How much converter/charger is really needed?

[Bobbo]

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?

[Bobbo]

The only REAL decision I have is whether I trust the dealer when I describe putting 2 panels in series on each side of the TT, then plugging the 2 sets into the prewired access on the TT roof. That would put the 2 sets in parallel with each other.

If I don't trust him, I will just have him put 2 more panels on the roof with all 3 plugged into the prewired access on the TT roof, putting all 3 in parallel.

I am going to do one or the other. After New Years, I am going to talk it over with them and decide which path.

[MEXICOWANDERER]

NOW THAT

Senor bobbo will work. Use the generator and charger until charge rate sags 20% for a 45 amp charger, this means when the charger drops to 36 amperes, shut off the generator then let the panels have time that's the secret giving the batteries enough time to climb into the 85% + charged range power by solar panel. When amps are low because voltage is high the realm of the solar panel becomes king.

My problem is "low" means 100 amperes at 29.6 volts. Float on my system is 20+ amperes with no loads. Champagne lifestyle Ripple Budget.

[Bobbo]

BFL13 wrote:

Bobbo wrote:
OP here. OK, I have my answer, stay with the 45 amp model. Mex and BFL can continue their duel. I don't understand most of it, but it is entertaining to follow.

That's no fun. We want to spend all your money on proposed upgrades to your rig whether you want them or not. 🙂

There could be some issue with the wiring of your PD45 to the battery bank (or something not right) since your batteries are poorly. I don't know how long you have had them though.

With the plan to keep that 45 with the new batteries, IMO check that out so the new batteries will do better if there is something not right now.

Oh, you are still going to spend my money! I am about to triple or quadruple the solar on my roof.

[BFL13]

Bobbo wrote:
OP here. OK, I have my answer, stay with the 45 amp model. Mex and BFL can continue their duel. I don't understand most of it, but it is entertaining to follow.

That's no fun. We want to spend all your money on proposed upgrades to your rig whether you want them or not. 🙂

There could be some issue with the wiring of your PD45 to the battery bank (or something not right) since your batteries are poorly. I don't know how long you have had them though.

With the plan to keep that 45 with the new batteries, IMO check that out so the new batteries will do better if there is something not right now.

[Bobbo]

OP here. OK, I have my answer, stay with the 45 amp model. Mex and BFL can continue their duel. I don't understand most of it, but it is entertaining to follow.

[BFL13]

Problem as Mex says, is having enough power supply, (Generator VA) to run the chargers at high enough amps to do a "saturation charge" on a typical RV size bank of batteries.

The ugly graph shows the diminishing returns in time saved as you go higher in amps where the time at constant amps gets shorter and shorter. Saturation would be where that curve on the left is nearly vertical and the amps at 50% is so high that there is no bulk stage.

With saturation, you start on the absorption stage curve with amps tapering from the start. But you don't save a whole lot of time compared with the shorter bulk stage you get with a somewhat lower charging rate.

Since this is all "controlled" by the size of your generator in VA, that is your first limit. Then knowing how much of a charger that will run (where most converters have a 0.7 PF) and the size of your bank in AH, you can predict your gen time to do a 50-80 or whatever you will do.

Now you have campground generator hours or if no limit there your own time limit (or gasoline supply for the gen limit) to figure whether that is enough time to get the job done. If not, you have to equip yourself with a bigger VA generator and a higher amp charger (or go with a smaller battery bank and more solar perhaps--if there is sunshine likely)

[MEXICOWANDERER]

BFL13 the only way to get an answer comparing full saturated charging and a maniac depressive converter, is to directly compare them both. I save well over an hour 50% - 100% I do not have the open ground nor money for 100 amperes @ 28 volts for panels. And my batteries are unforgiving of 40-90 constantly. Tropic blend electrolyte.

Bobbo you can save your money for a bigger bank and more generator run time. The difference in amperage and time would be negligible. Maybe save 15 minutes 50-100%.

