I have a 12v 700CCA 90Ah car battery with a odd behaviour. The loadtester says its performance are good and the readings are around 800 amps starting capacity. The digital batterytester says it good with a SOC of 70%, 500A and an internal restistance of about 5 mohms. All this looks good, but when I discharge it with a constant load of 3A , the battery drops to under 11volts in just 4hours, wich means it only delivers around 15Ah. Never experienced this behaviour before, what causes this behaviour ?
odd behaviour of lead acid battery
- Thread starter boc
- Start date
seneysolar
Solar Addict
Deep cycle batteries specify the AH ratings at different hourly rates. Example 1 hour rate or 5 hour or 10 hour, each with a respective amp draw. Then they will spec an ending point voltage somewhere around 10v. Assuming its a new battery? You likely were not fully charged with enough absorbtion time AND did not get down to the end point voltage to match the battery rating.
Those instant digital battery guessers are not accurate.
Car batteries are not deep cycle, no matter what the sticker says.
Brett V
Mad Scientist
Car batteries are not designed for continuous low current loads. They are designed and built to provide a high surge for starting and that's it.
Typical of a failing lead acid battery. Might recover it some with pulse charging but I would replace it myself. Testing would only find this if you used a carbon pile tester (high amperage) that could place a heavy load on the battery, many of the electronic type testers can indicate good even though the capacity is reduced to a unusable level.
My last tractor battery would not start my tractor and when I went to replace it the guy at the battery store tested it with an electronic tester and said it was good. Told him it wasn't and went home with a new one that did what it was suppose to do.
My last tractor battery would not start my tractor and when I went to replace it the guy at the battery store tested it with an electronic tester and said it was good. Told him it wasn't and went home with a new one that did what it was suppose to do.
Suijkerbuijk
I cannot be held responsible for this information.
Not really true .
The vw cars use with a stop and go system.
Use a agm battery that do 50% discharge.
From the factory .
Reason the eu law that a car stop by a stoplicht will shutdown and restart on the moment you use the gaspanel.
And wel the EU have a lot of stoplichts.
So its not like USA that have likes roads and see nothing on it.
Brett V
Mad Scientist
The main purpose of the battery in that car is to start the motor. I don't care if you start it once and drive 20 miles or start it 20 times in one mile...It's still there to start the motor. The OP did not specify if this was a sealed FLA or an AGM battery, not that it matters much. He identified it as a "Car battery".
Suijkerbuijk
I cannot be held responsible for this information.
No its not today.
Its even use the set a car in standby so you can start .
Cars with a start and stop systeem stay all the stuf running on the battery til you restart the engine again.
So its more a Hybrid than only to start .
Delmar
Solar Addict
You may be experiencing the Puekert Effect
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