93 Bigfoot 17CB - Magnetek Converter BAD!

[Michael Pupeza]

Hi;
We recently bought a 1993 Bigfoot 17CB (Our 2nd Bigfoot - a 13' L'il Bigfoot in 95, replaced by a pop-up Starcraft for 5 years, now this 'upgrade'!)
This 'new' Bigfoot is a real treasure - it looks almost new inside, BUT had a serious problem with the converter.
The battery, only in it's 3rd year, was almost dry, died fast, and the converter ran HOT!
A Magnetek 6332 was the converter - it is 'supposed' to be a 32 Amp unit with 3 Amp 'regulated' charging!
Maybe at one time!
It put out under 14V (should be 14V+ and 13.8V for the charger!) and was too hot to touch, even when not loaded. I disconnected the wires in the lower unit, the converter, leaving the 110V circuit breakers and the 12V distribution fuse panel and pulled the unit!
The floor was scorched where it sat these many years. The actual size of the '32 Amp' transformer is 1/2 the size of an old 15 Amp Battery Charger that I have. The regulation electronics was fried and I suspect that some of the windings in the transformer are shorted.! Thus, no charging, no power, just a lot of HEAT!
I've chucked it! Farewell!
I've ordered up some overkill, a Progressive Dynamics Intel-power PD9260 with Charge Wizard, that will fit in the lower compartment when I cut out the back.
Hopefully, with the normal power I use, it'll never even turn on the fan! Or maybe a little! It weighs 6 pounds, about 1/2 of the amount of stuff I cut out of the old lower unit!
In Magnetek's defence, I do like the front panel, the circuit breakers, and the 12V fuse distribution panel!
Now, off to see if there's any other problems to fix!
Mike in Ontario

[Pete Dumbleton]

The reason the older converters (Not just Magnetek, which is now also Parallax) weighed so much was that they had a copper-wound transformer inside them. Modern converters apparently do the same job electronically. PD products seem to be highly recommended by BulgeMobilers.

[scott fraser]

Michael, keep us posted on the steps you take. I'm in the same position with an '84 Bigfoot. I want to keep the breaker panel and fuse panel but the converter and the charge module have had it. I was thinking the same thing as you, toss the old converter and module and use the casing to mount an Intel-power unit.

I'm just nervous about starting on this project. I'm no electronics whiz and there are some pretty intimidating wire bundles going into the back of the unit. I don't suppose you have pictures of the steps you're taking?

[Pete Dumbleton]

Keep in mind that you might not have exactly the same configuration. The converter manfs have changed things from time to time over the years, as well has have the trailer manfs.

For example, my first converter had the 12VDC panel separate and the second one (different trailer) had the 12VDC panel inside. I have never even seen one, except in pictures, with the 120VAC breakers inside.

However, if the chosen replacement is intended by the manf as a drop-in replacement, the instructions and task should be straight-forward.

[Michael Pupeza]

Michael, keep us posted on the steps you take. I'm in the same position with an '84 Bigfoot. I want to keep the breaker panel and fuse panel but the converter and the charge module have had it. I was thinking the same thing as you, toss the old converter and module and use the casing to mount an Intel-power unit.

I'm just nervous about starting on this project. I'm no electronics whiz and there are some pretty intimidating wire bundles going into the back of the unit. I don't suppose you have pictures of the steps you're taking?

