How long would it take to charge 1 deep cycle battery with an 850W generator?

Submitted: Wednesday, Mar 05, 2008 at 18:12
ThreadID: 55214 Views:5514 Replies:6 FollowUps:2
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How long would it take to charge 1 deep cycle battery or gel 'drycel' battery with an 850W generator?
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Reply By: Robin Miller - Wednesday, Mar 05, 2008 at 18:17

Wednesday, Mar 05, 2008 at 18:17
Hi REdbac

It should take about the same length as with any other generator
as pretty all all can deliver more current than the battery can accept for long life.

Ball park - couple of hours for a useful top up and 4-6 hours
for optimum.


(I assume the battery is charged via an appropriate 240v to 12v charger)
Robin Miller

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AnswerID: 290953

Reply By: Member - Roachie (SA) - Wednesday, Mar 05, 2008 at 18:26

Wednesday, Mar 05, 2008 at 18:26
This is one of those typical "how long is a piece of string?" questions.

It depends on how flat the battery is; exactly what type of deep cycle battery it is etc. There are different "types" of battery that claim to be deep cycle. Some are true deep cycle, others are hybrid (they can be used for starting and or running accessories).

True deep cycle batteries need to be charged slowly (to avoid long term damage to the plates). I wouldn't consider hooking a deep cycle (or any other battery for that matter unless it was an emergency) up to the 12 volt output on a genny (any genny).

Instead, I would use a proper 3 stage battery charger on the 240 volt output side of the genny and charge the battery "properly". If you do it this way, it depends on 2 factors: how big your 240 volt charger is (I have 2 x 15amp jobbies) and how low the battery/ies is when you hook it up.

AnswerID: 290954

Follow Up By: Member - Norm C (QLD) - Wednesday, Mar 05, 2008 at 18:31

Wednesday, Mar 05, 2008 at 18:31
Gee Roachie, both our responses were at 17:26 and we both used the 'how long is a piece of string' analogy.

Hope your not my long lost twin. My mother always said 'if you were a twin, I'd have given one of you away'. Guess she didn't like twins. Perhaps she did it after all??
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Reply By: Member - Norm C (QLD) - Wednesday, Mar 05, 2008 at 18:26

Wednesday, Mar 05, 2008 at 18:26
Redbac, if you are using the gennie on 240V with a battery charger, it will have more to do with the size of the charger than the size of the gennie. And the time to charge using the gennie will be the same as the time with the charger plugged into mains power.

I guess my answer is about as good as 'how long is a piece of string', but that's the way it is sometimes.
AnswerID: 290956

Reply By: Dunaruna - Wednesday, Mar 05, 2008 at 18:33

Wednesday, Mar 05, 2008 at 18:33
The cheapie ALDI or GMC gennies are only good for about 6 amps.
AnswerID: 290958

Reply By: mowing - Wednesday, Mar 05, 2008 at 19:18

Wednesday, Mar 05, 2008 at 19:18
Hi Redbac, I see that from post 55212 you are looking at doing a 6 month trip with an on road jayco. I will make the assumption that the majority of the time you will use caravan parks but you would like to use bush camping when available. The genny that you are thinking of using is cheap, which is fine but you may (will) find it unreliable when using for extended periods. The smart chargers that Roachie mentions are really good but expensive.
Another option that you have is to have a second battery(deep cycle) in the van (battery box on the A frame or in the side boot) and have a "arrid"? style of solenoid with the appropriate wiring from the vehicle so that when you are driving you will be charging the battery slowly (which they like) and you can run the caravan fridge on 12 volt and then swap to gas when you have no power or 240 volt at the caravan park. The battery will be well charged to run the small stuff which I assume is 12 volt? Silly question but you never know.
You will need a good size deep cycle battery and make sure that the fridge works well as you van is 20 years old and swapping from 12 volt to gas may be a long process. If you need to charge the battery, start the car.
Something to consider

Regards

Mark
AnswerID: 290971

Reply By: Nomadic Navara - Thursday, Mar 06, 2008 at 00:14

Thursday, Mar 06, 2008 at 00:14
Redbac

How about a bit more info. How big is the battery. Are you using the 240V OP and charging the battery with a proper multistage charger? Are you using the 12V op straight onto the battery?

If you are using the 240 V OP and a multi stage battery charger, the time will be dependent on the battery size, the size of the charger and the depth to which you have discharged your battery.

If you are using the 12 V OP then see Site Link. Some forum members will reckon this a joke, but remember this was written by an engineer who is well versed in control circuitry and has measured these devices.

PeterD
PeterD
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AnswerID: 291068

Follow Up By: Mike Harding - Thursday, Mar 06, 2008 at 06:07

Thursday, Mar 06, 2008 at 06:07
Collyn's statement, in the link you supply, may have been correct in 2001 but it isn't now.

The problem with the cheap generators is that they produce too high a voltage for long term safe battery charging. Two GMCs I have measured both output an unloaded 23V which drops to 17V under load - it is also a full wave rectified output with full return-to-zero 100Hz ripple.

Robin's answer at the top is correct given the limited amount of information.

Mike Harding
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