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Old 04-04-2016, 04:21 PM   #11
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HOWEVER, this is all new to me so suggestions and corrections are most welcome.
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Old 04-04-2016, 04:44 PM   #12
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I suppose you are right... Amp hours in are amp hours in.

BUT... If I only have say 1.5 hours to run my generator I can get more charge into 1 bank rather than both banks. Limiting ultimate cycle time on the batts and bring 1 bank up closer to full than if I tried to charge all 4. All assuming that bulk charge cuts off around 90% of batt capacity.

I only have 60amp available for charging @ 14.6 bulk. I am going to remove the 8guage wire from the factory and replace it with 4gauge so the batts get full voltage from the charger.
OK...well you should and could upgrade to 90+ amps charging for a 420a/h system...but lets set that aside...and use an example.

1. You can either charge a 210 a/h bank or a 420 a/h bank. Lets assume you have depleted both to 50% and want to recharge in the time you have available and lets use 2 hours of charging to keep things easy!
2. So bank #1 needs 105 amp hours put back in. And bank 1+2 needs 210 amp hours put back in.
3. Lets further assume that your charging system goes into absorbtion stage at about 75% full and float stage at around 90% full.
4. In bank #1 you will be at 75% when you get to (.75x210=157.5ah)...or once you have added 52.5 amphours back in in bulk stage....LESS than one hour with a 60 amp charger. (FAR less with a proper sized charger...except that a SINGLE 210 a/h cannot take even your 60 amps during charging ...it will likely only take a max of 52 amps of charge current (25%). So in your first hour you will charge in bulk at 52 amps...THEN shift down to lower voltage absorbtion charging for the remainder of the time as resistance builds...so maybe 1/2 those amps on average if you are lucky. You'll never get to float so lets' disregard that...So you are left with 75 or 80 amp hours added in 2 hours to a single 210ah bank.

5. Now lets return to the bank #1+2 scenario.
Here we have a need to REPLACE 210 ah's ...in a 420ah bank. The 420 ah bank will be 75% full at 315 ah's. SO..we get to add 105 amp hours at bulk rate of 60 amps due to the larger bank size...before the charges cycles to absorbtion. You can see that we'll be able to do around 1.75 hours of BULK charging at 60 amps and about .25 hours of absorbtion charging and so will add about 120amp hours to the BIG bank in the same amount of time . Again, the difference would be even more dramatic with a 90 amp charger since the big bank can use ALL of it and the little one can only use 52 amps or so in bulk phase.

Hope that clarifies.
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Old 04-04-2016, 05:01 PM   #13
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That does make sense....

I remember reading somewhere that higher amp chargers are not always a good thing which is why I went with the 60. Can I go with a 100amp charger?

What effect would a 100amp charger have on my 3000is gennie?
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Old 04-04-2016, 05:16 PM   #14
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Here is what Trojan says about charging amps...

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There are many types of chargers available today. They are usually rated by their start rate, the rate in amperes that the charger will supply at the beginning of the charge cycle. When selecting a charger, the charge rate should be between 10% and 13% of the battery’s 20-hour AH capacity. For example, a battery with a 20-hour capacity rating of 225 AH will use a charger rated between approximately 23 and 30 amps (for multiple battery charging use the AH rating of the entire bank). Chargers with lower ratings can be used but the charging time will be increased.
Am I wrong in assuming that since my total AH of all four batteries is 460, then my ideal peak amp charging would be 59.8 amps using the 13% value.

