Solar battery tenders?

[slybunda]

Seen many of these around but they all seem to be 18v rated. Read on amazon that a lot of people use them too but wont 18v kill all car batteries?

 

[JamesBond]

I have a small solar charger and wondered the same thing. It seems like the consensus is that because the watts are so low that the 18 volts won't cause any damage.

 

[SwampSurvivor]

I have use them for quite a while on my vehicles that sit for weeks-months at a time. Longest was 9 months. The truck spun right over and started right up, surprisingly enough.

 

[macarose]

Any specific brands you guys would recommend?

 

[2strokeNorthstar]

Been using the Deltran Battery Tender solar for about a year to operate the lift gate on a stored trailer. No problems

 

[Shannow]

Bought an el cheapo store name solar tender a few years ago for $29.95.

I leave it hooked up to a battery (that WAS dead) that has a carrying handle 24/7.

Put some cad sulfate additive in the cells, and it's rescued me/others probably half a dozen times for flat batteries.

 

[Linctex]

18 volts = usually "open circuit voltage"

Don't worry about the volts so much when charging lead acid batteries. Amps is the bigger thing to watch.

 

[slybunda]

but i read here a lot that going higher than even 14.5v can cause the battery to gas out.

 

[meep]

without amps, the small panels will not have enough power to push a car batt over 14.5V. Most of these are 5 watts, which is measured as a short for PV panels. The real time charge current in bright sun on a cold day might be 1/4 amp.

make sure the panel has a blocking diode to prevent discharge through the panel at night.

 

[slybunda]

Yes i have read this about the need for a blocking diode.
Iv measured my cars drain at 40ma with it being locked and alarmed. So to counter that the solar charger needs about 100ma output to cover for charge lost overnight. May need more power if its overcast or indirect sunlight.