I was looking at the following battery charger for Lead-Acid/AGM 12V batteries between 35mAH - 45mAH batteries.

CTEK US 3000

I like the 4 stage charge method it describes but wish it had temperature compensation. For the most part I would be charging batteries with ambient temperatures between 45 deg F - 80 Deg F here in the North East. Out of that range the majority of the charging would be between 55 Deg F and 75 Deg F, which may not really warrant much compensation.

Sgt. Wookie mentioned a charger IC, the BQ2031 Lead-Acid Fast-Charge from TI. This, however is only a two step charger, but does have Temp. Compensation.

bq2031

I am looking at purchasing a couple of these and was interested in what others might think about the charging methods.

 

Bump......

 

I was looking at the following battery charger for Lead-Acid/AGM 12V batteries between 35mAH - 45mAH batteries.

Battery Charger

I like the 4 stage charge method it describes but wish it had temperature compensation. For the most part I would be charging batteries with ambient temperatures between 45 deg F - 80 Deg F here in the North East. Out of that range the majority of the charging would be between 55 Deg F and 75 Deg F, which may not really warrant much compensation.

Sgt. Wookie mentioned a charger IC, the BQ2031 Lead-Acid Fast-Charge from TI. This, however is only a two step charger, but does have Temp. Compensation.

bq2031

I am looking at purchasing a couple of these and was interested in what others might think about the charging methods.

do you mean 35 Amp-hour? As in like a car battery?

 

Yes, he means 35AH to 45AH.

 

Yes, I mean 35AH to 45AH! Yikes, that would be an awfully small Lead-Acid battery!

I also had the first link wrong... it fixed now.

CTEK US 3000

 

I've had the best luck with pulse chargers.

They dump in a constant current, hold it for a couple seconds, wait a few seconds to settle, then measure voltage, and apply again as needed.

If both have that feature, you should be good to go, I've never seen a battery overheat from a pulse charger, it stops charging if the pulses never change the voltage/current used by the battery.

 

Update:

Not sure I would recommend these chargers as I do not quite understand their charging methodology. I thought they had a float charge of 13.5V - 13.7V, but apparently they do not.

They are well constructed, they have nice battery clips, and even have a charge mode where, if the temperature is below a certain reading you can manually set it to charge to a slightly higher bulk voltage level. But the main grip is that once it achieves the bulk charge level, the battery is allowed to drift down to 12.9V before a charging voltage is reapplied again.

So, in other words, I got less than I had hoped from these chargers and can't figure out the reasoning behind their charge methodology.

ctek us 3000 Manual

 

Update:

Not sure I would recommend these chargers as I do not quite understand their charging methodology. I thought they had a float charge of 13.5V - 13.7V, but apparently they do not.

They are well constructed, they have nice battery clips, and even have a charge mode where, if the temperature is below a certain reading you can manually set it to charge to a slightly higher bulk voltage level. But the main grip is that once it achieves the bulk charge level, the battery is allowed to drift down to 12.9V before a charging voltage is reapplied again.

So, in other words, I got less than I had hoped from these chargers and can't figure out the reasoning behind their charge methodology.

The purpose of the float charge is to keep the battery fully charged with minimum overcharging. Apparently they feel that letting the voltage fall to 12.9V and then pulsing it periodically is as good as a steady float voltage. Since 12.9V is still above the nominal 12.6V open circuit voltage of a fully charged battery I'm inclined to think that the pulsing technique is likely just as good. Perhaps it may also help minimize sulphation of the battery.

Just my take.

 

I don't see how pulsing a float charge does anything to minimize sulphation. At this point on a fully charged good battery the plates are sponge lead on one electrode and lead dioxide on the other electrode. As long as a steady voltage to counter self-discharge is applied this condition will continue for the life of the battery.

 

Pulsing seems to be the latest fad. I doubt it hurts anything to use it occasionally for float charging. Since the unit already has that built in, that's probably why they used it.

 

The purpose of the float charge is to keep the battery fully charged with minimum overcharging. Apparently they feel that letting the voltage fall to 12.9V and then pulsing it periodically is as good as a steady float voltage. Since 12.9V is still above the nominal 12.6V open circuit voltage of a fully charged battery I'm inclined to think that the pulsing technique is likely just as good. Perhaps it may also help minimize sulphation of the battery.

Just my take.

Without historical data, it's hard to say one way or another.