Can you have two converters?

quicky06 · 07-21-2018, 11:11 AM

Looking ino replacing my 50 amp wfco POS with a progressive dynamics converter that will actually go into bulk mode and was wondering if I could put two 50 amp converters in instead of a single 80 amp.

We plan on winter camping a lot. Half of which will be boondocking so all my pipe and tank heaters are 12v to the tune of 65 amps of specified amperage ( I haven’t installed everything yet). I understand everything will be cylicing on and off and not everything will be cycled on at the same time.

I would like to have faster battery charging and redundancy with two separate converters.

Wire size is not an issue. Between the converter/ fuse box to the batteries is 1/0 welding cable and my 6v batteries are all wired togeather with the same cable. ( it’s a 30foot run)

D

Duckogram · 07-21-2018, 02:53 PM

Sure you can. My Jayco came with two 45’s. Just like a 50amp 120v service is really two 50amp 120v feeds, the two converters would service different loads. The issue would be splitting the feeds on the power distribution panel. One solution would be two panels.

BandJCarm · 07-21-2018, 03:00 PM

Call the guys at Bestconverter.com and discuss with them. They are very good and very helpful.

quicky06 · 07-21-2018, 03:07 PM

Quote:

Originally Posted by Duckogram

Sure you can. My Jayco came with two 45’s. Just like a 50amp 120v service is really two 50amp 120v feeds, the two converters would service different loads. The issue would be splitting the feeds on the power distribution panel. One solution would be two panels.

I know I can have two on separate circuits. What I was interested I was having two on a single dc circuit.

I would like to mount both of them behind my panel ( there is a large void need the counter) then wire them to a bus bar then to the power distribution panel.

Wiring them separately would be rather simple using a transfer switch.

Duckogram · 07-21-2018, 03:16 PM

If you are only using one it seems that all you would be accomplishing is that you would have a “prewired” spare that you could bring online with the flip of a switch.

quicky06 · 07-21-2018, 03:26 PM

Quote:

Originally Posted by Duckogram

If you are only using one it seems that all you would be accomplishing is that you would have a “prewired” spare that you could bring online with the flip of a switch.

I would like to run both at the same time.

2 50 amp converters give me more power than a 80 amp converter.

I just don’t know if this would cause issues or not.

**Bama Rambler** · 07-21-2018, 03:42 PM

As said above call Best Converter.

I'm afraid that they'd buck each other especially since they're not matched units. I may be wrong about that, and you may be able to bias one so that it only kicks in when the amp load on the other converter gets to a certain load or can't keep up.

bubbles · 07-21-2018, 04:02 PM

What happens when our RV two 12 batteries are connected in parallel?

BandJCarm · 07-21-2018, 04:03 PM

Quote:

Originally Posted by bubbles

What happens when our RV two 12 batteries are connected in parallel?

You get 12v with more amps.

**Bama Rambler** · 07-21-2018, 04:10 PM

Quote:

Originally Posted by bubbles

What happens when our RV two 12 batteries are connected in parallel?

Completely different situation. The converters are more than power supplies, they're also battery chargers and there's where the problem lies.

If they were just power supplies then connecting them in parallel isn't a problem at all.

bubbles · 07-21-2018, 06:37 PM

Yeah, I'm not sure there would not be problem with having to charge batteries and I'm not sure if isolation diodes would alleviate a possible issue.

quicky06 · 07-21-2018, 06:46 PM

You guys have verified my concern.

I’ll call progressive dynamics on Monday and see what they say.

To be clear I was speaking about replacing the current converter with two brand new converters that match.

I have warrantied the wfco converter once and it did not fix the issue. The converter will not bulk charge. It won’t provide more than 28 amps after a couple of minutes. It starts at 50 but quickly drops. This is with a battery state of charge below 60 percent. All information is from a Victron battery monitor.

I’m leaning more towards seeing if it’s an issue after I get all the heat pads on. That will be another thread. Going to use rope lights for everything but the tanks

UT_Grandpa · 07-22-2018, 01:53 PM

Whenever you have more than one source charging a battery problems can happen. The voltage regulators on multiple sources if not set exactly and have exactly the same foldback will create what is called hysteresis or a bouncing back and forth with the charging current.

