Inverter/charger sizing

[Perdiem]

2 questions: My Xantrex 3012 inverter charger has packed it in. Apparently it needs a new main board for ~$800. My previous inverter had a 100 amp
charger and would start charging at 105 amps and then slowly decrease as the battery got charged. The 3012 had a 150 amp charger and it would start charging at 120 amps but be below 100 amps in 10 minutes or so.

Will a 150 amp charger put more into the battery than a 100 amp charger even when both are charging at less than a 100 amps? For example will the 150 amp unit be putting in 75 amps at the same time the 100 amp one would be charging say 60 amps? If so, I'll go for the bigger charger - if not, it seems like a waste of money. On the inverter side, 1000 watts would be more than sufficient.

Also, I know that Xantrex doesn't have a very good name around here and I was going to change to either Victron or Magnum. reading the specs on the relatively new Xantrex XC Pro it weighs less than 19 lbs. I'm guessing they found a way to do some things in there electronically rather than with big heavy chunks of metal.

My six decade + old body likes the sound of that!

https://xantrex.com/wp-content/uploa..._Datasheet.pdf

[Jammer]

Depends on your batteries.


Lead acid batteries accept less charge current as they get older because internal series resistance goes up and the charger's voltage limit gets hit sooner.


Do you have lead acid batteries? How big is the bank? How old? How deeply discharged are your batteries when you charge them?


IMO it doesn't matter much unless you're using an auxiliary generator as a power source. If you're plugged in at the dock you're probably there overnight, so what's the rush?

[Perdiem]

- Do you have lead acid batteries? Yes
- How big is the bank? How old? 8 golf carts on their 10th season. Getting replaced with same this winter.
- How deeply discharged are your batteries when you charge them? They never get below 12.3 volts so ~50%?
- It doesn't matter much unless you're using an auxiliary generator. Yes, I am trying to limit the gen run time. Added 300 watts of solar last year so that really helps.

Thank you for your reply.

[Jammer]

800 amp hour bank then. 10 years is a lot, replacing them will improve charging performance with any charger.


Think about replacing the cables too, unless you're sure they're in good shape. At least check them with an IR thermometer while charging, hot spots are trouble



With new batteries at 50% a 150 amp charger, should put 150 amps into the batteries, until they get to like 90% charge or so.


Victron and Magnum make good products and should deliver their rated output.

[Stu Jackson]

Originally Posted by Perdiem

2 questions: My Xantrex 3012 inverter charger has packed it in. Apparently it needs a new main board for ~$800. My previous inverter had a 100 amp
charger and would start charging at 105 amps and then slowly decrease as the battery got charged. The 3012 had a 150 amp charger and it would start charging at 120 amps but be below 100 amps in 10 minutes or so.

Will a 150 amp charger put more into the battery than a 100 amp charger even when both are charging at less than a 100 amps? For example will the 150 amp unit be putting in 75 amps at the same time the 100 amp one would be charging say 60 amps? If so, I'll go for the bigger charger - if not, it seems like a waste of money. On the inverter side, 1000 watts would be more than sufficient.


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Para 1 describes how batteries get charged. I recommend you do some reading on that subject.


Para 2 - No. See Para 1 - the "acceptance" of the battery bank determines how much amperage it can absorb. An 800 ah bank at 50% will accept more than the same bank at 80%. As charging continues the amperage drops off once the voltage setpoint is reached. You can have a 1,000,000A charger, but you're going to get the same results as a charger normally sized.



If these terms are not familiar to you, they should be and constitute Basic Battery Charging 101. Any quality charger's manual will explain it to you. So will a good boat electrical systems book like Charlie Wing's.


Maine Sail's marinehowto.com explains how charging works too. Have at it.