45 amp vs 60 amp converter

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RamblingJohn

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Sep 3, 2018
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Whidbey Island, WA
My rig has a 45 amp old Todd Engineering converter that is not working. It may be a fuse or something but I can't store the rig at home and I just want to replace the converter and know I have modern technology. I purchased a 45 amp PD 9100 (without the Wizard). I didn't know about the wizard when I bought it. I plan on getting that as well.

I have two brand new car batteries (don't know the brand, etc. as I can't look at them now) that are 12V, hooked up in parallel (installed by the used car dealer). Is the converter I just bought sufficient? Does it limit me in some way? I've looked at amperage averages for some things and it seems like 45 amp will be sufficient but I don't want to make this purchase twice. I may upgrade the sound system at some point and I plan on replacing the two CRTs with LCD displays.

Also, my batteries got down to about 3V because I thought they were being charged from shore power and I discovered they only are charging when the engine is running (haven't checked with the generator yet). How bad is that?

Any thoughts welcome. I haven't opened the box yet so I could still return if I decide to go with a bigger converter. How do you like the wizard feature? I'm bummed I didn't know about it when I made the purchase.
 
Is the converter sufficent?  YES. Beyond a doubt. More in a bit
Are those the best batteries: NO you could have done better for less

Best battery for you is a pair of GC-2 Golf Car batteries in SERIES. this make one big (220 amp hour) 12 volt battery.. and being a true DEEP CYCLE you van use half of that over a 20 hour period. What you have now is likely aroung 200 amp hour and you can use 40-50 of them over 20 hours safely.

THe faster you draw 'em down the less you an use.

Now to the inverter

FOr all but LIFELINE AGM and possibly a few other AGM"s the MAXIMUM recommended rate is about 30% of C'20 or in your case 60 amps.

Trojan suggests 10 percent or 20 amps

Your 45 is a nice comprimise

What difference does it make

Charging (once you plug the wizard in) is in 3+1 stages
BULK is as fast as it can push power into the battery.. THis can (in theory) take a 50% discharged DEEP CYCLE to 90% in about 2 hours at the Maimum recommended rate (Source on that is Xantrex)

At 2/3 that add another hour

THen you go to Absorption (2-4 horus more) than float

The wizard, after 20 hours at float, goes to equalization for 15 mintues. as I recall.
 
Ok, John.. so based on your response my converter is a good balance to charge better batteries in the future. I didn't have a choice with the batteries.. they are what the car dealer provided. I guess I could have negotiated with them to get something else but I didn't know about the 6-volt batteries at the time. I figure I'll use them until they are bad and then get something more appropriate.
 
A 45 amp converter has a total capability to produce 45 amps  of 12v power.  That supplies your RV's 12v needs as well as charging the batteries.  If you are using 10 amps to power the RVs internal systems, then you have only 35 amps left to charge batteries.  It doesn't run your tvs (they are 120v) or air conditioners, so no worries there.  The only significant 12v power draw in your RV is lighting - most everything else is very small amounts, so with only two batteries, 45A should be sufficient for your needs. 

As for battery choices, please read my article on RV Battery selection in the forum Library at Choosing an RV battery
 
RamblingJohn said:
I have two brand new car batteries (don't know the brand, etc. as I can't look at them now) that are 12V, hooked up in parallel (installed by the used car dealer). Is the converter I just bought sufficient? Does it limit me in some way? I've looked at amperage averages for some things and it seems like 45 amp will be sufficient but I don't want to make this purchase twice. I may upgrade the sound system at some point and I plan on replacing the two CRTs with LCD displays.

Also, my batteries got down to about 3V because I thought they were being charged from shore power and I discovered they only are charging when the engine is running (haven't checked with the generator yet). How bad is that?
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If they really are car batteries instead of deep cycle batteries, they're pretty much worthless.  Car batteries are made to deliver brief bursts of power while deep cycle batteries are made to deliver long, gradual power.  Neither type will last long if used for the opposite function.

They may be Marine batteries, which are a compromise between the two types and sort of work OK in either service.

Letting the batteries deep discharge to 3 volts didn't do them any favors, though.  Especially if they were left in that condition for any length of time.  I'd plan on replacing them once you get the converter straightened out.

As noted above, 6 volt golf cart batteries give the most bang for the buck.  AGM batteries are also good  but they are more pricy.  Six volt batteries are about an inch or so taller than their 12 volt brethren, so make sure you have enough clearance.