This is the same reason you should not have solar AND a converter trying to charge the same battery bank at the same time.

As was said earlier you would have to split your DC load between the two chargers and you can bet there isn't enough spare wire to reach another panel and adding a foot of wire in with a splice is never a good idea. So I would stay with a single converter, one panel, and one source for power.

**Flybob** · 07-22-2018, 02:03 PM

Slight differences in thresholds and temp could result in conflicts and problems.

Larry-NC · 07-22-2018, 02:30 PM

Instead of two converters, why not just go with a bigger one. The Progressive Dynamics PD9280A delivers 80 amps. Is that enough?

Larry

ScottBrownstein · 07-22-2018, 02:36 PM

I would stick with a single converter. As others have indicated, the two converters in parallel may get confused and that will result in one backing off when it sees a higher voltage supplied by the other.

I know that 1/0 sounds like heavy cable, but you have a 60 foot round trip distance and at 70 amps that will cost you .4 volts into the batteries...meaning you will never see the 70 amps going into the bank. I have a 70 amp converter and seldom see more than 35 or 40 amps into the bank, although my feed is considerably smaller than yours.

PD9270 will give you 70 amps max...but will probably net out at 45 or so.

Splitshaft · 07-22-2018, 02:44 PM

Supplying safe DC voltage to power RV 12V devices without damage and charging batteries are two very different things. Ether can be done alone well, yet both can not be done as well together. Lead acid batteries are best charged at 14.8V bulk to include current high enough to create a temperature rise of the battery. Voltage that high or higher may damage some 12V devices (think about the control board in the frig or the 12V flat screen TV). And no battery is going to accept more current than it pushes back against the charger supplying it. Even a 1,000-amp battery charger if well made may only supply 2-amps to change batteries if that is all the batteries will accept. Lead acid batteries are best charged at no more than 35-percent of their amp-hour rating during bulk charge and beyond that, charged at much lower current to reach full charge which may take up to eight hours depending on how well the battery charger is programmed and the condition of the batteries being recharged. For my money, hybrid charging systems are best. Bulk charge is supplied by a three stage charger powered by a generator and then, solar panels supply the lower current need for several hours to top the batteries off when dry camping.

Larry-NC · 07-22-2018, 03:28 PM

Quote:

Originally Posted by Splitshaft

Supplying safe DC voltage to power RV 12V devices without damage and charging batteries are two very different things. Ether can be done alone well, yet both can not be done as well together. Lead acid batteries are best charged at 14.8V bulk to include current high enough to create a temperature rise of the battery. Voltage that high or higher may damage some 12V devices (think about the control board in the frig or the 12V flat screen TV).

I'm a little dubious about this part. Automotive electronics gets 14+ volts on it all the time, especially right after a start. It's designed to withstand that, either with internal regulators or simply by a tolerant design.

Larry

ScottBrownstein · 07-22-2018, 03:46 PM

Agree. Most engine alternators will put out 14.3 or more, as will most converters. Now, there is no hard and fast line for 12 volt appliances, but 14.8 to 15 is probably cutting it close. When equalizing batteries, all loads should be disconnected to avoid damage due to higher than normal voltage.

However, I have yet to see a converter that can supply anything near its rated amperage at more than 14.2 or so anyway.

quicky06 · 07-22-2018, 04:09 PM

Quote:

Originally Posted by ScottBrownstein

I would stick with a single converter. As others have indicated, the two converters in parallel may get confused and that will result in one backing off when it sees a higher voltage supplied by the other.

I know that 1/0 sounds like heavy cable, but you have a 60 foot round trip distance and at 70 amps that will cost you .4 volts into the batteries...meaning you will never see the 70 amps going into the bank. I have a 70 amp converter and seldom see more than 35 or 40 amps into the bank, although my feed is considerably smaller than yours.

PD9270 will give you 70 amps max...but will probably net out at 45 or so.

Only half of the run is through 1/0 the other half is through the frame. Voltage drop is not nearly as much as you would thinking have measured it before and it was less Than .1 volt and i atribute that to the he multiple connections to extend the test leads.

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