered if an alternator would fully charge a battery because a few times ive hooked up the zantrax 20 amp charger to the auxilary when it should be fully charged ie a lot of driving and sitting in the sun and it still takes some charge.Not 4 amps but somewhere less before it goes into float.The zantax has 20,16,12,8,4 and then charging amps before finally going to float.If the alternator fully charged especially being topped up with the solar it should go straight to float.?

regards Graeme.
FollowupID: 634487

Reply By: Robin Miller - Tuesday, May 26, 2009 at 12:49

Tuesday, May 26, 2009 at 12:49
These's a few variables their Graeme , but I think the order of 2 hours would be reasonable to get back up to 90% capacity.
Robin Miller

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AnswerID: 366798

Reply By: Steve - Tuesday, May 26, 2009 at 18:31

Tuesday, May 26, 2009 at 18:31

don't know whether this is feasible for you or not, but I put my panels on top of the car canopy and have them re-powering the batts as we go along with the alternator. Makes a big difference. Keeps them fully topped up as opposed to 80/90%.
AnswerID: 366842

Follow Up By: Maîneÿ . . .- Tuesday, May 26, 2009 at 21:26

Tuesday, May 26, 2009 at 21:26
ever thought of the idea that the two different charging systems own regulators (Alternator & Solar regulators) will be sencing the same battery being charged by the other charging source??

Maîneÿ . . .
FollowupID: 634535

Follow Up By: Steve - Tuesday, May 26, 2009 at 21:37

Tuesday, May 26, 2009 at 21:37
whether or not, it will keep topping up and floating once it gets there.
FollowupID: 634536

Reply By: ABR - SIDEWINDER - Tuesday, May 26, 2009 at 18:48

Tuesday, May 26, 2009 at 18:48
Hi Graeme

What make and size are the fridges and what will they be set to ?

What is the voltage at the aux battery when the engine is at full operating temperature ?


Derek from ABR
AnswerID: 366849

Follow Up By: ABR - SIDEWINDER - Tuesday, May 26, 2009 at 19:57

Tuesday, May 26, 2009 at 19:57
I use a MGL Bat-1 to monitor my aux battery.

It provides information that any other battery monitor can't.


Derek from ABR
FollowupID: 634517

Follow Up By: Member - graeme W (WA) - Tuesday, May 26, 2009 at 20:13

Tuesday, May 26, 2009 at 20:13
Hi Derek.

One is a trailblazer 60 litre that will be on freeze and the other an 80 litre waeco as a fridge so will be drawing a good 10 amps with both running.Made up a 5 metre lead with the anderson plugs { from You} with 6 mm cable so i can use the 110 amp full river in the camper on 1 fridge if i have to.Most times i guess the 2 fridges will only be running together while we are driving.Beats lifting a fridge out of the Hilux.Tried it an no voltage drop so 2 night stays should ok i think.Connected up the zantrax charger tonight and it stayed on the lowest setting for about 2 hours before going to float and lifted the voltage from 12.7 to 12.9 when the aux should have been fully charged.??

The trailblazer is old but very efficient because of the insulation will be interesting to see how the waeco goes{has the insulating bag]

Dont post much but read a lot and you and Mainy write some informative stuff and a lot of questions answered there.

Havent tested the voltage on the aux when the engine at full temp but i will now that you suggested it.

Would you expect the voltage to lower or higher.?

Regards Graeme.

FollowupID: 634520

Follow Up By: ABR - SIDEWINDER - Tuesday, May 26, 2009 at 20:31

Tuesday, May 26, 2009 at 20:31
Hi Graeme

I would say you will fall short on power as both those fridges draw heavy power and will need both those Fullriver batteries for a 2 day stop.

Please give me the voltage of the alternator when hot too.

Recharge time for 200A by alternator could be as high as 7 to 10 hours.

Please email me if you need more info as I am also concerned about the battery charger you have.



