HiMy TT has a Parallax 7345 converter. For the past year I have been using 550 watts of Solar and a MPPT controller charging my batteries. We have a 12V system at the moment. And I am using (4) 6V golf cart batteries. Duracell GC2. Specs: 20 amp hour rate:215, 5 amp hour rate:157, 6 amp hour rate:156 . Wired series/ParallelWe didn't seem to have any problems charging these batteries over the past year. So we thought. Through the sunny months, they seem to have stayed charged well enough. But when the cloudy months came around, they struggled. Recently is when I figured out the Parallax system has a useless charger. So I decided to get a Progressive Dynamics system having a smart charger. But I am unsure which Amp model to buy.We use the camper full time and the backup is a 4000 watt gas generator. Otherwise, we use it off grid with the batteries. So I need a converter that will work well with this generator, while providing good power whilst still giving the best charge to the 4 batteries. Their biggest model seems to be 55 amps. Thanks.

I have the same problem here with my latest planned battery system upgrade. I have the PD9260C 60AMPS COnverter/chargerI have been using three each GP24 85AH batteries and I have found my total demand from the batteries when first starting my 14.4VDC Boost charge will demand right at 52-53AMPS DC when first hit with 14.4VDC when they are at the the appx 50% charge state (Around 12.0VDC). This is around 17AMPS DC current for each of the three GP24 12VDC batteries in parallel.I see this 53ADC Current for about 15 minutes and then it starts tappering back and in an hours time it will be down to around 8AMPS DC Current demand.Then the PD9260C will go to the 13.6VDC Charge mode for the next two hours which will bring my three GP24 85AH Interstate batteries back up to their 90% charge state.My new battery bank will have two groups of 6VDC GC2 batteries in series that will give me around 440AHs at 12VDC. I was hoping to find out how many DC Amps the groups of 6VDC batteries in series will demand from the charger. My PD9260C is perfect for using my 2KW Honda generator providing 120VAC when camping off grid so hoping I will be ok using the 60AMP converter/charger. I am also hearing that the GC2 batterie like the Trojan T-105s which I am going to be using wants to see 14.8VDC boost charging voltage. I will only be providing 14.4VDC so I am planning all will be fine but will take a little longer to get from the 50% charge state to the 90% charge state.I haven't got my batteries yet so will have to wait until I do to see if my planning on keeping the PD9260C is going to be ok... The most I hear from other folks is that they use the PD9260C with their GC2 batteries and it works just fine haha I will know more this coming spring when I can afford to purchase the four each Trojan T105 batteries for my new metal battery box setup...this is what my three GP24 Interstate Batteries look like in parallel on my POPUP trailer tongue area...Roy's imageIf they were 12VDC batteries like my 85AH GP24 Interstates I would say base your converter/charger on having enough capacity for suppling 17-20AMPS DC Current for each 12VDC battery in parallel if you want to gain the 50% to 90% charge state in a three hour period of charging... If your total current is less that the 17-20AMPS DC current per battery the batteries will still charge just take longer to happen... This has been my experience at any rate...Roy Ken

I wouldn't be afraid to put a c/5 charge rate into those batteries. That would be an 86A charge. They may not always be low enough to take that. I would say anything between 50 and 90 amps should be fine. When charging from a generator instead of the grid I think a bigger charger and thus shorter gen. run time is better. A 4 kW generator shouldn't have a problem running even a 100 amp charger.

45 amp is fine plugged in. On generator I would go at least 55 amps and right up to 80 amps would be great for fast bulk charging four batteries. However you need to review the charging circuit before you go above 45 amps. Common #10 or #8 wire is too small to go big on the converter. Even if the wire does not burn up the voltage drop will cripple the fast charging of any three stage converter. I recommend #4 wire with anything above 45 amps and possibly mounting the new converter close to the battery if possible. PD 9280 deck mount would work great.www.bestconverter.com/PD-9280C-80-Amp-RV-ConverterYes if you want the converter to fit in the existing position you may need to stick with 4645, 4655, 9260 converters.Do not let Randy sell you a Boondocker unless you want a manually controlled unit.

Thanks for the advice about the Boondocker. I think I will stay with the 55 to 60 amp range. My camper already has a 45 amp. But I am sure it doesn't juice up the wire like the new one will. I am unsure what size wire comes off the batteries running into the camper. I am sure it is whatever is standard on a single battery TT. The PD4655V is a bit pricey to me. But probably well worth it. I wouldnt mind going with one cheaper. But I am not certain how much cutting I would need to do without going with the drop-in upgrade.

You can use any deck mount converter as a portable charger if you are willing to go outside and set up for the battery charging. You just use a cut- off end of #4 copper (or fatter cu-al) jumper cables. Ends go in the converter outputs and you clamp onto the batteries.I do that with a PowerMax ADJ 100 amp charger on four batteries. I kept the 7355 converter in place for when on shore power. It does that very well.