The generator doesn't charge the batteries, it merely provides 120 VAC to the converter which in turn charges them.  If your converter is dead on shore power, it will also be dead on generator power.
 
Thanks for your responses, guys! I'm learning a lot.  :))

Ok, so I got the rig for the weekend and I've done some troubleshooting. It appears the converter is not bad after all, it was just hard to see the green light in the sun and the refrigerator was causing the the GFCI in the garage to trip. I checked the batteries when I got home and they were at 12.35V. I don't see how that's possible as I only drove about 40 minutes total but that's what they read. I also am reading the same voltage with the converter going but it's around 14V when the alternator is running.

I checked the batteries and they have a sticker that reads D24M-500. I googled that and it looks like maybe they are generic marine batteries?

Anyway, like I said the refrigerator was causing the GFCI to trip and I think I narrowed down the issue to the AV heater. The left lead reads 1.9MΩ with the metal case of the heater and the right reads 2.2MΩ. The manual says if any reading observed, replace AC heater (document attached). I covered the PC board back up and applied power and sure enough, the GFCI did not trip. I'm leaving the fridge unplugged until I fix it.

Has anyone replaced one of these elements? I'm not sure how to get it loose. It looks like the chimney can pop open and pull the heater out but I don't want to force anything if there's a better way. I attached the best pic I could get of the heater element going into the chimney.

 

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The heater element is just a metal rod resting in a metal sheath or shield. It just lifts out, but quite likely is rusted in place somewhat.  If some "persuasion" doesn't loosen it, apply some penetrating oil and wait a day. Or just start with the penetrating oil first.  Try not to get excessive oil around, cause the heat from the boiler area (about 350 degrees) is going to have to burn it off when you restart it. 

Yeah, there should be infinite resistance to ground. Could be as simple as a stray strand of wire touch a rusty spot (high resistance ground), but most fridge heater elements are not real expensive. Might be just as well to replace  rather than fiddle with it.

The battery voltages you are reading is from the charge source.  The converter is probably applying 13.3-13.6v to the battery, but the battery charge is so low that it drags the voltage down to 12.3 or so.  It should drop when the charger is shut off, but often a "surface charge" remains that makes it look better than it is. Put a small load on it for 2-3 minutes and the voltage will probbaly drop to 11 or so.  It's gonna take 24+ hours to get it back to full charge, assuming it ever gets there.

D24-500 suggests it is a size 24 battery case with a 500 CCA rating. Could be a marine type or could be a generic car start battery. There isn't a heck of a lot of difference in them anyway.

 
The part number was D24M-500. The M makes me think it's a marine battery. They have regular battery posts and wingnut connectors to the side. Car batteries don't look like that, right?
 

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Gary RV_Wizard said:
The battery voltages you are reading is from the charge source.  The converter is probably applying 13.3-13.6v to the battery, but the battery charge is so low that it drags the voltage down to 12.3 or so.  It should drop when the charger is shut off, but often a "surface charge" remains that makes it look better than it is. Put a small load on it for 2-3 minutes and the voltage will probably drop to 11 or so.  It's gonna take 24+ hours to get it back to full charge, assuming it ever gets there.
Click to expand...

I checked the output from the converter and it's applying 12.09V. It should be applying more than that if it were working properly, right? The batteries are reading 12.10V. I have a new converter to swap in but I'm just wondering if it's really faulty or if it's tapering off the charge because the batteries are fully charged. It's a 55A Todd Engineering power supply. The manual says it should be putting out 13.2V. I installed the jumper and there was no change but the manual says it will do the 14.2 charge only if it senses the batteries are under 12.6V, which they're not.
 
I'd say your converter is toast.  It should read 13.2 volts without anything connected to it.

At 12.1 volts it's essentially useless, as the battery voltage is higher than that.
 
RamblingJohn:

That 99 Holiday Rambler looks like a nice unit! But with regard to a replacement converter, it looks like you may have buyer's remorse already. ;D

A lot may depend on what you foresee for the future. What sort of RVing are you interested in?  If you may be interested in several days at a time with no power connection, then you may want more than just two batteries, and you may want more than just a 45 amp converter. Buy with the future in mind.  Our 60 amp Progressive Dynamics converter was overkill for the twin battery setup on our travel trailer. However, now, with six batteries, it is only just adequate.

By all means, if you choose Progressive Dynamics, then get one with the charge wizard.
 
