I have a pair of NAPA 9824M Marine/RV batteries with a 20 hr rating of 79AH each, wired in parallel.Is there, really, any advantage in going from a 45 amp (PD4645V) converter/charger to a 55 amp (PD4655V) converter/charger? I know that bigger is ALWAYS better, and the cost is not much more, but, really, is there a real advantage?If not, how many AH do you need to make the jump from 45 amps to 55 amps useful?

You could charge, theoretically, those 2 drained to 50% in under 2 hours...bulk. I see no advantage.

Once the battery charging enters the absorption phase they won't accept big numbers. Charge with solar and you can "forget" all this anyway.

Bigger is not always better, bigger could be less efficient and waste more power. Converters/Inverters are not very efficient in the first place that's why they have those big fins to bleed off the waste heat.

Do you expect a fast charge from a generator? For the few $$ more get the 55.Even for a fast charge into a wet cell battery 20 amps per battery is fine.Mostly plugged in? 35 amp is more than enough.Usually the house load is under 5 amps so forget that unless you have multiple tank heaters etc camped well below freezing.

If you have a 1000w generator that runs the 45 amper, that gen will not be able to run the 55 amper. If you have a 2000w gen you are ok going to the 55.On 158 AH starting at 50% SOC, there will be only a few minutes difference in charging time to 80%. If you decide to get a higher AH battery bank such as a pair of 6s, now the 55 amper would be better (although a 75 amper would be just right.)If you don't do much generator charging but are on shore power or solar mostly, then IMO not worth changing to a 55.

How much converter/charger is really needed? | Good Sam Community

54 Replies

time2roll
Nomad
Nov 08, 2018
Do you expect a fast charge from a generator? For the few $$ more get the 55.
Even for a fast charge into a wet cell battery 20 amps per battery is fine.

Mostly plugged in? 35 amp is more than enough.

Usually the house load is under 5 amps so forget that unless you have multiple tank heaters etc camped well below freezing.
agesilaus
Explorer III
Nov 08, 2018
Bigger is not always better, bigger could be less efficient and waste more power. Converters/Inverters are not very efficient in the first place that's why they have those big fins to bleed off the waste heat.
Lwiddis
Explorer II
Nov 08, 2018
Once the battery charging enters the absorption phase they won't accept big numbers. Charge with solar and you can "forget" all this anyway.
2oldman
Explorer II
Nov 08, 2018
You could charge, theoretically, those 2 drained to 50% in under 2 hours...bulk. I see no advantage.

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How much converter/charger is really needed?

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