Magnetek TU-775-2 Converter Charger failed

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Magnetek TU-775-2 Converter Charger failed

January 04, 2023, 10:50:02 pm

After the recent Texas freeze, I went to check the coach and it is dead. There is no 12V power at all. Out of three 8D batteries, two are measured at 5 Volt, one at 11 volt. Apparently battery is dead. Bought a new 8D batter (ouch), hooked up and coach is back to life. But I noticed that the battery is not being charged. The Magnetek converter charger is pretty warm. It emits very loud buzzy sound, but the voltage on batter terminal is still around 12.4V same voltage as no shore power connected. It is probably dead after almost 30 years in service. The three 8D batteries probably never got fully charged.

Searching the forum, it seems like the Progressive Dynamics PD9270V is a nice upgrade, single stage to four stages.
Amazon.com: Progressive Dynamics PD9270V Inteli-Power 9200 Series Converter/C...

But at $349 that is little bit too expensive.

Other popular choice is the PowerMax brand.
Amazon.com: Powermax PM4 60A 110V AC to 12V DC 60 Amp Power Converter with...

At $175, it is more affordable.

Is it a drop-in replacement?
The original one is rated at 75AMP, can I use the 60AMP or the 55AMP version?

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Re: Magnetek TU-775-2 Converter Charger failed

Reply #1 – January 04, 2023, 11:12:26 pm

I had a PowerMax fail. I was never happy with the float voltage as it was never stable. The Progressive Dynamics I replaced it with has been outstanding with a very stable float voltage for the last couple of years. Read the reviews on Amazon. I replaced with a 45 amp as I never charge the batteries with the coverter/charger as we have solar, only dry camp and amost never at an RV park or hooked up to shore power except at home. The Progressive Dynamics also has a reconditioning cycle every 20 hours to keep sulfation from occuring. PD advertises a float voltage of 13.2V. It is always within 0.1 volts of what they advertised. +++

You may be able to bring the old batteries back to life with a battery reconditioner device that pulses higher voltage/frequency into the batteries. It can take a couple of weeks to get rid of all the sulfation. A couple of examples on YouTube videos.

Pierce

Re: Magnetek TU-775-2 Converter Charger failed

Reply #2 – January 05, 2023, 12:12:07 am

Thanks for the info.

Bought this one instead

Progressive Dynamics PD9245CV Inteli-Power 9200 Series Converter/Charger with Charge Wizard - 45 Amp Amazon.com: Progressive Dynamics PD9245CV Inteli-Power 9200 Series Converter/...

Is this the one you mentioned above?

I don't use the coach much. Most of time it stays at the storage facility plugged into 15amp.
Would 45 amp be enough to maintain 3 8D wet cell batteries?

Quote from: Pierce & Gaylie Stewart – January 04, 2023, 11:12:26 pm

I had a PowerMax fail. I was never happy with the float voltage as it was never stable. The Progressive Dynamics I replaced it with has been outstanding with a very stable float voltage for the last couple of years. Read the reviews on Amazon. I replaced with a 45 amp as I never charge the batteries with the coverter/charger as we have solar, only dry camp and amost never at an RV park or hooked up to shore power except at home. The Progressive Dynamics also has a reconditioning cycle every 20 hours to keep sulfation from occuring. PD advertises a float voltage of 13.2V. It is always within 0.1 volts of what they advertised. +++

You may be able to bring the old batteries back to life with a battery reconditioner device that pulses higher voltage/frequency into the batteries. It can take a couple of weeks to get rid of all the sulfation. A couple of examples on YouTube videos.

Pierce

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Re: Magnetek TU-775-2 Converter Charger failed

Reply #3 – January 05, 2023, 12:21:08 am

In general, the lower the current capacity, the longer it will take to charge a "drained" battery. You could charge a battery with a 5 amp charger...if you have a few days.

If you tend to use your batteries a lot between charges (this really assumes you have no or minimal solar) and you want to be able to recover them quickly, the more current the charger can produce, the quicker it will recharge them...during the bulk charge phase, which is where you get most of your charge back.
Also, when plugged in, your converter/charger is running all of your 12-volt devices (probably lights, A/C controls, refer controls, Inverter if you have one, etc.). If the converter cannot keep up with your 12-volt power demands and still have plenty of current left to charge the battery, it will take longer to charge them.

