Size does matter!!!

Submitted: Saturday, Jul 15, 2006 at 14:20

ThreadID: 35854 Views:2897 Replies:2 FollowUps:5

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Member - Crazy Dog (QLD)

Ok troops,

What is a good size battery (not imperial or metric please!) for the camper NOT being charged from the alternator moreover charged from the HONDA.

I see Mike H is using 88a/h batteries for something or other so do ya reckon that is big 'nuff? Just a smally fridge and 12v fluro occasionally...

Grrr!!!

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Reply By: Mike Harding - Saturday, Jul 15, 2006 at 14:41

Saturday, Jul 15, 2006 at 14:41

Current draw for fridge; about 4 amps
Current draw for light; about 1 amp

As you live in Cairns (you bastard! :) let’s assume your fridge will run for about 40% of a 24 hour period (serves you right! It would only run 20% here in Vic :) so that’s about 10 hours at 4A = 40Ah. Plus about 4 hours at 1A for the light – total of 44Ah per day. You may need to adjust the fridge figure – I’m just guessing.

At that rate you would be discharging my 88Ah battery to 50% each day which is OK but not great. That probably means you would get around 400 to 700 cycles from a quality AGM battery, a few more from a Gel Cell IIRC. If you use a larger battery it will suffer a lower percentage of discharge and last longer. otoh 550 days is a lot of camping so if you amortise the cost of the battery ($250?) over that time it works out at 45c battery cost per day.

Charge wise; if your Honda DC output can stuff 8 amps into the AGM (it will not manage that many into a Gel Cell) you’ll need to run it about 5 hours per day. May be better to buy a 3 stage charger which will probably do the job in 3 hours? Jaycar do a decent one – check if it still outputs 240V to the negative terminal.

Let us know what you buy and how it works out for you.

Mike Harding

PS. It’s raining and 9 deg C in Melbourne but I’m going out for the evening with a beautiful so I don’t care how nice it is in Cairns :)

AnswerID: 183619

Follow Up By: Member - Crazy Dog (QLD) - Saturday, Jul 15, 2006 at 15:12

Saturday, Jul 15, 2006 at 15:12

Yo Mike,

Thanks for the effort in your post.

I appreciate that....I used to live down there Frankston/Karingal infact - neva a'gin.....by the way it is overcast and drizzling at the moment and a freezing 22 degrees.

Goin' to the Mareeba Rodeo tomorrow so should be good.

Back to the battery stuff. I have an 88ah sealed L/A ups battery that was given 2 me so I thought I might stuff that on the CT.

Grrr!!!

FollowupID: 440248

Follow Up By: Member - Mike DID - Saturday, Jul 15, 2006 at 15:16

Saturday, Jul 15, 2006 at 15:16

I would only use the "DC" output from Honda or Kipor generators in an emergency - they are totally unregulated and could damage your battery if you don't disconnect it when the battery is fully charged. http://www.exploroz.com/vehicle/electrics/default.asp#Article_GeneratorPower

The Jaycar MB3612 is back in stock (without the high-voltage tingle option) for only $99. This is a 3-stage charger (I have tested it) even though Jaycar describe it as a 2-stage charger. Site Link

KMart have a 15 amp NVP 4-stage charger for $99.

Mike

FollowupID: 440249

Reply By: Member - andrew B (Kununurra) - Sunday, Jul 16, 2006 at 09:19

Sunday, Jul 16, 2006 at 09:19

just did a trip to Cape Dommett with a new exide extreme as the 2nd battery. It ran the 80l waeco for 50 hours no problem - battery was 12.2 volts when we started the drive back. The fridge was the only applience, and it had the partitions removed so was al fridge not fridge/freezer. It was reasonably cool for up here which would have helped, and was ran to almost freezing everything on the way out. We didn't run any other apliences off the battery for the trip. As a back up power source for the camp, we use a $20.00 el cheapo jumpstart battery, its small, cheap, and runs the fluro for a couple of days, along with the shower for us at night. Had it for a few years now, 400mA charger wont bring it up anymore, so a 4.4 amp does the trick in small bursts, or hook the jumper leads up to the aux battery for a half hour also brings it up......I think it is nearly dead though.

Cheers Andrew

AnswerID: 183722

Follow Up By: Alloy c/t - Sunday, Jul 16, 2006 at 11:46

Sunday, Jul 16, 2006 at 11:46

andrew B ,could you please tell us on what setting you had the fridge set at ,I find it rather hard to believe that an 80lt Waeco ran for 50hrs of the 1 batt charge with the batt only down to 12.2v ,,best case have Ever managed with our 80lt Waeco is 64amps total draw in 24hrs when used as a fridge and freezer ,when used as all fridge the Waeco 80lt actually uses more power due to the lack of the freezer "bank",,ergo to get 50hrs at just under 3amps per hr =150amps drawn ,must be 1 magic exide extreme.

FollowupID: 440372

Follow Up By: Member - andrew B (Kununurra) - Sunday, Jul 16, 2006 at 18:51

Sunday, Jul 16, 2006 at 18:51

Gday Alloy, the fridge was set on -15 for the 3.5 hour drive out, which put a few ice crystals in the milk and yoghurt. when we stopped I set it on -4 which seems to keep the warmest part of the fridge (3/4 of the way up the wall near the dairy section). We also had 6 porterhouse steaks frozen in the dairy compartment.

The battery is a month old and this was its first cycle, so along with bringing the temp right down while driving, and the frozen steaks to help, we probably had the best case scenario as far as this goes. Daytime temps were around 32 deg, night was about 10 at a guess.

The fridge was set at 'normal' for the compressor speed. After looking at the sums you did above, and I don't dispute these, we had an exceptional run. Planning another short trip next month, so I'll see how we go then.

Cheers Andrew

FollowupID: 440424