New RV'r - Batts + Chargers + Inverters = clueless

[tsweez]

First, I am a newbie in every sense of the word. New RV'r and new to the forum. So if you see any flaws in what I'm trying to do, please let me know.

I recently purchased my first RV. A late model, 91 Mallard Sprinter. Eventually I'd like to have it setup with solar, an inverter, and enough batteries to hold me for several days. But for now, I have a generator and a dead 12v coach battery in the engine compartment.

I thought that rather than replace the existing 12v, I'd build a vented battery enclosure in the basement area adjacent to the generator. The idea is to start with two 6 volt Trojan T105's or similar and have enough room to add two more once my battery needs become a bit clearer.

My first challenge is to better understand what I need to do as it relates to the simple relocation of the exiting battery to the new location. I know the existing coach battery charges via the generator and the engine via some form of isolator, but I'm clueless what I need to do to simply replicate these functions once I move to the new coach battery location. Any feedback is most appreciated.

For reference, the plan is to add a 1500w PSW inverter, battery charger, and transfer switch (All GoPower Products). The goal is to:

- Draw and charge from shore power when plugged in
- Draw and charge from gen when running
- Charge when engine is running
- And eventually, charge from solar

But all that comes once I simply setup the new battery config.

Thanks again, and kudos to all of you for having such a great community here. The information has been absolutely invaluable.

Thanks,

Tim

[tsweez]

Both are great suggestions.

I'll revisit the bracing issue but I do have a brace on the bottom of that part of the compartment. Albeit not much of one. I was also considering somewhat of a backwards approach as well. I currently have 3/4 inch ply which is secured to the floor. I thought of anchoring some stranded aircraft cable to the battery platform to the subfloor above. That might take some of the pressure off in the event of a catastrophic failure.

As for the sponge idea... I'm on it!

Cheers,

Tim

pianotuna wrote:
Hi tsweez,

Nice job.

You may need to add (weld?) a bracket under the entire storage cabinet. The compartment was not designed for that amount of weight. It would not be nice to have the batteries detach from the RV while trundling down the road.

I "hid" my air vent on the rear side of the compartment and used a sponge to keep dust and dirt out. That let me put the vent up a bit higher than if I had gone through the door. I'd suggest covering the "back side" of your vent with some thin sponge to keep out dirt as well.

[pianotuna]

Hi tsweez,

Nice job.

You may need to add (weld?) a bracket under the entire storage cabinet. The compartment was not designed for that amount of weight. It would not be nice to have the batteries detach from the RV while trundling down the road.

I "hid" my air vent on the rear side of the compartment and used a sponge to keep dust and dirt out. That let me put the vent up a bit higher than if I had gone through the door. I'd suggest covering the "back side" of your vent with some thin sponge to keep out dirt as well.

[HiTech]

Nicely done!

[tsweez]

Well, here's where I wrap up this little adventure before moving on to the next (my inverter install). Basically, the scope here was to replace an existing 12v coach battery with 4x6v golf cart batteries, upgrade the power converter and charger, and a battery monitor.

Power Converter Upgrade

As a new RV owner, I didn't even know where the power converter was located (under the fridge) so this was an adventure. The existing Magnetek 6345 had to be replaced in favor of a three stage charger. The recommendation was to consider a solution that would support 75 to 90 amps as to allow for the additional batteries. In doing so, I'd get a faster charge. But as with anything else, life is about tradeoffs. In the end, I opted for an easy replacement, e.g. the Progressive Dynamics PD4655 which is a 55amp charger/converter. The PD4655 is a mostly a direct replacement that also comes with a new DC fuse panel and built-in charge wizard (don't order the wizard pendant, it can't attach). Randy at Best Converter recommended this path and noted that the PD9280 I was considering wouldn't fit. Either way, I'm in for a lesson here. But it's in, and it's working. And for now at least, I'm happy.

Batteries

I didn't go with the Trojan T105's as I had originally planned. Based on price/performance comments regarding Sams Club and Costo batteries, that's the route I took, specifically, Costco. As I recall, each battery was 208Ah with a price of $87 each +$9 core charge. I had our local "Batteries Plus" outlet custom cut each of the cables (welding cables).

• 2/0 went from the relay in the engine compartment to the new battery location.
  
• 2/0 from the batteries to the shunt (for the trimetric monitor).
  
• 2/0 from the shunt to the chassis for ground.
  
• #2 gauge cable was used to wire the batteries together

Creating a new battery bay

We picked a spot for the new battery bay just behind the driver. This would be a short cable run from the isolator/relay making things relatively easy. We had to section off the basement storage compartment as to keep the batteries separate from the other air space. For those who are interested, here's a video I put together of what was done. I'm pleased with how the new bay came out.

YouTube Video: 1991 Mallard Sprinter Battery Relocation Project

Misc Pics

The new battery bay

https://picasaweb.google.com/111643192205869745892/June42013?authuser=0&feat=directlinkBattery bay vent

Trimetric panel install

Thank You

Special thanks to each of you for your help. It really made this process a great deal easier knowing that I had such a wealth of knowledge available. I hope someday I can give back as well.

Best,

Tim

[HiTech]

Does the fork truck rule of 100% of Ah starting rate in amps come into play, or is that only for the more rugged motive batteries?

Jim

[BFL13]

It is all about generator time to recharge the batts. You need lots of amps. 25% charging rate is about right. ie 100a on 400AH capacity bank starting at 50% SOC to 90% in under 2.5 hours. 55amps would be ok with a pair of batts, but is not enough for four batts for fast charging.