As a rule, manufacturers don't put converter/chargers that are way overpowered in their units as it would be a "waste of money" with no great benifit...so you probably want to shoot for as close to your original units current capacity as possible. That said, some leeway can be given if you have upgraded to LED lighting and/or have an inverter and upgraded some electronics (like picture tube TVs to LCD); in which case 60 amps is probably fine. Also, if you do not use your batteries as heavily (not so much boondocking), you don't need as much recharge "umph" as they will not get very discharged.

I cannot speak to Powermax, but I have heard multiple people suggest the Progressive Dynamics as a good choice; including the AZ Expert on YouTube.

Re: Magnetek TU-775-2 Converter Charger failed

Reply #4 – January 05, 2023, 12:24:02 am

In answer to your question about a 45 converter/charger being able to maintain your batteries, the answer is yes. Maintaining batteries takes very little power and, for your 3 batts, a 5 amp, maybe less, would do that.

If you always plug in when camping, you're probably fine with the 45 amp unit. EDIT: but, it depends on how much 12-volt power your coach uses...you have to, at least, keep up with that and have some power left to maintain/charge the batts.

Re: Magnetek TU-775-2 Converter Charger failed

Reply #5 – January 05, 2023, 10:08:34 am

Quote from: Running Odometer – January 04, 2023, 10:50:02 pm

After the recent Texas freeze, I went to check the coach and it is dead. The Magnetek converter charger is pretty warm. It emits very loud buzzy sound, but the voltage on batter terminal is still around 12.4V same voltage as no shore power connected.

Searching the forum, it seems like the Progressive Dynamics PD9270V is a nice upgrade, single stage to four stages.
Amazon.com: Progressive Dynamics PD9270V Inteli-Power 9200 Series Converter/C...

But at $349 that is little bit too expensive.

Other popular choice is the PowerMax brand.
Amazon.com: Powermax PM4 60A 110V AC to 12V DC 60 Amp Power Converter with...

At $175, it is more affordable.

Is it a drop-in replacement?
The original one is rated at 75AMP, can I use the 60AMP or the 55AMP version?

Your Magnatek was never intended to be a battery charger and is working as it should.

Our U225 came with a PD9160, and I added the remote charge wizard to have a 3-stage charger, then drowned 9160 in water and replaced it with two PD9260s mounted above the basement floor. Just in case another pipe lets loose.

An Interstate BCI 8D AGM battery is $300, and my U225 needs two, and if we go off grid for any length of time three. I don't think $300 dollars for a PD9260* is expensive when you remember that the computer controlled voltages will make your new battery last as long as possible.

FWIW I installed the second PD9260 to maintain the chassis battery after I came too close twice too many times to ruining the chassis battery trying to keep it up with my dumb charger AND I like the belt and suspenders aspect of having a power converter than can run the entire chassis electric system on the road if the engine driven alternator goes south for a vacation.

*An 8D lead acid battery is about 300 amp hours capacity and an industry standard charging rate is 0.3(capacity) in this case 90A, and I can live with 60A initial rate of charge.

PD9260CV Inteli-Power 9200 Series Converter/Charger with Charge Wizard - 60...

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Re: Magnetek TU-775-2 Converter Charger failed

Reply #6 – January 05, 2023, 11:52:10 am

Here is the exact charger/converter I installed: Progressive Dynamics PD9245CV Inteli-Power 9200 Series Converter/Charger with Charge Wizard - 45 Amp $255 delivered at that time. 45 amps is many times more than needed to run your coach. Old Toolmaker makes an excellent point in his third paragraph, the $300 is cheap as it extends the life of the expensive batteries.

I use my Pierce patented coiled cord from lighter plug to lighter plug to keep both banks as close to 13.2V as possible as seen in my attached photo.

I also installed 12V rotary cutoff switches for the Progressive Dynamics charger as well as my 3 inverters. Makes it safe when you do the installation of the equipment. Naturally, the house batteries should be disconnected during the installation but some will ignore this. One mistake, especially reversing the 12V cables ruins your converter as they are not protected against reverse polarity. Here is the exact switch: Amazon.com: Ampper Battery Switch, 12-48 V Battery Power Cut Master Switch...

You may also need copper fittings to crimp on the end of the 12V cables as they are too big to go straight into the converter. I purchased the nifty 16 ton hydraulic crimper off ebay for about $50. It makes picture perfect crimps in almost any size copper lugs. Buy lugs at auto parts store, Tractor Supply, welding shop, etc. Copper reducing pin: Cable Terminal Lugs to copper pin - Bing images

Pierce

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Re: Magnetek TU-775-2 Converter Charger failed

Reply #7 – January 05, 2023, 01:47:04 pm

Quote from: Pierce & Gaylie Stewart – January 05, 2023, 11:52:10 am

Here is the exact charger/converter I installed: Progressive Dynamics PD9245CV Inteli-Power 9200 Series Converter/Charger with Charge Wizard - 45 Amp $255 delivered at that time. 45 amps is many times more than needed to run your coach.

