Solar panel connected direct to battery bank

[George94]

I am temporarily without a charge controller, and am not connected to shore power. Would there be any danger in connecting a small panel direct to the batteries while they are below full charge?

 

Details: 17V 100W panel (actually two 50s in parallel). Two 255AH 12V AGM batteries in parallel. Smartguage reading 79%

 

Any opinions welcome. I am only using the fridge and laptop (and LED lights tonight), but would like to put something back into the batteries.

 

 

[MtB]

I see no problem with this. The fridge and laptop together are probably using more power than the solar is capable of delivering anyway so the only effect will be to slow down the rate of discharge of your batteries.

 

MtB

[George94]

I see no problem with this. The fridge and laptop together are probably using more power than the solar is capable of delivering anyway so the only effect will be to slow down the rate of discharge of your batteries.

 

MtB

 

That's what I thought, and it's good to have it confirmed by somebody I know is much more knowledgeable than me. Many thanks for your reply.

[MtB]

 

That's what I thought, and it's good to have it confirmed by somebody I know is much more knowledgeable than me. Many thanks for your reply.

 

You're welcome.

 

Someone even knowledgeable will be along soon and contradict me, no doubt!

 

MtB

[frangar]

I might be tempted just to keep an eye on the battery voltage just to be on the safe side.

 

Cheers

 

Gareth

[bottle]

Definitely watch the voltage and possible gassing of the batteries.

 

If you actually get 17v at the batteries some of your equipment may not like it.

[MtB]

Chances of 17v appearing at the battery terminals today are vanishingly small given the loads currently on the battery.

 

Stop using the lappy though and I'd do as bottle says and keep an eye on the batts for gassing. Even so, the 100w panel is only capable of delivering a theoretical maximum of about 8 amps, so chances are even in good sun it will be maxing out at only 4 or five amps, and a good deal less as the afternoon turns to evening.

 

MtB

[Arthur Brown]

If you are using power then there is little chance of overcharging the batteries, so connect up and get what free power you can.

 

Monitor the Smartgauge, If you get a prolonged period at 100% then let the panels charge the starter battery..

[smileypete]

Why not use the voltmeter feature on the SmartG to ensure the voltage doesn't go over 14.4V, or whatever the batt manufacturer recommends.

 

Disconnect a panel, tilt them away from the sun to drop the charge rate if need be. Do not assume the charge voltage is OK because the SmartG reading is below 100%...

 

cheers, Pete.

~smpt~

Edited August 31, 2013 by smileypete

[MtB]

 

Disconnect a panel, tilt them away from the sun to drop the charge rate if need be. Do not assume the charge voltage is OK because the SmartG reading is below 100%...

 

 

What? At this time of night?? Lol!

 

 

MtB