DON'T be intimidated!
The bottom Converter Section of my unit has basically 5 important wires!
At the left side, a black and white 110VAC wire pair come from the 110V Circuit Breaker panel above, they power the Converter!
At the right side, a Blue wire supplies the unfiltered DC to the Fuse panel above, supplying 12V raw to the left 6 fuse positions.
At that same side (right), the Red wire is connected to the Battery, AND the 3 right hand fuse positions for filtered DC Power.
A White wire is the Negative (V-) for the system.
If you remove all of the electronics from the lower unit, you will be left with those 5 wires!
You do need to pull out that box and drill out the pop rivets and unscrew the screws. You'll have a transfomer, heat sink with components, a big resistor and circuit breaker, a fan, a big useless relay, and a circuit board. You'll be none the worse off for it! Those 5 wires should tuck up (Insulated) until you get a replacement converter.
A replacement PD Converter will want the Left Hand black and white wires to supply the 110V input!
The Output will be the Blue and Red wires connected together for the Plus (V+) and the White wire for the Negative (V-)!
An additional Ground wire is recommended to connect to the case!
In my unit, I moved the Converter to an unused Circuit Breaker on the 110V panel, the farthest right!
Note the scorching of the floor when you pull out the lower box!
Some of the PD units, with Charge Wizard 'may' fit in the existing cleaned out box, but mine will need the back to be cut open to fit the extra depth. No problem!
I suspect that other newer converters will also fit the bill, preferably with 'Intelligent' charging circuitry!
I'm awaiting my replacement so my info is 'pre-install'! It's advice only, not experience!
Good luck.
Mike

[Ted Tuchsen]

Mike,

I have some cautionary notes for you.

You want to ensure that the wiring from the converter to the battery is adequate to support the Intellipower. I upgraded mine to AWG 8 gauge.

Equally important is the necessity to upgrade the circuit breaker that should be located near the battery. In my case I upgraded to a pd9140 (40 amp) with the charge wizard and so I changed the breaker to a 50 amp unit. Additionally, I mounted it on a heatsink.

The Intellipower will put out its full rated power to a partially discharged battery such as you might find after dry camping. Even the 8 gauge wire got warm and the cicuit breaker got too hot to touch and hence the reason for adding a heatsink (which I had).

I had added several additional accessories and as a consequence I had a lot of wires on the neutral stud. I solved that problem by adding a marine 100 amp bus bar (West Marine or other boat suppliers) right below the fuse panel.

My Magnetek has a split fuse panel. You want to tie the two 12 halves together if that is the case.

One last caution. The PD9260 might be too big for your battery. It is recommended that the peak charging current be limited to about 25% of the battery capacity in order to maximize its life. In my case I have a 115 AH battery so 25% would be about 29 amps. Thus my pd9140 is a bit overkill.

Having said all that, the Intellipower is a really great unit. It works as advertised.

Hope it helps,

Ted

[Michael Pupeza]

[quote]
Mike,

I have some cautionary notes for you.

You want to ensure that the wiring from the converter to the battery is adequate to support the Intellipower. I upgraded mine to AWG 8 gauge.

<SNIP>

Good information, Ted!
I had not really considered that aspect of excessive charging curret. The specs of the PD9200 series don't mention the actual charging currents - only the voltages! As a matter of fact, the graph shows the charging time of a dead 125 AHr battery in Boost Mode at 14.4V, WITHOUT specifying any actual size of converter! I guess that I thought the battery was self limiting!
I do have some 30Amp fuses in circuit - one at the battery, and one where the battery lead enters the TT, that 'should' blow if the current is excessive for a while. Should this be a problem, I'll have to find an current limit adjustment in the Converter, or, place some very heavy power resistors in series to limit the current. I do have 10 of 1 Ohm 40W heat-sinkable units that could be wired in a configuration that should provide protection! Maybe an additional easy access fuse at 25Amp?
I wasn't going to rewire the system, but will be tying the 6 and 3 fuse panels together. The 120V CB I'm using is rated at 15A where I have the converter, so it's OK.
I guess that very few systems are perfect, but this should be FAR superior to the original Magnetek that was failing! As you mentioned, only in the case where the size 24 deep cycle battery is severely depleted should I, maybe, have a problem! Let's hope that it won't be serious!
Thanks for the suggestions.
Mike.....>

[Pete Dumbleton]

I don't believe the batteries are self-limiting in any way -- I was at an auto parts place, having my rig checked after changing out my alternator (but not my voltage regulator; if the voltage regulator is not integral it's a really, really good idea to change out both alternator and VR at the same time, because one may have made the other bad in the first place!). The tech did something with the system to measure full alternator amps and, with the defective VR, the battery immediately started boiling over like I had never seen.... Clearly, my flooded lead-acid battery was not self-limiting.

