Charging deep cycle battery

Submitted: Thursday, Jan 05, 2006 at 12:40
ThreadID: 29363 Views:12681 Replies:4 FollowUps:0
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He folk, been a while since posting or replying with 2 babies and all, but happy new year to you all and hope you had a good Christmas.

My Jackaroo has a 60 a/hr deep cycle auxillary battery in it. Went on a trip to the Far West Coast SA recently and performed admirably. Got it home and accidentally left the fridge going in very high temperatures with nothing in it for a couple of days, it struggled and completely drained the battery.

Took the car for a drive, restored al lot of the charge but not all. My question is, what is the best way (apart from driving) to restore the charge in my DC battery? I know I need a battery charger, but what type and charge rate? I currently have a 14 a/hr /2 a/hr (trickle) setup but could not get it to do anything on the trickle charge setting, which is what I thought Deep Cycles are supposed to need. The charger is fully automatic, is it OK to charge it on the 14a/hr setting and trust the charger to do the right thing and decrease a/hrs when getting full before switching off, or do I need a more moderate charge rate?

Auto shops/battery shops all giving conflicting information.

Also, will completely flattenning the battery (so much so that the level indicator didn't even show a 'low' light) affect future performance?

Also (Sorry!) I have heard that My 1999 model Engel 40l doesn't have a low voltage cutout or protection, but it still works fine even after running the battery out 2 or 3 times prior. Any comments/suggestions?

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Reply By: Notso - Thursday, Jan 05, 2006 at 13:17

Thursday, Jan 05, 2006 at 13:17
The brains trust will tell you that a lot of deep cycle batteries will only accept something like 8 amps per hour, so if you have a dead flat deep cycle of this type then it will take at least 60 divided by 8 or around 8 hours charging to bring it to full charge.

You 14 amp charger should do fine as they, the brains trust also say that you need a charger with at least 10% of the Amp Hour capacity of the battery being charged. So 10% of 60 is around a minimum of 6 amps. Your two amp trickle wouldn't ever charge it fully.

Of course the best option, according to said brains trust, is a smart three stage charger worth about $300.

So give it a good hit with the 14 amps, which it won't accept fully anyhow and make sure it drops off to a trickle at some stage

AnswerID: 146561

Reply By: armbrup - Thursday, Jan 05, 2006 at 13:41

Thursday, Jan 05, 2006 at 13:41
Re the Engel,
The manual is unclear on the low voltage cutout.
It suggests that the fridge cuts out at 11.5 volts, but what that means is that the compressor will not operate under 11.5 volts. It still drags current trying to.
You can buy a small low voltage cut out at Kmart. I have had one on mine for several years. Projecta brand. This turns off at 11.5 volts or so to protect the battery.You just splice it into the 12v lead.
Regards Philip A
AnswerID: 146567

Reply By: Member - Phil G (SA) - Thursday, Jan 05, 2006 at 13:59

Thursday, Jan 05, 2006 at 13:59
Wecome back D-Jack,

Just keep charging your deep cycle battery. As mentioned above, it can take a long time to get it fully charged. You can leave it charging indefinitely at a regulated 13.8volts. If it was me, I'd pull it out of the vehicle, and leave it hooked up in the garage.

Your Engel is probably the E-series. None of the engels come with a low voltage cutout. The E-series will continue running (and very poorly!) at very low voltages. The next series (F-series) has a different compressor, and will not run at less than 10 volts (a defacto low voltage cutout). The difference with a good low voltage cutout is that it will wait until the voltage is restored (often to 12.6) before it allows the fridge to run again.

You have plenty of choices with the cutouts. The Projecta one mentioned above ("Sure start") comes with cig sockets, but if it were me, I'd hard wire it.

Engel sell two cutouts that incorporate LED "battery monitors". One cuts out at 10.5 and the other 11.5. I'd prefer the latter. Then theres the kits from DSE and Jaycar if you like using a soldering iron - I've used these and they work fine, and are adjustable. For overnight camping I don't bother hooking mine up - but do if theres more than one night.

Cheers, and congrats on the two babies


AnswerID: 146573

Reply By: Member - Nobby - Thursday, Jan 05, 2006 at 17:02

Thursday, Jan 05, 2006 at 17:02
G'Day D-Jack. I had the same problems with my Batteries. I have 2 x 105amp DC Trojans in my CT and it was in getting some work done to it and the fool did some welding using the trailer as an earth without unhooking the Batteries.Result was that both were at 3.1v. Holler for a Marshall said they were buggered but seeing they were Trojans he would give them a go on his 90amp Charger. Next day they were 13.1 and holding so I get them home and they had dropped to 12.2v. I have a 3 stage charger (12amp) and they have taken four days to come up to 100%.. So what I am saying, they will come up fast but to get that last bit in, it takes a fair while. Hook them up and forget about them for a couple of days.
AnswerID: 146606

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