Dual Battery Maintenance - Splitter or 2 chargers?

[Bolter]

Reading old posts, I see that @LANCECASPER has the BatteryMinder with splitter setup for dual 24V batteries.  Does anyone else?  I read reviews of the splitter (other sites) where 1 battery was lost without indication when using the splitter.  I am looking for owners with long term experience using a single charger plus splitter for dual batteries.  

-dan

[ilovecornfields]

I’ve been using the splitter for several years and have had zero problems.

[rbp]

i use the splitter. one of the batteries, however, didn't seem to charge. then I decided to hook one up at a time and it brought the battery back. so, yes, if one battery is bad, you'll only find out when you try to use it. so make sure you're monitoring the condition of each battery independently 

[carusoam]

If you have two identical batteries…

Using the splitter is a practice recommended by the BatteryMinder people…

 

If you have dissimilar batteries… one takes the chance of overcharging one… 

If you don’t use the splitter… always connect the #1 battery (as a priority), as it has all the long term memory devices attached to it…

 

PP thoughts only, not a mechanic…

-a-

[rbp]

in case someone comes to this topic wonder what the resolution is: 

BatteryMinder says that if you have two batteries with a switch, you need 2 kits, one for each battery. The splitter goes between the batteryminder and the two trailer-to-anderson converters (pictured) 

[jaylw314]

AFAIK if you have two identical batteries in parallel, it should work fine.  However, with a 3-phase charger with dissimilar batteries, it has to decide when to change from constant-current to constant-voltage to float voltage, and it will be wrong for one of the batteries.   Practically, it's hard to see this being a huge issue (all batteries are constant-voltage charged while the motor is running for several hours at a time, for example), but I suppose there are some edge cases this could cause a problem.

[Aerodon]

20 hours ago, jaylw314 said:

AFAIK if you have two identical batteries in parallel, it should work fine.  However, with a 3-phase charger with dissimilar batteries, it has to decide when to change from constant-current to constant-voltage to float voltage, and it will be wrong for one of the batteries.   Practically, it's hard to see this being a huge issue (all batteries are constant-voltage charged while the motor is running for several hours at a time, for example), but I suppose there are some edge cases this could cause a problem.

I would say that the airplane running/charging is hard on the batteries, but it is only for say 100hrs a year.  I've bought into the concept that a simple 'battery tender' is not good enough to leave connected to your airplane for the other 8700hours a year.  I believe the temperature charts and voltages set for individual brands of batteries on the BatteryMinder series.  If you have the 2 battery system and use the splitter, one battery will be looked after, the other not so much. How this manifests over time, I do not know.  Golf cart operators have the luxury of having enough batteries in the maintenance shop to put together a balanced set. Google 'battery balancing' and you will see many articles and products.

To me, the point of spending $250 on a Battery Minder is to look after a $1000 battery and extend its life by many years.  So if I had a plane with 2 batteries, I would buy 2 BatteryMinders.  Or experiment with alternating the chargers every / week or month.  I would also use B1 more often than B2 so that I would not be buying 2 new batteries at the same time.  Its not like a golf cart where you are trying to match the capacities.

I've had very good experience with Concorde AGM batteries, typically 8-12 years on a battery.

The only other thing I can add is that the life of you battery is dramatically affected by degree of discharge and operating temperature.

A 20% discharge will give you 3000 cycles.  A 60% discharge will give you 1000 cycles.  Operating at 25C will last twice as long as 35C.

Aerodon

 

[LANCECASPER]

On 1/30/2022 at 6:12 PM, Bolter said:

Reading old posts, I see that @LANCECASPER has the BatteryMinder with splitter setup for dual 24V batteries.  Does anyone else?  I read reviews of the splitter (other sites) where 1 battery was lost without indication when using the splitter.  I am looking for owners with long term experience using a single charger plus splitter for dual batteries.  

-dan

I ended up with an extra Battery Minder and now use one for each battery.

[Bolter]

1 hour ago, LANCECASPER said:

I ended up with an extra Battery Minder and now use one for each battery.

Thanks for that update.  Was there a particular event or new knowledge that drove that change?  

[LANCECASPER]

22 minutes ago, Bolter said:

Thanks for that update.  Was there a particular event or new knowledge that drove that change?  

Long story but had a battery fail, no Concordes available back in March 2020, reluctantly bought a Gill 7423 and a battery minder for that battery. Gill failed in a little over a year. Bought a new Concorde and had the other battery minder converted to an -S5 for the Concorde.