OTOH if you only use the converter on shore power then time is not a factor, so a slow charge is ok. But then you don't need much battery either!

[tsweez]

Curious about what you think in regard to PD4655. This was Randy's recommendation. I did shoot him another email about charge times etc. as it was only a 55amp charge controller. At any rate, Randy noted that this product was an upgrade to what I have now. While it looks super easy to install, I'm curious what I might be sacrificing. Here's the URL for the product...

http://www.bestconverter.com/PD4655-55-Amp-Converter-Upgrade-Section_p_352.html#.UZrrIJwSpwM

Thoughts?

BFL13 wrote:
You will note the "Max " in the Go Power converter line nowadays (they used to re-brand Iotas) Now they are PowerMax. Same same except price! IMO Go Power has high prices. Randy and PowerMax has good prices by comparison.

You need high amps to fast charge four batts. The PowerMax 100 would be ideal for the price. It has one disadvantage, in that it drops to 13.7v for Absorption voltage vs 14.2v for Iota. But this has no meaning when on shore power or if you have solar.

On solar, and for some reason like cloudy days, you get down to 50% SOC, then you want a quick shot of gen charging in the morning using your fast charger (the PowerMax 100 amper) and it will get you back to 75% SOC in quick time (an hour or less) then drop to 13.7v and go to slow time at that voltage. BUT, now you are back to 75% SOC and you have all the rest of the day on solar to get caught up so you shut down the gen and go solar.

So IMO (I have a PowerMax 100amper and solar and dry camp with four 6s) you would get no advantage for the higher cost of an Iota 90, plus, and this is very important as mena said, the PowerMax has power factor correction so it can run on an AC 15a circuit.

[BFL13]

You will note the "Max " in the Go Power converter line nowadays (they used to re-brand Iotas) Now they are PowerMax. Same same except price! IMO Go Power has high prices. Randy and PowerMax has good prices by comparison.

You need high amps to fast charge four batts. The PowerMax 100 would be ideal for the price. It has one disadvantage, in that it drops to 13.7v for Absorption voltage vs 14.2v for Iota. But this has no meaning when on shore power or if you have solar.

On solar, and for some reason like cloudy days, you get down to 50% SOC, then you want a quick shot of gen charging in the morning using your fast charger (the PowerMax 100 amper) and it will get you back to 75% SOC in quick time (an hour or less) then drop to 13.7v and go to slow time at that voltage. BUT, now you are back to 75% SOC and you have all the rest of the day on solar to get caught up so you shut down the gen and go solar.

So IMO (I have a PowerMax 100amper and solar and dry camp with four 6s) you would get no advantage for the higher cost of an Iota 90, plus, and this is very important as mena said, the PowerMax has power factor correction so it can run on an AC 15a circuit.

[tsweez]

Thank you for the sentiment. As mentioned in a previous post, it's amazing just how lightning fast the community responds and contributes to the dialog. The level of expertise, and the pace at which you all contribute is key to my projects success. This is pretty awesome.

Best,

Tim

Canadian Rainbirds wrote:
You know, it's really gratifying to see someone who knows what they want to do, researches what they might need, then ask pertinent questions of the very knowledgeable people on this board. You have received suggestions from very a wide variety of helpful people, from experienced solar users to a battery design engineer. Your installation will go much easier for your preparation.

Much nicer to read and respond to than "I put in 1000 watts of solar but my group 24 marine battery won't last the night", or "I installed 6 GC batteries but the 40 watt solar panel won't recharge them".

I thought I knew all I needed to know about batteries and charging until I began doing a little more dry camping. It took me about two years of fooling around and asking questions here to realise that one day I just might learn enough.

[Canadian_Rainbi]

You know, it's really gratifying to see someone who knows what they want to do, researches what they might need, then ask pertinent questions of the very knowledgeable people on this board. You have received suggestions from very a wide variety of helpful people, from experienced solar users to a battery design engineer. Your installation will go much easier for your preparation.

Much nicer to read and respond to than "I put in 1000 watts of solar but my group 24 marine battery won't last the night", or "I installed 6 GC batteries but the 40 watt solar panel won't recharge them".

I thought I knew all I needed to know about batteries and charging until I began doing a little more dry camping. It took me about two years of fooling around and asking questions here to realise that one day I just might learn enough.

[mena661]

tsweez wrote:

I also took some videos of each stage of this process which I'll post on youtube once completed.

Sweet! Can't wait to see them.

[tsweez]

Well, it wasn't so much the heat as I figured there was a pilot light in there. But no big deal, I think I have all this figured out. I segmented part of my basement just behind the drivers door today. Almost there.

I also took some videos of each stage of this process which I'll post on youtube once completed. Perhaps someone else can find some value. Now I need to order my new controller/charger so I don't fry my new batteries.

Almot wrote:
Hydrogen doesn't care if it's hot. It's flowing up no matter what. What it doesn't like is sparks.

[Almot]

Hydrogen doesn't care if it's hot. It's flowing up no matter what. What it doesn't like is sparks.

[tsweez]

Well, Costco had 6v deep cycle 208Ah batteries for $87 so I picked up four.

I also picked up the materials I needed for the battery enclosure. But then I noticed that my vents to the outside would be just below the hot water heater where it's marked "HOT". I assume it's not likely prudent to vent hydrogen here.

So now another evaluation for the battery location. More to come.

Tim