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Battery: Concorde vs. Odyssey or others

John Owen

Well Known Member
Hello,
My RV-8 is acting like it needs a new battery. The Concorde that is in it is almost 4 years old. If I don't leave the battery minder connected and it has been a few days, it will barely move the prop. If I keep after it, sometimes, after 6-8 tries of 1 blade, I will get 2 or 3 blades and it will be enough to start it, sometimes not. A couple of days ago, my AFS showed 12.2V when I powered it up.

I have looked and disconnected everything that I think could be a parasite draw and it still does it.

I have read through seemingly countless VAF threads about various batteries. I have the standard battery box on the firewall. I am not sure that the Odyssey 680 will fit in the box due to the height. I found the Odyssey 925 that looks to have the same dimensions, weight and better power than my Concorde RG 25XC and is over $100 less expensive. The powersport reviews look great.

Any advice about this situation? I don't want to be stranded someday because I delayed the replacement decision or buy the wrong battery.

Thanks,
John
RV-8, purchased built
 
A lot of -10 owners use the Odyssey 925. So it seems like overkill (and over-weight) for a 4 cylinder engine. There?s another 6xx Odyssey that should fit, I forget the number.
 
4 years is about right for most SLAs.

The 925 is great, just make sure you get the matched post polarity. I find I always need an adapter stackup in a Concorde RG25XC box.

I like the Deka line, too. ETX-30L, you may have a local source. Will take some shimming, 5x6.5x1 inch from my notes.
 
A quick look at dimensions; seems the 925 is a lot wider; by ~1.6". Will it fit?

Have you looked at the PC625? Lighter (no metal jacket) and higher AH than the 680.

My personal preference is one of the 'no name' SLAs. Typically about half the price of an Odyssey and comparable performance (for me, anyway).
edit: One example; one of the 1st I hit doing a search:
https://www.bigtimebattery.com/store/ps625235.html

Charlie
 
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wingx

Take the time and look at the EarthX batteries, They have a computer for each cell for protection and have more current and are much lighter.
 
Direct substitute for the RG-25X/C:

https://www.gruberpower.com/12-volt-35-amp-hour-ah-battery-elite

Less than 1/3 the cost.

The terminals are reversed but the battery can be flipped around.

Works great if you need the weight up front.

That really is just about a direct replacement and a lot less expensive. I don't really need the weight up front, though. Getting this one would save me from having to do a new weight and balance and give me some more capacity than the Deka. Even with shipping, it will be about 1/3 the cost of the Concorde. That is 5+ hours of avgas! Bob, have you used this battery?

Thank you.
John
 
Yes I have used that battery multiple times and multiple sizes. They have another one thats a direct replacement for the smaller Odyssey thats only $40. I've been very impressed by them.
 
Yes I have used that battery multiple times and multiple sizes. They have another one thats a direct replacement for the smaller Odyssey thats only $40. I've been very impressed by them.

Sounds good. Even with shipping from Phoenix to KC, it was right at $100. This is a great online community. Thanks, again, to everyone for their help.

John
 
Bob,
Have you ever tried B&C battery https://bandc.com/product/sealed-recombinant-gas-battery-12v-16ah/ what's your opinion on those? I am replacing my 680 every two years with a new. Wondering if this one would last longer.

Vlad no experience with that one but I've replaced Odysseys with these:

https://www.gruberpower.com/12-volt-18-amp-hour-ah-battery

The terminals are slightly different but no big deal. I have one that's three years old and still cranks like new.
 
Vlad,

SLA batteries are no longer 'rocket surgery'. Just about any of the 'off brand' SLAs will work, if you know what to look for. The biggest difference among the SLA offerings is their intended use. The ones listed for wheel chairs, mobility scooters, and UPS (power supplies) tend to have a higher 'source (internal) impedance/resistance', but most with AH ratings above ~16AH will crank a Lyc just fine. SLAs with their chemistry tweaked toward starting duties will have lower source impedance.

The one Bob linked has 16 milliOhm source impedance, while an Odyssey PC680 is rated at 7 milliOhms. Lower is 'better' because it can supply more current to a near-short like a starter motor, but remember, 'Better is the enemy of good enough'. I have no doubt that Bob's recommendation will work, because I've used similar batteries to crank Lycs.

There are SLAs with AH ratings up to around 22AH, if you do some digging, that will fit in a PC680 battery box. The higher AH batteries can have significant advantages over a PC680 if you have an electrically dependent plane & only one alternator. In a relatively slow discharge situation, they will have significantly more *energy* (as opposed to *power*) to keep electronics alive in an alternator-out situation. The PC680 is 16AH, so if you bought a 20AH it would have ~25% more capacity (run time) than the Odyssey to keep your electronics awake.

I had a 22AH model in my -4 for about 4 years. It started to seem a bit 'weak' for starting, so I ordered a replacement. When I removed the connections on the old battery, I discovered that I had some corrosion on the terminals. Turns out, the battery was fine; just not getting a full charge or able to deliver full power to the starter, due to the corroded terminals. (I should have known better; chasing defective electrons was my living in a couple of past lives.)

edit: a couple of examples:
https://www.apexbattery.com/ub1220-12v-22ah-battery.html?gclid=Cj0KCQjw9JzoBRDjARIsAGcdIDUINMhDwodc8FXFKtcyPLmFb-4zVVqbNJWcNUDCC6MHgRs56mlRB3waAg3CEALw_wcB
or
https://www.apexbattery.com/adventure-power-ub50-n18l-a-battery-12v-22ah.html
or
https://www.osibatteries.com/p-14793-csb-evh-12240-battery-12v-24ah-sealed-lead-acid.aspx?gclid=Cj0KCQjw9JzoBRDjARIsAGcdIDW40m288cSRCGjEekNSr4Lj7dcS9EZ566ogEWU6LU8IkK8MRqf_2j4aAkwpEALw_wcB

I've bought from Apex in the past and gotten good service from them and their batteries. Never bought from OSI, but I probably wouldn't worry about doing a paypal or credit card purchase with them, either. There are many other sources, as well.