Naturally, the house batteries should be disconnected during the installation but some will ignore this. One mistake, especially reversing the 12V cables ruins your converter as they are not protected against reverse polarity.

Pierce

According to the Progressive Dynamics literature, the automotive style user replaceable flat fuse will blow first if the battery cables are connected incorrectly. But I'm too old to do that to see what happens.

Re: Magnetek TU-775-2 Converter Charger failed

Reply #8 – January 05, 2023, 06:51:53 pm

Me too!

P

Re: Magnetek TU-775-2 Converter Charger failed

Reply #9 – January 06, 2023, 11:43:15 pm

I was reading past posts about batteries on the forum. For U300 It seems like the engine start battery is not being charged when connected to shore power. Only if the boost switch is turned on. But @Pierce & Gaylie Stewart made it very clear that it is not a good idea to leave the boost switch on.

I think there are two options on the forum
1. use a small gauge wire to connect the both lugs of the boost solenoid when in storage. In this way there will be a physical connection. When house battery is charged via shore power, it will also charge the start battery too.

2 buy a small battery charger maintainer to charge the start battery
like this one
Amazon.com: NOCO GENIUS2D, 2A Direct-Mount Smart Onboard Car Battery...

Option 1 is certainly easier(cheaper), but what if I forget to take the wire off? or am I reading it wrong.

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Re: Magnetek TU-775-2 Converter Charger failed

Reply #10 – January 07, 2023, 12:40:56 am

While my jumper from lighter plug receptical to lighter plug receptical works great on GVs with a lighter outlet on the dash and another on the HWH panel, all Foretfravels don't have the two plugs. The most important advantage to my arrangement is that the lighter plugs are both fused, the jumper is also fused and it can be quickly removed/unpluged. While the lighter receptical has a large capacity fuse, the jumper's fuse at each end is only 5 amps so there is no possibility of fire.

The jumper goes hand in hand with the twin voltmeters so a quick glance tells the voltage on both banks so it's easy to tell what of about 100 reasons the voltages are.

If you want to spend a little more time on charging both banks from one charger/converter, you could install a latching relay close to where the isolator and boost solenoid are. Latching relays don't use any juice once activated unlike the boost solenoid and only need a momentary voltage to go in operation much like the water pump latching relay. The extra wires all Foretravels have is close to where they would be needed at the electrical panel and the coach dash where a momentary switch could be installed.

Here is an Amazon page with a Cole-Hersee latching solenoid along with a couple of momentary push button switches. It only take a quick push of the switch to latch and another quick push to unlatch. All from the drivers seat or anywhere else you would like. The voltmeters are good to check to see if both banks are being equalized.

On your U300, the relay to operate the water pump is just a VW Bug latching relay used for the change from high beam to low beam headlights.

But the best solution is to eliminate the boost solenoid as fitted and replace it with a solid state latching relay like this one: Amazon.com: Stinger SGP32 200 AMP Battery Relay Isolator and Relay : Automotive The only change needed would be to remove the boost switch on the instrument panel and replace it with a momentary switch. This kind of relay has no coil heating (on mechanical or magnetic) so no draw itself so it can charge both banks when at home, act as a boost solenoid and basically, get rid of the isolator. No one is installing isolators today in new coaches. Other brands are available like BlueSeas, etc.

Pierce

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Re: Magnetek TU-775-2 Converter Charger failed

Reply #11 – January 07, 2023, 08:15:29 am

Quote from: Running Odometer – January 06, 2023, 11:43:15 pm

Option 1 is certainly easier(cheaper), but what if I forget to take the wire off? or am I reading it wrong.

I got his one. When the batteries are unbalanced enough, and you hit the starter, the wire turns into a piece of fried spaghetti with concomitant odor release.

Re: Magnetek TU-775-2 Converter Charger failed

Reply #12 – January 07, 2023, 09:35:13 am

I would just like to add this one piece of advice: whatever you install make sure you have a back up for charging your batteries. The 12 volt system is the life of the coach.

I have a 1991 too and my converter is long gone, replace with an inverter/charger. But I also have 4 stage charger installed too, incase the inverter/charger goes out (just a matter of time, right?). I'm typically at a park these days and if that inverter/charger goes out I don't want it to be a scramble to do an emergency fix while cutting into my vacation time. All I have to do is plug in my backup 4 stage charger. I don't have solar and running the engine while there is 120VAC right there is crazy. Even if I'm boondocking and the inverter charger goes out, I at least can charge the batteries from generator power.

