I've run into a charging problem with my 2006 Damon Daybreak that I could use some feedback on. Simply, the battery cannot seem to pull enough charging current from the converter. At a ~60% state of charge, I'm only getting 20A from the converter. At the same time, I can get about 40A from the alternator. I noticed the issue because I used to get quite a bet more amps out of the converter.The coach has a Progressive Dynamics PD9160 60A converter (with Charge Wizard) and a 220Ah battery bank (dual 6v batteries). Everything is monitored via a Xantrex XMB with DC shunt.The converter is putting out 14.4v in boost mode (as expected). I'm getting ~13.4v at the battery. That's about a 7% drop. It looks to be about a 50' run on #2 wire from the converter to the distribution panel to the disconnect to the battery. The charts show a 4.4% drop for that distance at 40A but with all the extra connections I'm not surprised that it's higher. All the connections and grounds look fine that I can see.Progressive Dynamics is telling me that if the converter is putting out 14.4 volts in boost mode it's working fine. They think resistance on the line is reducing the charging voltage. However, it USED to work fine and I don't think the wiring is an issue based on what I've seen.I'd love to hear some feedback before I proceed. I don't want to buy a new converter is mine is okay and I won't want to rewire the coach if the converter is bad.Thanks!Mike

Clean and check connections first. Yes 50' (assume that is "round trip" or is it 100' is a LONG run for 60 amp output converter.Any location closer to the battery bank where you could install the converter? Any closer very large gauge wire that you can connect to (something like cables to jack motor)?

Assumption: 50' one way, grounding through the frame. If it used to work fine and now doesn't, disconnect and clean each connection including converter to frame ground and frame ground to battery. Visually they may look "good" but there can be corrosion that you cannot see.

Progressive is absolutely right in this case, I think. Certainly it sounds as though the converter is working exactly as designed. It has no way of telling what the voltage at the battery is, since it doesn't have any sense lines, just what the voltage at its outputs is.Your expected voltage drop should be computed (for comparison with actual) based on the actual current, or 20A, which would be a bit over 2%. That would work out to about a quarter volt. You're seeing four times that, so you have a poor connection or something similar somewhere.If you could shorten the leads between the converter and the battery, perhaps by relocating the converter, that would be a big help. There's no real need for the converter to be wired into the distribution panel; it could be connected directly to the battery (with appropriate fusing) just as effectively. (Of course, if you connect it on the other side of the disconnect switch, it will alter what happens when it's set to disconnect. You would not be able to operate 12V things of the converter, as you presumably can now, but you would be able to charge the battery with the converter.)If you have a meter with a sufficiently low enough DC voltage range, you can check along the lines to see where the voltage is dropping. Measuring between the battery negative and the converter negative terminals will show if it's in the ground path, and between the positives if it's in the positive path. Checking across the wire at various intermediate points might track down where it's happening.

I keep harping the point.One tenth volt difference (under load) between a soldered joint and an oxidized crimp joint TIMES TEN connections equals ONE volt. Check VOLT DROP across EACH connection...NO not terminal to terminalCopper wire to copper wireWhile under MAX loadAnd you will see.How many connections between power origin and the lead battery posts?Supervising Armando, I repaired many large motorhomes so that total voltage drop under high amp full load was .3 or less.

CJW8 is correct. 50' one way, grounded through the chassis. Damon really didn't think things out very well when they put the converter at the very back of the coach, the disconnect at the very front of the coach and the battery roughly in the middle. Moving the converter is easy but moving the dedicated AC circuit not so much.Some other measurements that might offer insight...Converter: 14.4vDistribution panel: 14.05v (~15' from converter)Disconnect: ~13.29v (~40' from converter)I'll go through the connections next. Since the battery is pulling a good charge from the alternator I know any issue has to be between the converter and the disconnect so that narrows things down a bit.There could be 8+ connection points on the positive side between the converter and the battery (1 at converter, 2 at distribution panel, 2 at disconnect, 2 at fuse/breaker, 2 at isolator...).Thinking about the ground... the ground from the converter to the chassis and from the battery to the chassis are the only two that should matter in this case right?Thanks for the feedback!

Class A house charging system issue help needed

42 Replies

Mike_Schriber
Explorer
Oct 11, 2016
Rewired. At ~60% SOC it's still down a volt but taking just over 40 amps.

I'll take it.

Thanks for all the feedback and advice!
BFL13
Explorer II
Oct 04, 2016
Good news and that battery voltage should come up to 14.x as it is recharged. Takes some time.
Mike_Schriber
Explorer
Oct 04, 2016
Just ran a test. I connected the converter directly to the generator (which has a 2 gauge wire run directly to the battery) using dual 4 gauge steel wires I had around. The converter put out slightly less voltage (14.3v instead of 14.4v)) but the battery took 41A instead of 20A or less like before (67% SOC). Voltage at the battery was still down quite a bit at 13.54v but it sure charged.

