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Open Roads Forum  >  Tech Issues

 > Question about charging amps

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renoman69

Edmonton Alberta

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Posted: 07/21/12 11:10pm Link  |  Print  |  Notify Moderator

I have 4 6v batts wired in series/parallel in two separate locations on my fiver. My question is ....If my converter is putting out 40 amps, once the amps hit the battery switch and charge the two separate banks of batts do the amps drop to 20amps per bank or should I see 40 amps to each bank??


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BFL13

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Posted: 07/21/12 11:23pm Link  |  Print  |  Notify Moderator

I bet you are sorry already you asked that! or is that ?

The real question is whether each set gets 20 or is it uneven? I find it is uneven and you can see this by taking voltages of each set as they charge up. Difference is small and that shrinks as they get higher in SOC. As soon as you stop charging both sets will show the same voltage of course.


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2oldman

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Posted: 07/21/12 11:27pm Link  |  Print  |  Notify Moderator

The 40 amps (theoretically) will be divided somewhat equally among all batteries.

renoman69

Edmonton Alberta

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Posted: 07/21/12 11:57pm Link  |  Print  |  Notify Moderator

2oldman wrote:

The 40 amps (theoretically) will be divided somewhat equally among all batteries.


That is somewhat what I am seeing. Converter was at at 23 amps and the reading on the clamp on amp meter was about 9.3 amps at each bank.

Golden_HVAC

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Posted: 07/22/12 12:18am Link  |  Print  |  Notify Moderator

renoman69 wrote:

2oldman wrote:

The 40 amps (theoretically) will be divided somewhat equally among all batteries.


That is somewhat what I am seeing. Converter was at at 23 amps and the reading on the clamp on amp meter was about 9.3 amps at each bank.


My guess was that only about 15 amps would be going to each battery, with the remainder being used in side he RV.

40 amps is pretty small, and will work fine if you don't do dry camping and rely on a generator for a quick charge now and then.

If you dry camp frequently, then a ideal converter would put out 10% to 15% of your battery capacity each hour, to recharge our house battery, yet you are getting much less than a 10 hour charge. A 10 hour charge on a 440 amp hour battery bank means that 44 amps needs to go into the battery, in addition to any power for the furnace, lights, pump, ect while the converter is working on recharging the batteries. So 65 amp charger will put around 45 amps toward the battery, and have 20 amps to run a furnace or other 12 VDC loads.

Yet spending $350 to change to a 60 amp charger is also unrealistic.

Weekend Warrior used to put in 30 amp chargers that barely kept up with the load, never really giving a good charge on a cool night when the generator is on, the furnace is also on, and the 30 amp charger had to supply most of the amperage for the furnace and lights.

Fred.
e

BFL13

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Posted: 07/22/12 07:46am Link  |  Print  |  Notify Moderator

"If you dry camp frequently, then a ideal converter would put out 10% to 15% of your battery capacity each hour, to recharge our house battery, yet you are getting much less than a 10 hour charge. A 10 hour charge on a 440 amp hour battery bank means that 44 amps needs to go into the battery"

Fred, that is so mixed up it is "beyond repair"

However it is true that charging is with "net amps" through the battery and it goes faster if there is no draw down while you are trying to charge them up

renoman69

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Posted: 07/22/12 08:37am Link  |  Print  |  Notify Moderator

Getting ready to hit the road in a couple weeks and I have been doing some testing. I actually had my 45 amp Iota and my 40Amp True charge 2 putting 82amps into the batts running off the Honda 20001 for a few minutes. I turned them off and when I tried it agian I could not get the TC2 to put out the 40 amps again. I guess the Iota had it tricked into believing the batts were charged. So the TC2 was too "smart" for it's own good.

BFL13

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Posted: 07/22/12 08:59am Link  |  Print  |  Notify Moderator

The Iota has a higher voltage than the TC2, so start the TC2 first and get it running and then turn on the Iota. If the batteries are high enough SOC that battery voltage rises quickly, then the TC2 will soon not have any voltage diff to make any current so it will not contribute ane the Iota will continue as normal.

When the Iota drops to 14.2 then both will contribute but no point unless amps are still above 40, since one can do it all.

Golden_HVAC

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Posted: 07/22/12 09:49am Link  |  Print  |  Notify Moderator

renoman69 wrote:

Getting ready to hit the road in a couple weeks and I have been doing some testing. I actually had my 45 amp Iota and my 40Amp True charge 2 putting 82amps into the batts running off the Honda 20001 for a few minutes. I turned them off and when I tried it agian I could not get the TC2 to put out the 40 amps again. I guess the Iota had it tricked into believing the batts were charged. So the TC2 was too "smart" for it's own good.


I bought a TC 20 after it got great reviews in Home Power Magazine. It is very intelligent, and will monitor the battery bank it is connected to even if you drop the 120 volts for a while.

The Truecharger will monitor the output voltage and if it drops below 11.9 volts will automatically go into the equalize mode when 120 volt power is restored. It also counts 30 days of continuous 120 volt power and equalizes on day 30 as well.

So if you had just hooked up the TC 40, it will have said no output voltage so I must go into the equalize mode. Then once it sees more than 12.6 volts it will not automatically return to the equalize mode until it has lost power and gone below 11.9 volts. (I can not wait out the 30 day timer)

There should be 2 switches on the front to control the output voltage by inputting via this switch what type of battery profile and if it is a warm, cold or hot environment (or use a battery temp sensor). I normally leave mine set on "Hot" as I don't want my charger to put out the maximum voltage.


As for confusing commets made yesterday at 11 pm, I had a long day, great time at the beach, and yes it is confusing but also true. You do need between 10% and 15% of your battery capacity to recharge at a good rate, and that would be about 44 amps as a minimum dedicated to providing power to the battery. Because you would be using the RV at the same time, at least 2 amps will be consumed by the RV, so you would typically desire to upsize the charger with this in mind.

So if your plans include using about 15 amps within the RV and providing 44 amps for the battery, then 59 amps in the minimum size, or 60 can be purchased. I think they sell a 65 amp charger, but even a 40 am or 45 amp will work, just that it will take more time.

At 15% of your battery capacity, you can size the charger at 66 amps (+ what you expect to be using inside the RV) so in reality, anything between 40 and 75 amps will work fine.

Yes I think that turning on the True Charger first will provide better amperage out of it than turning it on second. Yes you should be able to set it at 13.5 volts fixed or tell it you have cold lead acid batteries that need a much higher voltage.

Fred.

MEXICOWANDERER

las peñas, michoacan, mexico

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Posted: 07/22/12 10:07am Link  |  Print  |  Notify Moderator

A hostess should in theory see 8 canapés be divided 4 ways, two to each guest. Batteries are like that too, guests I mean.

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