12.09v is definitely inadequate for charging, but may we ask how you checked that?  Batteries disconnected and the voltmeter across the leads from the converter/charger?

At 19 years of age, it's hardly surprising that the Todd unit has died, and a new one will be superior in technology anyway. Do add the Charge Wizard, though, or maybe exchange the 9145 for a 9260.  You don't need more amps, but they won't hurt either.
 
Frank B said:
A lot may depend on what you foresee for the future. What sort of RVing are you interested in?
Click to expand...


Right now, we just want to have a safe cross-country trip. At some point, I'm sure I'll upgrade the batteries, etc., but for now I'm just trying to use what I got and not spend too much money. We've already spent hundreds more since buying the RV just to take the first trip! This converter will work fine for now and if we end up upgrading, maybe I'll sell it or something. I take back about what I said about not wanting to buy something twice! That's in the rearview mirror now.

Gary RV_Wizard said:
12.09v is definitely inadequate for charging, but may we ask how you checked that?  Batteries disconnected and the voltmeter across the leads from the converter/charger?
Click to expand...

I didn't disconnect the batteries as they are heavy and really hard to get out but I checked the converter output from the back of the unit and the battery voltage from the battery posts (not the wingnutted wires). I already planned on replacing the converter anyway, I was just trying to decide whether to keep the Todd unit as a backup. As of now, I'm thinking no.
 
You don't have to physically remove the batteries to test the Todd - just disconnect the wires from either the battery posts or the converter end. Measure the voltage on the wires without having the battery in the circuit.  The thing is, a battery that is internally shorted will cause the converter/charger to look bad. 
 
Gary RV_Wizard said:
You don't have to physically remove the batteries to test the Todd - just disconnect the wires from either the battery posts or the converter end. Measure the voltage on the wires without having the battery in the circuit.  The thing is, a battery that is internally shorted will cause the converter/charger to look bad.
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I've got the Todd unit replaced so I can plug it in by itself and bench test it. The Progressive Industries converter is in. It's reading 12.95V output from the converter. I tested the current output from the converter and it is zero amps. I'm afraid one of the batteries has a bad cell as the brand new unit should be outputting 13.6V. I pulled them and one battery reads 12.33V and the other 12.48V. The converter with no batteries attached is putting out 13.4V. I'll take them to an auto parts store and have them check them.
 
if it's a flooded cell battery, you can remove the cell caps and use a battery hydrometer to check the cells. A bad cell will usually show as a poor reading on the hydrometer.  Charge the batteries as close as they come to "full" and then test. Battery hydrometers are cheap, about $6 at O'Reilly's of Advance or even Walmart.

A free load test at the auto store is a better check, but you have to transport the batteries.
 
Gary RV_Wizard said:
if it's a flooded cell battery, you can remove the cell caps and use a battery hydrometer to check the cells. A bad cell will usually show as a poor reading on the hydrometer.  Charge the batteries as close as they come to "full" and then test. Battery hydrometers are cheap, about $6 at O'Reilly's of Advance or even Walmart.

A free load test at the auto store is a better check, but you have to transport the batteries.
Click to expand...

I have a battery charger at the house. I'll report back once I've charged them and had them tested. We want to do a dry run this weekend at a nearby campsite to make sure we know how everything works and clean the water tanks out. Can't wait!
 
It sounds like this may be a "new to you" unit. If it is, then a Whole New World awaits you! Especially if you like quiet out-of-the-way places, then Boondock camping can be wonderfully enjoyable! Do let us know how it works out, and all the best to you!
 
Frank B said:
It sounds like this may be a "new to you" unit. If it is, then a Whole New World awaits you! Especially if you like quiet out-of-the-way places, then Boondock camping can be wonderfully enjoyable! Do let us know how it works out, and all the best to you!
Click to expand...

Turns out my external battery can actually tell me if a cell is bad. Sure enough, one of the batteries is bad. I would think there should still be some DC current running since the batteries are wired in parallel though. I may just buy some new batteries and know I'm good. The RV was sold as-is with supposedly new batteries so I doubt the dealer will give me another one.. I'm going to ask though.
 
The bad battery will drain the good one. Probably a good idea to replace both, as you want them well matched as to type and age.  If you have the room, consider using 4 golf cart batteries. Best bang for the buck in RV use.  GC-2 batteries are a bit taller, and a pair of them may be longer. I don't remember anymore. Costco is a good source for something middle of the road.
 
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