I invite anyone anywhere to 50-100% charge (using specific gravity as the guide) a battery rated double in amp hours vs INITIAL charger output fixed voltage set at 14.8 versus 14.4 wimping down to 13.6 volts automatically.
Use a CLOCK. Use a hydrometer then tell me the difference in minutes between the two charging sources. No handheld wizards dongles or other paraphernalia. Just a simple converter like the OP uses. Versus a constant voltage charger source set at 14.8 volts.

Again! The battery cannot be more than 85 ampere hours to get a true and accurate reflection of saturated voltage regulated charging. The 400 watt Meanwell or Megawatt will do fine. Remember! Fixed voltage.

[MEXICOWANDERER]

Annotated Answer

NO!

My question was directed at BFL13 directly above my response.

[BFL13]

My point that the batteries are already shot does relate to the question of whether to go with a new converter or not at this time.

Earlier it was mentioned that maybe the OP would get a higher amp converter when he got more of a battery bank, perhaps AGMs. I thought that meant the time was here, but the OP is sticking with the batteries he has for now, so that's that.

IMO the OP would not like the care and feeding of AGMs. With Wets he can ignore the 20% rule and does not need an ammeter to be sure they are fully recharged and all that.

A pair of those Sam's or Costco 6s and keep the PD 45 (but do use the boost button on a recharge) would be the least bother. The 6s there don't cost much and will last a few years under the PD's care (as long as they are watered, which is no big hassle)

Plus the furnace could now be used!

[Bobbo]

LittleBill wrote:

Bobbo wrote:

BFL13 wrote:
Not answered by the OP is the post in another thread where he said he can't get through one night with his current battery bank with the furnace running at a decent temperature, so they freeze under many blankets. the usual rule is one night per battery and he has two.

So that must mean his batteries are already shot, and need replacing now unless he is not going off grid for a while.

Sigh. You are fixated on my batteries. I am not focusing right now on my batteries. I am focusing on whether I should go to the trouble of pulling out my 45 amp charger and replacing it with a 55 amp charger. Will the answer to that question change depending on whether the batteries are good or not? I have not answered about the batteries until now because that is not my focus. I will not answer about my batteries again after this. If and when I become concerned about my batteries, I will do something about them. I don't know about your furnace fan, but my furnace fan, running all night, tends to take a lot of battery power. With only 158 a-h of battery power, it isn't hard to run them down to 50% SOC on a very cold night with the furnace running non-stop. We have found a solution that works for us.

NinerBikes wrote:
My solution... find another heater, that doesn't require electricity and your batteries all night.... there is stuff out there that runs on propane and a cracked vent and a cracked window for proper ventilation.


Olympic Wave 3 or Wave 6.

Please note that this thread is not about discharging my batteries. This thread is not about heating my RV. This thread is only about whether I would gain enough in recharging discharged batteries to justify replacing a 45 amp charger with a 55 amp charger. The way the batteries get discharged is immaterial.

unless you need every second of generator time to get charged back up before running out of time, and your wiring supports the 55amp model.

there is nothing gained other then time, and even then it will be a small amount. you have to decide if the time savings is worth it to you, that's about all your gonna gain, in bulk mode

Thank you. The answer I was looking for has now been provided. The time savings is probably less than 1/2 hour run time over a 4 hour +/- recharge time. That is not significant to me. I will leave the 45 amp alone, and if/when I do replace the batteries, I will stay at or below 225 a-h. That won't be hard because I only have room for 2 batteries and would have trouble getting more power out of just 2 batteries.

[LittleBill]

Bobbo wrote:

BFL13 wrote:
Not answered by the OP is the post in another thread where he said he can't get through one night with his current battery bank with the furnace running at a decent temperature, so they freeze under many blankets. the usual rule is one night per battery and he has two.

So that must mean his batteries are already shot, and need replacing now unless he is not going off grid for a while.