So, I think I'm going to make a run of 2 gauge wire between the converter and the generator and call it a day. It should be the least disruptive and costly solution.
BFL13
Explorer II
Oct 02, 2016
"Thinking about grounds, if we're looking at voltage and current between the converter and the battery, aren't those the only two grounds that would matter in that calculation?"

Depends on the set-up in that rig. The neg path from converter to battery via the frame can include the grounding of the converter inside the power centre with their metal chassis touching and the converter sharing the big 120v bare copper wire from the power centre 120v intake (shore) cord to the frame plus maybe having its own wire to the frame. Might be a shore/gen transfer switch amongst that. Behind the converter there might be a whole bunch of white wires wire-nutted together with the converter's mixed in with them.

At the battery you might have a Trimetric monitor shunt which means the battery ground to frame is on the other side of the shunt from the battery post neg connection to the shunt. You might have a battery disconnect on the neg side near the battery too.

Could be more variations, especially in a MH, which are complicated compared with trailers. As a trailer owner, I find MH electric set-ups just baffling :)
Mike_Schriber
Explorer
Oct 02, 2016
Well, it's not that fat of a wire. The 6 gauge connection between the converter and the disconnect is going to lose more than half a volt at 20A in perfect conditions with no connections. A shorter run of 2 gauge should improve that considerably.

Thinking about grounds, if we're looking at voltage and current between the converter and the battery, aren't those the only two grounds that would matter in that calculation?

I'll certainly be doing more testing!

BFL13 wrote:
You can improve the converter to battery amps flow by reducing the R of either the pos path or the neg path or both paths by any amount. Each path can have different Rs. It is the total R of both paths that counts.

You might still find if you improve the pos path that it doesn't help much since it already has fat wire. Assuming the neg path is mostly frame, any big R on that will be connections that need cleaning as was mentioned.

You can measure the R along a path that is carrying a known current with your voltmeter. Put one lead at each end of the wire. You can do this by adding speaker wire to the leads, even 40 feet of speaker wire will still give you proper voltage readings.

The voltage on the meter will be the voltage between each end of the wire and you have the current, so you get the R. You can do this along the path between sections and find where there is a big R in the path, such as across a fuse holder.

With the long speaker wire leads you can run this test from the converter to outside the rig to the batteries, by- passing the whole frame to see if the neg path is your culprit before rewiring the pos path on speculation. Measure both paths first and then see what to do.
MEXICOWANDERER
Explorer
Oct 01, 2016
I did it in reverse fashion - inherent over-current protection for the Cheap-O-Watt power supply. By calculating the lowest possible battery voltage the battery was likely to encounter, I set the power supply voltage limit.

Then, using a calculated length of 14 gauge copper coated aluminum duplex wire, I have via inherent resistance in the wire limited current potential to 30 amperes or less with a Delta T of 2.4 volts. Not recommended for speedy charging. Highly recommended to improve survival rate of Cheap-O-Watt.
BFL13
Explorer II
Oct 01, 2016
You can improve the converter to battery amps flow by reducing the R of either the pos path or the neg path or both paths by any amount. Each path can have different Rs. It is the total R of both paths that counts.

You might still find if you improve the pos path that it doesn't help much since it already has fat wire. Assuming the neg path is mostly frame, any big R on that will be connections that need cleaning as was mentioned.

You can measure the R along a path that is carrying a known current with your voltmeter. Put one lead at each end of the wire. You can do this by adding speaker wire to the leads, even 40 feet of speaker wire will still give you proper voltage readings.

The voltage on the meter will be the voltage between each end of the wire and you have the current, so you get the R. You can do this along the path between sections and find where there is a big R in the path, such as across a fuse holder.

With the long speaker wire leads you can run this test from the converter to outside the rig to the batteries, by- passing the whole frame to see if the neg path is your culprit before rewiring the pos path on speculation. Measure both paths first and then see what to do.
Mike_Schriber
Explorer
Oct 01, 2016
Yep, current measured at the battery posts. The converter is charging though more than 35` of 2 gauge wire and I know the PD9160 is capable of putting out more than that.

The interesting thing is that the alternator is connected (via the chassis battery and isolator) by a much shorter run of 2 gauge. I'd expect to see a greater delta in voltage (but then again, I haven't measured output at the alternator so I don't know what voltage it's actually producing which makes that observation moot).

Sam Spade wrote:
Mike Schriber wrote:

Does anyone else think that 11A is a big difference for a delta of .32v?

NO not really.

The alternator has a higher current capability and the converter might be approaching it's practical current limit, regardless of what it's rated capacity is.

I assume those voltage measurements were both taken at the battery posts ??
Sam_Spade
Explorer
Oct 01, 2016
Mike Schriber wrote:

Does anyone else think that 11A is a big difference for a delta of .32v?

NO not really.

The alternator has a higher current capability and the converter might be approaching it's practical current limit, regardless of what it's rated capacity is.

I assume those voltage measurements were both taken at the battery posts ??
MrWizard
Moderator
Oct 01, 2016
No reason....
Sounds like it might be a solid idea

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Class A house charging system issue help needed

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