EC850 Battery Upgrade
#1
Any suggestions for a replacement for the group 24 batteries in my 2010 EC850? The door opening is 7-3/4 X 11-1/2 (WxH), and the compartment is 26-3/4 deep. However, the corners are rounded, so the maximum inscribed rectangular opening is slightly smaller. It looks like the compartment would hold group 31 or 6V GC, if you were to make the connections with the batteries outside and then stuff/tip them in.

What's the maximum AH battery anyone has managed to put in the 850 (or other, if the compartment size is the same)?

Regards,
Nick
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#2
I can’t speak for the 850 but by removing the sliding battery tray on my 995 I was able to fit in two 6v GC’s..While removing the tray makes battery watering the most difficult of endeavors, I added an automatic watering system from Camping World that makes this super easy with batteries in place...

The nice thing about sixers is that since they are ‘true’ deep cycle batteries, they can safely be brought down below the standard 50% SOC (state of charge) without suffering any long term damage...What this means is that while the total (or gross) amp/hr capacity may be the same as with 12v types, the ‘usable’ or available amp/hr capacity is greater while the footprint is the same....

Golf carts can regularly drop down to nearly 80% DOD (depth of discharge), and recharge to recovery at days end without a hitch (though I don’t normally use or need this much capacity), thus 200 amp/hrs total could provide about 160 amp/hrs of ‘usable amp/hrs’ versus 100 usable amp/hrs with a 12v....

Note too that most so called (advertised) 12v deep cycle batteries are really of a hybrid design, thus still considered to be starting batteries rather than true deep cycle...FWIW,

3 tons
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#3
Yeah - I'm sold on the advantages of the 6V GC batteries, I just need to find a set that's small enough to fit. My battery compartment doesn't have a slide so there's no room to gain. I think the Trojan T-105 is too tall, and so is the Duracell equivalent that Batteries Plus sells. 

Amazon has the NPP 225 AH 6V AGM listed for $440/pair (free shipping) and they have the right dimensions. Any info on these? I can't find many reviews. 

https://www.amazon.com/gp/product/B077KK...M6NIMLYBIZ

Nick
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#4
I’ve never tried AGM’s but from what I understand they also have a DOD equivalent to flooded wet cell GC’s, and that they seem to be compatible with the algorithms of the EC’s Progressive Dynamics charger converter.... More money, but you’d save about $50 on the watering system...You might double check this with PD...

3 tons
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#5
3 tons,

Would you mind telling me which GC batteries you use? Most that I've seen are at least 10.5" tall, and I'm not sure if that's to the top of the case or the top of the terminals. I'm drawn to the AGMs that I mentioned mostly because they're 6V and they'd fit my compartment. I'm open to anything that's an improvement on my group 24 pair. I think I can fit group 27, but I'm pretty sure group 31 is too long, or right on the edge (2x13" in a 26.5" compartment). 

Nick
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#6
Sorry for my belated response, just returned from a brief road trip...

My GC’s measure about 10.75” to the top of threaded post, and my battery box measures about 12” x 13.5” usable opening and two GC’s deep...

I’ve tried more expensive makes but now just running Costco GC’s (208 amp/hr gross) for about $85 each...I’ve had zero issues with these and they will even run my 11k btu air cond (via inverter) during brief roadside stops of an hour or so (compressor cycling) - because of the reliability (over three years old) and uber high bang for the buck, I wouldn’t hesitate to buy them again...However, AGM’s may be a bit shorter so a better option for your needs...

3 tons
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#7
No worries and thanks for the info. 

There's a Costco nearby; maybe they'd do a test fit. Even if the batteries go in, the next trick is connecting them. I might have to extend the cables so I can make the connections outside the compartment. Do you think a 24" extension (same gauge wire) would adversely affect the current flow?

Those AGMs look like a good option, but I can't find much feedback from people who've bought them.

Nick
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#8
Understand that with low voltage DC, the voltage drop that naturally occurs in cables can become an issue where cable is undersized or of excessively long runs, thus it’s best to keep cable lengths as short and as heavy as practical... You may not ever notice this (or not an issue) unless using a high current device like a medium to large size inverter where a drop in voltage (due to cabling bottlenecks) of around 1.2v equals a whopping 10% (< >) drop in voltage - not so good for 120v appliances, just saying...

3 tons
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#9
BTW, I think that the real value to AGM’s are that the require no watering, produce no H2 off-gasses (so can be installed in the interior and even on their sides), and have a faster recharge-recovery time (i.e. less internal chemical resistance) which can be benificial during seasonally shorter (or at higher latitudes) peak solar harvest times...JMO

In my case, having 440w (gross) of solar means fairly rapid recovery times (net) even with conventional wet-cell batts, and during inclement weather... Nowadays, solar is less costly and a fair alternative...

3 tons
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#10
So extending the battery compartment cables shouldn't be an issue until I decide to add an inverter, and I can re-cable with a thicker gauge at that time, if necessary. Does that sound reasonable? 

I'm also exploring the possibility of using AGMs stored in the basement ski tray, since fumes aren't an issue. The access door isn't very tall, but I might be able to tip them in. 

Nick
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