Or am I to treat that 10-13% value for EACH battery?
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Old 04-04-2016, 07:16 PM   #15
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Trojan is dealing in generalities...not in boondocking with generator based charging systems. Most would say 10% is minimal and in NORMAL plugged in situations just fine. When the idea becomes to charge as much and as fast as you can...then you run into the charging current capacity of the battery TYPE itself which is between 20 & 25% on wet cells.
I would suggest either the progressive dyn. 9280amp w/ charge wizard or the Iota DLS90 amp with IQ4 smart module would be better choices for you. I have not found a 100+ amp converter unit OR inverter unit or straight charger that I have confidence in but others may suggest alternatives. Neither of the ones I recommended will put any strain on your genny... as they will max out at around 15 amps and generally run at less.
EDIT...note that I would hardwire either one of these OR upgrade to a 20amp socket with appropriate gauge wiring for the length pf the run.
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Old 04-04-2016, 07:40 PM   #16
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One of the down sides of having a Trimetric is that it generally bursts your bubble about converters. I have a PD 70 amp unit and I might get 45 amps or so for a few minutes but then it drops back to 15 or 20...even on boost. The batteries fight back when the SOC climbs and you just cannot get that much current flowing at higher SOCs. Solar BOB recommends higher voltages which will drive more current for a while, but eventually you run a long time to get to 95%. Solar is the way to go to get the last 10% with little effort and a lot less gasoline.
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Old 04-04-2016, 07:44 PM   #17
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Hmmm.... My 60amp boondocker just got loaded on the FedEx truck from Best Converters. Which is replacing a WFCO 8955 and we haven't even used the trailer yet!
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Old 04-04-2016, 07:45 PM   #18
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One of the down sides of having a Trimetric is that it generally bursts your bubble about converters. I have a PD 70 amp unit and I might get 45 amps or so for a few minutes but then it drops back to 15 or 20...even on boost. The batteries fight back when the SOC climbs and you just cannot get that much current flowing at higher SOCs. Solar BOB recommends higher voltages which will drive more current for a while, but eventually you run a long time to get to 95%. Solar is the way to go to get the last 10% with little effort and a lot less gasoline.
I certainly see the merit of letting solar top off the batteries.
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Old 04-04-2016, 07:51 PM   #19
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Since I have no idea how much time we will spend with hook-ups compared to no hook-ups, I'm going to put the boondocker in and let it ride. Once we get some time in the trailer and I can monitor the battery monitor for usage and charging, I can then determine IF I need to charge the batteries faster.

I still need to run the 4 gauge wiring from the panel to the batteries and buy 2 more batteries.
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Old 04-04-2016, 11:37 PM   #20
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Originally Posted by camaraderie View Post
OK...well you should and could upgrade to 90+ amps charging for a 420a/h system...but lets set that aside...and use an example.

1. You can either charge a 210 a/h bank or a 420 a/h bank. Lets assume you have depleted both to 50% and want to recharge in the time you have available and lets use 2 hours of charging to keep things easy!
2. So bank #1 needs 105 amp hours put back in. And bank 1+2 needs 210 amp hours put back in.
3. Lets further assume that your charging system goes into absorbtion stage at about 75% full and float stage at around 90% full.
4. In bank #1 you will be at 75% when you get to (.75x210=157.5ah)...or once you have added 52.5 amphours back in in bulk stage....LESS than one hour with a 60 amp charger. (FAR less with a proper sized charger...except that a SINGLE 210 a/h cannot take even your 60 amps during charging ...it will likely only take a max of 52 amps of charge current (25%). So in your first hour you will charge in bulk at 52 amps...THEN shift down to lower voltage absorbtion charging for the remainder of the time as resistance builds...so maybe 1/2 those amps on average if you are lucky. You'll never get to float so lets' disregard that...So you are left with 75 or 80 amp hours added in 2 hours to a single 210ah bank.

5. Now lets return to the bank #1+2 scenario.
Here we have a need to REPLACE 210 ah's ...in a 420ah bank. The 420 ah bank will be 75% full at 315 ah's. SO..we get to add 105 amp hours at bulk rate of 60 amps due to the larger bank size...before the charges cycles to absorbtion. You can see that we'll be able to do around 1.75 hours of BULK charging at 60 amps and about .25 hours of absorbtion charging and so will add about 120amp hours to the BIG bank in the same amount of time . Again, the difference would be even more dramatic with a 90 amp charger since the big bank can use ALL of it and the little one can only use 52 amps or so in bulk phase.

Hope that clarifies.

I think you nailed it. Maybe, just Maybe at night run one and keep the other in reserve ----- But then who's going to stay up for the switch over. OK, NO ONE. SO UNLESS you are facing a special problem sounds like buy four new and run them all the time. Keep them serviced well and maybe the insure they are balanced swop them around once in a while the same way you rotate your tires to assure even wear.
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