converter replacement time...

[RISK]

I had a nice chat with Salty today who made a great effort to clear this up for me. Thank you sir.

I do have a confession to make though, I have really only been giving this task a small percentage of my available brain power. Once I really bite onto something I'll actually apply some aptitude to figure out and learn what it is I am after.

This thread will hopefully help someone down the line and I will see this project through to a satisfactory ending, I swear it...

Ian

[KYAvion]

I was curious what Progressive Dynamics and PowerMax (who makes the Boondocker converter I bought) would say about converter output when charging the battery. I didn’t get a reply from PowerMax, but I did get one from Progressive Dynamics. Based on what I’ve read in this thread, I suspect their answer may not be entirely correct. Nonetheless, here’s what I got...

Question:
I am interested to know the maximum amp output of your converters when charging the batteries? That is, what is the maximum number of amps that your converters will push to a battery when charging?

Answer:
The converter can output the full amperage it is rated to the batteries.

This is limited by other 12 volt items in use.
The length and size of the wire from charger to battery.
The batteries themselves will only accept a certain charge at a given voltage depending on depth of discharge.

Follow-up Question:
Thank you. So just to clarify, under some conditions a pair of batteries might receive 65 amps of output from a 65 amp converter, 90 amps of output from a 90 amp converter, etc?

Follow-Up Answer:
Yes.

[Salty]

hMMM...
Damn good thing I'm not charging my batteries off my converter then.
However....
Scenario.
You've been boon docking for a month. You finally run out of 12V power - you can't even run your fridge anymore 'cause there no 12VDC to run the control board.
Lets say you are charging your batteries with that glorious 90 amp converter and they are completely discharged. damn near dead . so of course you begin to charge them and they're pulling that full 90 amps. Then you turn on a 30 watt light in the kitchen......
How would the power supply know to back down the charge current to supply power to the light? What circuit would do that? I'd be interested in those schematics.

[RISK]

Well I finally got around to completing my converter replacement. I replaced the original Progressive Dynamics converter with a Mighty Mini PD4045 all in one unit.

I still have to complete the install by mounting the unit after I clean up the rats nest (figuritivly, all the wires) and screw the unit to the cabinet insert I made. The hardest part was getting the old one out, they must have installed it then finished building the cabinet around it because there was no way to access the rear of the unit and I had to cut a bunch of wires just remove it.

Really surprised how heavy it was, I’m guessing 30+ lbs.
The new unit weighs about 5lbs.

The best part is that the fridge started working again!

About $200 total and maybe 6hrs of my time.

Pics to come...

Ian

[Salty]

Congrats Ian. best of luck tidying up the wires. Always tedious, but worth it.

Something I wish to acknowledge is something KYAvion posted previously about my converter - according to the mfr, the converter will allow the battery to pull full available current - in my case, 90 amps. Since that would certainly burn up an 8 gauge wire, it wouldn't be wise to use the charging circuit.
In my particular case, I'm not using this function and it was never the plan to use this function.

[Kep]

Well that was an interesting read.

Using a wire size calculator ( https://www.wirebarn.com/Wire-Calculator-_ep_41.html ) our # 8 awg charge wire will carry 60 amps at 7 feet in length. At 45 amps it will go just over 9.5 feet.

The real issue is the connections, they must be clean and tight. The next issue is fuse size. Seems Avion used two 20 amp glass fuses for the protection. You could upgrade to two 30 amp fuses but I think the fuses could get hot if the connections are not clean and tight.

The next issue is the inline fuse for the batteries is 40 amps. you could replace it with a Maixi fuse and should be okay.

https://www.amazon.com/Inline-Maxi-Fuse ... way&sr=8-5

https://www.amazon.com/Bussmann-MAX60-M ... Caps%2C787

The decision to go to 60 amps ultimately is not a good one as our battery banks do not need nor should they get fast charged. They should get equalized every so often though but that is a volts thing not amps. The 45 amp unit seems high enough to top off the batteries with all accessories on so a bigger unit is not needed. You should be able to equalize them at that amperage too with a modern charger.

Glad the original poster decided to stick with the lower output convertor. A low rate of charge will in fact extend the life of your batteries. The modern chargers have 4 modes and as such are far better at caring for your batteries. I will just throw this out there... A pair of 6v golf cart batteries is far better for boondocking and battery life than a pair of 12v batteries.

Here is an informative read about batteries and charging.
http://popupbackpacker.com/state-of-cha ... tery-bank/

.

[Salty]

nice read. Would have been nice to address LiFePo4 batteries. Different ball game.

[Kep]

nice read. Would have been nice to address LiFePo4 batteries. Different ball game.

Yes there are many improved battery technologies out there but the nickel iron batteries (Ni-Fe) or Edison batteries are still my favorite battery technology. However when I designed my Solar system the Inverters, Charge controllers and chargers were not designed to take advantage of the Edison batteries virtues. Being more expensive it would be a waste to buy them back then. Now however the Edison battery is being supported more and more.

Advantages...
https://www.electrical4u.com/nickel-iro ... -batteries

Negatives... Although it is now being supported more and more.
https://www.rpc.com.au/solar-news/161/d ... eries.html

One source in the US to get them...
https://ironedison.com/nickel-iron-ni-fe-battery

If I was to buy them I would get them here...
I would likely try to get a group together group to buy them as the minimum order quantity is a bit steep.
https://www.alibaba.com/trade/search?fs ... Fe+battery

[Johnatron]

This post update couldn’t have come at a better time... I’m about to replace my converter with the PD4560 on my ‘81 34V. I apologize for my lack of understanding, but will this charge at 60amps? I won’t be using the full 60amps in my trailer for fixtures and etc. The power center is in the rear, so I need to run 30’ to the batteries. According to the wire run chart you linked, I need 2gauge(assuming I filled in the chart correctly). I thought the 8gauge wire was sufficient enough, but now I’m not so sure. Can you please advise?

[Kep]

You are correct and yes it is accurate.

If you use the 10% in the drop down box labeled "percent loss" you can use #8. It may hinder your ability to top off the batteries but only by a few percent. It should be okay but monitor your wire and connections to be sure their not getting hot. I would clean and secure any connections before you do this. You also can check and verify at each end of the #8 wire with DVOM to see just how much drop you are getting. I don't think it will be much though. You really don't care if every amp is getting to the battery you just want to be sure the voltage drop is negligible or you may not fully top off your batteries.