I have an RV garage with power, so what I have been doing during storage is disabling the "charger" on the Inverter/Charger and plugging in my 4 stage. This saves wear and tear on the Inverter/Charger which has a fan that seems to run a lot. One thing I don't do is keep both charge sources on at the same time. Probably OK, I just don't do that.

To keep my engine battery up while in storage, I have a high amp, manual battery combiner switch that links engine and house batteries cables together. It usually stays closed (connecting both) unless I'm boondocking.

Re: Magnetek TU-775-2 Converter Charger failed

Reply #13 – January 07, 2023, 09:56:00 am

Quote from: Pierce & Gaylie Stewart – January 07, 2023, 12:40:56 am

But the best solution is to eliminate the boost solenoid as fitted and replace it with a solid state latching relay... The only change needed would be to remove the boost switch on the instrument panel and replace it with a momentary switch. This kind of relay has no coil heating (on mechanical or magnetic) so no draw itself so it can charge both banks when at home, act as a boost solenoid and basically, get rid of the isolator. No one is installing isolators today in new coaches.

I decided to go this route. It was a gradual transition. First I replaced our OEM isolator with a newer model. Then I replaced the OEM boost solenoid with a Blue Sea 7701 (magnetic latching relay). Then I eventually decided I didn't need the isolator and removed it. See revised wiring diagram below. This system works fine for me. DWMYH

Delco Remy 28SI Alternator Installation

Re: Magnetek TU-775-2 Converter Charger failed

Reply #14 – January 07, 2023, 11:14:35 am

Chuck just pointed out to me that the Stinger isolator/relay is not a magnetic type so for those wanting that type, choose a Blue Sea or other with the same specs. What is a magnetic type of latching relay?: What are the advantages of a magnetic latching relay- Zhejiang Zhongxin New...

Nice post Chuck! Schematic makes it clear.

Foretravel put the panel in the worst possible location where all the spray from the road can get on it and make servicing hard. Some members like Brett, have moved the panel up under the bed. The cables should be long enought without modification. Actually, Chucks original panel was not as bad as some. Treated roads kill exposed electrics.

Pierce

Re: Magnetek TU-775-2 Converter Charger failed

Reply #15 – January 07, 2023, 07:56:23 pm

Hey Chuck, did you have to adjust the voltage after installing the Blue Seas?

Pierce

Re: Magnetek TU-775-2 Converter Charger failed

Reply #16 – January 07, 2023, 09:58:50 pm

Quote from: Pierce & Gaylie Stewart – January 07, 2023, 07:56:23 pm

...did you have to adjust the voltage after installing the Blue Sea?

No, because the sense wire is connected to the chassis battery, just like it was when I had the isolator in place. The alternator puts out whatever it takes to keep the battery happy. If I have all 3 batteries combined, the 200A 28SI is more than capable of keeping them all charged.

Re: Magnetek TU-775-2 Converter Charger failed

Reply #17 – January 08, 2023, 08:00:12 am

Quote from: Chuck & Jeannie – January 07, 2023, 09:58:50 pm

No, because the sense wire is connected to the chassis battery, just like it was when I had the isolator in place. The alternator puts out whatever it takes to keep the battery happy. If I have all 3 batteries combined, the 200A 28SI is more than capable of keeping them all charged.

Correct!

The sense wire in both original form (connected to the chassis battery side of the diode-based battery isolator) and after the removal of the "voltage sucking diode-based battery isolator" (about .7 VDC) and use of either a solenoid-based battery isolator OR a manual battery switch still senses voltage at the chassis battery side of any isolator.

So, the exact same voltage will be seen at the batteries in either case. Just that the alternator will not need to work so hard to provide the extra .7 VDC that the diode-based isolator turns in to HEAT. That heat is why all the aluminum fins are on the diode-based isolator.

For those wondering about using a manual battery switch (like the marine Perko ON-OFF switch) it couldn't be simpler. It is the most KISS theory way to allow both combining and separating the battery banks. Cable from chassis battery removed from the diode-based battery isolator and connected to one terminal of the switch. Sense wire to the same terminal. Cable from house battery removed from the diode-based battery isolator and connected to the other terminal of the switch. Switch off= batteries separated. Switch on= batteries combined. They can be combined so that the on-board charger can charge the chassis batteries as well from shore power/generator. Also, when the engine is running, on means house bank as well as chassis batteries are charged by the alternator. On also gives a very high amp "battery combine"/battery boost for starting. At least on our Foretravel, it was easy to install the Perko switch at the foot of the bed so it is easy to access. No need to change any wires. Also a good time to move the panel with the relays on it to the nice dry "electrical area" at the foot of the bed. If interested in discussing this, please start a new topic.

