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Electrical Discussion of preventative/corrective maintenance and other technical issues regarding your coach's electrical system.

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Old 02-20-2019
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ICBM99 ICBM99 is offline
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Default Battery Quandry

So I've ruined another set of flooded lead acid batteries. I just cant seem to remember to check the water levels. So I need to swap to AGM's.

Some time before I owned the bus one of the previous owners combined the house and chassis batteries. Well technically there is a disconnect switch that lets you select bank 1 or 2 or 1+2 or "off". Anyway I was told to just leave it in 1+2 so that everything gets charged. We very rarely boondock, and are almost always plugged into 50A service. So my original thought was to just get 5 group 27s or 31s AGM Deep Cycle, and leave all 5 tied together. But have been reading that starting with deep cycle may not be good for them, and will shorten their life. I know they also make a "dual" purpose agm which might fit the bill.

After reading a bit on here, it seems the best solution is 2 12v starts in parallel, and then a set of like 6 6v deep cycle in series/parallel. Is there a way to set them up so they get charged when running/plugged in, but not run down the start batteries if we boondock without a manual disconnect.

Or I can just go AGM start batteries all around to save money and know I wont have a ton of boondocking reserve.

I'm also looking for a way to isolate the generator start battery. Right now its connected and disconnected via a "blade" switch, which is a pain in the...I would like to make sure it's charged, but that it doesn't get discharged when boondocking.

What would y'all do?
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Old 02-20-2019
badandy badandy is offline
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1) starting usage on a deep cycle does not harm them in any way
2) dual purpose batteries are not good at starting and not good at deep cycling

The right way to isolate two banks is to use an Eaton battery separator, such as the 1315-200. This thing combines the battery banks for charging, but when you're stopped it will isolate the starting batteries from being discharged. It also allows you to connect the start wire to the unit so that it will combine both banks for starting with all the batteries, if you want to.

Whatever you do, I would suggest buying all the same. If you truly rarely boondock then just get all starting batteries to save some money. If you want to be able to boondock longer then I would get all deep cycles. Deep cycle AGMs are big money.
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Old 02-20-2019
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Thanks Andy. I guess I need to sit down with the wife and decide if we want to do any boondocking in the foreseeable future. No doubt getting all the same. I have a Magnum 2800 inverter/charger with AGM setting, so if I changed it would be all, including the generator battery.
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Old 02-20-2019
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Default All AGM’s or Mix Them?

Quote:
Originally Posted by ICBM99 View Post
... After reading a bit on here, it seems the best solution is two 12v starts in parallel, and then a set of like 6 6v deep cycle in series/parallel. Is there a way to set them up so they get charged when running/plugged in, but not run down the start batteries if we boondock without a manual disconnect.

Or I can just go AGM start batteries all around to save money and know I wont have a ton of boondocking reserve...

What would y'all do?
My recommendation would be to NOT mix battery types between the coach and engine starting. Initially, I did and had nothing but problems. So...

Go with your “best solution”. That’s exactly what I did HERE (starts around post #57). Notice that I used both -31 & L-16s, 12v & 6v. If you use all the same manufacturer (FullRiver), battery type (AGM) and battery series (DC’s), charging them all connected at 12v with your Magnum MS2812 will work great! This design will allow you to connect both banks without worrying about a separator, because they use the exact same charging profile. If you are worried about running your start batts down when off-grid, you could separate them without an issue. Just don’t forget to recombine them after starting up. Although I chose very large L-16 sized coach batteries, you could easily downsize yours (since you say your don’t boondock much), while realizing you would also have less capacity. You would of course buy the form factor your battery tray requires. This would save you some $$. We boondock allot and can vouch for this setup. IF you go this route, DO NOT use one of the two Magnum “”standard” charging profiles. You should instead use the Custom Charging Profile and enter the specific charging numbers that your battery manufacturer recommends. “Custom” is another much more accurate charging option with the Magnum. I have been very happy with the FullRivers “on” a Magnum. They come with a 7-year warranty and are quite a bit less $$ than Lifelines. Notice you’re in Texas. Have you tried Metroplex Battery? Excellent prices and they might be close to you. Even if not, it’d be worth the drive!

If you end up going this route and need advice on which to buy, wiring or setting up the charging profile - PM me.
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Old 02-20-2019
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Quote:
Originally Posted by NoGas View Post
This design will allow you to connect both banks without worrying about a separator, because they use the exact same charging profile. If you are worried about running your start batts down when off-grid, you could separate them without an issue. Just don’t forget to recombine them after starting up.
The Eaton 1315-200 does all of this for you automatically. When one bank or the other has charging voltage applied the contacts close so both banks charge. This works with the inverter/charger, 120v charger, alternator, anything. When the charger stops charging and the voltage settles on the batteries it will separate the banks again. If you want starting assist you just connect one wire to the device and it will combine them again just when cranking.

If you want an additional layer of CYA you would also install a separator for the generator battery because it's really a 3rd bank. Again, it's all automatic.
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Old 02-20-2019
rrueckwald rrueckwald is offline
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Just as a slightly related issue, do not be fooled by the round marine selector shut-off switch which shows 1 or 2 or 1+2 or off. If you have one cable in and one cable out, it is only working on one bank. Why BB did this we'll never know, but it has fooled a lot of people. It is best to have a switch for each bank, just in case you need to shut one off in a hurry.

I use AGM's for the house, and lead-acid no maintenance (NOT gel cells) for start (chassis) batteries. They can be charged together. Gels cannot be charged with AGM's. I was planning to use AGM's for start also, to get away from the corrosive gas coming from flooded lead-acid batteries , but the dealer (on this forum) said I would be wasting money and should go to NAPA to get the no maintenance batteries for the start bank. Good advice. Have worked well on two buses.
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Old 02-28-2019
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So I ended up getting Duracell platinum agms from Sams. If I remember correctly those are made by penn east/deka. The only technical data I could find on the Duracell’s was in German. I can use the deka charge profile right?

I thought I had group 31’s, but turns out they were 27’s, and there just wasn’t really a good way to fit 31’s without major modification.

I’ll probably get going on the isolators Andy suggested in a few weeks.
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