Auxillary battery cable size.
Submitted: Monday, Aug 24, 2009 at 21:10
ThreadID:
71767
Views:
3868
Replies:
6
FollowUps:
3
This Thread has been Archived
Member - graeme W (WA)
The only damage we had on our
Gibb river trip was with the auxillary battery.With the new Hilux the auxillary battery tray has legs of differing lengths to fit in the space provided.These bolt straight to the top of the mudgard with small bolts that screw into nuts welded to the underside of the mudgard.With a 37kg battery and rough correcated roads eventually the mudgard cracks where the 4 bolts are attached.After fixing the cracks and designing a better battery carrier i decided to put a smaller 55 amp full river as the first auxillary in the battery cradle {less weight and redesigned}and put my original 100 amp full river under the tray down back.Would 8mm cable be big enough to run between the 2 batterys.As everything is wired to the original position and i had this cable already down back via an anderson plug to charge the battery in the camper while travelling, it would save a rewire and then i could simply run a short wire via anderson plug from the 100 amp battery now in the back to charge the camper battery while travelling.Bit complecated isnt it.
Aparrently Hiluxs and Prados suffer the same problem poor design so owners be aware.
Regards Graeme.
Reply By: Maîneÿ . . .- Monday, Aug 24, 2009 at 21:27
Monday, Aug 24, 2009 at 21:27
Graeme,
I use 32mm² battery cable (2B&S)
less will give too much Voltage loss
is thicker than some starter cables
Maîneÿ . . .
AnswerID:
380347
Reply By: Member - Fred B (NT) - Monday, Aug 24, 2009 at 23:43
Monday, Aug 24, 2009 at 23:43
Graeme,
go to this web page, scroll down and you will see a comparison table of different wire gauges/sizes. A bit further down it gives a table of voltage drop over different amps and distances. It will help you choose a more realistic cable size for the job, and then give you less chance of problems in the future. Do it right the first time and save the drama.
Collyn Rivers Cable Sizes
regards,
AnswerID:
380363
Follow Up By: Member - Mike DID - Tuesday, Aug 25, 2009 at 09:11
Tuesday, Aug 25, 2009 at 09:11
The two AGMS could draw up to 60 amps when charging, so keep that in mind when deciding cable size.
To avoid a fire
hazard, make sure that fuses or Circuit Breakers you place at BOTH ends of the cable are rated LESS than the current rating of the cable.
FollowupID:
647726
Reply By: palmy - Tuesday, Aug 25, 2009 at 11:32
Tuesday, Aug 25, 2009 at 11:32
I've got a 90AH wet cell battery in the tray of my 4WD. I'm using 6mm square cabling to charge this battery and have fused the connection with a 50Amp fuse (cable rated at 60AMP). Originally I thought this cable was too small, based on other recommendations etc, but having used this setup, and having my father-in-law having the exact same setup I see no reason for alarm. I certainly wouldn't try and start the car with this cable though...
AnswerID:
380409
Reply By: RV Powerstream P/L - Tuesday, Aug 25, 2009 at 17:51
Tuesday, Aug 25, 2009 at 17:51
Hi Graeme
Give me the lenght of cable run overall from the cranking battery to the camper battery and I will give you the figures for voltage drop to cover some cable for that.
Based on these figures you can decide what you want to do and the Aux battery in the tray will also be covered within the figures.
Ian
AnswerID:
380461
Follow Up By: Member - graeme W (WA) - Tuesday, Aug 25, 2009 at 20:29
Tuesday, Aug 25, 2009 at 20:29
Hi Ian.
My set up had a 100 amp full river in engine bay next to the cranking battery.The bad design of the auxillary battery cradle and where it fits caused the top of the mudgard to crack in all 4
places where the cradle bolts to.Have redesigned the cradle and fixed all the cracks but to make certain it wont happen again have purchased a 55 amp full river {less weight} to go in the engine bay and will move the 100 amp hour battery to the back under the tray .I already had an 8m cable running from the auxillary in the engine bay down back to an anderson plug that i connected to the camper while travelling that also has a 100 amp full river.My intention was to simply connect the 8m cable from the auxillary in the engine bay to the battery at the back and then from there a short cable to an anderson plug so as to hook up to the camper when in use.About 10ft of 8m cable to the back.This setup seemed to keep the auxillary and camper battery somewhere close to full as on a recent trip to the gibb we were able to get 2 nights
camping running a 60 litre trailblazer on freeze and an 80 litre waeco on fridge.Neither cut out on low voltage and i guess we were travelling about 100klms plus per day plus i have a 64 w solar panel on top of the hilux adding a bit.Mind you were also adding an odd bottle of wine and beer to the freezer about an hour before
camp each night.Also getting 14.2 volts at the camper battery when connected and car running.
Regards Graeme.
FollowupID:
647819
Reply By: RV Powerstream P/L - Wednesday, Aug 26, 2009 at 06:55
Wednesday, Aug 26, 2009 at 06:55
Graeme
As you say you have 10Ft of 8B&S cable to me that appears to be not long enough to feed the camper battery but would get to the Anderson Plug at the back of the vehicle.
Anyway the following figures are for 10Ft and if you have 20A available the drop would be 0.258V and if you have 25A available the drop would be 0.323V and this is within an acceptable standard of 0.36V
If you had 30A available the drop would be 0.387V so efficiency would be declining.
If for example your overall cable run is 15Ft and you have 20A available the drop would be 0.387V and with 25A available the drop would be 0.484V so immediately you have an inneficiency.
The drop has to be deducted form the alternator output to determine what charge you will get.
If your alternator maintains 14.4V you may be OK but if it reduces voltage then you may eventually have problems.
The higher the voltage you can get to the batteries you want to charge the quicker they can charge saving you run time and money.
If you didnt have the Trailblazer and solar panel in the equasion I think it would be a different story that you may be telling.
Ian
AnswerID:
380516
Follow Up By: RV Powerstream P/L - Wednesday, Aug 26, 2009 at 06:59
Wednesday, Aug 26, 2009 at 06:59
Is your stated voltage at the camper continuous or only tested on start up of the vehicle.
Ian
FollowupID:
647861
Reply By: Member - graeme W (WA) - Wednesday, Aug 26, 2009 at 21:07
Wednesday, Aug 26, 2009 at 21:07
Hi Ian. And thanks for the replies.You are right the 10 ft is an estimate to the anderson plug at the back of the hilux.As the 8m twin core is already in place the easy way for me is to divert this to the 100 amp battery now in the back left behind the rear mudgard.If you think its its not enough i can simply replace with 16mm allthough the 8mm has been fine so far and tested voltage at the camper battery with car running has always been 14.2 the same as at the starter and 100 amp auxillary when in the front.Havent tested after a long run only in the driveway.Hoped id get away with adding the extra lighter battery to stop the unbrakable hilux falling apart.One thing i have done though after a long trip back home is to plug in the 20 amp zantrax smart charger {wired in the camper for use in parks and with a genny] and it always goes to charge which is the setting less than 4 amps which tells me the camper battery is not far from full.The next setting is float and it doesnt stay on charge long.Zantrax goes 20,16,12,8,4,charge and then ready.
Regards Graeme
AnswerID:
380610