Charlie
 
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The one Bob linked has 16 milliOhm source impedance, while an Odyssey PC680 is rated at 7 milliOhms. Lower is 'better' because it can supply more current to a near-short like a starter motor, but remember, 'Better is the enemy of good enough'. I have no doubt that Bob's recommendation will work, because I've used similar batteries to crank Lycs.

While the battery impedance is low for either battery the contactor and cable impedances are much higher which makes the battery impedance insignificant.
 
I put an Apex 30L-BX in my -10. 30 AH, 440 CCA for $70. I can throw it away every year for a fraction of owning a Concorde or Odessey. I need the weight in back for CG. YMMV
 
Direct substitute for the RG-25X/C:

https://www.gruberpower.com/12-volt-35-amp-hour-ah-battery-elite

Less than 1/3 the cost.

The terminals are reversed but the battery can be flipped around.

Works great if you need the weight up front.

Follow up on this is that it is "almost" the same size as the RG25XC. It is about an 1/8" longer....just enough that it will not fit in my battery box. It is very precisely made for the 25XC. I didn't build it but enjoy working on it but didn't think that it would have that tight of tolerances. After a lot of head scratching, knuckle scratching, collusion with hangar neighbors and consternation later, I think that I am going to have to get another battery.

I appreciate the help and advice and thought that I would pass this along to potentially help someone else. Just check that battery box size very closely!

Thanks,
John
 
Follow up on this is that it is "almost" the same size as the RG25XC. It is about an 1/8" longer....just enough that it will not fit in my battery box. It is very precisely made for the 25XC. I didn't build it but enjoy working on it but didn't think that it would have that tight of tolerances. After a lot of head scratching, knuckle scratching, collusion with hangar neighbors and consternation later, I think that I am going to have to get another battery.

I appreciate the help and advice and thought that I would pass this along to potentially help someone else. Just check that battery box size very closely!

Thanks,
John

I wonder if this one would have fit better. The dimensions look to be slightly smaller.

https://www.gruberpower.com/12-volt-26-amp-hour-ah-battery-elite

I am having trouble hitting that "buy" button for $300 for a Concorde......
 
And don't be afraid to oversize a battery box by a bit. Properly strapped down, it'll never move side to side or fore/aft unless it's the last thing to get 'rearranged'.
 
Follow up on this is that it is "almost" the same size as the RG25XC. It is about an 1/8" longer....just enough that it will not fit in my battery box. It is very precisely made for the 25XC. I didn't build it but enjoy working on it but didn't think that it would have that tight of tolerances. After a lot of head scratching, knuckle scratching, collusion with hangar neighbors and consternation later, I think that I am going to have to get another battery.

I appreciate the help and advice and thought that I would pass this along to potentially help someone else. Just check that battery box size very closely!

Thanks,
John

The battery box can't be removed and slightly modified?
 
Just going by the specs, the Gruber is slightly smaller

in all dimensions--- not that I have ever read specs wrong
 
I don't get where you get the Gruber is 1/8" longer. It is not. I just installed one last week in a customer airplane and it fit slightly looser than the Concorde it replaced as expected.
 
I don't get where you get the Gruber is 1/8" longer. It is not. I just installed one last week in a customer airplane and it fit slightly looser than the Concorde it replaced as expected.

Bob,
You are right on paper but side-by-side the Gruber that I received is slightly longer(???). I had a mechanic friend there with me staring it down and both of us trying several times to get it to fit the space that the RG-25XC came out of. I think that I will just get a longer carriage bolt, wiggle it some more and see if I can't get this one to fit. Where it is located is a very tight fit on the firewall, anyway. Maybe, I am doing something wrong. I'll keep trying.

Thanks for the advice, I really appreciate it.

John
 
John,

Have you measured the battery you received, and compared with the advertised spec? That might be your best starting point when looking for a solution. Gruber might be willing to work with you if the battery is out of spec.
 
John,

Have you measured the battery you received, and compared with the advertised spec? That might be your best starting point when looking for a solution. Gruber might be willing to work with you if the battery is out of spec.

That is a good idea. I measured both batteries and took pictures of the two. There is a clear 1/8th inch difference on the battery that I purchased with the Gruber being longer than the Concorde and the dimensions of the Gruber on their web page.

However, all is well that ends well. My hangar neighbor came up with a high density rubber pad that has belts in it like a tire without the tread. I cut a piece to fit in the battery tray and the battery sat down squarely on it with all of the fittings perfect without getting new, longer hardware. I got it connected and it shows 12.3V on my AFS 5600 right out of the box. Rerouting the wires to accommodate the reversed positive/negative side on the battery took a few minutes but it all fit. I had to leave before I got it all buttoned up but it looks like it is going to work perfectly.

Thanks, again, for all of the suggestions and help. It made a difference.

John
 
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