FollowupID: 634525

Follow Up By: Member - graeme W (WA) - Tuesday, May 26, 2009 at 22:40

Tuesday, May 26, 2009 at 22:40
Hi Derek.

The charger is a 20 amp zantrax .it has been only new used about 3 or 4 times in the shed at home and wired in the camper by me on an ally plate that has clearance all around.As it is in the storage box at the front of the camper with the battery underneath i would only use it with the storage box lid open.Instead of hard wiring i have split with an anderson plug so as to use it on other batteries as and if neededwith an extension lead.

Will only use it with a generator or in a caravan park or at home.Plan was instead of wiring 240 to simply plug in the charger and run everything on 12 volt if at a caravan park or with a generator.

The waeco is only new but with the trailblazer on freeze ive had no problems with 2 days in the past.Figured with another battery in the camper with one of the fridges should be the same,but as most of our trips are 2 day camping fishing with a long drive home and then not using the fridge for another week {driving solar etc brings everything up again] was always worried that travelling 100 klms between stops would not be enough.?

Do you have concerns about the charger and the way i intend to use it. regards Graeme
FollowupID: 634553

Follow Up By: ABR - SIDEWINDER - Wednesday, May 27, 2009 at 07:19

Wednesday, May 27, 2009 at 07:19
Hi Graeme

The charger should float at approx 13.5 to 13.8 volts. (12.9 is not acceptable) Unless this is after the charger is removed and the battery has had time to cool down and rest but connected to mains should be greater than 13.5V.

Your new CF80 will use about 60A/hrs per day so you will be using about double the power you did last trip.

For safety margin is it possible to add another 100A Fullriver in the ute. I would say this would be perfect.

Please double check your charger for bulk and float charge voltages.



FollowupID: 634568

Follow Up By: Member - graeme W (WA) - Wednesday, May 27, 2009 at 16:01

Wednesday, May 27, 2009 at 16:01
Hi Derek.

Battery in the camper was 13.2 and after connecting the zantrax went to float at 13.5.Aux in the hilux was 14.58 and acually went down to 14.52 after connecting the zantrax and did not go to float.Could this be because of the solar panel and regulator confusing the charger.

The zantrax is a three stage with also three positions for flooded batteries {AGM]? cold warm and hot. Also has cold warm and hot for gel batteries.The instruction book recommends warm for temps between 10and 27 which is the setting im using.With the charger hooked up to the camper battery and the waeco plugged in and running the charger is putting in 4 amps which seems about right to me as the right draw.?With a fully charged battery would the charger pump in whats being drawn out.

Only expected 2 days at most maybe a little longer with the battery in the hilux with the solar panel.

Regards and thanks for your imput. Graeme.

FollowupID: 634663

Follow Up By: ABR - SIDEWINDER - Wednesday, May 27, 2009 at 18:10

Wednesday, May 27, 2009 at 18:10
Disconnect the solar panel and fridge and try again.

The load is causing the charger to charge at bulk.

FollowupID: 634695

Reply By: Maîneÿ . . .- Tuesday, May 26, 2009 at 21:44

Tuesday, May 26, 2009 at 21:44
I think a charging cable of just 8B&S from the Camper trailer 110ah battery to Alternator is too thin and will give you some unwanted Voltage drop!!

Maîneÿ . . .
AnswerID: 366877

Follow Up By: Member - graeme W (WA) - Tuesday, May 26, 2009 at 22:23

Tuesday, May 26, 2009 at 22:23
Hi Mainy.

Last 4x4 i used welding cable and suitable lugs for battery connections ,no votage drop with that.The cable i used to the back of the car seemed thick enough and no voltage drop with a volt metre.Be a few guys intersested in this because they all used the same cable.Will hook up the camper tomorrow and double check at the the three batteries and hope they will be the same.

Always read your posts or comments with interest.

Gegards Graeme.

FollowupID: 634547

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