Sigh. You are fixated on my batteries. I am not focusing right now on my batteries. I am focusing on whether I should go to the trouble of pulling out my 45 amp charger and replacing it with a 55 amp charger. Will the answer to that question change depending on whether the batteries are good or not? I have not answered about the batteries until now because that is not my focus. I will not answer about my batteries again after this. If and when I become concerned about my batteries, I will do something about them. I don't know about your furnace fan, but my furnace fan, running all night, tends to take a lot of battery power. With only 158 a-h of battery power, it isn't hard to run them down to 50% SOC on a very cold night with the furnace running non-stop. We have found a solution that works for us.

NinerBikes wrote:
My solution... find another heater, that doesn't require electricity and your batteries all night.... there is stuff out there that runs on propane and a cracked vent and a cracked window for proper ventilation.


Olympic Wave 3 or Wave 6.

Please note that this thread is not about discharging my batteries. This thread is not about heating my RV. This thread is only about whether I would gain enough in recharging discharged batteries to justify replacing a 45 amp charger with a 55 amp charger. The way the batteries get discharged is immaterial.

unless you need every second of generator time to get charged back up before running out of time, and your wiring supports the 55amp model.

there is nothing gained other then time, and even then it will be a small amount. you have to decide if the time savings is worth it to you, that's about all your gonna gain, in bulk mode

[Bobbo]

BFL13 wrote:
My ugly graph says that on a 220AH bank starting at 50%, the time difference is about 18 minutes from 50-75% and it is the same times after 75%

So you will save about 18 minutes of gen time doing a 50-80 or 50-90 (75-100 same times, so no advantage past 75% SOC.) by choosing a 60 over a 45 on 220AH.

Now, THIS is extremely useful information. Going from a 45 amp unit to a 55 amp unit saves me about 18 minutes of charge time. I consider that negligible over a 4 hour +/- runtime. Thank you.

MEXICOWANDERER wrote:
At what voltage sir? Starting with maximum absorbsion voltage of 14.8 and continuing?

I get out the 2000 watt Honda when my solar control panel shows 12.0v to 12.1v first thing in the morning. I don't think my PD4645V does 14.8v, it does 14.4v. Thank you for addressing the topic rather than worrying about heating the RV or replacing the batteries.

BFL13 wrote:
Not answered by the OP is the post in another thread where he said he can't get through one night with his current battery bank with the furnace running at a decent temperature, so they freeze under many blankets. the usual rule is one night per battery and he has two.

So that must mean his batteries are already shot, and need replacing now unless he is not going off grid for a while.

Sigh. You are fixated on my batteries. I am not focusing right now on my batteries. I am focusing on whether I should go to the trouble of pulling out my 45 amp charger and replacing it with a 55 amp charger. Will the answer to that question change depending on whether the batteries are good or not? I have not answered about the batteries until now because that is not my focus. I will not answer about my batteries again after this. If and when I become concerned about my batteries, I will do something about them. I don't know about your furnace fan, but my furnace fan, running all night, tends to take a lot of battery power. With only 158 a-h of battery power, it isn't hard to run them down to 50% SOC on a very cold night with the furnace running non-stop. We have found a solution that works for us.

NinerBikes wrote:
My solution... find another heater, that doesn't require electricity and your batteries all night.... there is stuff out there that runs on propane and a cracked vent and a cracked window for proper ventilation.


Olympic Wave 3 or Wave 6.

Please note that this thread is not about discharging my batteries. This thread is not about heating my RV. This thread is only about whether I would gain enough in recharging discharged batteries to justify replacing a 45 amp charger with a 55 amp charger. The way the batteries get discharged is immaterial.

[NinerBikes]

My solution... find another heater, that doesn't require electricity and your batteries all night.... there is stuff out there that runs on propane and a cracked vent and a cracked window for proper ventilation.


Olympic Wave 3 or Wave 6.

[BFL13]

MEXICOWANDERER wrote:
At what voltage sir? Starting with maximum absorbsion voltage of 14.8 and continuing?

Based on the charger at 14.6 and holding with no drop till batteries charged right up. However, the amps taper at a lower battery voltage than the 14.6 due to voltage drop while still at higher amps.

You only get the 14.6 at the batteries when amps have tapered right down.