Re: Magnetek TU-775-2 Converter Charger failed

Reply #18 – January 10, 2023, 09:48:30 am

A stick man drawing of what @wolfe10 talked above.

I hope it is not too wrong from the above post.

It will make the electricity diagram so much simpler!

KISS

Re: Magnetek TU-775-2 Converter Charger failed

Reply #19 – January 10, 2023, 09:53:44 am

Quote from: Running Odometer – January 10, 2023, 09:48:30 am

A stick man drawing of what @wolfe10 talked above.

I hope it is not too wrong from the above post.

It will make the electricity diagram so much simpler!

KISS

NO.

Alternator B+, Alternator sense wire and CHASSIS Battery to one lug. House battery to the other lug. Yes, the alternator sense wire can go anywhere that reads the chassis battery.

Particularly for those who stay at CG's most nights (shore power), just leave the switch OFF when driving. No point in OVER-charging the house battery bank, along with using a little more diesel and creating a little more heat in the alternator when you will be back on your smart charger at the end of the drive.

Re: Magnetek TU-775-2 Converter Charger failed

Reply #20 – January 12, 2023, 04:53:07 pm

New charger installed.

Based on the suggestions posted above, I bought the Progress Dynamics PD9260CV
Amazon.com: Progressive Dynamics PD9260CV Inteli-Power 9200 Series Converter/...

This one got great reviews almost everywhere. Since 12V is the back bone of the RV, I think it is worth investing a better converter/charger. It should be able extend the life of the batter to justify the cost of it. And also no MORE loud buzzy sound

Also replaced the battery terminal, old one has some rust on it. Hopefully this can provide battery electric connection.

Everything installed

new terminal installed

Old and new terminal

30 years of technology improvement

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Re: Magnetek TU-775-2 Converter Charger failed

Reply #21 – January 12, 2023, 05:01:03 pm

I would sure suggest you locate the charger in the NEXT COMPARTMENT from the batteries.

There, it will be in a cooler location and less sulfuric acid vapor and in the event of overcharging and outgassing of Hydrogen will not present an explosion risk.

Re: Magnetek TU-775-2 Converter Charger failed

Reply #22 – January 12, 2023, 07:32:06 pm

Quote from: Running Odometer – January 12, 2023, 04:53:07 pm

New charger installed.
Based on the suggestions posted above, I bought the Progress Dynamics PD9260CV
This one got great reviews almost everywhere. Since 12V is the back bone of the RV, I think it is worth investing a better converter/charger. It should be able extend the life of the batter to justify the cost of it. And also no MORE loud buzzy sound

Congratulations on your purchase. I chose this brand because the advertising wasn't too "emotional."
I bought my first PD in 2011 to replace a Magntek. Firstly, I thought that between my 1973 Winnebago (New, Pioneer RV) and my 1986 Rockwood (Derelict, field.) that power converters had improved. Nope. Still a harmonically regulated transformer seemingly designed to boil batteries dry. It wasn't until the advent of switching mode power supplies that the little box in your hand became possible and practical. Luckily for me the U225 came with a PD9160 and all I need add was the Charge Wizard.
I installed both of ours under the front steps in our center door design only one bay away from the battery/wet bay with welding cables, two inches off the floor.

Re: Magnetek TU-775-2 Converter Charger failed

Reply #23 – January 12, 2023, 07:35:52 pm

The "Charge Wizard" should be in the box without paying extra.

Pierce

Re: Magnetek TU-775-2 Converter Charger failed

Reply #24 – January 12, 2023, 08:34:07 pm

Quote from: Pierce & Gaylie Stewart – January 12, 2023, 07:35:52 pm

The "Charge Wizard" should be in the box without paying extra.

Pierce

The U225 came to me sans charge wizard, with a BCI Group 24 for the engine and a group 27 gel cell for the house. When working with a dealer there are somethings you just need to do yourself. Besides, the 9200 series has the charge wizard built in and the pendent gives you manual control over the charging modes. Only the 9100 series requires the external pendent for 3-stage charging. And yes, of the 3 9200s I purchased last summer all three came with the pendent in the box at no extra charger.

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