BTW, I was wearing my reading glasses, as I do in situations like that, partly to see stuf and partly to keep other stuf out of my eyes. The tech, moonlighting from the USAF, had no eye protection and I strongly recommended that he use some in future...

I believe the smart charging systems use standard curves and feedback from the battery as to how much energy to deliver, in terms of both voltage and amperage. If there isn't a manual switch for different types, and one doesn't know what curves are in the controller, one risks one's non-standard (flooded lead-acid deep cycle is likely 'standard') specialty battery.

BTW, it is my belief that one of the strengths of AGM batteries in general is that they will accept a much higher charge rate (amps) than FLA, so if using one, the wiring and fusing should be beefy!

BTW, if one has a 125AH battery that is 50% depleted, one needs to put back 62.5AH. If the recharge time is one hour, the rate will be greater than 60A (bulk higher, absorption lower), if two hours, >30A, and so on.

[Ted Tuchsen]

Mike,

I would strongly advise against using resistors to limit the current as that would largely negate the advantage of the Intelli-power unit.

I considered using, for awhile, the Magnetek upgarade converter which while capable of furnishing full output, doesn't have the advantage of the Intellipower.

It's interesting what Magnetek says about the upgrade:

"Since the upgrade can deliver full rated output current to the battery bank, the wiring to
and from any batteries connected to the converter system must be checked (and replaced
if necessary) as the upgrade, and current NEC code, requires # 8 AWG minimum, with
a 90 degree Celsius insulation rating, protected by a battery breaker or fuse appropriately
rated at 50-55 ampere maximum."

The full comment can be found at:
http://www.parallaxpower.com/7300/7345RU_7...%20contents.pdf

I could not find a way to change the current limit in the Intellipower. You might want to give them a call. I have found them to be very responsive in the past.

I believe that Pete is right about AGM batteries accepting a higher charge than flooded batteries.

When I tested my setup, I had pulled approximately 40-50 AH out of my 115 AH deep cycle trolling motor. The wiring from the PD9140 to the battery ran warm for about 1 hour and then the charge dropped like it should.

Ted

Ted

[Michael Pupeza]

Ted, et al;
David, Service Department Technician at Progressive Dynamics said that:
" Boost mode is only enabled for up to 4 hours , to prevent overcharging.
See attached Wizard specs.
The larger amperage capacity will only bring the battery up faster from a
full discharge."

However, he also forwarded a PDF on the Charge Wizard, which gave me an idea for a solution!
I've ordered a PD92201 Converter Status Remote Pendant for $10.95 + $7 shipping.
This will allow me, when the battery is really low after a dry boondocking trip, to bypass the Boost Mode, or shorten it with the control switch. That will default to the Normal Charge Mode,
Other than requiring Manual Intervention at that time, I feel this is a Very Elegant solution to the potential problem.
If necessary, I see that I have room for an additional Type 27 Deep Cycle battery on the other side of the dinette, which would give me a total of over 150 AHr of batteries. Even the 14.4V Boost Mode wouldn't over current that capacity!
So now, I'm happy again!
Mike.....>

In Theory, there's no difference between Theory and Practice; In Practice, there is!

[Per Walthinsen]

Michael:

I rebuilt my Newmark electrocenter (the design came over on the Mayflower) with the PD 9245 and added the pendant to tell me what's going on (or change it, which I have had no reason to do). Two group 31 deep cycle batteries.

Almost the best thing I ever did, electrically speaking. Best thing was to add a Xantrex Link 10 battery meter. With it I can track every little electron, where it is going, and why.

[Morgan]

Pete is right, an AGM battery can be charged at a charge current of 4 times its capacity where a flooded battery can be charged at a charge current of just 1/8 of its capacity and a gel cell can be charged at only 1/20 of its capacity.

For a 100 AH battery:

Flooded - max charge rate 12.5 amps
Gel cell - max charge rate 5 amps
AGM - max charge rate 400 amps *

* Charging at 400 amps is not very practical (the cables would be enormous), but the AGM can accept whatever current any reasonable charger wants to send it.

