Is too much charge OK?

Submitted: Monday, May 08, 2017 at 21:55
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Is it possible to put too much charge, too quickly back into a deep cycle battery? E.g 105 a/hr battery is somewhat depleted after a few nights in one place and the next day's drive is not going to be long enough to top it back up. Could I also plug in my 2 solar panels (150W + 120W) while I'm driving along or do I risk doing damage to a component? Battery is a glass mat type and both panels have their own regulators. Thanks.
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Reply By: HKB Electronics - Monday, May 08, 2017 at 23:05

Monday, May 08, 2017 at 23:05
What system are you using to charge the battery off car?

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Follow Up By: Deejay - Tuesday, May 09, 2017 at 09:20

Tuesday, May 09, 2017 at 09:20
Hi HKB.
I have a CTEK D250S dual and the standard Nissan Patrol alternator.
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Follow Up By: HKB Electronics - Tuesday, May 09, 2017 at 10:05

Tuesday, May 09, 2017 at 10:05
Ok so you get 20A from the ctek, you need to look at the battery specs, if the battery can accept high charge rates then the additional charge from the solar controller might contribute some extra charge current when the battery is low, once the battery terminal voltage is forced to 14.4V the chargers will throttling back.

It will be upto the batteries charge acceptance as to weather its worth it, I had 200Ah of gel batteries at one stage and a 20A charger, I upped the charger to a 40A unit and it made no difference to the recharge times, the gels just wouldn't accept more than 20A.

One other thing to keep in mind also is how the chargers work, the ctek will pump 20A into the battery until it gets to 14.4V for example, it will then start reducing the charge current to keep the voltage at 14.4V until the charge current drops to less then .5A for example then go into float charge. If you have three chargers pumping current in they can confuse each other and they think the battery is fully charged so go into float mode early. This interaction can result in actually lengthen the time it takes to go from say 80% - 90% to fully charged.

So may be of value when the battery is low if the battery will accept high charge currents but could lengthen charge times at higher SOC's

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Reply By: lancie49 - Monday, May 08, 2017 at 23:06

Monday, May 08, 2017 at 23:06
My thoughts are that you'd be fine if your regulator is in good nick and capable.

What regulator are you using ?
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Follow Up By: Deejay - Tuesday, May 09, 2017 at 09:21

Tuesday, May 09, 2017 at 09:21
Hi Lancie
I have a CTEK D250S dual and the standard Nissan Patrol alternator.
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Reply By: Member - Racey - Tuesday, May 09, 2017 at 09:54

Tuesday, May 09, 2017 at 09:54
What load do you have connected to the battery
How old is your battery.
Have you previously flattened is , I.E. below 11 volts

These factors will have a big bearing on your set up.

Cheers

Jon
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Follow Up By: Deejay - Tuesday, May 09, 2017 at 11:32

Tuesday, May 09, 2017 at 11:32
Racey. The battery is about 18mths old and 2 fridges would be running off it while we are driving along. It would also be being charged by the alternator and the 2 solar panels. So discharging and being recharged at the same time.
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Follow Up By: Frank P (NSW) - Tuesday, May 09, 2017 at 17:27

Tuesday, May 09, 2017 at 17:27
Deejay,

The two fridges running while you are driving will be using a portion of your Ctek's output, so your battery won't be getting the full output of the Ctek.

It is simple to improve your setup to get the max out of your Ctek.

You need a 5 pin (single pole double throw, or SPDT) automotive relay like this one.

Supply the coil from an IGN source in the car. Wire the normally closed contacts to power the fridges from the aux battery. Wire the normally open contacts to power the fridges from the vehicle's electrical system when the engine is running.

Here's how it looks on my setup. The red line is an IGN-controlled source. The Ranox DC-DC charger is like your Ctek.

FrankP

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Follow Up By: Member - Racey - Tuesday, May 09, 2017 at 18:01

Tuesday, May 09, 2017 at 18:01
Hi Deejay, if you are running 2 frigs , is one run as a freezer?

I generally agree with most of the comments from other contributors. A freezer unit would make the situation worse.

Cheers
Jon
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Follow Up By: Deejay - Tuesday, May 09, 2017 at 21:26

Tuesday, May 09, 2017 at 21:26
Yes Racey, one fridge (30L) runs as a freezer while the other, a 60L Engel, runs as a fridge.
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Reply By: Les - PK Ranger - Tuesday, May 09, 2017 at 12:12

Tuesday, May 09, 2017 at 12:12
Deejay, if staying one place a few nights, then yes the deep cycle won't like this long term anyway, best to only run it down to say max 50% SOC before recharging . . .

Buuuut . . . why don't you just put the solar panels on the deep cycle when you are camped up ??

It's the logical thing as one 150w panel (in decent sunshine most of the day) would easily have the fridge needs covered, and still have enough to top off the battery almost totally after minimal night use of the fridge and some led lighting etc.