Help choosing the right converter/charger? | Good Sam Community

38 Replies

RJsfishin
Explorer
Jan 07, 2017
Quote:
But I am wondering if it would be a smart idea to put on the two extra batteries and then switch the PD to Boost mode and let it go. Assuming it will not hurt them and eventually switch back to Auto when it needs to? I just don't want to fry anything.
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It don't matter what stage you manually put the PD in, it still always stays in automatic mode.
You can connect 14 batteries to your converter, and you WILL NOT fry anything.
RJsfishin
Explorer
Jan 07, 2017
Quote:
But I still don't really understand how a charger can tell the difference between two batteries versus four
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It can't, forget that idea.
time2roll
Nomad
Jan 07, 2017
Unplug, connect the two additional batteries, plug back in.
The PD4655 will do the right thing. No need to force boost mode.
BTW the PD4655 does give a boost charge for 15 minutes every 21 hours so just stay plugged in and you are good to go.
PaulJ2
Explorer
Jan 07, 2017
Camping World sells a 3 1/2 digit volt meter that simply plugs into any 12 volt lighter socket. $15. Have one,love it.
joem789
Explorer
Jan 07, 2017
You guys have been really helpful. I'd probably be lost without this forum. lol.

My solar controller is one of those Tracer MPPT that simply gives a blinking green light when the batteries are fully charged. Assuming its accurate.

SO I will pick up the digital meter and put the other two batteries back on. I have a pretty basic understanding of electronics and such. But I still don't really understand how a charger can tell the difference between two batteries versus four being connected to the circuit. The extra two batteries seemed to be what was keeping things down before, since I believe the Parallax couldn't hack it.

But I am wondering if it would be a smart idea to put on the two extra batteries and then switch the PD to Boost mode and let it go. Assuming it will not hurt them and eventually switch back to Auto when it needs to? I just don't want to fry anything.

I'm amazed at some of the knowledge members have here. ;) Thanks!
time2roll
Nomad
Jan 07, 2017
joem789 wrote:
because my old charger had problems charging 4 batteries, I had taken 2 of them off for the time being. So with this new unit, it is charging 2 batteries.

Get the second pair reconnected asap for best results.
BFL13
Explorer II
Jan 07, 2017
Joel_T wrote:
BFL13 wrote:
If you are on shore power as it seems, then the converter will first run everything "12v" in the rig, and whatever amps are left over out of the 55 amps (simple explanation of voltage diffs etc) will go towards battery charging.

Hadn't really thought of the implications of that factor. Can converters only do their bulk and absorption modes properly if all 12volt drains are removed. Seems that amps irregularly lost to 12v draws would screw with any logic built in to the converter.

Not exactly. The 14.4 and 13.6 should not be affected, just the amount of amps to the battery.

The PD "bulk" and "absorption" are just voltage output levels, 14.4 and 13.6, NOT to be confused with battery charging stage "bulk" and "absorption" terms. ( I think I got things mixed up there a bit earlier about the 4 hour timer in the Charge Wizard" for how long it stays in "bulk" too. )

The amount of 12v being used by the rig does affect the PD between the 13.6 and the 13.2 though. If using any 12v, it stays at 13.6. 13.2 happens when your rig is not being used but has shore power.

BTW until you get that digital multi-meter, I hope you are using the voltmeter display on your solar controller to tell you something about what is happening with your batteries.
RJsfishin
Explorer
Jan 07, 2017
Joel_T wrote:
BFL13 wrote:
If you are on shore power as it seems, then the converter will first run everything "12v" in the rig, and whatever amps are left over out of the 55 amps (simple explanation of voltage diffs etc) will go towards battery charging.

Hadn't really thought of the implications of that factor. Can converters only do their bulk and absorption modes properly if all 12volt drains are removed. Seems that amps irregularly lost to 12v draws would screw with any logic built in to the converter.

Maybe you are over thinking the whole thing.
Seems to me that is would be just the opposite.
The converter puts out only what it is asked for. If no 12v loads, and batteries charged, it would put out bare minimum in float mode.
What I really like about my PD converter, is that I don't have to think about how it works.
But I do have a Volt/Amp meter in plain view, shunted into the positive "out" of the converter, just to make sure everything behaves itself, and to know when to shut down the generator on those cloudy..... short on solar days.
Joel_T
Explorer
Jan 07, 2017
BFL13 wrote:
If you are on shore power as it seems, then the converter will first run everything "12v" in the rig, and whatever amps are left over out of the 55 amps (simple explanation of voltage diffs etc) will go towards battery charging.

Hadn't really thought of the implications of that factor. Can converters only do their bulk and absorption modes properly if all 12volt drains are removed. Seems that amps irregularly lost to 12v draws would screw with any logic built in to the converter.
time2roll
Nomad
Jan 07, 2017
Consider a low cost panel meter to mount near the converter in the RV.
ebay has tons of them.

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Help choosing the right converter/charger?

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