[Michael Pupeza]

Ok Gang;
It's DONE! Installed and working!
The PD9260 Inteli-Power specs were a bit off, in the measurements - it did fit perfectly into the 7 1/2" depth box space. Mine is the newer PD9260C, so the measurements must have changed a bit!
I used a hole punch to knock out 1 hole where the Monitor Pendant will plug in, and 1 for the power cord.
Instead of hard wiring the AC power, I installed a duplex outlet in the area, connecting to the circuit breaker, and just plugged the new converter/charger into that. The existing heavy Blue and Red Positive leads, and the White Negative lead were all just long enough to connect into the Terminal Block, and I ran a White ground wire from the Chassis Ground to a mounting screw of the case. The whole unit just slides into the case, and I used 2 small wooden strips to wedge the unit from moving. I just need to pull those strips and can remove it for service - none needed, I hope!
I turned on 10 lights at 1A apiece and put the fridge on Battery and the unit barely got warm - voltage sitting at 13.6, as per spec's.
Now, I just have to keep an eye on how it charges the battery!
Neat and clean changeover!
I'm pleased!
Mike.....>

[Michael Pupeza]

Talk about re-inventing the wheel!
I just found this:
<http://home.comcast.net/~rabarber/magnetek.htm>
Other than a few minor changes, it looks almost the same as my conversion!
So, Scott Fraser, you get your pictures after all!
Good Luck!
Mike.....>
Practice makes perfect - Yah, right!

[scott fraser]

Great link Michael, thanks very much! It's quite different from my set up but I'm sure the basic idea is the same and it will be a big help.

Now..if I ever get my trailer back from the kid..I can get started on it.

[Morgan]

This link shows step-by step several Magnetek replacements.

Best Converters

I've bought two Progressive Dynamics converters from Best Converters, good service and prices.

[Pete Dumbleton]

I don't believe the batteries are self-limiting in any way -- I was at an auto parts place, having my rig checked after changing out my alternator (but not my voltage regulator; if the voltage regulator is not integral it's a really, really good idea to change out both alternator and VR at the same time, because one may have made the other bad in the first place!). The tech did something with the system to measure full alternator amps and, with the defective VR, the battery immediately started boiling over like I had never seen.... Clearly, my flooded lead-acid battery was not self-limiting.

I've thought this over and decided that the limiting factor is the voltage, not the current. As long as the charge voltage is higher than the battery voltage, current will flow and how much flows is based on the voltage difference.

Stumbled across a table on another group suggesting wire sizes (Take expected current and expected wire length to get wire size) for monster automotive sound systems (aka thumpers) but I don't know the underlying voltage drop assumption in the table. Here's the audio source and here's more copper wire info.

[Michael Pupeza]

Peter, et al;
There IS a limiting factor in the current drawn in charging a battery, and how much it can supply also.
Basically, the current drawn by the battery will be a function of the difference between the charging voltage minus the existing battery voltage divided by the Internal Resistance of the battery - excluding voltage drops in the cables, as you mentioned.
When new, an SLA battery has a lower Internal Resistance and this increases as the battery gets older and used up.
Internal Resistance of the battery is somewhat predictable by using a High Discharge Battery Tester!
I have a 100 Amp tester that, when discharging the battery for about 10 seconds at that amount, shows the Status of the battery as a function of Weak all the way to Good! What it is actually doing is measuring the voltage across the fixed resistance, a function of the Internal Resistance!
A regular size 24 Canadian Tire Marine Deep Cycle battery shouldn't give excessive current draw when charging in my application, but a depleted new AGM battery, with it's VERY LOW internal resistance would probably melt fuses and cables!

I just replaced mine and will keep an eye on it when charging after it's been depleted! As mentioned, I can use my Charge Wizard controller to drop the charge voltage to 13.6 or 13.2, if 14.4 gets too warm.

This advice and explanations are my own, after doing some research, and may NOT accurately reflect the total physics or reality of what does happen! Like ALL Internet advice, use your own judgement as to it's validity!

Now for some more camping!

Mike

[Pete Dumbleton]

The reason I had the link and table above was that someone on another forum was popping 30A fuses when his truck was recharging his AGM house battery after a lot of discharge.