Short battery life. Kirkland battery quality or system?

Bikersmurf

Expedition Leader
Started out with bad diodes in the alternator when I bought the rig. I lucked out and got a new OEM Ford one for $300. Screaming deal since they retail for $859 (and no stock in North America).

The starting batteries have no parasitic drains. House batteries don't get drained if I don't leave the fridge on. I can even leave the inverter on without draining the house batteries. Before sinking a ton of money into other things, I'll convert to LEDs and get a more efficient fridge... although I'll need to win the lottery to afford close to a grand for a good fridge. I have a mini bar fridge I may use when on shore power... and the ice in the freezer will keep things cold when unplugged.
 

Bikersmurf

Expedition Leader
I have an option to buy a used set of Sonnenschein A602/250 2V batteries for very little. Any recommendations on how to check their condition?

I don't want to waste money on them but if they haven't reached their end of life, they are rated for @ 250 AH which would provide tons of power.
 

dwh

Tail-End Charlie
Charge properly. Then discharge at known rate to determine true amp*hour capacity. Compare resistances under various conditions to factory specs.

They probably have a technical doc about how to test them.

Seems like a lot of work and wiring for used batteries. Trojan T-105 6v are rated 245ah IIRC. Get a couple and wire in series and call it a day until they need replacement, which will be easy and fit in the same space with the same wiring.
 

SoCal Tom

Explorer
You may want to look into a Dorm room fridge if you are plugged into shore power as much as you say. A decent one should pull in the neighborhood of 50AH per 24 hours. If you are plugged in for 12 hours, then you would only be using about 25 from your battery bank. Of course you would need an invertor that can handle the starting amps, but there are several folks at tnttt that swear by this method.
Tom
 

Bikersmurf

Expedition Leader
I have a newer dorm fridge that had a faulty thermostat. It wasn't shutting off and was freezing everything. Made a good freezer. I'm waiting for a new thermostat I've ordered to get it working.

I have a 2000 W Inverter that can handle 3000 (or 4000) W surge which should cover it.

Asking price for the used batteries is $200 and they'll entertain all offers "they want them gone ASAP"... for $100 they could either be worth it or they could be an expensive set of paperweights. I've not yet found much on testing... mostly that they'll suffer harm if they're left below 2.04 V for long periods of time. Other than that, they'll last for very long periods of time with minimal/no charge loss.

50 AH for 24 hrs would make it so I'd be good for a couple days without any form of charging... with even 100 W of solar, that would be stretched out a lot.
 

Bikersmurf

Expedition Leader
Big. About 14" tall and 45 lbs each. They'll fit in the existing battery
Box without much effort... they'd weigh roughly twice as much as the two 31 series they'd replace. Or I'd mount them on the side that's roughly 700 lbs lighter and keep the current house batteries also.

An extra 100 pounds wouldn't be noticed in a 9k lb dual Type III Ambulance... and space isn't an issue.
https://www.tayna.co.uk/industrial-batteries/sonnenschein/a602-250/

Looks like they are good for up to 275 AH
 

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Bikersmurf

Expedition Leader
Proper 20-hour load test, only accurate way.

​Search for "20 hour capacity test" here https://marinehowto.com/programming-a-battery-monitor/

Better yet, read it all, and check out the rest of the site.

If the bank tests over 85% of new rated capacity, pay half or less of the new price.

If under 70% hardly worth the trouble even if free.
Thanks

They are stupid expensive batteries. They'd cost about $2k for a set... so $200 obo is nearly free... but not worth it if they're crap.
 

john61ct

Adventurer
Thanks

They are stupid expensive batteries. They'd cost about $2k for a set... so $200 obo is nearly free... but not worth it if they're crap.
If your test shows 80% residual capacity, means maybe a few years service life left, that would be a bargain worth jumping at. You might even get 5+ if you coddle them as per mfg specs.

But only if local to you.
 

Bikersmurf

Expedition Leader
They are local... about 20 minute drive. Seller hasn't responded to either of my emails. They're likely gone/sold.

I'll keep my eyes open for deals, but in the meantime I'll run what I've got.
 

john61ct

Adventurer
In my experience 2nd-hand batt deals are very rarely worth pursuing unless you personally you know their history, owners often grossly overvalue their worth.

Unless a friend or kind soul's practically giving them away. . .
 

Bikersmurf

Expedition Leader
Agreed. Sometimes deals (or better values) can be found on new. Usually most shops around here give a special treatment that involves bending over a barrel.
 

calicamper

Expedition Leader
As a side note larger capacity doesnt really sound like its needed. You just need the correct charging method to keep the batteries happy.
 
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