You could put other solar panel on the main if you wanted, just to make use of the sun and keep that in full condition too.

I have a couple of folding type blanket panels . . . a 100w (6amps full sun, 3 amps cloudy) and a 150w (9 amps sun, not tested cloud), and usually do this, the 150w on the aux, the 100w on the main.
Very rare I spend a day somewhere, so don't set it up much, but good to have on board for touring.

Set it up on the aux if camping early, from say 1500hrs, face car to sun and put panel over windscreen :)
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Follow Up By: Deejay - Tuesday, May 09, 2017 at 13:41

Tuesday, May 09, 2017 at 13:41
Thanks PK. My question would apply to a worse case scenario where we were camped in overcast conditions. I also wanted to know if there was a limit to how much charge could be put into a battery. I'm hoping the above never happens.
Thanks for your advice.
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Follow Up By: Les - PK Ranger - Tuesday, May 09, 2017 at 14:52

Tuesday, May 09, 2017 at 14:52
In overcast conds, you could have a panel on each battery and run a fridge off your main and other off your aux.
Panels will (should) put in ample to cover 2 fridges, even with one running as a freezer.
Well, at least in cloud for a few days it should keep your batteries up to decent levels, you might in rare circumstances have to turn the fridge off at night to keep things in check.
Of course just an hours driving a day would put a lot of power back into them too.
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Follow Up By: Sigmund - Tuesday, May 09, 2017 at 17:32

Tuesday, May 09, 2017 at 17:32
Sounds like measuring what's going out and what's coming in so you can avoid going below 50% SoC might be an idea.

I'm guessing with two fridges one is running as a freezer. During warmer parts of the year you might be drawing 100 Ah or more a day*. What are the panels putting back on an average day?

* http://12voltblog.com.au/how-much-power-does-12volt-stuff-use/
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Follow Up By: Deejay - Tuesday, May 09, 2017 at 21:29

Tuesday, May 09, 2017 at 21:29
Sorry Sigmund, can't tell you what the panels put back into the battery.
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Follow Up By: Sigmund - Saturday, May 13, 2017 at 10:14

Saturday, May 13, 2017 at 10:14
I think you need another battery.

If you plan to do any camping of more than a day you don't have enough reserve power.
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Reply By: RMD - Tuesday, May 09, 2017 at 14:07

Tuesday, May 09, 2017 at 14:07
The charge rate for that style of battery is 20amps, otherwise if discharged and receiving more than 20amps for much of the duration of the charge the battery may get too hot internally. You would only get that amp flow with a higher charge voltage though. or multiple sources inputting.
All sources combined probably shouldn't exceed the 20amps for battery life.
AnswerID: 610960

Reply By: gbc - Tuesday, May 09, 2017 at 16:59

Tuesday, May 09, 2017 at 16:59
If fastest charging is what you are after, add the ctek smart pass to the existing ctec, and wire the fridges to the smart pass as non critical users. You can also remove the solar regs and plug the panels into it as well - even on the move. The smart pass will effectively isolate the fridges from the battery allowing it to charge unimpeded at max rate (you'll definitely need the temperature sensor on the battery because they sing) until such time as the 250 kicks in again.
For an extra couple of hundred dollars you'll have a first class system which becomes set and forget with the panels.
AnswerID: 610965

Follow Up By: GREG T11 - Tuesday, May 09, 2017 at 21:20

Tuesday, May 09, 2017 at 21:20
Going by what the website says ( Baintech ) the smart pass is a given. The charger will not recognise the solar while an alternator is running, it is either one or the other.

Having said that trying to run 2 fridges off a 105 ah battery is always going to be a uphill battle.

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Follow Up By: gbc - Wednesday, May 10, 2017 at 04:21

Wednesday, May 10, 2017 at 04:21
THats right, the 250 won't combine power sources, the smart pass will. It is a tricky bit of kit. With that sort of draw seconds count and having the panels being brought in and out seamlessly as they are required would make a difference.
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Reply By: swampy - Wednesday, May 10, 2017 at 00:46

Wednesday, May 10, 2017 at 00:46
hi
20-30% of battery capacity is typical fast charge rate
Smart pass is a good idea up to 80 amps altenator charge. Once under 20 amps it will multistage charge .

Solar
With sun at 100% Psh [peak sun hours ] av summer /winter is 5 1/2 hrs per 24hr
160w harvests 38ah per 24 hr period
200w harvests 48 ah per 24hr period
U can only use what u recharge

U need to do a consumption audit
A single 32lt in 24hr would be enough for a 100ah battery typically
In your case in hotter weather 70-80ah per 24hr consumption at least
Check volts after 24hr period around 6-7 am if below 12.oo volt shortening of battery life occurs.
AnswerID: 610985

Follow Up By: Deejay - Wednesday, May 10, 2017 at 10:01

Wednesday, May 10, 2017 at 10:01
Thank you for all that Swampy.
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