Battery charge rate on shore power ?

[iceclimber]

Hi, my converter says it's the 55amp model, does anyone happen to know at what amp rate it will charge the batteries at when I am plugged in ?

[ScottBrownstein]

Maybe 20 amps when the bank is below 80%, after 80% maybe 7 amps or less. Of course this depends on if you have a converter that will stay in boost mode (PD converters are pretty good at it) They say 4 hours...and there it is!

Here is a real test starting from 66% SOC and running up to 88%. This was a PD9270 that was manually forced into a 4 hour boost cycle. 4 12 volt batteries in house bank. I have a very long feed from the converter to the bank and it is only #8 or #6, so you can see I would do a lot better if I upped it to maybe #4 or larger. Costs me a more than a volt at 35 amps.

[iceclimber]

Interesting, so it's pretty capable. The reason I am asking is when I use my generator, does it make more sense to hook it directly to a battery charger or to the trailer. Thing is stand alone battery chargers only push so much unless you go to like a 30/40 amp Xantrex and they ain't cheap,

I'll hook to the trailer I guess.

[babock]

The best thing to do is relocate the converter close to the batteries so you have low voltage drop.

[Flybob]

Some of the generators do not recommend using the 12V output to charge the battery. In general you are best off to connect the RV power cord to the generator and let the converter charge the battery.

[iceclimber]

Not sure what you are referring to. I've never seen a generator with a 12v output. I was talking about using a battery charger plugged into the generator.

[bikendan]

Originally Posted by iceclimber

Not sure what you are referring to. I've never seen a generator with a 12v output. I was talking about using a battery charger plugged into the generator.

Most inverter generators have 12v charging cables but it's the slowest way to charge the battery.
Using jumper cables to the TV battery is faster.

[iceclimber]

So now you made me go look, and sure enough it has a 12v socket and a couple small bayonet plugs, so I learned something.

I'd never use those. Idea is to push maximum amps at my 230 Amp hour batteries and that's either a Xantrex or the trailer plug in, which is what I have traditionally used. At the end of the day my generator is 30 amps anyway.

[camaraderie]

Your generator is 30 AC amps..or roughly 300 DC amps!
Your converter is capable of putting out 55 DC amps into a battery bank with large wiring and close proximity.
If you have 230 amp hour batteries (2x6V??) you probably CANNOT push more into them than 46amps even with a 100amp charger...and that would only be for the first couple of hours in bulk mode before they settle into absorbtion and then float mode.
Wetcell Batteries can only take about 20% of their rating in charge current.

So..you have all the charging capability you need right on board. If you get a battery monitor (which you should have if you boondock ...see Victron or Trimetric)...or if you get a clamp on DC meter ...you will be able to read instantly what is getting to your batteries including most other stuff ...(when do I need to recharge, when can I stop charging, how much longer can I use this stuff before needing to recharge, what charge stage am I in, how many amps does my blender use etc.) NOTHING else will tell you this stuff about IN USE batteries.

[Larry-NC]

Originally Posted by camaraderie

If you get a battery monitor (which you should have if you boondock ...see Victron or Trimetric)...or if you get a clamp on DC meter ...you will be able to read instantly what is getting to your batteries including most other stuff ...(when do I need to recharge, when can I stop charging, how much longer can I use this stuff before needing to recharge, what charge stage am I in, how many amps does my blender use etc.) NOTHING else will tell you this stuff about IN USE batteries.

I still have an old -50/0/+50 amp ammeter I used in a with only idiot lights back in the early 1960s. I've got heavier leads on it now, and can put it in series with a battery charger or converter and the batteries. It's a Stewart-Warner with a nice chrome bezel, white on black face.

I was just looking to see if these are still available--a really inexpensive way to see what's going on. I found this one.

Larry

[camaraderie]

Originally Posted by Larry-NC

I still have an old -50/0/+50 amp ammeter I used in a with only idiot lights back in the early 1960s. I've got heavier leads on it now, and can put it in series with a battery charger or converter and the batteries. It's a Stewart-Warner with a nice chrome bezel, white on black face.

I was just looking to see if these are still available--a really inexpensive way to see what's going on. I found this one.

Larry

Yeah...that will show you the charge current but it won't show you what is going on with the batteries or individual items or any of those questions I posed for a real monitor...Still at 16 bucks you at least know a bit more!

[babock]

The problem with those is you have to run the wires to the gauge which will cause to you to have a huge voltage drop unless you use extra heavy duty cables to account to the run to the gauge.

[Larry-NC]

Originally Posted by babock

The problem with those is you have to run the wires to the gauge which will cause to you to have a huge voltage drop unless you use extra heavy duty cables to account to the run to the gauge.

You couldn't put it right on the batteries with heavy 4" pigtails on both sides?

A little inconvenient to read but you don't need to check it every time you use the battery, just now and then to see that the converter is behaving properly.

For what it's worth, in the Cherokee, the converter (and its battery connection) is located on the forward bulkhead of the trailer, just below the TV. The batteries are located about three feet forward, on the tongue. It would be pretty easy to mount the meter without lengthening the cables at all.

The converter on our older trailer is mounted under the sink, about midships. I don't know why they did that since the bed is all the way forward and they could have easily mounted it there. That's not a mod I'm likely to make soon. Too much work and I have to replace most of the roof decking and a few trusses first.

Larry

[Skyliner]

Voltage losses from thin wiring at distances too far from batteries result most converters unable to bulk charge a battery at the necessary higher voltages. In my RV, the voltage loss was 0.4 volts!

Anyway, the best thing you can do is move your converter within several feet of your batteries.

A trimetric battery monitor or Victron is a must if you are serious about battery usage. The majority of people who camp with plug in power really don't need to ever worry about their batteries.

[babock]

Originally Posted by Larry-NC

You couldn't put it right on the batteries with heavy 4" pigtails on both sides?

You could do that.

For the low price that Victron battery monitors run, I would never put in something like that.

I got my Victron BMV-712 with builtin bluetooth for $185. Hard to beat that.

[iceclimber]

I am not moving my converter, seriously.
Simple question was best way to charge the batteries with my generator. I will hook it to the trailer. Thanks all.